Macroencapsulation devices and methods of forming macroencapsulation devices

Abstract

To provide macroencapsulation devices and methods of forming macroencapsulation devices.SOLUTION: The present disclosure relates to macroencapsulation devices and related methods of manufacture where membranes of a device may be attached to an associated frame in a relaxed, or slack, configuration prior to filling with a desired material. In one embodiment, a macroencapsulation device for housing a population of cells comprises a first membrane, and a second membrane disposed on the first membrane. The first and second membranes are bonded along a perimeter of the first and second membranes to form an internal volume therebetween. The first membrane and / or the second membrane is semipermeable. The device also comprises a frame that extends along at least a portion of the perimeter of the first and second membranes. A surface area of the first and / or second membrane is greater than a transverse cross-sectional area of the frame to which the first and second membranes are attached.SELECTED DRAWING: Figure 4A

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit under 35 U.S.C. §119(e) of U.S. Provisional Application No. 62 / 828,915, filed April 3, 2019, the disclosure of which is incorporated herein by reference in its entirety.

[0002] The disclosed embodiments relate to a macroencapsulation device and a method for making the same. [Background technology]

[0003] Therapeutic devices that deliver biological products can be used to treat metabolic disorders such as diabetes. Therapeutic devices can be implantable to provide a biological product, such as insulin, over an extended period of time. Some of these devices include macroencapsulation devices that are used to house cells and generate a desired biological product, cell-laden matrix, or other desired therapeutic agent within them. Summary of the Invention [Means for solving the problem]

[0004] In one embodiment, a macroencapsulation device for containing a cell population includes a first membrane and a second membrane disposed on the first membrane, the first membrane and the second membrane being joined along the periphery of the first and second membranes to form an interior volume therebetween, and the first membrane and / or the second membrane being semipermeable. The device also includes a frame extending along at least a portion of the periphery of the first and second membranes, the surface area of the first and / or second membrane being greater than the cross-sectional area of the frame to which the first and second membranes are attached.

[0005] In another embodiment, a macroencapsulation device for containing a cell population includes a first membrane and a second membrane disposed on the first membrane. The first membrane and the second membrane are joined along the perimeter of the first and second membranes to form an interior volume therebetween, and the first membrane and / or the second membrane is semipermeable. The device also includes a frame extending along at least a portion of the perimeter of the first and second membranes, and the portions of the first and second membranes connected to the frame are deformed to fit within an area of the frame that is smaller than the area of the portions of the first and second membranes in their undeformed configurations.

[0006] In another embodiment, a method of forming a macroencapsulation device includes deforming a first membrane and a portion of a second membrane disposed on the first membrane in an out-of-plane direction of the first and second membranes, and connecting a frame to the second membrane and / or the first membrane while the portions of the first and second membranes are deformed out-of-plane, wherein the frame limits a maximum transverse dimension of the macroencapsulation device, and the first membrane and / or the second membrane is semipermeable.

[0007] In yet another embodiment, a method of forming a macroencapsulation device includes deforming a periphery of a first membrane and a second membrane disposed on the first membrane from a first maximum transverse dimension to a second maximum transverse dimension that is smaller than the first maximum transverse dimension, and connecting a frame to the second membrane and / or the first membrane to restrict the maximum transverse dimension of the first and second membranes to the second maximum transverse dimension, wherein the first membrane and / or the second membrane is semipermeable.

[0008] It should be noted that the above-mentioned ideas, and the additional ideas described below, may be arranged in any suitable combination, as the disclosure is not limited in this respect. Furthermore, other advantages and novel features of the present disclosure will become apparent from the following detailed description of various non-limiting embodiments when considered in conjunction with the accompanying figures.

[0009] In the event that the present specification and a document incorporated by reference include conflicting and / or inconsistent disclosure, the present specification shall control. If two or more documents incorporated by reference include conflicting and / or inconsistent disclosure with respect to each other, the document having the later effective date shall control. The present invention is susceptible to, for example, the following. (Item 1) 1. A macroencapsulation device for containing a population of cells, comprising: a first membrane; and a second membrane disposed on the first membrane, the first membrane and the second membrane being joined along a periphery of the first and second membranes to form an interior volume therebetween, the first membrane and / or the second membrane being semipermeable; a frame extending along at least a portion of the perimeter of the first and second membranes, the surface area of the first and / or second membranes being greater than a transverse cross-sectional area of the frame to which the first and second membranes are attached. (Item 2) Item 10. The macroencapsulation device of item 1, wherein the frame extends entirely along the perimeter of the first and second membranes. (Item 3) 3. The macroencapsulation device of any one of items 1 or 2, wherein the first and second membranes are configured to block the movement of the cell population out of the device. (Item 4) 4. The macroencapsulation device of claim 3, further comprising the cell population disposed within the interior volume. (Item 5) 5. The macroencapsulation apparatus according to any one of items 1 to 4, wherein the internal volume comprises a plurality of channels. (Item 6) Item 6. The macroencapsulation device of item 5, further comprising a plurality of connecting portions of the first and second membranes disposed radially inward from the frame, the connecting portions forming the plurality of channels, and through holes extending through at least some of the connecting portions. (Item 7) 7. The macroencapsulation apparatus according to any one of items 1 to 6, wherein the first film and / or the second film are sintered. (Item 8) 8. The macroencapsulation apparatus according to any one of items 1 to 7, wherein the first and / or second membrane comprises a hydrophilic coating. (Item 9) 1. A macroencapsulation device for containing a population of cells, comprising: a first membrane; and a second membrane disposed on the first membrane, the first membrane and the second membrane being joined along a periphery of the first and second membranes to form an interior volume therebetween, the first membrane and / or the second membrane being semipermeable; a frame extending along at least a portion of the perimeter of the first and second membranes, wherein the portions of the first and second membranes connected to the frame are deformed to fit within an area of the frame that is smaller than an area of the portions of the first and second membranes in an undeformed configuration. (Item 10) 10. The macroencapsulation apparatus of claim 9, wherein the portions of the first and second membranes connected to the frame include a plurality of locations disposed along the periphery of the frame where the first and second membranes are deformed from a first larger area to a second smaller area. (Item 11) 11. The macroencapsulation apparatus of any one of items 9 or 10, wherein the surface area of the first and / or second membrane is greater than the transverse cross-sectional area of the frame to which the first and second membranes are mounted. (Item 12) 12. The macroencapsulation apparatus according to any one of items 9 to 11, wherein the frame extends entirely along the periphery of the first and second membranes. (Item 13) 13. The macroencapsulation device according to any one of items 9 to 12, wherein the first and second membranes are configured to block migration of the cell population out of the device. (Item 14) 14. The macroencapsulation device of claim 13, further comprising said cell population disposed within said internal volume. (Item 15) 15. The macroencapsulation apparatus according to any one of items 9 to 14, wherein the internal volume comprises a plurality of channels. (Item 16) Item 16. The macroencapsulation apparatus of item 15, further comprising a plurality of connecting portions of the first and second membranes disposed radially inward from the frame, the connecting portions forming the plurality of channels, and through holes extending through at least some of the connecting portions. (Item 17) 17. The macroencapsulation apparatus according to any one of items 9 to 16, wherein the first film and / or the second film are sintered. (Item 18) 18. The macroencapsulation apparatus according to any one of items 9 to 17, wherein the first and / or second membrane comprises a hydrophilic coating. (Item 19) 1. A method of forming a macroencapsulation device, comprising: deforming a first film and a portion of a second film disposed on the first film in an out-of-plane direction of the first and second films; and connecting a frame to the second membrane and / or the first membrane while the portions of the first and second membranes are under out-of-plane deformation, the frame restricting a maximum transverse dimension of the macroencapsulation device, and the first membrane and / or the second membrane being semipermeable. (Item 20) 20. The method of claim 19, wherein the surface area of the first and / or second membrane is greater than the transverse cross-sectional area of the frame to which the first and second membranes are attached. (Item 21) 21. The method of any one of items 19 or 20, wherein the first and second membranes are configured to block the movement of the cell population out of the device. (Item 22) 22. The method of claim 21, further comprising loading the cell population into the interior volume of the device. (Item 23) 23. The method according to any one of items 19 to 22, wherein the first film and / or the second film are sintered. (Item 24) 24. The method according to any one of items 19 to 23, further comprising coating the first and / or second membrane with a hydrophilic material. (Item 25) 25. The method according to any one of items 19 to 24, wherein the out-of-plane deformation of the portions of the first and second membranes comprises placing a surface of the first membrane opposite the second permeable membrane on a curved support. (Item 26) 26. The method of claim 25, wherein the curved support comprises a spherical dome. (Item 27) 27. The method of any one of items 25 or 26, further comprising applying a vacuum to one or more non-diffusive portions of the first and second membranes to maintain the first and second membranes adjacent to the curved support. (Item 28) 28. The method of claim 27, wherein the non-diffusible portion is disposed radially outward from an interior volume disposed between the first and second membranes. (Item 29) 29. The method of any one of items 19 to 28, further comprising bonding one or more portions of the first and second membranes to form a plurality of channels therebetween before connecting the frame to the second membrane. (Item 30) 30. The method of claim 29, further comprising forming one or more through holes in the one or more bonding portions before connecting the frame to the second membrane. (Item 31) 1. A method of forming a macroencapsulation device, comprising: deforming a periphery of a first membrane and a second membrane disposed on the first membrane from a first maximum transverse dimension to a second maximum transverse dimension that is smaller than the first maximum transverse dimension; and connecting a frame to the second membrane and / or the first membrane to restrict the maximum transverse dimension of the first and second membranes to the second maximum transverse dimension, wherein the first membrane and / or the second membrane is semipermeable. (Item 32) 32. The method of claim 31, wherein the surface area of the first and / or second membrane is greater than the transverse cross-sectional area of the frame to which the first and second membranes are attached. (Item 33) 33. The method according to any one of items 31 to 32, wherein the first and second membranes are configured to block migration of the cell population out of the device. (Item 34) 34. The method of any one of items 31 to 33, further comprising loading the cell population into the interior volume of the device. (Item 35) 35. The method according to any one of items 31 to 34, wherein the first film and / or the second film are sintered. (Item 36) 36. The method according to any one of items 31 to 35, further comprising coating the first and / or second membrane with a hydrophilic material. (Item 37) 37. The method according to any one of items 31 to 36, wherein deforming the outer peripheries of the first and second membranes from a first maximum transverse dimension to a second maximum transverse dimension smaller than the first maximum transverse dimension comprises placing a surface of the first membrane opposite the second permeable membrane on a curved support. (Item 38) Item 38. The method of item 37, wherein the curved support comprises a spherical dome. (Item 39) 39. The method of any one of items 37 or 38, wherein maintaining the first and second membranes adjacent to the curved support further comprises applying a vacuum to one or more non-diffusive portions of the first and second membranes. (Item 40) 40. The method of claim 39, wherein the non-diffusible portion is disposed radially outward from an interior volume disposed between the first and second membranes. (Item 41) 41. The method according to any one of items 31 to 40, further comprising bonding one or more portions of the first and second membranes to form a plurality of channels therebetween before connecting the frame to the second membrane. (Item 42) Item 42. The method of item 41, further comprising forming one or more through holes in the one or more bonding portions before connecting the frame to the second membrane.

[0010] The accompanying drawings are not intended to be drawn to scale. In the drawings, each identical or nearly identical component illustrated in various figures may be represented by a like numeral. For clarity, not every component may be labeled in every drawing. In the drawings, [Brief explanation of the drawings]

[0011] [Figure 1A] 10A-10C illustrate first and second membranes positioned within a fixture during a bonding and cutting process according to one embodiment. [Figure 1B] FIG. 1B is a plan view of FIG. 1A. [Figure 1C] 10A-10C illustrate a process for joining portions of a first and second membrane within a fixture according to one embodiment. [Figure 1D] FIG. 10 illustrates a membrane within a fixture after bonding according to one embodiment. [Figure 1E] FIG. 1D is a plan view of FIG. [Figure 1F] 10A-10D illustrate a process for introducing through-holes into a membrane while it is in a fixture according to one embodiment. [Figure 1G] FIG. 1F shows the resulting through-holes formed in the membrane of FIG. 1F. [Figure 1H] 10A-10C illustrate a process for cutting away a portion of the bonding membrane while in the fixture according to one embodiment. [Figure 1I] 10A-10D illustrate a process for removing a cut-out portion of the membrane from a fixture according to one embodiment. [Figure 1J] FIG. 1D is a plan view of the membrane removed from FIG. 1I. [Figure 2A] 1A-1C illustrate a process for positioning a stack of films on a curved support according to one embodiment. [Figure 2B] FIG. 1 shows a stack of membranes disposed on a curved support, according to one embodiment. [Figure 2C] 10A-10C illustrate a process of positioning a frame on a stack of membranes after positioning on a curved support according to one embodiment. [Figure 2D] FIG. 10 shows a frame positioned on a stack of membranes and then placed on the surface of a second membrane according to one embodiment. [Figure 2E] 10A-10D illustrate a process for bonding a frame to a second membrane according to one embodiment. [Figure 3] FIG. 10 illustrates a frame positioned between first and second membranes according to one embodiment. [Figure 4A] FIG. 2 is a side view of a macroencapsulation apparatus prior to filling according to one embodiment. [Figure 4B] FIG. 4B is a plan view of the macroencapsulation apparatus of FIG. 4A. [Figure 4C] FIG. 4B is a side view of the macroencapsulation apparatus of FIG. 4A after being filled with a desired material. [Figure 5A] FIG. 1 is a schematic diagram of a curved support according to one embodiment. [Figure 5B] FIG. 5B is a plan view of the curved support of FIG. 5A. [Figure 5C] 5B is a cross-sectional view of the curved support of FIG. 5A taken along a central plane. [Figure 5D] 5B is a cross-sectional side view of the curved support of FIG. 5A. FIG. [Figure 6A] 1 is an image of a stack of films disposed on a curved support according to one embodiment. [Figure 6B] 1 is an image of a frame mounted on a stack of films disposed on a curved support according to one embodiment. [Figure 7A] 1 is a photograph of the macroencapsulation device before loading with cells. [Figure 7B]7B is a photograph of a portion of the macroencapsulation apparatus of FIG. 7A. [Figure 8A] FIG. 1 is a scanning electron micrograph of a cross-section of a first macroencapsulation device with a first amount of membrane sag loaded with beads. [Figure 8B] FIG. 10 is a scanning electron micrograph of a cross section of a second macroencapsulation device with a second amount of membrane sag loaded with beads. [Figure 9] FIG. 10 is a schematic diagram of the relative change in membrane sag with changes in frame sizing. [Figure 10A] 1 is a schematic drawing of a section of a first exemplary macroencapsulation device with a first amount of membrane slack during loading after filling. [Figure 10B] 10 is a schematic drawing of a section of a second exemplary macroencapsulation with a second amount of slack during mounting after filling. DETAILED DESCRIPTION OF THE INVENTION

[0012] Driven by the increasing need to deliver biological products to treat metabolic disorders such as diabetes, different types of implantable therapeutic devices have been designed. However, the inventors have recognized that typical methods for manufacturing such devices are often tedious and difficult to control. For example, there is often a lack of precision and control in forming specific structural features associated with the device (e.g., chamber height and volume). In addition, the inventors have recognized that it is often difficult to controllably load these devices with biological entities of interest (e.g., cell populations) to desired concentrations and / or without causing excessive cell death and / or the formation of cell aggregates.

[0013] In view of the above, the inventors have recognized an advantage associated with macroencapsulation devices in that the relative sizing and positioning of the membrane and the device frame can be controlled to alter one or more parameters of the resulting macroencapsulation device. For example, the relative sizing of the membrane and corresponding frame can provide a simple and easily controllable method for producing macroencapsulation devices with a range of different dimensions and / or operating parameters, as described in more detail below. This can include controlling the amount of membrane slack retained within the frame prior to loading with a desired therapeutic agent, such as a cell population.

[0014] As used herein, the aforementioned general concept of controlling the amount of membrane slack during frame attachment may be referred to interchangeably as slack attachment or attachment loosening. This concept may refer to attaching at least two or more layers of flexible membranes (e.g., a first membrane and a second membrane) under controlled, loose tension to form a device containing an internal chamber of a defined volume and / or height upon filling. By adjusting the degree of membrane slack during the slack attachment process, devices with a desired set of geometric properties for accommodating cell populations can be created. For example, in some embodiments, the degree of membrane slack during the slack attachment process can be controlled by combining the degree of deformation introduced into the membrane during manufacturing with mechanical constraints applied to the membrane (e.g., using a perimeter frame to limit the maximum transverse dimension of the membrane relative to its total surface area), as further described below.

[0015] In some embodiments, during the manufacturing process of a macroencapsulation device, at least one (possibly at least two, or more) flexible membranes of the device may be deformed to at least partially fit within a frame and then bonded to the frame to form the macroencapsulation device. The frame may hold the membrane in a desired configuration (where the membrane has a desired amount of slack extending between opposing portions of the frame). For example, in one embodiment, the periphery of a first membrane and a second membrane disposed on the first membrane may be deformed from a first maximum transverse dimension to a second maximum transverse dimension smaller than the first maximum transverse dimension prior to bonding with the frame. This deformation and subsequent holding of the membrane in the deformed configuration may hold the membrane within the frame with a desired amount of slack to accommodate excess material contained within the frame. Such deformation and holding may be achieved in many different ways.

[0016] In one embodiment, a frame can be used to restrict the maximum transverse dimension of the first and second membranes to a maximum transverse dimension that is smaller than the maximum transverse dimension of the membranes in their undeformed configuration. Specifically, the frame can be connected to the second membrane and / or the first membrane while portions (e.g., central portions) of the first and second membranes are deformed out-of-plane relative to the plane in which the membranes extend in their flat configuration. The frame can then restrict the maximum transverse dimension of the macroencapsulation device when the force exerting the out-of-plane deformation on the membranes is removed. In this manner, the frame can cause the surface area of the first and / or second membrane to be larger than the second maximum transverse dimension, resulting in slack in the membranes between opposing portions of the frame.

[0017] As previously described, when a frame is connected to a deformed membrane of a macroencapsulation device during the manufacturing process, the frame can maintain a portion of the membrane in a deformed configuration to provide a desired amount of slack in the membrane. For example, a first membrane and a second membrane can be bonded together along the periphery of the membrane. This bonded portion of the membrane can be deformed to fit within a frame that is bonded to and extends along at least a portion of the periphery of the first and / or second membrane, although in some embodiments, the frame can also extend along the periphery of the entire membrane. Specifically, the portions of the first and second membranes connected to the frame can be deformed to fit within an area of the frame that is smaller than the area of the portions of the first and second membranes in their undeformed state. Specifically, to achieve a desired amount of membrane slack in the device, a frame with a maximum transverse dimension smaller than the transverse dimension of the membrane in its undeformed state can be connected to the membrane. In such embodiments, the portions of the first and second membranes connected to the frame can include multiple locations disposed along the periphery of the frame where the first and second membranes are deformed to accommodate the reduced area. For example, in some embodiments, the deformed portion of the membrane may include wrinkles, creases, corrugations, plastically or thermally deformed sections, and / or any other suitable type of deformation that allows the portion of the membrane to accommodate an area change from a first larger area to a second smaller area.

[0018] Depending on the desired configuration, the frame of the macroencapsulation device may be positioned in any number of different locations relative to the different membranes of the device. For example, in one embodiment, the frame may be connected to the exterior surface of one of the outer membranes of the device. In one such embodiment, a first membrane may be positioned on a second membrane, and the frame may be positioned on and connected to the outer surface of the second membrane opposite the first membrane. In another embodiment, the frame may be connected to both the first and second membranes, such that the frame is located between the membranes and in a portion of the membrane that may be near or otherwise extend along at least a portion of the perimeter of the first and second membranes. Thus, it should be understood that the present disclosure is not limited to any particular positioning of the frame relative to the individual membranes of the device.

[0019] In some embodiments, the volume and height associated with one or more portions of the interior volume of a macroencapsulation device can be controlled by adjusting the degree of membrane slack (i.e., sag) of the first and second membranes for a given membrane size and corresponding frame size. The amount of sag present in the membranes prior to cell loading can be related to the difference in the surface areas of the first and second membranes relative to the corresponding cross-sectional area of the frame to which the membranes are attached during the attachment process, which can also be referred to as the relative mismatch in the sizing of the membrane and frame areas. The relative difference in these areas, and the resulting sag in the attached membrane, can be controlled by adjusting the size of the frame relative to the size of the membrane. For example, the cross-sectional area of the frame can be smaller than the corresponding surface area of the membrane held within the frame. Thus, the greater the difference in membrane surface area relative to the cross-sectional area of the frame to which the membrane is attached, the greater the corresponding sag in the membrane. Conversely, the smaller the difference in membrane surface area relative to the cross-sectional area of the frame, the less corresponding sag can be.

[0020] In view of the above, the surface area of one or more membranes mounted within a frame can be greater than the cross-sectional area of the frame to which the one or more membranes are mounted. The surface area of one or more membranes can include portions of the membranes that are joined together at interior portions of the membranes that are disposed radially inward from or otherwise disposed within the corresponding frame. Furthermore, the surface area of one or more membranes can be greater than the cross-sectional area of the frame by 1% or more, 2% or more, 3% or more, 4% or more, 5% or more, 10% or more, 20% or more, and / or any other suitable percentage. Correspondingly, the surface area of one or more membranes can be greater than the cross-sectional area of the frame by 30% or less, 20% or less, 10% or less, 5% or less, and / or any other suitable percentage. Combinations of the foregoing are also contemplated. For example, the surface area of one or more membranes can be greater than the cross-sectional area by 1% to 30% (inclusive). Of course, both greater and lesser percentages than those stated above are contemplated, and the present disclosure is not limited to the foregoing.

[0021] Similar to the above, one or more portions of the membrane that are deformed in the out-of-plane direction of the membrane during the attachment process to the frame can be deformed by any suitable amount to provide a desired amount of slack in the membrane once attached to the frame. In some embodiments, this out-of-plane deformation may correspond to an out-of-plane deformation that would result in the membrane's projected two-dimensional area relative to its flat, planar configuration decreasing by 0.3% or more, 0.5% or more, 1% or more, 2% or more, 3% or more, and / or any other suitable percentage. Correspondingly, the deformation may result in the membrane's projected two-dimensional area decreasing by 7.5% or less, 7% or less, 6% or less, 5% or less, 4% or less, 3% or less, and / or any other suitable percentage. Combinations of the foregoing are also contemplated, e.g., in the range of 0.3% to 7.5%, inclusive. Furthermore, in some embodiments, this deformation may correspond to an out-of-plane deformation of about 1 mm to 10 mm, inclusive, in the out-of-plane direction of the membrane in its flat, planar configuration. Of course, the specific deformation ranges are expected to vary for different frame and membrane sizes, and in any case, both larger and smaller ranges for the percentage change in area and / or absolute amount of deformation are contemplated, and the present disclosure is not limited as set forth above.

[0022] In certain embodiments, deformation of the device membrane during frame attachment can be assisted through the use of supports onto which the membrane stack can be placed during the frame attachment process. The supports can extend over at least a portion (or even the entire area) of the membrane to be placed thereon. The specific profile of the support can be tailored to control the degree of membrane deformation. For example, a stack of two or more membranes can be placed on a curved support or other appropriately shaped support that can deform the membrane stack placed thereon in a desired manner. The curved support can also have any suitable shape, including, without limitation, a sphere, a spherical dome, a cylinder, a partial cylinder, an oval, a partial oval, and / or any other suitable shape that can impart the desired deformation to the membrane stack placed thereon or at least partially placed thereon. In either case, the first and second membranes of the macroencapsulation device may be placed on a support, causing a portion of the membrane stack to deform in an out-of-plane direction of the first and second membranes, such that the membranes are deformed from a first, larger maximum transverse dimension associated with the membrane in an undeformed, planar configuration to a second, smaller maximum transverse dimension associated with the membrane in a deformed state (e.g., the membrane in a bent or curved configuration), and a frame may be attached to the membranes while they are held in the deformed configuration.

[0023] Although the use of curved supports for deforming stacks of membranes is discussed above, the present disclosure is not limited to the use of curved supports. For example, in some embodiments, methods for deforming first and second membranes from a first maximum transverse dimension to a second, smaller maximum transverse dimension for mounting frames thereon can include deforming the membranes using thermoforming, mechanical deformation, and / or any suitable method that mounts the frames to the membranes in a desired configuration while maintaining at least a desired portion of the membranes extending between the frames in a flexible configuration with a desired amount of slack.

[0024] In some embodiments, it may be desirable to hold a stack of two or more films in a desired position and / or orientation on an underlying support. This may be done in any suitable manner, but in one embodiment, the support may be configured to apply a vacuum to one or more portions of the film stack to maintain the films adjacent to the support. To avoid compaction of the diffusive portions of the macroencapsulation device, a vacuum may be applied to a non-diffusive portion of one or more films. For example, the non-diffusive portions of the first and second films may include the bonded region (e.g., the bonded periphery and / or the bonded interior portion of the first and second films) and / or portions of the films located outside the active region of the device (e.g., radially outward from the bond extending along the periphery of the device that forms the internal volume of the device). Thus, a vacuum may be applied radially outward from the internal volume located between the first and second films or other suitable non-diffusive portions of the films.

[0025] As previously mentioned, a macroencapsulation device can include multiple membranes. At least one outer membrane of these multiple membranes can be semipermeable. However, embodiments are contemplated in which each membrane is semipermeable or in which at least one membrane in the device is substantially impermeable. Furthermore, a device can include two stacked membranes, three stacked membranes, and / or any other suitable number of membranes, and the present disclosure is not limited as described above. For example, in an embodiment including two membranes, one membrane can be semipermeable and the other impermeable, or both can be semipermeable. Therefore, it should be understood that the present disclosure is not limited to any particular combination of membranes in a stacked structure.

[0026] In some embodiments, a macroencapsulation device can include at least one cell population disposed within an interior volume of the device. For example, the cell population can be disposed within an interior volume formed between two or more opposing exterior membranes of the device. The exterior edge of the interior volume can be defined by one or more bonds extending around the periphery of the membranes or other suitable portions of the membranes. In such embodiments, at least the exterior membrane of the device can be configured to block the movement of one or more cell populations out of the device. Thus, one or more cell populations can be retained within the interior volume of the device. It should be appreciated that while the use of two exterior membranes forming a single interior volume is shown, the use of multiple intermediate membranes positioned between the exterior membranes of the device and / or between multiple unconnected interior volumes within the device is also contemplated.

[0027] In addition to retaining cell populations within the device, in some embodiments, the membrane of the device may be configured to protect one or more cell populations disposed within the device from immune attack while allowing the passage of desired biological products produced by the cells (e.g., insulin) as well as waste products and nutrients used and produced by the cells. In some embodiments, the membrane is configured to protect the cells from immune attack in the absence of immunosuppressive therapy.

[0028] The membrane of the macroencapsulation device can be formed from any suitable biocompatible material. The biocompatible material can be substantially inert to the cells contained within the macroencapsulation device and the surrounding tissue. Biocompatible materials include synthetic polymers or naturally occurring polymers. In some embodiments, the polymer can also be a linear polymer, a cross-linked polymer, a network polymer, an addition polymer, a condensation polymer, an elastomer, a fibrous polymer, a thermoplastic polymer, a non-degradable polymer, a combination of the foregoing, and / or any other suitable type of polymer, and the present disclosure is not limited as such. Suitable types of polymers include: The polymeric materials may be polyvinyl chloride (PVC), polyethylene (PE), polypropylene (PP), polymethyl methacrylate (PMMA), polystyrene (PS), polytetrafluoroethylene (PTFE), expanded polytetrafluoroethylene (ePTFE), polyurethane (PU), polyamide (nylon), polyethylene terephthalate (PET), polyethersulfone (PES), polyetherimide (PEI), polyvinylidene difluoride (PVDF), polycaprolactone (PCL), poly(lactic-co-glycolic acid) (PLGA), poly-L-lactide (PLLA), any combination thereof, and / or any other suitable polymeric material. The synthesis methods used to form porous membranes from one or more of the aforementioned polymeric materials may include, but are not limited to, swelling, solution casting, immersion precipitation and phase separation, electrospinning, methods resulting in a reticulated network, methods resulting in a trabecular network, or any other suitable method for forming porous polymeric membranes.

[0029] Sintering of a membrane can be used to alter the membrane's porosity and flux characteristics. For example, sintering can increase the membrane's porosity while maintaining its pore structure. Sintering can also improve the membrane's mechanical stability and diffusion flux. Thus, sintering can be used to alter the membrane's porosity and / or mechanical properties, which can then be used to tailor the porosity and flux characteristics of the macroencapsulated device. Thus, in some embodiments, any desired combination of sintered and / or non-sintered membranes can be used. For example, two outer membranes of the device can be bonded together. A sintered and non-sintered membrane can be bonded together, two sintered membranes can be bonded together, or two non-sintered membranes can be bonded together. Additionally, any number of intermediate membranes positioned between these outer membranes can be used. These intermediate membranes can be sintered or non-sintered.

[0030] The membranes of the macroencapsulation devices described herein can be formed from porous membrane materials configured to allow transport of the following through the membrane of material, such as biological products having a molecular weight of less than about 3000 kDa, 2000 kDa, 1000 kDa, 500 kDa, 400 kDa, 300 kDa, 200 kDa, 100 kDa, 50 kDa, 40 kDa, 30 kDa, 20 kDa, 10 kDa, 6 kDa, 5 kDa, 4 kDa, 3 kDa, 2 kDa, 1 kDa, and / or any other suitable range of molecular weight depending on the desired application. For example, one or more membranes of a macroencapsulation device can be configured to allow insulin having a molecular weight of about 5.8 kDa to flow through the membrane.

[0031] To achieve the desired selectivity, the porous membranes used with the macroencapsulation devices disclosed herein can be of an open porous structure with average pore sizes of about 1 nm or more, 5 nm or more, 10 nm or more, 15 nm or more, 20 nm or more, 30 nm or more, 40 nm or more, 50 nm or more, 60 nm or more, 70 nm or more, 80 nm or more, 90 nm or more, 100 nm or more, 200 nm or more, 300 nm or more, and / or any other suitable size range. Correspondingly, the average pore size of the various membranes described herein can be 2500 nm or less, 2000 nm or less, 1700 nm or less, 1500 nm or less, 1400 nm or less, 1300 nm or less, 1200 nm or less, 1100 nm or less, 1000 nm or less, 900 nm or less, 800 nm or less, 700 nm or less, 600 nm or less, 500 nm or less, 400 nm or less, 300 nm or less, 200 nm or less, 100 nm or less, 90 nm or less, 80 nm or less, 70 nm or less, 60 nm or less, 50 nm or less, 40 nm or less, 30 nm or less, 20 nm or less, and / or any other suitable size range. Combinations of the foregoing are also contemplated. For example, average pore sizes between 1 nm and 20 nm (inclusive), between 1 nm and 2500 nm (inclusive), and / or any other suitable combination. It should be understood that although particular average pore sizes are described above, any suitable average pore size may be used for the various membranes described herein, including, for example, both larger and smaller average pore sizes than those described above.

[0032] To provide sufficient strength and / or rigidity for the macroencapsulation device, the various membranes and frames may be formed from sufficiently stiff materials. The desired stiffness may be achieved through an appropriate combination of material Young's modulus, thickness, and overall construction that can be balanced with the desired permeability of the device. Suitable Young's moduli for the various membranes and frames described herein are at least 10 5 Pa, 10 6 Pa, 10 7 Pa, 10 8 Pa, 10 9 Pa, 10 10The Young's modulus may be any suitable modulus of elasticity both above and below these ranges. Of course, ranges between the aforementioned Young's moduli are also contemplated. For example, about 10 6 Pa~10 10 is Young's rate of interest at Pa (inclusive).

[0033] In some embodiments, it may be desirable for one or more of the membranes included within the macroencapsulation device to be hydrophilic to facilitate cell loading within the device and / or to facilitate the flow of one or more fluids, biological compounds, therapeutic agents, cellular nutrients, cellular waste products, and / or other materials through the device membrane. Furthermore, a hydrophilic outer membrane may also reduce the occurrence of fibrosis when the device is located in vivo. Therefore, the membrane of the macroencapsulation device may be formed from a hydrophilic material and / or treated with a hydrophilic coating. Suitable hydrophilic materials may include, but are not limited to: suitable hydrophilic polymers, polyethylene glycol, polyvinyl alcohol, polydopamine, any combination thereof, and / or any other suitable hydrophilic material that can form a coating on or form a membrane.

[0034] The membranes described in the various embodiments of the macroencapsulation devices described herein may be bonded to one another using any suitable bonding method, and the disclosure is not limited as such. For example, adjacent membranes may be bonded to one another using adhesives, epoxies, welding or other fusion-based techniques (e.g., ultrasonic bonding, laser bonding, physical bonding, thermal bonding, etc.), mechanical clamping using a frame or fixture, and / or any other suitable bonding method. In one particular embodiment, bonding of adjacent membranes may be performed using a heated tool used to press or butt two or more membranes against one another with a predetermined pressure and / or force for a set fusion time. With the above in mind, it should be noted that the disclosure is not limited to using any particular method for bonding membranes to one another.

[0035] In some embodiments, after the membranes are bonded together, and optionally after a frame is attached to the membranes, the laminate of bonded membranes may be subjected to one or more heat treatments. For example, the membranes may be bonded with bonds extending along the membrane's perimeter, and / or one or more bonds may be formed within an interior region of the membrane (e.g., within the bonded perimeter) before the membranes are heat-treated. This post-bonding heat treatment may strengthen the membrane bonding in the bonded region. The specific heat treatment temperature and duration to improve the bonding between the membranes may vary depending on the specific materials used. However, in some embodiments, the heat treatment temperature may be between the glass transition temperature and the melting temperature of the polymer membrane.

[0036] In some embodiments, it may be desirable to limit the maximum thickness of the macroencapsulated device in a direction perpendicular to the plane in which the device's largest transverse dimension lies. Accordingly, one or more interior portions of the first and second membranes disposed within the frame may be bonded together to limit the extent to which the membranes can move relative to one another. These bonded portions of the membrane may be uniformly dispersed within the interior portions of the membranes disposed within the frame. These bonded portions may have any suitable shape, such as dots, lines, curves, or any other suitable shape. While the bonded interior portions may have any suitable size for the desired application, in one embodiment using bonded dots, the diameter of the bonded dots may be about 0.5 mm or more, 0.75 mm or more, 1 mm or more, 1.25 mm or more, 1.5 mm or more, and / or any other suitable diameter. Correspondingly, the diameter of the dots may be about 3 mm or less, 2.75 mm or less, 2.5 mm or less, 2.25 mm or less, 2.0 mm or less, and / or any other suitable diameter. Combinations of the foregoing ranges are also contemplated, such as diameters between 0.5 mm and 3 mm, inclusive. Although specific shapes and size ranges are given above, it should be understood that other shapes and sizes smaller and larger than those set forth above are contemplated and the present disclosure is not limited as set forth above.

[0037] In some embodiments, it may be desirable to improve the vascularization of the macroencapsulation device. Thus, in certain embodiments, one or more through-holes may be formed in one or more bonded portions disposed in an interior portion of the membrane disposed radially inward from the frame of the device. These through-holes may allow vasculature to grow through the through-holes in addition to growing around the upper and lower surfaces of the device. The one or more through-holes may be formed in the bonded portions of the membrane using laser ablation, mechanical puncturing, cutting, or any other suitable method that forms through-holes in one or more bonded portions of the membrane.

[0038] In some embodiments, the aforementioned bonding portions and corresponding through-holes in the interior region of the device may be formed before mounting the frame on the device while the membrane is disposed in a flat, planar configuration, which may simplify the manufacturing process when working with a flexible membrane that is mounted to the frame with a desired amount of slack that may complicate forming other features after being mounted to the frame.

[0039] As described in more detail below, in some embodiments, one or more portions of adjacent membranes may be coupled together such that the interior volume within the device is subdivided into multiple interconnected channels. The channels may be shaped like lumens in some embodiments, although any suitable shape or configuration of channels may be used. The interior maximum transverse dimension (e.g., inner diameter) of a channel may be 40 μm or more, 50 μm or more, 100 μm or more, 200 μm or more, 300 μm or more, 400 μm or more, and / or any other suitable dimension. Correspondingly, the interior maximum transverse dimension of a channel may be 800 μm or less, 700 μm or less, 600 μm or less, 500 μm or less, 400 μm, and / or any other suitable dimension. Combinations of the foregoing are also contemplated. For example, the interior maximum transverse dimension of multiple channels may be between 40 μm and 800 μm, inclusive. Furthermore, the density of interconnected channels forming the various chambers of the device may be such that the density per unit area within the cross-section of the device is less than about 10 channels / cm. 2Over 15 channels / cm 2 Over 20 channels / cm 2 Over 25 channels / cm 2 Over 30 channels / cm 2 Over 35 channels / cm 2 Over 40 channels / cm 2 Over 45 channels / cm 2 Over 50 channels / cm 2 Over 60 channels / cm 2 Over 70 channels / cm 2 Over 80 channels / cm 2 Over 90 channels / cm 2 Over 100 channels / cm 2 Over 110 channels / cm 2 Over 120 channels / cm 2 Over 130 channels / cm 2 Over 140 channels / cm 2 Over 150 channels / cm 2 or more, 175 channels / cm² or more, or 200 channels / cm² 2 Ranges extending between any of the aforementioned densities of channels are also contemplated, for example, a channel density of about 10 channels / cm 2 ~200 channels / cm 2 (inclusive), however, densities both above and below the aforementioned ranges are contemplated.

[0040] The macroencapsulation devices described herein can have any suitable combination of internal volume, external dimensions, and / or other suitable physical parameters. For example, the internal volume encompassed by the outer membrane of the macroencapsulation device can be between 40 μL and 250 μL, inclusive. The width or maximum cross-sectional dimension of the macroencapsulation device can be between about 20 mm and 80 mm. Furthermore, to achieve the desired oxygen diffusion into the interior of the macroencapsulation device to support the contained cells, the maximum oxygen diffusion distance from the exterior of the device to the interior portion of the device containing the cell population can be less than 50 μm, less than 100 μm, less than 150 μm, less than 200 μm, less than 250 μm, less than 300 μm, less than 350 μm, less than 400 μm, less than 450 μm, or less than 500 μm. Correspondingly, the maximum thickness (or dimension perpendicular to the maximum transverse dimension) of the entire device and / or the interior volume disposed within the device can be less than 50 μm, 100 μm, 150 μm, 200 μm, 250 μm, 300 μm, 350 μm, 400 μm, 450 μm, or 500 μm. Further, in some embodiments, the external surface area to volume ratio of the device is less than about 20 cm -1 Over 40cm -1 Over 60cm -1 More than 80cm -1 More than 100cm -1 Over 120cm -1 or above, or 150cm -1 Ranges extending between any of the recited values for the various dimensions and parameters, as well as ranges both larger and smaller than those recited, are also contemplated.

[0041] While certain dimensions, parameters, and relationships relating to the macroencapsulation devices and the materials from which they are formed have been described above, it should be understood that larger and smaller dimensions, parameters, and relationships are contemplated and the disclosure is not limited as such. Accordingly, any suitable combination of sizes, configurations, material properties, and / or relative performance parameters may be used for the devices depending on the desired application.

[0042] In some embodiments, the cell population contained within the interior volume of the macroencapsulation device can be an insulin-secreting cell population. In some embodiments, the cell population includes at least one cell derived from a stem cell. In some embodiments, the at least one cell is genetically modified. Optionally, the at least one cell is genetically modified to reduce an immune response in a subject upon device implantation compared to a comparable cell that is not genetically modified. In some embodiments, the cell population is a stem cell-derived cell capable of glucose-stimulated insulin secretion (GSIS). For example, suitable cell populations can include pancreatic progenitor cells, endocrine cells, beta cells, a matrix comprising one or more of the foregoing, or any combination thereof. Additionally, the matrix can include isolated islet cells, isolated cells from the pancreas, isolated cells from a tissue, stem cells, stem cell-derived cells, induced pluripotent cells, differentiated cells, transformed cells, or expression systems (capable of synthesizing one or more biological products). Optionally, in some embodiments, the matrix can include a second type of cell that supports the first type of cell synthesizing one or more biological products. In some embodiments, the cells can be encapsulated prior to being placed within the matrix. In such embodiments, the cells may be microencapsulated or conformally coated, although naked (i.e., uncoated) cells may also be used.

[0043] Depending on the particular embodiment, cells may be loaded into the interior volume of the macroencapsulation device at a therapeutically effective density. Suitable cell densities disposed within the interior volume may be about 1,000 cells / μL or more, 10,000 cells / μL or more, 50,000 cells / μL or more, 100,000 cells / μL or more, 500,000 cells / μL or more, and / or any other suitable cell density. Suitable cell densities disposed within the chamber may be about 1,000,000 cells / μL or less, 500,000 cells / μL or less, 100,000 cells / μL or less, 50,000 cells / μL or less, 10,000 cells / μL or less, and / or any other suitable cell density. Combinations of the foregoing are also contemplated. For example, cell densities between about 1,000 cells / μL and 1,000,000 cells / μL. Of course, both higher and lower cell densities than those mentioned above may be used depending on the desired application and the cell type being used.

[0044] The macroencapsulated devices described herein may be implanted in a subject's body at various sites. In one example, the device may be implanted in the subject via preperitoneal or retrorectal implantation. In another example, the device may be placed via intraomental implantation. In another example, the device may be placed via subcutaneous implantation. In another example, the device may be placed via suprahepatic implantation. In some cases, the macroencapsulated devices described herein may be fixed in the body at the implantation site using any suitable fixation method (e.g., application of a tissue adhesive). Suitable tissue adhesives may include, but are not limited to: fibrin, cyanoacrylate, polyethylene glycol, albumin-based adhesives, polymer-based adhesives, and / or any other suitable adhesive. In another example, fixation of the device may be performed using platelet-rich plasma and / or any other suitable fixation method, and the present disclosure is not limited as such.

[0045] Certain non-limiting embodiments will be described in more detail with reference to the figures. It should be understood that the various systems, components, features, and methods described with respect to these embodiments may be used separately and / or in any desired combination, as the present disclosure is not limited to only the specific embodiments described herein. For clarity, the figures are described in connection with methods and devices that include only first and second outer membranes bonded to one another. It should be understood, however, that the methods and devices described with reference to the figures may include any number of intermediate membranes disposed between these outer membranes, and the present disclosure is not so limited.

[0046] 1A-1H illustrate one embodiment of a process for bonding two or more membranes together and forming various other features on the membranes prior to attaching the membranes to a frame.

[0047] 1A-1B, a first membrane 102 is positioned on the bottom of a fixture 106 such that the first membrane 102 is directly or indirectly positioned on a surface of the bottom of the fixture. A second membrane 104 is positioned on a surface of the first membrane 102 opposite the bottom of the fixture. In some embodiments, the bottom of the fixture can include one or more sensors 110 distributed across the surface of the bottom of the fixture on which the membranes are positioned. These sensors can be configured to sense force, pressure, and / or temperature applied to corresponding portions of the first and second membranes.

[0048] Once the first and second films 102, 104 are properly positioned on the lower fixture portion 106, the upper fixture portion 108 may be brought into contact with one or more portions of the second film, clamping or otherwise holding both the first and second films 102, 104 in place between the upper and lower fixture portions. In the illustrated embodiment, the first and second films are held in a substantially planar configuration on the planar surface of the lower fixture. However, embodiments are contemplated in which the films are held in a different configuration during the initial formation step. Also illustrated in the figures, the upper fixture portion 108 includes an opening (or other arrangement) through which central portions of the stacked first and second films are left uncovered or otherwise exposed for further processing. Thus, the lower and upper fixture portions may be configured to clamp one or more peripheral portions of the first and second films disposed radially outward from the central, uncovered portions of the films intended to form part of the macroencapsulation device. This arrangement of exposed central portions of the films is best illustrated in FIG. 1B. Although the figures illustrate a circular opening at the top of the fixture, it should be understood that the present disclosure is not limited to any particular shape for the exposed portion of the membrane and / or how the membrane is held in place during the bonding and initial forming process.

[0049] After positioning the first and second membranes 102, 104 within the fixture, the membranes may undergo many different processes (e.g., bonding at one or more locations). Figures 1C-1E illustrate one embodiment of a process for bonding the first and second membranes together. Referring to Figure 1C, a bonding tool 120 is used to bond the first and second membranes together at the desired locations. In one particular embodiment, the bonding tool includes a heated tip that is positioned at the desired location on the upper surface of the second membrane and pressed downward with a predetermined temperature and force for a predetermined duration to form a bond between the two membranes. One or more sensors 110, as described above, distributed across the lower surface of the fixture 106 may transmit signals to a corresponding processor (not shown) to provide feedback control of the bonding process. Once a bond is formed at the desired location, the bonding tool may be moved to an adjacent portion of the membrane that at least partially overlaps the previously formed portion of the bond until the desired shape and size of the particular bond is formed; however, different bonding methods may be used, as described above. The tool can then proceed to form any number of other bonds between the two membranes in any number of desired locations using any number of desired patterns depending on the particular application. For example, as shown in Figures 1D and 1E, a first membrane and a second membrane can be bonded along the perimeter 122 of the active portion of the membranes intended to form an interior volume therebetween.

[0050] As best shown in the plan view of FIG. 1E , in some embodiments, a bonding tool may also be used to bond one or more portions 124 of the membranes disposed radially inward from the resulting bonded perimeter 122. In this particular embodiment, these bonded portions disposed within the bonded perimeter 122 may take the form of bonded dots distributed across the surface area of the membrane. However, any suitable shape and / or configuration of these bonded regions may also be used. Due to the presence of these bonded regions disposed radially inward from the bonded perimeter of the membranes, the interior volume formed between the membranes, once in the filled configuration, may take the form of a plurality of interconnected channels 126 corresponding to the unbonded regions of the membranes extending between these bonded portions.

[0051] In some cases, the bonded portions of membranes 102 and 104 may be substantially less permeable due to the bonding process and may be considered non-diffusive portions of the membranes. This may include both the bonded perimeter 122 of the membranes and the interior bonded portion 124 disposed radially inward from the bonded perimeter. In contrast, the non-bonded portions of the membranes (e.g., channels 126 in the illustrated embodiment) may be considered diffusive portions of the membranes. The diffusive portions may have significantly higher permeability than the non-diffusive portions of the membrane and, in some embodiments, may be substantially the same as the parent membrane material. In addition to the bonded portions of the membranes being considered non-diffusive portions of the membranes, portions of the membranes disposed radially outward from the bonded perimeter 122 that are not in direct fluid communication with the resulting interior volume formed therebetween may also be considered non-diffusive portions of the membranes for purposes of this description.

[0052] In some embodiments, after portions of the first and second membranes 102 and 104 are bonded together, one or more through-holes 132 may be formed in one or more of the bonded portions 122 and 124. For example, with reference to FIGS. 1F-1G, an apparatus, such as a laser, punch, cutter, or other suitable apparatus, may be used to form the through-holes 132 in one or more of the bonded portions of the first membrane 102 and the second membrane 104. In one particular embodiment, the through-holes may be formed via laser ablation, where a laser removes the bonded portion of the first and second membranes while leaving the bonded portion surrounding the membranes to act as a seal between an interior volume formed by the membranes and the exterior of the device.

[0053] In situations where the outer shape and size of the bonded membranes are already in their final desired configuration, the bonded membranes may simply proceed to the next step in the manufacturing process. Alternatively, in some embodiments, one or more peripheral portions of the membranes may be cut from the membranes to provide a desired size and / or shape for the bonded membranes. One embodiment of such a process is illustrated in FIG. 1H, where a blade 140 (or other cutting tool) may be used to form a cut extending along the bonded perimeter 122 of the membranes. In the illustrated embodiment, the blade is extended through the first and second membranes and then moved relative to the membranes along any desired cutting profile around the bonded perimeters of the membranes to cut away one or more peripheral portions of the membranes that are held within a fixture and positioned radially outward from the bonded perimeters. It should be understood that while the illustration shows the blade moving relative to the membranes held within a fixture, any suitable method of cutting away peripheral regions of the bonded membranes to provide a desired size and shape for the bonded membranes may be used, and the present disclosure is not limited as described above.

[0054] Regardless of whether a cutting process has been performed, after the various desired portions of membranes 102 and 104 have been bonded together, the bonded membranes may be removed from the fixture corresponding to the upper and lower fixture portions 106 and 108, as shown in FIG. 1I. This may be done in any number of ways, including, for example, simply opening the fixture and manually removing the bonded membrane. Alternatively, the system may automatically lift the membrane and remove it from the fixture. For example, the system may apply a vacuum to one or more non-diffusive portions of the bonded membrane to lift it from the surface of the fixture. However, any suitable method of removing the bonded membrane from a fixture or other device may be used, and the present disclosure is not limited as described above.

[0055] A plan view of the resulting bonded membrane stack is illustrated in FIG. 1J. In the figure, the top surface of the second membrane 104 is shown with the membrane's bonded perimeter 122 extending along the perimeter of the bonded membrane (e.g., where the first and second membranes are bonded). While the bonded perimeter is shown extending to the membrane's outer edge, embodiments are contemplated in which the bond extending along the membrane's perimeter is inserted from the membrane's outer edge. The bonded membrane also includes one or more bonded portions 124 disposed radially inward from the bonded perimeter. Additionally, through-holes 132 may be formed within one or more bonded portions. The through-holes extend from the outer surface of the first membrane to the opposing outer surface of the second membrane. Due to the presence of the bonded portions of the membranes disposed radially inward from the perimeter bond, the interior volume formed between the first and second membranes may be formed into a plurality of interconnected channels 126 corresponding to the unbonded portions of the membranes.

[0056] In some embodiments, after the membranes are bonded together (e.g., bonding the perimeter and / or interior portions of the first and second membranes), the first and second membranes may be coated with a hydrophilic material and / or may undergo other treatments that may be incompatible with the bonding process, including various high temperature treatments that may subject the membranes to various heat treatments that may strengthen the bonding of the membranes in some embodiments.

[0057] In some embodiments, a pre-bonded membrane stack (e.g., the bonded first and second membranes described above) may be attached to the frame. Alternatively, in some embodiments, the membrane stack may be bonded together around its perimeter and attached to the frame simultaneously. In either case, a method for attaching the membranes to the frame may be used to provide a desired amount of slack in the membranes once attached. One such embodiment is described in more detail below in connection with Figures 2A-2E.

[0058] 2A-2B illustrate the concept of deforming the first and second membranes 102 and 104 from a first maximum transverse dimension prior to attachment (e.g., in FIG. 2A , the membranes are in a relatively flat, planar configuration) to a second maximum transverse dimension thereafter (e.g., in FIG. 2B , the membranes have been deformed to conform to the shape of the underlying support 200). Specifically, the surface of the first membrane opposite the second membrane may be positioned on and conform to the curved surface 206 of the support 200, causing portions of the first and second membranes to deform in an out-of-plane direction of the first and second membranes. For example, because the central portions of the membranes are deformed in an out-of-plane direction of the membranes by the underlying curved surface of the support, the peripheries of the first and second membranes are deformed from a first transverse dimension in the planar configuration of FIG. 2A to a smaller transverse dimension in FIG. 2B . In some embodiments, the curved surface of the support is a spherical dome, as illustrated in FIGS. 2A-2E . However, embodiments using supports with different shapes are also contemplated.

[0059] In some embodiments, the support 200 may include one or more ridges 202 disposed near the edge of the curved surface 206 of the support 200 that supports the stack of films 102 and 104 thereon. These ridges may be disposed at multiple locations around the perimeter of the support so that the first and second films 102 and 104 disposed on the curved support 200 may flare out near their perimeters and / or otherwise deform as described above to accommodate the presence of excess film material at these locations. Specific examples of these ridges and their interaction with films disposed thereon are described in more detail below in connection with FIGS. 5A-6B . Regardless, in the illustrated embodiment, a bonded film stack (including the first and second films 102 and 104) is disposed on the support 200. The perimeters of the first and second films contact the ridges 202, deforming the portions of the films adjacent the curved surface of the support. In the illustrated embodiment, the ridges may serve to deform portions of the membrane by forming wrinkles, creases, corrugations, folds, or otherwise deforming the membrane at this location to accommodate excess material forced into a smaller area when the membrane is deformed from a larger first transverse dimension (e.g., a planar configuration) to a smaller second transverse dimension (e.g., a deformed configuration disposed on a support).

[0060] Although the above embodiments illustrate the use of ridges, it will be appreciated that any method of transforming one or more locations around the periphery of the bonding membrane from a first larger area to a second smaller area may be used.

[0061] In some cases, it may be desirable to maintain the orientation and / or position of a stack of membranes on a support while mounting a frame thereon. Thus, in some embodiments, as shown, a vacuum may be applied to one or more non-diffusive portions of the first and second membranes to maintain the first and second membranes adjacent to the curved support. For example, with reference to FIG. 2B , curved support 200 may include a vacuum chamber 210 connected to a vacuum source (not shown) to apply a negative pressure. The vacuum chamber may be fluidly connected to one or more suction holes 212 disposed on the surface of curved support 200. While the suction holes may be disposed on any desired portion of the surface of the support, in some embodiments, the suction holes may be disposed on a surface portion of the support where a corresponding non-diffusive portion of a bonded membrane may be disposed, such as bonded perimeter 122 of the membrane, a portion of the membrane disposed radially outward from the bonded perimeter, bonded portion 124 of the membrane disposed within the bonded perimeter, and / or any other suitable portion of the membrane. For example, a plurality of suction holes may be located adjacent to or in the ridges 202 around the periphery of the curved surface 206 of the support. Of course, other methods of maintaining the position and / or orientation of the membrane relative to the underlying support may be used, such as, without limitation, mechanical fastening, clamping, temporary adhesives, and / or any other suitable temporary fastening method.

[0062] After the first and second membranes 102 and 104 are deformed from a first maximum transverse dimension to a second, smaller maximum transverse dimension, a frame 220 can be attached to the membranes, as shown in FIGS. 2C and 2D . Specifically, the frame 220 (e.g., a perimeter frame) can be placed on the laminated membranes while the central portion of the membranes is deformed out-of-plane by the underlying curved support 200. The frame can extend around at least a portion of the perimeter (and in some embodiments, around the entire perimeter) of the combined membranes. The size and shape of the frame can be selected to maintain the maximum transverse dimension membranes at the second, smaller maximum transverse dimension after attachment. The maximum transverse dimension can be measured in the plane in which the planar frame extends. For example, the maximum transverse dimension in the illustrated embodiment can correspond to the diameter of a circular frame placed on the combined membranes. However, embodiments using frames and membranes with different shapes and sizes are also contemplated.

[0063] As previously mentioned, in some embodiments, the frame 220 can extend along at least a portion of the perimeter of the bonded membranes 102 and 104. To avoid reducing the active diffusive area of the bonded membranes, at least a portion of the frame, and in some cases the entire frame, can be aligned with and / or positioned radially outward from the bonded perimeter 122 of the membranes. This can prevent the frame from being positioned over the diffusive portion of the bonded membrane and blocking diffusion through the underlying portion of the membrane. Thus, the frame can have a transverse dimension equal to or slightly larger than the bond extending along the membrane's perimeter, forming the membrane's internal volume. For example, referring to FIG. 2D , the frame 220 overlaps only a portion of the bonded perimeter 122 of the membranes. Of course, while the membranes do not extend past the frame in the illustrated embodiment, embodiments are contemplated in which the frame extends past the bond into a region positioned radially inward from the bonded perimeter.

[0064] As shown in FIG. 2E , after positioning the frame 220 on the bonded film stack 102 and 104, the frame may be bonded to the film. In some embodiments, the frame and film may be bonded at multiple locations around the periphery of the frame using adhesives, heat staking, welding (thermal, ultrasonic, etc.), mechanical fastening, or another suitable method. For example, the frame and film may be bonded to each other at each location where they contact the ridges 202 located along the periphery of the curved surface 206 of the support 200. In the illustrated embodiment, a fastening device 230 may be used to form adhesive points between the frame and portions of the first and second film at one or more desired locations. The fastening device 230 may correspond to a port used to dispense a curable adhesive in combination with a light source that may be used to cure the adhesive once it is disposed on the frame and film. The duration of the bond and the viscosity of the adhesive may be selected to avoid excessive wicking of the adhesive into the diffusive portions of the film. Furthermore, while specific bonding methods are described, other suitable types of bonds may also be used, as previously discussed. After bonding the frame to the membrane, the resulting macroencapsulation device, including the frame and attached membrane, can be removed from the curved support. After initially securing the membrane to the frame in this manner, further processing of the attached frame and membrane can then be performed, such as adding additional planar adhesive between the attached frame and membrane to improve the bond therebetween.

[0065] In the above-described embodiment, the frame is connected to the outer surface of the second membrane 104 opposite the first membrane 102, which rests on the support 220. However, embodiments are also contemplated in which the frame 220 is disposed between the first membrane 102 and the second membrane 104, as shown in FIG. 3 . In such embodiments, portions of the first and second membranes extending radially outward from the bond 122 that extends along the membranes' peripheries may be open, and the frame may be positioned between the membranes at a location disposed radially outward from the membranes' peripheral bond. As previously described, the first and second membranes may then be bonded to the frame using any suitable bonding method. While the figures show specific angular orientations of the frame, membranes, and underlying support, it should be understood that any suitable orientation of these components may be used, and the present disclosure is not limited as described above. In either case, the frame may still serve to maintain the desired transverse dimensions of the membranes once removed from the underlying support.

[0066] 4A-4B show one embodiment of a macroencapsulation device after the membranes have been attached to their corresponding frames but before they have been filled with a desired material, such as a cell mass. Specifically, as illustrated in the figures, the macroencapsulation device may include a first membrane 102, a second membrane 104, and a frame 220 extending along at least a portion of the periphery of the first and second membranes. The device is illustrated in an unfilled, relaxed state. In this state, the excess surface area of the first and second membranes relative to the cross-sectional area of the frame to which the membranes are attached results in the attached membranes hanging below the frame due to the resulting slack in the membranes. Because the membranes already have bonding portions 122, through-holes 132, and other suitable features located within the interior region of the device, the macroencapsulation device may be easily filled with a desired material (e.g., a cell mass) with minimal further processing and handling. The interior volume may be filled using ports, openings in the peripheral bonds, and / or any other suitable method. In either case, after filling the macroencapsulation device with the desired material, the internal volume contained between the first and second membranes 102 and 104 may expand, taking up slack within the membranes because the membranes are placed under tension in the filled configuration due to the expansion of the internal volume between them. This may result in the first and second membranes deforming, causing the membranes to generally extend in a direction generally parallel to the plane of the frame 220 (see FIG. 4C). Correspondingly, due to this increase in the internal volume of the filled device, the first and second membranes may extend approximately equal distances outward from the opposing faces of the frame. In situations where membrane portions 132 are bonded together at locations disposed radially inward from the frame, the expanded structure again forms a plurality of interconnected channels 126.

[0067] Any suitable filling method may be used to fill the macroencapsulation device. For example, a cell population (or other desired material) may be flowed into the interior volume of the macroencapsulation device formed between the outer membranes of the device. This may be accomplished through the use of a sealable or removable port extending into the interior volume and / or by the presence of openings in the peripheral bonds and / or frame of the macroencapsulation device that can then be sealed. While any suitable inlet to the interior volume may be used to flow material into the interior volume of the device, this flow of material may be controlled in many different ways to achieve the desired filling of the interior volume. For example, in one embodiment, applying pressure to the interior volume of the macroencapsulation device may correspond to the presence of a desired amount of tension in the membrane of the device in a filled configuration. Thus, filling of the device may continue until a predetermined pressure and / or membrane tension threshold is reached. However, any suitable method for controlling the amount of material flowing into the interior volume may be used, and the present disclosure is not limited as described above. This may include, for example, control based on the absolute volume of material flowing into the interior volume, the duration for a given flow rate, and / or any other suitable control method.

[0068] 5A-5D illustrate a specific embodiment of a support 200 that can be used during frame mounting of a membrane held on the support. The support can include a curved support surface 206 used to support the active diffusive portion of the membrane stack during the frame mounting process. In the illustrated embodiment, the support surface is a spherical dome, although other suitable shapes for the support surface can be used, as previously described. The support surface can be used to support and deform a membrane disposed thereon, as previously described in connection with FIGS. 2A-2E. The support can also include a corrugated surface extending along the periphery of the primary curved support surface. For example, the corrugated surface can include a plurality of alternating ridges 202 and valleys 204 extending radially outward from adjacent portions of the curved support surface. In some cases, the ridges can extend vertically upward above adjacent portions of the curved support surface, and the valleys can extend vertically downward below adjacent portions of the curved support surface. However, different vertical orientations of the ridges and valleys relative to adjacent curved support surfaces are also contemplated. In either case, the corrugated surface, which varies in height along its length, may extend at least partially (and in the illustrated embodiment entirely) around the periphery of the adjacent curved support surface, and as further detailed in the examples below, this corrugated surface may help guide a portion of the membrane stack into a desired folded, pleated, corrugated, or otherwise deformed configuration and handle excess membrane material at this location during the framing process.

[0069] In the foregoing embodiments, the normal direction of the support may be defined as perpendicularly upward relative to the base of the support underlying the curved support surface.

[0070] In some embodiments, as previously described, the support 200 may be configured to apply a vacuum to a stack of membranes disposed thereon. For example, as shown, the vacuum connection 208 may be fluidly connected to a central vacuum chamber 210 formed within the support. This central vacuum chamber may also be fluidly connected to suction holes 212 extending upward to the curved support surface 206 of the support, onto which a stack of membranes may be disposed. These suction holes may be distributed along the periphery of the support surface, although the suction holes may be located in other suitable locations. For example, as illustrated in the figure, the suction holes may be distributed such that at least one suction hole is located on each ridge 202 and valley 204 of the corrugated surface extending around the curved support surface 206. However, it should be understood that any suitable arrangement of suction holes may be used, and the present disclosure is not limited to using suction holes only in these locations. Again, in some embodiments, the suction holes may be positioned such that they can be applied to non-diffusing portions of membranes disposed over the suction holes during the frame mounting process. Regardless, the suction holes may apply vacuum suction from the vacuum connection to one or more portions of the membrane stack disposed on the support surface, thereby helping to maintain the orientation and / or position of the membrane stack on the support.

[0071] Example: Fabrication of a Macroencapsulation Device

[0072] 6A-6B illustrate the use of a support 200 similar to that described above in connection with FIGS. 5A-5D. Again, the support may include a curved support surface 206 and a corrugated surface including a plurality of alternating ridges 202 and valleys 204 extending at least partially around the periphery of the curved support surface. A bonded membrane stack 214 is disposed on the support surface, with the outer portions of the membranes extending over the ridges and valleys of the corrugated surface. Due to a size mismatch between the undeformed planar configuration of the membrane and the diameter of the curved support surface adjacent the corrugated surface, the membrane size at this location is larger than the diameter of the curved support. The resulting excess membrane material extends outward onto the corrugated surface, but may be deformed to conform to the shape of the ridges and valleys of the corrugated surface, accommodating the presence of this excess material. Deformation of the membrane stack may be accomplished using a vacuum applied to one or more portions of the membrane by a vacuum connection 208 on the support, although other fastening methods, such as mechanical clamping, temporary adhesives, and other suitable methods, may also be used. In either case, the membrane stack may be deformed into a folded, pleated, wrinkled, corrugated, or otherwise deformed shape, deforming the membrane from a first larger area to a second smaller area within the cross-section of the system to account for the size discrepancy discussed above. Due to the periodic nature of the corrugated surface, these deformations, which reduce the membrane stack to smaller areas, may be located along the membrane stack's periphery. Once properly positioned and held in the deformed configuration on the support, a frame 220, in the illustrated embodiment, may be placed on the surface. The frame contacts the portion of the membrane located on the multiple ridges extending around the curved support. A subsequent bonding process, as previously described, may then be performed to bond the frame to the membrane stack.

[0073] Figures 7A-7B are photographs of a macroencapsulation device fabricated using a process similar to that described above. The device is in a relaxed state before being loaded with cells, with visible areas of deformation (i.e., wrinkles) in the attached membrane distributed along the periphery of the device due to the presence of slack in the membrane. The device includes an array of channels disposed between junctions (indicated by indented dots) formed on the first and second membranes. Figure 7B clearly shows the channels 126 and junctions 124.

[0074] Example: Device filling

[0075] Figures 8A-8B show scanning electron micrographs of two cross-sectioned macroencapsulation devices with different amounts of membrane slack (i.e., 5% and 10% frame undersizing relative to the corresponding membrane size). The devices were loaded with 150 μm beads. The bead size represents the average diameter of a human pancreatic islet, and the chamber height of the loaded device was measured. As shown, the first device, shown in Figure 8A, contained fewer beads than the second device, shown in Figure 8B, which corresponds to a 5% frame undersizing and a 10% frame undersizing. The first device also corresponds to a smaller chamber height relative to the second device. Thus, both the chamber height and the loading volume are larger for devices with a greater degree of frame undersizing relative to the corresponding attached membrane. Additionally, loading of devices with 0% percent membrane slack was attempted. The device failed to load, confirming that loading the device with cells or other materials may be easier if the membrane is loaded in a loose configuration with some slack.

[0076] Example: Various frame sizes

[0077] Figure 9 illustrates the concept of membrane slack, in which membranes of a given size are mounted on frames of different diameters. As shown, a pair of bonded membranes (e.g., first and second membranes bonded around their perimeters) has a diameter of 42.3 mm and is mounted on frames of various sizes (e.g., diameters of 42.3 mm, 40.2 mm, and 38.3 mm). The degree of frame undersizing was calculated as the ratio of the difference in diameter between the membrane and the surrounding frame to the diameter of the membrane stack. Frame undersizing by 0%, 5%, and 10% corresponded to perimeter frames of 42.3 mm, 40.3 mm, and 38.3 mm, respectively. To accommodate the excess surface area of the membrane module when mounting the membrane on an undersized frame, an increase in the degree of membrane slack (i.e., membrane sagging) was observed with an increase in the degree of frame undersizing relative to the membrane size.

[0078] Example: Internal Volume Dimensions vs. Sag

[0079] 10A and 10B illustrate diagrams of filled macroencapsulation devices. The two devices differ in the amount of undersizing of the frame relative to the undeformed dimensions of the corresponding membrane. Specifically, macroencapsulation device 300A of FIG. 10A was modeled using a smaller amount of undersizing compared to macroencapsulation device 300B of FIG. 10B. Similar to the previous embodiment, the device can include first and second membranes 104, which are bonded along their perimeters to form an interior volume 250 between the membranes. The illustrated device also includes a bonded portion 124, with a through-hole 132 located within the central portion of the membrane, which is disposed within a frame (not shown). Mathematical modeling was used to determine the membrane structure when filled to a predetermined membrane tension under equilibrium conditions. The determined cell height H, associated with the channels forming interior volume 250, can be measured in a direction perpendicular to the plane in which the membranes and corresponding frames generally lie, as shown. The device 300A of FIG. 10A, which has a smaller degree of frame undersizing, was observed to have a smaller chamber height after filling compared to the device 300B of FIG. 10B, which has a larger degree of undersizing and a correspondingly larger amount of membrane looseness or sagging.

[0080] Example: Control of device structure

[0081] Without being bound by theory, it is possible to control the chamber height and total internal volume of the channels formed in the device by controlling the degree of undersizing of the frame relative to the corresponding membrane size. As before, a 42.3 mm diameter membrane can be mounted on frames with various diameters, and channels with fixed channel spacing and diameter can be formed in the membrane. Using mathematical modeling, chamber height and volume were estimated by fixing the geometric characteristics of the channels (e.g., channel spacing, channel diameter). The internal volume and chamber height were then predicted at packing equilibrium. The prediction was made by the difference in surface area between a bonded membrane mounted under tension and a loosely mounted state, achieved by reducing the surface area corresponding to the frame dimensions. As shown in the table below, both chamber height and total internal volume increased with decreasing frame diameter. This corresponds to an increased mismatch between the membrane and frame areas and an increased amount of membrane sag before packing. [Table 1]

[0082] While the present teachings have been described in connection with various embodiments and examples, it is not intended that the present teachings be limited to such embodiments or examples. On the contrary, the present teachings encompass various alternatives, modifications, and equivalents, as will be appreciated by those skilled in the art. Accordingly, the foregoing description and drawings are by way of example only.

Claims

1. A macroencapsulation apparatus for containing a cell population, the macroencapsulation apparatus comprising: a first membrane; and a second membrane disposed on the first membrane, the first membrane and the second membrane being joined along a joined perimeter of the first membrane and the second membrane to form an interior volume therebetween, the first membrane and / or the second membrane being semipermeable; a frame extending around at least a portion of the outer edges of the first membrane and the second membrane, the frame positioned radially outward from the joined perimeter; A macroencapsulation device comprising:

2. A macroencapsulation apparatus as described in claim 1, wherein the surface area of the first membrane and / or the second membrane is larger than the cross-sectional area of the frame to which the first membrane and the second membrane are attached.

3. A macroencapsulation apparatus as described in either claim 1 or claim 2, wherein the frame extends entirely around the periphery of the first membrane and the second membrane.

4. A macroencapsulation device described in any one of claims 1 to 3, wherein the first membrane and the second membrane are configured to block the movement of the cell population out of the device.

5. The macroencapsulation device described in any one of claims 1 to 4, further comprising the cell population disposed within the internal volume.

6. The macroencapsulation device described in claim 5, wherein the cell population is an insulin-secreting cell population.

7. A macroencapsulation device described in any one of claims 1 to 6, wherein the first membrane and / or the second membrane are configured to enable the transport of insulin.

8. A macroencapsulation apparatus as described in any one of claims 1 to 7, wherein the internal volume includes a plurality of channels.

9. The macroencapsulation device described in Claim 8, further comprising a plurality of connecting portions of the first membrane and the second membrane arranged radially inward from the frame, the plurality of connecting portions forming the plurality of channels.

10. The macroencapsulation apparatus of claim 9, wherein at least some of the plurality of connecting portions include through holes extending therethrough.

11. A macroencapsulation apparatus as described in any one of claims 1 to 10, wherein the first film and / or the second film are sintered.

12. A macroencapsulation apparatus as described in any one of claims 1 to 11, wherein the first membrane and / or the second membrane includes a hydrophilic coating.

13. A macroencapsulation apparatus as described in any one of claims 1 to 12, further comprising a filling port formed in the frame, the filling port being configured to allow the cell population to be flowed into the apparatus.

14. A macroencapsulation device as described in any one of claims 1 to 13, wherein the bonds along the periphery include openings, the openings being configured to allow the cell population to flow into the internal volume.

15. A macroencapsulation device as described in any one of claims 1 to 14, wherein a portion of the first membrane and the second membrane connected to the frame is deformed to fit within an area of the frame that is smaller than the area of the portion of the first membrane and the second membrane in an undeformed configuration.

16. A macroencapsulation device as described in any one of claims 1 to 15, wherein the surface area of the first membrane and / or the second membrane is 1% to 30% (including both ends) larger than the cross-sectional area of the frame.

17. The macroencapsulation apparatus of claim 16, wherein the ratio is between 5% and 10% (inclusive).

18. A method of forming a macroencapsulation device for containing a population of cells, said method comprising: bonding a first membrane to a second membrane along a periphery of the first membrane and a second membrane to form an interior volume therebetween, the first membrane and / or the second membrane being semi-permeable; connecting a frame to the first and second membranes along at least a portion of an outer edge of the first and second membranes, the frame being positioned radially outward from the joined perimeter; A method comprising:

19. The method described in claim 18, wherein the surface area of the first membrane and / or the second membrane is larger than the cross-sectional area of the frame to which the first membrane and the second membrane are mounted.

20. A method according to any one of claims 18 or 19, wherein the first membrane and the second membrane are configured to block movement of the cell population out of the device.

21. The method described in claim 20, further comprising filling the internal volume with the cell population.

22. A method according to any one of claims 18 to 21, wherein the first film and / or the second film are sintered.

23. A method according to any one of claims 18 to 22, further comprising coating the first membrane and / or the second membrane with a hydrophilic material.

24. A method according to any one of claims 18 to 23, further comprising deforming the first membrane and the second membrane in an out-of-plane direction of the first membrane and the second membrane, the step of connecting the frame being carried out while the portions of the first membrane and the second membrane are being deformed out-of-plane, and the frame limiting the maximum cross-dimensional dimension of the macroencapsulation device.

25. The method described in claim 24, wherein out-of-plane deforming the first membrane and the second membrane includes placing the surface of the first membrane opposite the second membrane on a curved support.

26. The method of claim 25, wherein the curved support comprises a spherical dome.

27. A method according to any one of claims 25 or 26, further comprising maintaining the first membrane and the second membrane adjacent to the curved support by applying a vacuum to one or more non-diffusive portions of the first membrane and the second membrane.

28. The method described in claim 27, wherein the non-diffusible portion is positioned radially outward from the internal volume.

29. A method according to any one of claims 18 to 28, further comprising forming a plurality of channels between the first membrane and the second membrane by joining one or more portions of the first membrane and the second membrane before connecting the frame to the first membrane and the second membrane.

30. The method of claim 29, further comprising forming one or more through holes in the one or more joining portions before connecting the frame to the second membrane.

31. A method according to any one of claims 18 to 30, further comprising deforming the outer peripheries of the first membrane and the second membrane from a first maximum transverse dimension to a second maximum transverse dimension smaller than the first maximum transverse dimension, and connecting the frame limits the maximum transverse dimension of the first membrane and the second membrane to the second maximum transverse dimension.

32. The method described in claim 31, wherein deforming the outer periphery of the first membrane and the second membrane from the first maximum transverse dimension to the second maximum transverse dimension includes placing the surface of the first membrane opposite the second membrane on a curved support.

33. The method of claim 32, wherein the curved support comprises a spherical dome.

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