Macroencapsulation Equipment

Abstract

A macroencapsulation device and associated manufacturing method are described in which a bonded membrane of the device may be attached to an associated frame in an arrangement that provides stress relief between the frame and a seal perimeter of the bonded membrane, and the seal perimeter may be disposed radially inward from an outer periphery of the membrane such that when the membrane is attached to a corresponding peripheral frame, the seal perimeter is spaced radially inward from the frame and an unbonded portion of one or more membranes is provided between the frame and the seal perimeter.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit under 35 U.S.C. §119(e) to U.S. Provisional Application No. 63 / 233,667, filed August 16, 2021, which is incorporated by reference in its entirety herein.

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

[0003] To treat metabolic disorders such as diabetes, therapeutic devices can be used to deliver biological products. Therapeutic devices can be implantable to provide long-term supply of biological products such as insulin. Some of these devices include macroencapsulation devices, which are used to contain cells that produce the desired biological product, a matrix that contains the cells, or other desired therapeutic agents. Summary of the Invention

[0004] Described herein are various embodiments of a macroencapsulation apparatus that may provide improvements related to manufacturability, fatigue resistance, automation compatibility, and / or other advantages, as described in more detail below.

[0005] 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 are bonded together to form a seal extending around an interior volume disposed between the first membrane and the second membrane. The seal is disposed radially inward from an outer periphery of the first membrane and the second membrane. The first membrane and / or the second membrane are semipermeable. The macroencapsulation device further includes a frame, the first membrane and the second membrane are disposed on the frame, the frame extends along at least a portion of the outer periphery of the first membrane and the second membrane, and the seal is disposed radially inward from the frame.

[0006] 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 bonded to each other to form a seal extending around an interior volume provided between the first membrane and the second membrane. The first membrane and / or the second membrane are semi-permeable. The macroencapsulation device further includes a frame disposed on the first membrane or the second membrane extending along at least a portion of the periphery of the first membrane and the second membrane, the frame including a fill port extending from an outer portion of the frame to an inner portion of the frame, an opening of the fill port located on the inner portion of the frame in fluid communication with the interior volume and flush with an adjacent portion of the inner portion of the frame.

[0007] In another embodiment, a method of forming a macroencapsulation device includes attaching a first membrane and a second membrane onto a frame, where the first membrane and the second membrane are bonded to one another to form a seal extending around an interior volume disposed between the first membrane and the second membrane, the seal being disposed radially inward from an outer periphery of the first membrane and the second membrane, and the method further includes connecting the frame to the second membrane and / or the first membrane at one or more locations radially outward from the seal along the outer periphery of the first membrane and the second membrane.

[0008] In yet another embodiment, a method of forming a macroencapsulation device includes disposing a first membrane and a second membrane on a first surface of a frame, where the frame includes a fill port extending from an outer portion of the frame to an inner portion of the frame, and the frame includes a second surface opposite the first surface, the method further includes disposing a first flap of the first membrane on a portion of the first surface adjacent the fill port and disposing a second flap of the second membrane on a portion of the second surface adjacent the fill port such that a portion of the fill port is disposed between the first flap and the second flap, and sealing the first flap and the second flap together with the frame such that the fill port is in fluid communication with an interior volume disposed between the first membrane and the second membrane.

[0009] It should be appreciated that the disclosure is not limited in this respect, and that the concepts set forth above, and the additional concepts described below, may be contemplated in any suitable combination. Moreover, 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.

[0010] In the event that the present specification and a document incorporated by reference include conflicting and / or inconsistent disclosure, the present specification shall control. In the event that 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.

[0011] The accompanying drawings are not intended to be drawn to scale. In the drawings, each of the same or nearly identical components illustrated in various figures may be represented by a similar numeral. For clarity, not every component may be labeled in every drawing. [Brief description of the drawings]

[0012] [Figure 1A] FIG. 2 is a front view of a macroencapsulation device bonded membrane prior to attachment to a frame, according to one embodiment.

[0013] [Figure 1B] FIG. 1B is a side view of the embodiment of FIG. 1A.

[0014] [Figure 2A] FIG. 2 is a front perspective view of a frame of a macroencapsulation apparatus, according to one embodiment.

[0015] [Figure 2B] FIG. 2B is an enlarged view of section 2B of the embodiment of FIG. 2A.

[0016] [Figure 2C] FIG. 2B is a front view of the frame of the embodiment of FIG. 2A.

[0017] [Figure 2D] FIG. 2D is a front enlarged view of section 2D of FIG. 2C.

[0018] [Figure 2E] FIG. 2B is a side view of the frame of the embodiment of FIG. 2A.

[0019] [Figure 2F] FIG. 2F is an enlarged side view of section 2F of FIG. 2E.

[0020] [Figure 3A] FIG. 2 is a front view of a macroencapsulation apparatus according to one embodiment.

[0021] [Figure 3B] FIG. 3B is an enlarged perspective view of a cross section of the embodiment of FIG. 3A.

[0022] [Figure 3C] FIG. 3B is a side view of the macroencapsulation apparatus of the embodiment of FIG. 3A.

[0023] [Figure 3D] FIG. 3B is a side view of the macroencapsulation apparatus of the embodiment of FIG. 3A after it has been loaded with a desired substance.

[0024] [Figure 4] 1 illustrates a process for connecting a bonding membrane to a frame according to one embodiment.

[0025] [Figure 5A] FIG. 1 is a front view of a macroencapsulation device showing fatigue failure due to stress concentrations around the bonding membrane.

[0026] [Figure 5B] FIG. 13 is a front view of a macroencapsulation device showing fatigue failure due to stress concentration at an elongated fill port. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] Driven by the increasing need to deliver biological products to treat metabolic disorders such as diabetes, various types of implantable therapeutic devices have been designed. However, the inventors have recognized that typical methods for making such devices are often cumbersome 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., adhesive application during installation). In addition, the inventors have recognized that it is often difficult to precisely form such devices within tolerances to prevent mechanical failure of such devices once implanted.

[0028] For example, in some embodiments, during the manufacturing process of the macroencapsulated device, at least one, and possibly two or more, flexible membranes of the device may be bonded together to form a seal that extends around the interior volume provided between the membranes. The bonded flexible membrane may be attached to a corresponding semi-rigid frame, and the two may be bonded together. The inventors have recognized that the transition from the semi-rigid frame to the flexible membrane may result in high stress concentrations at the membrane-frame interface. In addition, imperfect application of adhesive at this interface may increase localized stresses on the membrane during repeated flexing of the device during implantation. These stress concentrations may result in fatigue failure delamination and / or membrane rupture. Other structural features of the frame (such as a fill port extending into the interior volume provided between the membranes) may also increase localized stresses on the membrane, which again may promote fatigue failure and membrane rupture during use.

[0029] In view of the above, the inventors have recognized an advantage associated with macroencapsulation devices in that one or more parameters of the resulting macroencapsulation device may be altered by controlling the relative placement of the device's membrane and frame, as well as the adhesive application technique for bonding them together. For example, the relative sizing and placement of the membrane and associated frame may result in a simple and easily controllable method for producing a macroencapsulation device with low stress on the membrane at the frame interface and low risk of membrane failure. This may include relieving stress between the frame and the seal perimeter of a bonded membrane held within the frame to allow the unbonded flexible membrane to accommodate the relative deformation between the more rigid frame and the seal perimeter. For example, the seal perimeter may be spaced radially inward from the membrane's perimeter when the membrane is attached to a corresponding peripheral frame, with one or more unbonded portions of the membrane being spaced radially inward from the frame and the seal perimeter. The space between the frame and the seal perimeter may create a stress buffer (also referred to herein as a buffer zone) between the frame and the membrane seal perimeter that may reduce fatigue failure of the membrane.

[0030] The inventors further recognize that it may be desirable to prevent the adhesive used to bond one or more membranes of the device to an associated frame from spreading to undesired adjacent locations of the membrane. This may include limiting the adhesive from spreading to a buffer area between the seal perimeter and the frame that extends at least partially around the interior volume of the device. The technique may include bond initiation locations located around the perimeter of the frame. The bond site may include a reservoir at the perimeter of the frame in which the liquid adhesive is deposited and from which it creeps up to the peripheral portion of the membrane. The viscosity, amount of adhesive, size of the reservoir, and properties of the membrane may be selected to allow the adhesive to cure and bond the membrane to the frame while limiting the spread of the adhesive to desired locations. After bonding the membrane to the frame at each bond site, a second adhesive application may be used to deposit either the same adhesive or a different adhesive on the frame perimeter in sections between and / or around the bond sites to create a strong bond between the membrane and the frame. In some embodiments, both adhesive applications allow the unbonded portion of the membrane to remain between the frame and the membrane seal perimeter to provide the stress relief discussed above.

[0031] Depending on the particular embodiment, the reservoir formed in the frame to receive the adhesive during manufacture may have any suitable size and / or shape. For example, in some embodiments, the size of the reservoir included in the frame may be about 50 μL to about 500 μL. In some embodiments, the size of the reservoir included in the frame has an average volume of about 250 μL. In some embodiments, the size of the reservoir included in the frame is adjusted in volume depending on the design. For example, in some embodiments, the size of the reservoir included in the frame is about 1.6 μL / cm. In addition, depending on the particular embodiment, the reservoir may occupy any desired amount of the surface area of ​​the mounting surface on which the membrane is disposed (including, for example, 10% or more, 25% or more, and / or 50% or more of the surface area of ​​the frame portion to which the membrane is attached). Correspondingly, the reservoir may occupy 80% or less, 75% or less, 50% or less, and / or 25% or less of the surface area of ​​the frame portion to which the membrane is attached. Combinations of the foregoing ranges are contemplated to include, for example, that the reservoirs may occupy greater than or equal to 10% and less than or equal to 80% of the surface area of ​​the frame portion to which the membrane is attached, and the disclosure is not so limited, and both greater and lesser volumes and area occupancies of the individual reservoirs are contemplated.

[0032] In addition to the above, the inventors have recognized that it may be desirable to avoid stress being applied to the membrane of the device due to a structural inclusion extending into the device interior volume between opposing portions of one or more membranes. Thus, in some embodiments, the opening of the fill port that is in fluid communication with the interior volume may be flush with the adjacent frame inner portion (i.e., the fill port does not extend into the interior volume formed by one or more membranes). This may reduce or eliminate stress concentrations and potential stresses applied to the membrane due to the use of a fill port that extends into the membrane. The inventors have recognized and appreciated techniques for sealing the bonded membrane around the flush opening, which are described in further detail below. As with the case of having a fill port that extends into the membrane, it has been shown that with a flush attached opening, cell populations flow into the interior volume of the sealed bonded membrane. For example, in testing of devices with flush and extended fill ports, the fill efficiency measured for the device with flush fill port was 93.33% fill rate, while the fill efficiency measured for the device with extended fill port was 90% fill rate. In embodiments including flush fill ports, the fill efficiency measured may be about 85%, 90%, 91%, 92%, 93%, 94%, and / or 95% or more. The fill efficiency may also be about 99.99%, 99%, 98%, 97%, 96%, and / or 95% or less. In embodiments including extended fill ports, the fill efficiency measured may be about 80% or more and 99.99% or less, or more preferably 90% or more and 99.99% or less. However, other combinations of the above ranges may also be used.

[0033] As mentioned above, the macroencapsulation device may include multiple layers of membranes. At least one outer membrane of these multiple layers may be semipermeable. However, embodiments are also contemplated in which each membrane is semipermeable or at least one of the membranes in the device is substantially impermeable. Furthermore, the device may also include two laminated membranes, three laminated membranes, and / or any other suitable number of membranes, but the disclosure is not limited in this manner. For example, in an embodiment that includes two membranes, either one membrane may be semipermeable and the other impermeable, or both may be semipermeable. Therefore, it should be understood that the disclosure is not limited to any particular combination of membranes in a laminated structure.

[0034] In some embodiments, the macroencapsulation device may include at least one cell population disposed in an internal volume of the device. For example, the cell population may be disposed in an internal volume formed between two or more opposing outer membranes of the device, where the periphery of the internal volume may be defined by one or more bonds extending around at least a portion of the membrane, possibly the entire membrane, the membrane perimeter, or other suitable portion of the membrane. In such embodiments, at least the outer membrane of the device may be configured to block the passage of one or more cell populations out of the device. Thus, one or more cell populations may be retained in the internal volume of the device. Although the use of two outer membranes forming a single internal volume is described, the use of multiple intermediate membranes located between the outer membranes of the device and / or between multiple unconnected internal volumes within the device is also contemplated. Additionally, the internal volume may be formed by folding a single membrane and bonding it to itself to obtain two opposing membranes.

[0035] 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 (such as 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. Depending on the particular embodiment, the desired exchange and immune response protection properties of the membrane may be based on: size exclusion, where the pore size distribution of the membrane is selected to exclude immune cells based on size; balancing the diffusion rate of larger immune cells through the membrane through the use of pore size, tortuosity, membrane thickness, and other suitable parameters to be significantly less than the diffusion rate of desired biological products, cellular waste products, and nutrients; combinations of the foregoing; and / or other suitable exclusion techniques.

[0036] The membrane of the macroencapsulation device may be formed from any suitable biocompatible material. The biocompatible material may be substantially inert to the cells contained within the macroencapsulation device and the surrounding tissue. The biocompatible material may include synthetic or naturally occurring polymers. In some embodiments, the polymer may also be a linear polymer, a crosslinked 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, although the disclosure is not limited in this manner. In one embodiment, the polymer may include expanded polytetrafluoroethylene (ePTFE). Suitable types of polymers may also include 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 fluoride (PVDF), polycaprolactone (PCL), polylactic-co-glycolic acid (PLGA), poly-L-lactide (PLLA), polyacrylonitrile (PAN), electrospun PAN / PVC, any combination of the foregoing, and / or any other suitable polymeric material. In some embodiments, the membrane used in any of the embodiments disclosed herein may include PVDF. In some embodiments, the membrane used in any of the embodiments disclosed herein may include electrospun PAN PVC. In some embodiments, the membrane used in any of the embodiments disclosed herein may include PES. In some embodiments, the membrane used in any of the embodiments disclosed herein may comprise PS. In some embodiments, the membrane used in any of the embodiments disclosed herein may comprise PAN. In some embodiments, the membrane used in any of the embodiments disclosed herein may comprise polycarbonate.In some embodiments, the membrane used in any of the embodiments disclosed herein may comprise polypropylene.The synthesis method used to form one or more porous membranes from the above polymeric materials can include, but is not limited to, swelling method, solution casting method, immersion precipitation and phase separation method, electrospinning method, etc., methods that produce reticulated networks, methods that produce trabecular networks, or any other suitable method that forms porous polymeric membranes.

[0037] Sintering of the membrane may be used to modify the porosity and flux properties of the membrane. For example, sintering may increase the porosity of the membrane while maintaining the pore structure of the membrane. Sintering may also improve the mechanical stability and diffusion flux of the membrane. Thus, sintering may be used to modify the porosity and / or mechanical properties of the membrane, which in turn may be used to adjust the porosity and flux properties of the macroencapsulation device. Thus, in some embodiments, any desired combination of sintered and / or non-sintered membranes may be used. For example, if two outer membranes of the device can be bonded to each other, a sintered membrane and a non-sintered membrane are bonded to each other, two sintered membranes are bonded to each other, or two non-sintered membranes are bonded to each other. Furthermore, if any number of intermediate membranes located between these outer membranes can be used, these intermediate membranes may be sintered or non-sintered.

[0038] The membranes of the macroencapsulation devices described herein can be made from porous membrane materials configured to allow transport of substances (such as biological products) having molecular weights 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 depending on the desired application. For example, one or more membranes of the macroencapsulation device can be configured to allow insulin having a molecular weight of about 5.8 kDa to flow through the membrane.

[0039] To obtain the desired selectivity, the porous membranes used in the macroencapsulation devices disclosed herein can have an open pore structure with an average pore size 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 range of sizes. Correspondingly, the average pore size of the various membranes described herein may 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 range of sizes. Combinations of the foregoing are contemplated, including, for example, average pore sizes of 1 nm or more to 20 nm or less, 1 nm or more to 2500 nm or less, and / or any other suitable combinations. Although specific average pore sizes are described above, it should be understood that 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 set forth above.

[0040] In some embodiments, charge exclusion properties can be included in the membrane. For example, the surface charge of the membrane can be adjusted with an external coating, plasma treatment, or other surface treatment to achieve neutral, positive, negative, or zwitterionic properties based on the isoelectric point of the desired auxiliary. The auxiliary can be a protein, a complex small molecule, and / or any other suitable auxiliary depending on the desired application.

[0041] In order for the macroencapsulation device to have sufficient strength and / or rigidity, the various membranes and frames may be made from materials of sufficient stiffness. The desired rigidity may be obtained by an appropriate combination of the material's Young's modulus (also called elastic modulus), thickness, and overall structure, which may 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 and / or 10 10 Other suitable Young's moduli may be used for the various membranes and frames described herein, including, for example, Young's moduli both above and below these ranges. The aforementioned Young's modulus ranges may include, for example, about 10 6 Pa or more 10 10It is believed that Young's modulus of less than 1 Pa may be included. In some embodiments, suitable materials for the frame may include polyetheretherketone (PEEK). Suitable materials for the frame may include, but are not limited to, polycarbonate, polyurethane, polyetheretherketone (PEEK), polyvinyl chloride (PVC), poly(oxymethylene), poly(methyl methacrylate) (PMMA), thermoplastic polymer-based composites, polypropylene, fluorinated ethylene propylene (FEP), low density polyethylene (LDPE), high density polyethylene (HDPE), ultra high density polyethylene (UHDPE), polycaprolactone, poly(lactide), poly(glycolic acid), polylactide-co-glycolide, ethylene vinyl acetate copolymer, polyamide, poly(butylene) terephthalate, and combinations of the foregoing. In some embodiments, suitable materials for the frame may include polyetheretherketone (PEEK). In some embodiments, suitable materials for the frame may include polypropylene. In some embodiments, suitable materials for the frame may include fluorinated ethylene propylene (FEP). In some embodiments, suitable materials for the frame include ultra-high density polyethylene (UHDPE), while in other embodiments, suitable materials for the frame or portions of the frame may include titanium, graphene, stainless steel, or other suitable biocompatible materials that exhibit sufficient rigidity to function as a frame for the macroencapsulation device.

[0042] In some embodiments, it may be desirable for one or more of the membranes included in the macroencapsulation device to be hydrophilic to facilitate loading of cells into 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 substances through the membrane of the device. In addition, a hydrophilic outer membrane may also reduce fibrosis when the device is located in vivo. Thus, the membrane of the macroencapsulation device may be made of a hydrophilic material and / or may be treated with a hydrophilic coating. Suitable hydrophilic coatings include, but are not limited to, polyhydroxyacrylate, PEG, pHPA, carboxymethylcellulose, alginate, agarose, and / or a thermoplastic coating impregnated with a solute. Suitable hydrophilic materials may also 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 the membrane or from which the membrane can be made.

[0043] The membranes described in the various embodiments of the macroencapsulation apparatus described herein may be bonded together using any suitable bonding method, although the disclosure is not limited in this manner. For example, adjacent membranes may be bonded together using adhesives, epoxy resin bonding, 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 specific embodiment, adjacent membranes may be bonded using a heated tool used to press or hammer two or more membranes together with a defined pressure and / or force for a set fusion time. In view of the above, it should be understood that the disclosure is not limited to the use of any particular method of bonding membranes together.

[0044] In some embodiments, after the membranes are bonded together and, optionally, after the membranes are attached to a frame, one or more heat treatments may be applied to the laminate of bonded membranes. For example, the membranes may be bonded together by extending a bond along the perimeter of the membranes and / or one or more bonds may be formed in the interior region of the membrane (e.g., inside the bond perimeter) before the membranes are heat treated. This post-bonding heat treatment may strengthen the bonding of the membranes 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.

[0045] In certain embodiments, it may be desirable to limit the maximum thickness of the macroencapsulation device in a direction perpendicular to the plane of the largest transverse dimension of the device. Thus, one or more internal portions of the first and second membranes disposed within the frame may be bonded together to limit the extent to which the membranes may be positioned apart from one another. These bonded portions of the membrane may be uniformly distributed within the internal portions of the membranes disposed within the frame. These bonded portions may have any suitable shape, including, for example, points, lines, curves, or any other suitable shape. The bonded internal portions may be any size suitable for the desired application, but in one embodiment using point bonds, the diameter of the point bonds 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 point 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, including, for example, a diameter of 0.5 mm or more to 3 mm or less. Although specific shapes and size ranges are set forth above, it should be understood that other shapes and sizes, both smaller and larger than those set forth above, are contemplated and the disclosure is not limited in this manner.

[0046] 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 located in the interior portion of the membrane that is 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 portion of the membrane using laser ablation, mechanical puncturing, cutting, or any other suitable method that causes the through-holes to be formed in the one or more bonded portions of the membrane. As described in more detail herein, in some embodiments, the one or more through-holes may also be located radially inward with respect to both the unbonded stress buffer region of the device and the seal perimeter that extends around the perimeter of the sealed interior volume of the device. This may help to avoid the development of stress concentrations inside the membrane adjacent to the frame.

[0047] Depending on the particular size of the bonded portion of the membrane, different sizes of through holes may be used. For example, in some embodiments, the maximum transverse dimension of the through holes formed in the bonded portion of the membrane may be 0.25 mm or more, 0.5 mm or more, 0.75 mm or more, 1.0 mm or more, 1.25 mm or more, 1.5 mm or more, etc., and / or any other suitable maximum transverse dimension. Correspondingly, the maximum transverse dimension of the through holes may be 2.0 mm or less, 1.5 mm or less, 1.25 mm or less, 1.0 mm or less, 0.75 mm or less, 0.5 mm or less, and / or any other suitable maximum transverse dimension. Combinations of the above ranges are possible, for example, the maximum transverse dimension of the through holes formed in the corresponding bonded portion of the membrane may be 0.25 mm or more and 2.0 mm or less, in which case the maximum transverse dimension of the through holes is also smaller than the maximum transverse dimension of the corresponding bonded portion of the membrane in which they are formed. Although specific dimensions are set forth above, it should be understood that the disclosure is not so limited and that other ranges both greater than the dimensions set forth above and less than the dimensions set forth above are also contemplated.

[0048] In some embodiments, the bonding portions and corresponding through-holes in the interior region of the device can be formed with the membrane positioned in a flat planar configuration and prior to attaching the frame to the device, which can simplify the manufacturing process when dealing with a flexible membrane that is attached to a frame with a desired amount of slack that can complicate the formation of other features after attachment to the frame.

[0049] As described in more detail below, in some embodiments, one or more portions of adjacent membranes may be bonded together such that the interior volume within the device is subdivided into multiple interconnected channels. The channels may be tubular shaped in some embodiments, although channels of any suitable shape or configuration may also be used. The interior maximum transverse dimension (e.g., inner diameter) of the channel may be 40 μm or more, 50 μm or more, 100 μm or more, 200 μm or more, 300 μm or more, and / or 400 μm or more. Correspondingly, the interior maximum transverse dimension of the channel may be 800 μm or less, 700 μm or less, 600 μm or less, 500 μm or less, and / or 400 μm or less. Combinations of the foregoing are contemplated, including, for example, a plurality of channels having an interior maximum transverse dimension of 40 μm or more and 800 μm or less. Furthermore, the density of interconnected channels providing the various compartments of the device may be about 10 channels / cm per unit area of ​​the cross-section of the device. 2 , 15 channels / cm 2 , 20 channels / cm 2 , 25 channels / cm 2 , 30 channels / cm 2 , 35 channels / cm 2 , 40 channels / cm 2 , 45 channels / cm 2 , 50 channels / cm 2 , 60 channels / cm 2 , 70 channels / cm 2 , 80 channels / cm 2 , 90 channels / cm 2 , 100 channels / cm 2 , 110 channels / cm 2 , 120 channels / cm 2 , 130 channels / cm2 , 140 channels / cm 2 , 150 channels / cm 2 , 175 channels / cm 2 , or 200 channels / cm 2 A range between any of the above channel densities is also contemplated, for example, up to about 10 channels / cm 2 More than 200 channels / cm 2 The following channel densities are included: However, densities both greater and less than the above ranges are also contemplated.

[0050] The macroencapsulation devices described herein may 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 may be greater than or equal to 40 μL and less than or equal to 250 μL. Also, the width, or maximum transverse dimension, of the macroencapsulation device may be between about 20 mm and 80 mm. Additionally, to optionally diffuse oxygen into the interior of the macroencapsulation device to support the cells contained therein, the maximum oxygen diffusion distance from the exterior of the device to the interior portion of the device containing the cell population may 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. In some embodiments, the maximum oxygen diffusion distance from the exterior of the device to the interior portion of the device containing the cell population is less than or equal to 150 μm. In some embodiments, the maximum oxygen diffusion distance from the exterior of the device to the interior portion of the device containing the cell population is less than or equal to 200 μm. In some embodiments, the maximum oxygen diffusion distance from the exterior of the device to the interior portion of the device containing the cell population is 250 μm or less. Correspondingly, the maximum thickness (or dimension perpendicular to the maximum transverse dimension) of the entire device and / or of the interior volume located within the device may 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. In some embodiments, the maximum thickness (or dimension perpendicular to the maximum transverse dimension) of the entire device and / or of the interior volume located within the device is 500 um or less. Additionally, in some embodiments, the ratio of the exterior surface area to the volume 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 more, or 150cm -1 Ranges ranging between any of the recited values ​​for the various dimensions and parameters are contemplated, as well as ranges both larger and smaller than those recited above.

[0051] Although certain dimensions, parameters, and relationships associated with the macroencapsulation apparatus and the materials from which the macroencapsulation apparatus is made are described above, larger and smaller dimensions, parameters, and relationships are contemplated. However, it should be understood that the disclosure is not limited in this manner. Thus, any suitable combination of sizes, configurations, material properties, and / or relative performance parameters may be used for the apparatus depending on the desired application.

[0052] In some embodiments, the cell population contained within the internal volume of the macroencapsulation device is an insulin-secreting cell population. In some embodiments, the cell population includes at least one cell derived from a stem cell-derived cell. In some embodiments, the at least one cell is a genetically engineered cell. In some cases, the at least one cell is genetically engineered to reduce an immune response in the subject upon implantation of the device compared to a comparable cell that is not genetically engineered. In some embodiments, the cell population is a stem cell-derived cell capable of glucose-stimulated insulin secretion (GSIS). For example, suitable cell populations may include pancreatic progenitor cells, endocrine cells, beta cells, a matrix comprising one or more of the foregoing, or combinations thereof. Additionally, the matrix may include isolated pancreatic islet cells, cells isolated from the pancreas, cells isolated 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 may include a second type of cells that support the first type of cells synthesizing one or more biological products. In some embodiments, the cells may be encapsulated and then placed within the matrix. In such embodiments, the cells may be encapsulated in microcapsules or conformally coated. However, naked (i.e., uncoated) cells may also be used.

[0053] Depending on the particular embodiment, a therapeutically effective density of cells may be loaded into the interior volume of the macroencapsulation device. Suitable densities of cells disposed within the interior volume may be about 1000 cells / μL or more, 10,000 cells / μL or more, 50,000 cells / μL or more, 100,000 cells / μL or more, and / or 500,000 cells / μL or more. Suitable densities of cells disposed within the compartments 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, and / or 10,000 cells / μL or less. Combinations of the foregoing are contemplated, including, for example, cell densities between about 1000 cells / μL and 1,000,000 cells / μL. In some embodiments, the cell density is about 100,000 cells / μL to 1,000,000 cells / μL. Both higher and lower cell densities may also be used depending on the desired application and cell type used.

[0054] Depending on the particular application and the desired period of use, the macroencapsulation device may be configured to have any suitable fatigue life when implanted within a subject's organism. For example, in some embodiments, the macroencapsulation device may be configured to be implanted within abdominal tissue of a subject, where the macroencapsulation device may be subject to abdominal contractions during use. Thus, in some embodiments, the fatigue life of the macroencapsulation device may be 50,000 cycles or more, 60,000 cycles or more, 70,000 cycles or more, 80,000 cycles or more, 90,000 cycles or more, 100,000 cycles or more, 150,000 cycles or more, 200,000 cycles or more, 300,000 cycles or more, 400,000 cycles or more, and / or 500,000 cycles or more. The fatigue life may also be 200,000 cycles or less, 100,000 cycles or less, and / or 80,000 cycles or less. Combinations of the foregoing ranges are contemplated, including, for example, a fatigue life of at least 50,000 cycles and no more than 200,000 cycles. In some embodiments, the fatigue life is between 1,000 cycles and 50,000 cycles. In some embodiments, the fatigue life is between 50,000 cycles and 100,000 cycles. In some embodiments, the fatigue life is between 100,000 cycles and 500,000 cycles. Also, both devices having fatigue lives longer than those listed above and devices having fatigue lives shorter than those listed above are contemplated, although the disclosure is not limited in this manner. For purposes of this application, the fatigue life of the macroencapsulated device may be determined using a cyclic fatigue testing procedure discussed in the Examples section, using a cyclic load of 12N to 45N, similar to the forces the device may experience when implanted in abdominal tissue in a living subject.

[0055] The macroencapsulation devices described herein may be implanted at various sites within a subject's body. In one example, the device may be implanted in a subject by preperitoneal or retrorectus abdominis implantation. In another example, the device may be placed by implantation within the omentum. In another example, the device may be placed by subcutaneous implantation. In another example, the device may be placed by implantation above the liver. In some cases, the macroencapsulation devices described herein may be secured at the implantation site within a subject's body using any suitable fixation method, including, for example, 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, the device may be secured using platelet-rich plasma and / or any other suitable fixation method, although the disclosure is not limited in this manner.

[0056] In use, the macroencapsulation device may be implanted at any desired location within the subject's body as described above. Once implanted, the macroencapsulation device may be exposed to the environment within the surrounding portion of the subject's body. The cell population disposed within the macroencapsulation device may produce one or more desired biological compounds, which may diffuse out of the macroencapsulation device through one or more semipermeable membranes of the device. In some embodiments, one or more medical conditions of the subject may be treated by the one or more biological compounds produced by the cells. Waste products excreted by the cell population may also diffuse from the internal volume of the device through the one or more semipermeable membranes to the surrounding environment. Correspondingly, oxygen and nutrients from the surrounding environment may diffuse through the one or more semipermeable membranes into the internal volume of the device, thereby maintaining a suitable environment within the internal volume to support the cell population. In some embodiments, the one or more semipermeable membranes of the device may also exclude immune cells of the subject from the internal volume of the device, as further detailed herein.

[0057] With reference to the figures, certain non-limiting embodiments are described in more detail. It should be understood that the present disclosure is not limited to only the specific embodiments described herein, and therefore the various systems, components, features, and methods described in connection with these embodiments can be used individually and / or in any desired combination. For clarity, the figures are described in terms of methods and devices that include only a first outer membrane and a second outer membrane bonded to each other. However, it should be understood that the methods and devices described in connection with the figures may include any number of intermediate membranes disposed between these outer membranes, and therefore the present disclosure is not limited in this manner.

[0058] 1A-1B show an embodiment of a macroencapsulation device bonded membrane prior to attachment to a frame. As shown, the first membrane 102 and the second membrane 104 may be bonded to one another at a bond perimeter 122 and a bonded portion 124 located within the bond perimeter. In FIG. 1A, the top surface of the second membrane 104 is shown, with the bond perimeter 122 of the membrane (e.g., where the first and second membranes are bonded) extending around the perimeter of the bonded membrane. The bond perimeter 122 may form an interior volume disposed between the first and second membranes. In some embodiments, the bond perimeter 122 may extend completely around the perimeter of the membrane. However, as shown in FIG. 1A, the bond perimeter may have a non-bonded portion 135. As described below, when the membrane is connected to the frame, the non-bonded portion 135 may be disposed and sealed around a fill port of the frame such that the fill port is in fluid communication with the interior volume.

[0059] As shown, the bonded perimeter may be disposed radially inward from the outer perimeter 150 of the membrane. The bonded portions 124 may take the form of bonded points distributed in a hexagonal array across the surface area of ​​the membrane. However, any suitable shape, arrangement, and / or configuration of such bonded regions may be used. Due to the presence of these bonded regions located radially inward from the bonded perimeter of the membrane, the interior volume formed between the membranes, once in the filled configuration, may take the form of a plurality of interconnected channels 126 that extend between these bonded portions and correspond to the unbonded regions of the membrane.

[0060] In some cases, the bonded portions of the membranes 102 and 104 may have a substantially lower membrane permeability due to the bonding process, and therefore may be considered to be non-diffusive portions of the membrane. This may include both the bonded perimeter 122 of the membrane and the internal bonded portion 124 located radially inward from the bonded perimeter. In contrast, the non-bonded portions of the membrane (e.g., the channels 126 in the illustrated embodiment) may be considered to be diffusive portions of the membrane. In the diffusive portions, the permeability of the membrane may be significantly higher than the non-diffusive portions, and in some embodiments may be substantially unchanged from the original membrane material. In addition to the bonded portions of the membrane being considered to be non-diffusive portions of the membrane, portions of the membrane located radially outward from the bonded perimeter 122, which would not be in direct fluid communication with the internal volume formed inward from that portion, may also be considered to be non-diffusive portions of the membrane for purposes of this description.

[0061] In some embodiments, after portions of the first and second membranes 102, 104 are bonded together, one or more through holes 132 may be formed in one or more of the bonded portions 122, 124. For example, a device (such as a laser, punch, cutter, or other suitable device) may be used to form the through holes 132 in one or more of the bonded portions of the first and second membranes 102, 104. In certain embodiments, the through holes may be formed by laser ablation, where the laser removes the bonded portions of the first and second membranes while leaving the membranes around the bonded portions to act as a seal between an interior volume formed by the membranes and the exterior of the device.

[0062] As shown in FIG. 1A, some of the bonded portions 124 located within a particular distance of the bond perimeter 122 may not include a through hole 132 such that the through hole is located radially inward from the bond perimeter. When the membrane is bonded to the frame, the through holes 132 located near the bond perimeter 122 may cause stress concentrations when the device is implanted in vivo, which may result in tearing of the membrane at the perimeter 122. Thus, while specific dimensions may vary based on the particular design, in some embodiments, bonded portions located within about 2 mm or less, 1.75 mm or less, 1.5 mm or less, 1.45 mm or less, or 1.25 mm or less of the bond perimeter 122 may not include a through hole 132. However, embodiments are contemplated in which various distances are used, both greater and less than the distances noted above.

[0063] In some embodiments, after bonding the membranes together (e.g., bonding the periphery 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 be subjected to other treatments that may not be compatible with the bonding process, which may include various high temperature treatments, where in some embodiments the bonded membranes may be subjected to various heat treatments that may enhance bonding of the membranes.

[0064] In some embodiments, a pre-bonded membrane stack (a combination of a first membrane and a second membrane as described above) may be attached to a frame (see Figures 2A-2F). Alternatively, in some embodiments, the membrane stack may be bonded together around its periphery and attached to the frame at the same time. In either case, a method may be used to attach the membrane to the frame such that the membrane has a desired amount of slack once attached. One such embodiment is described in more detail below in connection with Figure 4.

[0065] 2A-2F illustrate an embodiment of a frame 220 of a macroencapsulation device. The frame may be a peripheral frame that suspends the membrane within an opening in the frame. The frame may extend around at least a portion (and in some embodiments, the entire perimeter) of the bonded membrane. The size and shape of the frame may be selected to maintain a maximum transverse dimension of the membrane compared to a first maximum transverse (e.g., width) dimension of the membrane, which is larger in a flat configuration before attachment, with a second maximum transverse dimension that is smaller after attachment. The maximum transverse dimension may be measured in a plane in which the planar frame extends. For example, the maximum transverse dimension in the illustrated embodiment may correspond to the diameter of a circular frame that is placed on the bonded membrane. However, embodiments using frames and membranes having different shapes and sizes are also contemplated.

[0066] As shown in the figures, frame 220 may be circular in shape, although it should be noted that the frame may include any shape that corresponds to the shape of the membrane to be attached thereto. Frame 220 may include an outer portion 222 and an inner portion 224. As shown in Figures 2E-2F, outer portion 222 may be rounded in shape and taper inwardly toward inner portion 224 to form an inner periphery 226 that extends around the periphery of frame 220.

[0067] The inner periphery 226, or other portion of the frame configured to receive and position one or more membranes thereon, may include one or more reservoirs 228 corresponding to through holes, cavities, or other structures configured to receive liquid adhesive during the attachment process. For example, the reservoirs may be arranged around the inner periphery of the frame for attaching the periphery of the membrane to the frame, as described in more detail below with respect to FIG. 4. The reservoirs 228 may be evenly spaced around the inner periphery 226, although the disclosure is not so limited and the reservoirs may be arranged in any arrangement around the inner periphery. The membrane may have holes or other markings that mate with the reservoirs 228 for positioning the membrane on the frame during the attachment procedure.

[0068] As shown in FIG. 2F, in some embodiments, the reservoir may be a tapered hole that extends through the frame from a first side of the frame to a second side opposite the first side. Thus, the reservoir 228 may be tapered such that the diameter D1 of the reservoir on the first side is smaller than the diameter of the reservoir on the second side opposite the first side. In some embodiments, the reservoir 228 may not extend completely through the frame such that the reservoir may only have an opening on the first side or the second side of the frame.

[0069] Returning to FIGS. 2A-2D, the frame 220 may include a fill port 230 extending from the outer portion 222 to the inner portion 224 of the frame. The fill port 230 may include an opening 232. The opening 232 may be flush with the inner portion 224 of the adjacent frame perimeter such that the opening does not protrude beyond the inner portion 224 of the frame. The thickness of the inner perimeter 226 may increase surrounding the opening to accommodate a channel 236 (see FIG. 3C) extending from the opening through the fill port. The fill port 230 may also include a protrusion 234 extending outwardly from the outer portion of the frame. The channel 236 may extend from the opening 232 through the protrusion 234 such that a desired substance may flow through the fill port into the interior volume of the membrane when the membrane is attached to the frame.

[0070] 3A-3D illustrate one embodiment of a macroencapsulation device after the membranes have been attached to a corresponding frame. FIG. 3A is a front view of the device, and FIG. 3B is a cross-sectional perspective view of a portion of the frame-membrane interface. As illustrated, the combined membrane, including the first membrane and the second membrane (only the top surface of the second membrane 104 is shown in FIGS. 3A-3B), is connected to the inner periphery 226 of the frame 220. Although the frame 200 extends around the entire circumference of the combined membrane, the disclosure is not so limited, and in some embodiments the frame may extend around a portion of the combined membrane. The size and shape of the frame may be selected such that the maximum transverse dimension of the membrane after attachment is maintained at the smaller second maximum transverse dimension. The maximum transverse dimension may be measured in a plane in which the planar frame extends. For example, the maximum transverse dimension in the illustrated embodiment may correspond to the diameter of a circular frame that is placed on the combined membrane. However, embodiments using frames and membranes having different shapes and sizes are also contemplated. Without being bound by theory, the ratio of the first, larger maximum transverse dimension before attachment to the second, smaller maximum transverse dimension of the binding membranes can control the volume of the internal volume provided between the membranes when the membranes contain a therapeutic composition, such as a cell population.

[0071] As discussed above with respect to FIGS. 1A-1B, the membrane used to form the macroencapsulation device may include a bonding perimeter 122 that forms a seal that extends around the interior volume provided between the first and second membranes, which may correspond to a folded single membrane or two separate membranes. In the illustrated embodiment, the bonding membrane is placed on the frame 220 such that the bonding membrane covers the inner peripheral surface 226 of the frame with the outer perimeter 105 of the bonding membrane located at or near the outer edge of the inner peripheral surface 226, leaving only the outer portion 222 of the frame exposed. An adhesive layer 400 attaches the bonding membrane to the inner peripheral surface 226 or other suitable portion of the frame. The adhesive layer 400 may extend around the entire inner peripheral surface of the frame, although embodiments are contemplated in which other types of connections (e.g., welding) are used, or in which the membrane and frame are bonded together only along a portion of the frame or membrane perimeter. Suitable adhesives used may also include UV-curable or heat-curable biocompatible adhesives, including, but not limited to, urethanes, epoxies, or acrylates. Suitable adhesives used may include epoxy-acrylate copolymers such as Epotek and / or Cyberlite. Alternatively, suitable adhesives may include molten thermoplastics in heat staking or welding applications such as, but not limited to, polycarbonate, polypropylene, polyethylene, ethylene vinyl acetate, polyether (ether ketone), polyvinyl chloride (PVC), polyvinylidene fluoride (PVDF), polystyrene, acrylonitrile butadiene styrene (ABS), polyurethane, and / or polymethyl methacrylate (PMMA).

[0072] As shown, the bonded perimeter 122 of the membrane is located radially inward from the outer perimeter 105 of the bonded membrane. An unbonded portion or buffer region 402 of the bonded membrane separates the bonded perimeter 122 from the adhesive layer 400 that bonds the membrane to the inner perimeter 226 of the frame. In some embodiments, the transverse dimension (e.g., width) of the buffer region 402 between the bonded portion of the frame and the membrane can be 350 μm or more, 400 μm or more, 500 μm or more, 750 μm or more, and / or 1 mm or more. In some embodiments, the transverse dimension (e.g., width) of the buffer region 402 can be 2 mm or less, 1.5 mm or less, 1.25 mm or less, 1 mm or less, 750 μm or less, and / or 500 μm or less. Combinations of the foregoing ranges are contemplated, including transverse dimensions (e.g., widths) of the buffer region that may be, for example, about 350 μm to 750 μm, 400 μm to 750 μm, 350 μm to 2 mm, or other suitable combinations of the foregoing. However, embodiments are also envisioned having buffer regions with transverse dimensions between the adhesive layer 420 and the bonding perimeter 122 that differ from those described above. The liquid adhesive used to bond the membrane to the frame may have specific viscosity and wicking characteristics balanced with the membrane properties (e.g., porosity, tortuosity, etc.) to prevent the liquid adhesive from penetrating the buffer region 402 when bonding the membrane to the frame. The adhesive may also have a modulus of elasticity that is greater than the modulus of elasticity of the flexible membrane and less than the modulus of elasticity of the rigid frame in some embodiments. Thus, the modulus of elasticity of the macroencapsulated device may decrease in the order of the outer frame, adhesive layer, and membrane, and the device may be more flexible moving from the outer portion of the device toward the center of the device.

[0073] As a result of the above structure, the stress concentration near the bond perimeter 122 may be reduced or substantially eliminated by the relief region 402. This may reduce the risk of fatigue failure of the membrane. As mentioned above, to further reduce the stress concentration near the bond perimeter, the bond portion 124 located near the bond perimeter may not have holes 132 formed therein.

[0074] Figure 3C shows a side cross-sectional view of the macroencapsulation device of Figure 3A along line 3C after the membranes have been attached to corresponding frames and before loading with a desired substance, such as a cell population. As shown, the device can 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 unloaded, relaxed state, where 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 causes the resulting sagging of the membranes to cause the combined membranes to hang below the frame relative to the direction of gravity.

[0075] As shown on the right side of FIG. 3C, the membranes 102 and 104 are bonded to the frame 220 on the inner periphery 226. However, surrounding the fill port 230, the first membrane 102 is bonded to a first side of the frame and the second membrane 104 is bonded to a second side of the frame opposite the first side, as shown on the left side of FIG. 3C. As will be described in more detail below, slits 406 in the membranes (see FIG. 3A) create flaps 403 and 404 in the first and second membranes, which are sealed around the opening 323 of the fill port 230. By sealing the flaps around the opening 323, the opening of the fill port is in fluid communication with the interior volume provided between the membranes.

[0076] With the binding portions 124, through holes 132, and other suitable features already formed on the membranes located in the interior region of the device, the macroencapsulation device can be readily filled with the desired material (such as a cell population) with minimal additional processing and handling. The interior volume can be filled using the fill port 230, openings around the binding, and / or any other suitable method. In either case, after the macroencapsulation device is filled with the desired material, the interior volume enclosed by the first membrane 102 and the second membrane 104 can expand and take up the slack in the membranes because the membranes are under tension in the filled configuration due to the expansion of the interior volume between the membranes. This can result in the deformation of the first and second membranes such that the membranes generally expand in a direction approximately parallel to the plane of the frame 220 (see FIG. 3D). Correspondingly, the first and second membranes can expand approximately equal distances outward from the opposing faces of the frame due to this increase in the interior volume of the filled device. In the example where the membrane portions 124 are bonded together in a field located radially inward from the frame, the expansion structure may re-form a plurality of interconnecting channels 126 .

[0077] The macroencapsulation device may be filled through the fill port 230. 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 fill port 230 or using a sealable or removable port that extends to the interior volume. Alternatively, there may be an opening in the bonded periphery and / or frame of the macroencapsulation device, which may then be sealed. Any suitable outlet into the interior volume may be used to allow material to flow into the interior volume of the device, but the flow of material may be controlled in many different ways to make the filling of the interior volume desirable. For example, in one embodiment, applying pressure to the interior volume of the macroencapsulation device may correspond to a desired amount of tension being present in the membrane of the device in the filled configuration. Thus, the 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, as the disclosure is not limited in this manner. This may include, for example, control based on absolute volume of material flowing into the interior volume, duration at a given flow rate, and / or any other suitable control method.

[0078] FIG. 4 illustrates one embodiment of a process for attaching a frame to a bonded membrane. As shown in FIG. 4, a frame 220 is placed on a support 200. Once the frame is secured to the support, the bonded membranes 102 and 104 can be placed on the frame 200. In some embodiments, the membranes can be "attached with slack" to the frame. For example, the support 200 can include curved surfaces 206 for deforming the first membrane 102 and the second membrane 104 from a first maximum transverse dimension before attachment (e.g., when the membranes are in a relatively flat planar configuration) to a second maximum transverse dimension after attachment (e.g., when the membranes are deformed to conform to the shape of the underlying support 200). This concept of controlling the amount of membrane slack during attachment to a frame can refer to attaching at least two or more layers of flexible membranes (e.g., a first membrane and a second membrane) under controlled relaxed tension to form a device that includes an interior compartment of a defined volume and / or height when filled. In some embodiments, the curved surface of the support is a spherical dome structure, as illustrated in Figure 4. However, embodiments are contemplated in which supports of different shapes are used.

[0079] In some embodiments, the membranes 102, 104 may include holes or other markings (not shown) located around the circumference of the membranes corresponding to the location of the reservoirs 228 (see also FIGS. 2A-2D) of the frame for aligning the membranes on the frame. In some cases, it may be desirable to maintain the orientation and / or position of the membrane stack on the support during attachment to the frame. Thus, in some embodiments, 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 in close proximity to the curved support, as shown in FIG. 4. For example, the support 200 may include a vacuum chamber 210 connected to a vacuum source (not shown) that provides a negative pressure. The vacuum chamber may be in fluid communication with one or more vacuum holes 212 located on the surface of the support 200. The vacuum holes may be located at any desired portion of the support surface, but in some embodiments, the vacuum holes may be located at portions of the support surface where corresponding non-diffusive portions of the combined membranes may be located. The location may include, for example, the bonding perimeter 122 of the membrane, the portion of the membrane located radially outward from the bonding perimeter, the bonding portion 124 of the membrane located inside the bonding perimeter, and / or any other suitable portion of the membrane. Other methods of maintaining the position and / or orientation of the membrane relative to the support below the membrane may be used, including, for example, but not limited to, mechanical fixation, clamping, temporary adhesion, and / or any other suitable temporary fixation method.

[0080] After the frame 220 and the first and second membranes 102 and 104 are positioned on the support, the frame and membranes may be subjected to many different processes, including bonding at one or more locations. FIG. 4 illustrates a process of bonding the first and second membranes to the frame. In certain embodiments, adhesives, heat staking, welding (thermal, ultrasonic, etc.), mechanical fastening, or another suitable method may be used to bond the frame and membranes at multiple locations around the frame perimeter. This bonding may be done sequentially or simultaneously, depending on the manufacturing process. For example, the frame and membranes may be bonded together at each location where the frame includes a reservoir 228 located around the perimeter of the frame inner perimeter 226 (see FIGS. 2A-2D). In the illustrated embodiment, a bonding tool 500 may be used to create bond points between the frame and portions of the first and second membranes at one or more desired locations. The bonding tool 500 can accommodate a combination port for dispensing a curable adhesive and a light source that can be used to cure the adhesive once it is placed on the frame and membrane.

[0081] In one specific embodiment, a bonding tool 500 (e.g., needle, syringe) can deliver liquid adhesive to the reservoir 228 on the inner periphery of the frame 220. The bonding tool 500 can extend through the membranes 102 and 104 (e.g., by penetrating the membranes or by extending through pre-placed holes in the membranes) to deposit the liquid adhesive in the reservoir 228. The liquid adhesive can then wick through the portions of the first and second membranes above the reservoir 228. Alternatively, the bonding tool 500 can apply liquid adhesive to the top surface of the first and / or second membranes above the reservoirs, and the liquid adhesive can wick through the membranes toward the reservoir 228. In other embodiments, the first and second membranes 102 and 104 can be placed on the support 200, and then the frame can be placed on the second membrane. The bonding tool 500 can extend through the reservoir 228 to deposit liquid adhesive on the underside of the second membrane. The reservoir can be tapered in the insertion direction to allow easy insertion of the bonding tool. The liquid adhesive can wick through the membrane to bond it to the frame.

[0082] Once the liquid adhesive has been applied and has had time to wick through the membrane, a light source can be used to cure the adhesive. Once bonds are formed at the desired locations, the bonding tool 500 can be moved around the circumference of the device to adjacent reservoirs 228 (see FIGS. 2A-2D) until a sufficient number of bonds are formed. As shown, the frame can include reservoirs evenly spaced around the circumference of the frame, although the disclosure is not so limited and non-equidistant spacing can be used. As discussed above, the bond duration and viscosity of the adhesive can be selected to avoid excessive wicking of the adhesive into undesirable portions of the membrane (e.g., the diffusive portion and / or buffer region 402). In some embodiments, the viscosity of the adhesive can be about 100 cP or more, 200 cP or more, and / or 300 cP or more. The viscosity can also be about 1000 cP or less, 750 cP or less, and / or 500 cP or less. Combinations of the foregoing are contemplated, including, for example, viscosities that may be from 100 cP to 1000 cP, or more preferably from 100 cP to 500 cP. Other viscosities greater than those described above and less than those described above are also contemplated. The adhesive bond duration may be about 5 seconds or more, 10 seconds or more, and / or 15 seconds or more. The bond duration may also be about 60 seconds or less, 30 seconds or less, and / or 20 seconds or less. Combinations of the foregoing durations are contemplated, including, for example, bond durations that are from 5 seconds to 60 seconds, or more preferably from 10 seconds to 30 seconds. Other durations greater than those described above and other durations less than those described above are also contemplated. In addition, although specific bonding methods have been described, other suitable types of bonds may be used, as discussed above.

[0083] Although the use of a liquid adhesive is described above, the disclosure is not so limited and other suitable types of bonding techniques may also be used, such as heat staking, ultrasonic welding, laser welding, or any other suitable bonding technique.

[0084] The bonding locations can be predetermined so that an associated processor (not shown) can be configured to control the bonding tool 500 during an independent bonding procedure to go around the device and form the bonds, so that the bonding tool 500 is appropriately positioned with respect to each reservoir 228 of the frame. In some embodiments, the bonding tool 500 can include one or more sensors for detecting the reservoir sites, such as by visual tracking, magnetic sensing, or other suitable robotic device targeting methods. Thus, the bonding tool and support can include one or more sensors 110 distributed over the lower portion surface of the fixture 106, so that signals can be transmitted to the processor to perform feedback control of the bonding process.

[0085] After initially fastening the membrane to the frame in this manner, the attached frame and membrane may then be subjected to further processing, including, for example, placing additional adhesive between the attached frame and membrane to improve the bond therebetween. If the membrane was mounted on top of the frame in the first fastening step (as shown in FIG. 4), the device may remain fastened to the support 200. If the frame is mounted on top of the membrane (by a bonding tool extending through the reservoir to attach the underside of the second membrane to the frame, as described above), the macroencapsulation device including the frame and attached membrane may be removed from the curved support and refastened to the support in an inverted state (i.e., with the membrane on top of the frame). The device may be subjected to another process step in which an adhesive layer 400 (see FIGS. 3A-3B) is applied to further bond the membrane to the inner periphery of the frame. The bonding tool may apply adhesive in portions between each reservoir 228, applying and curing adhesive in each section until the entire periphery is bonded before moving to the adjacent section. Any wrinkles or creases in the membrane can be smoothed out during the bonding process. As mentioned above, the bonding duration and viscosity of the adhesive can be selected to avoid excessive wicking of the adhesive into undesirable portions of the membrane (e.g., the diffusive portion and / or the buffer region 402) such that the seal and buffer regions of the bonded membrane are located radially inward relative to both the frame and the adhesive or other type of connection bonding the membrane to the frame.

[0086] After the frame is bonded to the membrane, the device may be removed from the support. To fill the internal volume of the device (e.g., with cells), the first and second membrane portions surrounding the fill port 230 may be placed on opposite sides of the frame and sealed around the opening 323 of the fill port 320. Returning to reference to FIG. 3A, with the membranes positioned over the frame, starting from the first side of the frame, the first and second membrane portions over the fill port area may be cut away. In embodiments having a non-fused portion 135 of the bond perimeter 122, the membrane may only need to be cut away to the buffer area 402. However, in embodiments without a non-fused portion 135 (i.e., the bond perimeter extends around the entire perimeter of the membrane), the membrane may need to be cut away beyond the bond perimeter. After the membranes are sufficiently cut away, a cut 406 may be created in the first and second membranes on each side of the fill port 230. The cut 406 is perpendicular to the adhesive seal 400 and extends from the membrane perimeter 105 to the bond perimeter 122. The cuts 406 create a first flap 403 on the first membrane and a second flap 404 on the second membrane 104 opposite the first flap. The second flap 404 is then folded back onto the top surface of the second membrane 104 to reveal the first flap 403 (see the dotted fold between the cuts 406 in FIG. 3A). The first flap 403 of the first membrane is then pushed inwardly through the inner portion 224 of the frame so that it protrudes from a second side of the frame opposite the first side. The first flap 403 is then pulled onto the inner periphery 226 of the second side of the frame and the flap is flattened so that it rests on and is flush with the first upwardly facing surface of the frame. The second flap 404 is pulled over the first side of the frame and flattened so that the flap rests on a second downwardly facing surface of the frame opposite the first surface, and adhesive is then applied to the flap and allowed to cure, sealing the flap around the fill port opening, although other bonding and sealing methods may be used.

[0087] In the above embodiment, the frame is connected to the outer surface of the first membrane 102 opposite the second membrane 104. However, embodiments are also contemplated in which the frame 220 is disposed between the first membrane 102 and the second membrane 104. In such an embodiment, the portions of the first and second membranes extending radially outward from the bond 122 extending along the periphery of the membranes may be opened, and the frame may be disposed between the membranes at a location radially outward from the bond periphery of the membranes. The first and second membranes may then be bonded to the frame using any suitable bonding method, as previously described. Although the figures show the frame, membranes, and underlying supports in a particular angular orientation, it should be understood that the disclosure is not limited in this manner, and any suitable orientation of these components may be used. In either case, the frame may still function to maintain the desired transverse dimension of the membrane even when removed from its underlying support. EXAMPLES

[0088] Example: In vivo fatigue test

[0089] The mechanics of the macroencapsulation device was studied using Gottingen minipigs. The macroencapsulation device designs tested included the design described above as well as a prior design. The prior design included a bonded membrane attached to a peripheral frame such that the sealing perimeter of the membrane was located on the frame (i.e., there was no gap between the inner perimeter of the frame and the sealing perimeter). Test results of the prior design showed fatigue failure at the frame interface due to stress concentrations at the frame interface, which motivated a new design of the macroencapsulation device with a stress relief zone at the frame interface.

[0090] Compared to the peripheral frame, which is tailored to allow only slight flexibility, the area of ​​the device that is primarily composed of the membrane is highly plastic, providing a mechanical transition zone between the adhesively bonded frame and membrane. In silico and non-clinical testing of prototype devices identified this area as the most likely location for fatigue failure in the device, and this was corrected in subsequent versions by adding a stress relief zone to strengthen the interface, as described herein. To examine the mechanical durability of the device at the frame-membrane interface, fatigue testing was developed to accelerate the functional testing period beyond the proposed non-clinical testing period.

[0091] Example: In vitro fatigue testing

[0092] To simulate the forces exerted by myofibroblast-based abdominal contractions within the central mesh of the macroencapsulation device, in vitro fatigue testing was performed by developing a biphasic full reverse loading strategy in which the clamped membrane cycles symmetrically through displacement extremes. During testing, the device frame is fixed between two parallel aluminum plates and the clamps on the central mesh are actuated axially while applying a cyclic tension on the mesh, defined by the relevant physiological load. Alternatively, in the case of design exploration, the load is ramped to allow for rapid iterative feedback.

[0093] 5A-5B illustrate an embodiment of the prior design of the macroencapsulation device 300 after fatigue testing. In such an embodiment, the membrane 302 is attached to a frame 306 such that the seal perimeter 304 is located at the frame interface. The device 300 also includes a fill port 308 extending from the frame perimeter into the membrane. As shown in FIG. 5A, the membrane 302 fractured from the frame 306 at the seal perimeter 304 due to a stress concentration at the interface. Fatigue testing of the prior design and the new design showed that the prior design failed after approximately 10,000 cycles, while the new design failed after over 30,000 cycles. FIG. 5B shows the fill port interface and a close-up of the tear at the fill port interface caused by the high stress concentration. Internal fill port failure was observed in 52% of the devices. As described in more detail below, the new design, which does not have an internal fill port, showed improved fatigue life.

[0094] Example: Damage mode investigation

[0095] Tests were performed to investigate potential causes of membrane failure, and results showed that device failure was primarily caused by adhesive irregularities and lack of concentricity.

[0096] A. Ease of manufacturing: Adhesive application

[0097] One cause of device failure at the frame interface may be due to poor application of adhesive by trainees. Devices made by experts may have minor irregularities, while devices made by trainees may have major irregularities. Testing confirmed that devices with minor irregularities failed at approximately 6000 cycles, while devices with major irregularities failed in less than 1000 cycles, resulting in earlier failure. Fatigue testing of the devices also showed membrane failure consistent with failure of devices tested in vivo. Prior designs required tight mounting tolerances and precision in adhesive application to reduce the risk of failure, which is difficult to automate and requires highly skilled manufacturing. The newer designs with stress relief zones and manufacturing methods described above allow for greater tolerances on adhesive application, which allows for manufacturing by less skilled trainees or through automation (e.g., utilizing a reservoir on the perimeter of the frame as described above). For example, adding a reservoir on the perimeter of the frame provides a reliable method of reducing the number of rough inflows that significantly impact the number of cycles before a device cracks. The devices with crude inflow cracked at approximately 1000 cycles, whereas the devices without inflow cracked at over 7000 cycles. A specific advancement in fatigue test methodology was made by developing a biphasic full reverse loading strategy in which the clamped membrane cycles symmetrically through displacement extremes to mimic the forces exerted by myofibroblast-based abdominal contractions within the central mesh. During testing, the frame of the device is fixed between two parallel aluminum plates and the central portion of the membrane is clamped to a loading system such as an Instron fatigue tester to apply an axial displacement to the membrane relative to the frame and a cyclic tension on the membrane defined by the associated physiological load. Alternatively, in the case of design exploration, the load is ramped to allow for rapid iterative feedback. The applied and cyclic forces during these fatigue tests varied from 30N to 45N depending on the particular fixture and frame being tested. With the provision of the reservoir, the number of crude inflows in the new device was approximately 5, whereas the number of crude inflows in the prior device was approximately 20.

[0098] B. Quality of adhesive

[0099] Tests were conducted to determine whether the quality of the adhesive used could affect the frame interface. For example, it was investigated whether degradation or changes in the properties of the adhesive would affect the interface and whether there would be an advantage to using an alternative plastic adhesive (e.g., Cyberlite). In the first stage of testing, a standard adhesive (Epotek OG198-54) in a dogbone shape and Cyberlite were tensile tested at 0, 3, 6, 9, and 12 months to measure the tensile strength at break. The results showed that Epotek did not show any embrittlement over time and remained stable. For example, the tensile strength at break of the adhesive was consistent at approximately 20-25 MPa when tested at each time interval. It was also shown that Epotek had a stable Young's modulus of approximately 1000-1250 MPa over the 12 months. However, Cyberlite showed some embrittlement over time, with tensile strengths of approximately 10 MPa at 0 months and less than 5 MPa at 12 months. The Young's modulus of Cyberlite also decreased over 12 months from approximately 500 MPa to approximately 100 MPa.

[0100] The second stage of testing included fatigue testing of the newly designed macroencapsulated device (e.g., with stress relief zones) with various adhesive combinations (Epotek only, Cyberlite / Epotek combination, and Cyberlite only). Results showed that the device using Epotek only had a fatigue life of 10 5 The Cyberlite / Epotek combination failed after over 10 cycles. 4 The Cyberlite-only device failed after a minimum of 10 cycles. 4 It was shown that failure occurred in less than 10 cycles.

[0101] As a result, the repositioning of the seal perimeter was shown to improve the manufacturability and fatigue resistance of the device. For example, the new design reduces operator dependency through increased tolerances, improves concentricity and bond uniformity, and reduces the complexity of visual inspection. Based on the presented testing of the device, the expected fatigue life of the device is estimated to be approximately 5 years with continuous coughing, which corresponds to a peak load of 11.6 N on the device and 87,600 cycles.

[0102] While the present teachings have been described in conjunction 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. 1. A macroencapsulation device for containing a population of cells, comprising: a first membrane; and a second membrane disposed over the first membrane, the first membrane and the second membrane being bonded to one another to form a seal extending around an interior volume disposed between the first membrane and the second membrane, the seal being disposed radially inward from an outer periphery of the first membrane and the second membrane, and the first membrane and / or the second membrane being semipermeable; a frame, the first membrane and the second membrane being disposed on the frame, the frame extending along at least a portion of the outer periphery of the first membrane and the second membrane, and the seal being disposed radially inward from the frame; A macroencapsulation device comprising:

2. The macroencapsulation apparatus of claim 1 , further comprising a buffer region disposed between the seal and the frame.

3. 3. The macroencapsulation device of claim 2, wherein the buffer region creates a gap between the seal and the frame of at least about 400 microns and no more than about 2 mm.

4. 4. The macroencapsulation apparatus of claim 3, wherein the gap is less than or equal to about 750 microns or greater than or equal to 750 microns.

5. 10. The macroencapsulation apparatus of claim 1, wherein the frame has a Young's modulus greater than the Young's modulus of the first membrane and the second membrane.

6. 10. The macroencapsulation apparatus of claim 1, further comprising an adhesive bonding the first and second films to the frame, the adhesive having a Young's modulus greater than that of the first and second films and less than that of the frame.

7. 7. The macroencapsulation device of claim 6, wherein the adhesive is an epoxy-acrylate copolymer.

8. 10. The macroencapsulation apparatus of claim 1, further comprising a plurality of reservoirs disposed about an inner circumference of said frame.

9. 10. The macroencapsulation apparatus of claim 1, wherein the frame extends completely around the circumference of the first membrane and the second membrane.

10. 10. The macroencapsulation apparatus of claim 1, wherein the frame includes a fill port including a channel, the channel including an opening disposed at an inner periphery of the frame that extends through the frame and is in fluid communication with the interior volume.

11. 11. The macroencapsulation apparatus of claim 10, wherein the opening is flush with the inner periphery of the frame.

12. 10. The macroencapsulation apparatus of claim 1, further comprising a plurality of bonded portions of the first and second membranes disposed radially inward from the frame that form a plurality of interconnected channels disposed between the first and second membranes.

13. 13. The macroencapsulation apparatus of claim 12, wherein at least some of the mating portions include through holes therethrough, the mating portions including the through holes being disposed radially inward from the seal extending around the interior volume.

14. 10. The macroencapsulation device of claim 1, wherein at least one of the first membrane or the second membrane is comprised of ePTFE or is a semi-permeable membrane.

15. The macroencapsulation device of any one of claims 1 to 14, wherein the macroencapsulation device has a fatigue life of at least 70,000 cycles.

16. 1. A method of forming a macroencapsulation device, the method comprising: attaching a first membrane and a second membrane onto a frame, the first membrane and the second membrane being bonded to one another to form a seal extending around an interior volume disposed between the first membrane and the second membrane, the seal being disposed radially inward from an outer periphery of the first membrane and the second membrane; connecting the frame to the second membrane and / or the first membrane along the outer periphery of the first membrane and the second membrane at one or more locations located radially outward from the seal; A method comprising:

17. 17. The method of claim 16, further comprising injecting a liquid adhesive into a reservoir disposed around an inner circumference of the frame and wicking the liquid adhesive to adjacent portions of the first membrane and the second membrane.

18. The method of claim 17, wherein the liquid adhesive is an epoxy-acrylate copolymer.

19. 18. The method of claim 17, wherein the reservoir disposed around the inner periphery of the frame is a through hole extending between a first side of the frame and a second side of the frame opposite the first side.

20. 20. The method of claim 19, wherein the through-hole has a transverse dimension of at least 0.25 mm and not more than 2.0 mm.

21. 20. The method of claim 19, wherein the reservoir tapers from the first side of the frame to the second side of the frame.

22. 18. The method of claim 17, further comprising applying a liquid adhesive onto the first film and / or the second film around the perimeter of the first film and the second film.

23. 23. The method of claim 22, further comprising curing the liquid adhesive to bond the first membrane and the second membrane to the inner periphery of the frame.

24. A method as described in claim 22, wherein the liquid adhesive is applied and cured individually, sequentially and / or simultaneously, between the reservoirs arranged around the inner circumference of the frame.

25. 17. The method of claim 16, further comprising loading the interior volume of the device with a cell population.

26. 26. The method of claim 25, wherein the cell population comprises insulin-secreting cells.

Images