System for connecting a biological organ to a vascular graft and method for connecting a biological organ to a vascular graft

Abstract

The present invention relates to a system for connecting a biological organ to a vascular graft under ex vivo conditions and to a method for connecting a biological organ to a vascular graft, wherein once connected, the vascular graft is placed within the biological organ and a stent is placed within the vascular graft and the biological organ.

Description

[Technical Field]

[0001] The present invention relates to a system for connecting a biological organ to a vascular graft under ex vivo conditions, and a method for connecting a biological organ to a vascular graft, wherein, once connected, the vascular graft is placed within the biological organ and a stent is placed within the vascular graft and the biological organ. [Background technology]

[0002] Various types of stents are known from the prior art. Stents for medical use are primarily designed to expand after narrowing of blood vessels. An example of such a stent is described in European patent EP 1 608 299, which presents a self-expanding or balloon-expandable stent that can be expanded simultaneously from both ends of the stent within the blood vessel until the stent is fully expanded. The stents described herein are further provided with markers in the working portion, which allow the device to be positioned inside the human body. The tips of the stents are intended to be non-traumatic.

[0003] Another document related to stents, European Patent Application EP3160400, presents a stent for use in the human body that includes a flexible tip to facilitate insertion into a target site, a loop at the connection portion to securely fix the stent, and an X-ray marker to be used to evaluate the position of the stent. The stent provides a connection that allows fluid flow between the recipient's body part into which the stent is inserted and the other end of the stent. Such a stent is not self-expanding and is connected to a catheter to supply fluid to or drain fluid from the body. Its use in the human body is temporary.

[0004] European Patent Application EP 2146674 describes a self-expanding stent that is inserted into a blood vessel using a special mandrel. Such a mandrel has a sharp tip that, when inserted into a target site, breaks open to allow the stent to exit through the tip. The mandrel is then withdrawn, and the stent is expanded and remains in place at the target site.

[0005] A similar solution is presented in another patent, JP4857125, in which a stent is delivered to the target site within a mandrel with a longitudinally breaking tip. Upon insertion, the tip breaks off, providing a sufficient lumen for the stent to pass through. The stent then self-expands and remains at the target site.

[0006] The prior art also describes the possibility of connecting blood vessels using stents, as shown, for example, in US Patent US9241782. This document describes the use of self-expanding or balloon-expandable stents to connect two blood vessels. Such a connection may further include the use of expansion rings and clamps at both ends of the stent designed to securely fix the blood vessels to the stent. The stent may be located either outside or inside the blood vessels. The connection between the stent and the blood vessels is performed as follows (in the case of a stent located outside the blood vessels): 1) The stent in a compressed state is placed between the spaced blood vessels to which it is to be connected and expanded so that its diameter is larger than that of the blood vessels. 2) The blood vessel is placed within the stent. 3) The stent is contracted so that its diameter is smaller than that of the expanded stent but larger than that of the compressed stent. 4) The stent may be fixed onto the blood vessel using expansion rings or microclamp stents (placed inside the blood vessels) so that the blood vessel is clamped between the stent and the rings at both ends of the stent. Multiple such rings or other corresponding fasteners (flanges, clamps, etc.) may be used, but are not required. If the stent is to be used inside a blood vessel, the assembly process is similar, with the rings (clamps) placed on the outside of the blood vessel. Mixed configurations are also possible, with one end of the stent located within a first blood vessel and the other end of the stent surrounding a second blood vessel.

[0007] Another US patent, US6336937, describes the possibility of using self-expanding stents to bypass ambolic fragments of blood vessels. In such a bypass, two expandable stent tips are placed upstream and downstream of the occlusion in the blood vessel and connected by a flexible tube (e.g., made of polymer). The length of the tube is selected as needed to provide the bypass. To place the device in the blood vessel, the vessel is opened as needed and the tip of the stent is inserted into the vessel. The tip expands and becomes fixed within the vessel. Blood flows through the tube to the other end of the bypass connection, which is then placed in the blood vessel at a location behind the occlusion in a similar manner.

[0008] U.S. Patent Application US20200360126A1 describes a self-expanding or balloon-expandable stent used at the junction of two blood vessels to prevent vascular stenosis after an anastomosis. To perform the anastomosis, the blood vessels are connected by sutures, clips, or other elements used to connect the vessels. In this solution, the stent provides structural support and ensures that the blood vessels are properly secured to one another. The stent further prevents restenosis of the blood vessels. Because the blood vessels being connected may have different diameters, the stent inserted therein must also have different diameters after expansion at both ends. The change in diameter may be gradual along the length of the stent or may be sudden at a specific point on the stent. Summary of the Invention [Problem to be solved by the invention]

[0009] The object of the present invention is to develop a method for securely and permanently connecting a living organ to a vascular graft outside of the living body under ex vivo conditions. This object is achieved by employing a system designed for this purpose. DETAILED DESCRIPTION OF THE INVENTION

[0010] The present invention relates to a system for connecting a biological organ to a vascular graft, the system comprising a self-expanding stent, a casing, and a mandrel having a breakable tip, wherein, in an assembled state, the stent is placed in a compressed state within the casing, the casing holding the stent in the compressed state until the stent is removed, the mandrel being placed inside the stent for removing the stent from the casing, the assembled state having lengths of the casing and mandrel ranging from 20 to 40 cm, and the stent length ranging from 10 to 40 mm, the diameter of the stent being selected such that, in the compressed state, the diameter of the stent is smaller than the diameter of the vascular graft, and, when expanded, the diameter of the stent is equal to or greater than the diameter of the vascular port of the biological organ. Preferably, in an expanded state, the diameter of the stent is in the range of 0.2 mm to 50 mm, preferably in the range of 1 to 20 mm.

[0011] In the assembled state, the casing and mandrel may have a length of 30 cm and the stent may have a length of 20 mm.

[0012] Preferably, the mandrel is provided with a circumferential notch that allows the frangible tip of the mandrel to break off.

[0013] The frangible tip of the mandrel may be conical with a rounded end.

[0014] Preferably, the stent comprises at least one fixation loop, preferably two fixation loops, one at each end of the stent.

[0015] Preferably, the casing is provided with a depth indicator.

[0016] Optionally, the system comprises a set of at least two samplers that allow selection of the diameter of the stent to match the diameter of the vascular port, the samplers having different diameter sizes in the range of 0.2 mm to 50 mm, preferably 1 mm to 20 mm.

[0017] The present invention relates to a method for connecting a biological organ to a vascular graft, said connection being achieved by the system of the present invention, said method comprising: a) inserting the assembled system into the vascular graft; b) partially removing the stent from the casing and attaching the stent to the vascular graft, preferably using loops; c) cutting the tip of the mandrel, preferably with a circumferential notch; d) inserting the vascular graft with the stent attached within the casing into the vascular port of the living organ; e) removing the stent from the casing using the mandrel; f) removing the casing (3) and the mandrel from the vascular port of the living organ; The present invention also relates to a method comprising:

[0018] The following may be used as vascular grafts: - decellularized or recellularized blood vessels of animal origin, or -Preserved blood vessels of animal origin, or autologous blood vessels, preferably the saphenous vein, or - Preserved blood vessels from deceased donors, or - Non-preserved vessels harvested from deceased donors, or - Artificial blood vessels, preferably made of EPTFE (expanded polytetrafluoroethylene).

[0019] Before carrying out step a), the vascular graft may be decellularized and then implanted with endothelial cells.

[0020] The biological organs may be fabricated using 3D bioprinting technology.

[0021] Preferably, the insertion depth in step d) is regulated by a depth indicator, said depth corresponding to the length of the stent used.

[0022] Preferably, in step d), the stent is inserted to a depth of 10 to 40 mm, more preferably to a depth of 15 to 30 mm, most preferably to a depth of 20 mm.

[0023] Most preferably, the sequence of steps a) to f) is performed for each of the vascular ports of the living organ. [Brief explanation of the drawings]

[0024] The object of the invention in this embodiment is illustrated in the following drawings.

[0025] FIG. 1 shows a stent 2 in a compressed state prior to insertion into a vascular graft 4, with 1 being the stent mandrel and 3 being the stent casing.

[0026] Figure 2 shows the stent 2 after it has been secured to a vascular graft 4 and before it is placed in a vascular port 7 in a living organ 8, where 1* is the mandrel after the tip has been broken off, 5 is a depth indicator, and 6 is a fixation loop.

[0027] FIG. 3 shows a stent 2 connected to a vascular graft 4 after placement in a vascular port 7 .

[0028] FIG. 4 shows a set of samplers with different diameters for selecting the diameter of a stent 2 for a vascular graft 4 .

[0029] FIG. 5 shows an artificial pancreas biological organ 8 connected by a stent 2 through a vascular port 7 to a vascular graft 4 and the flow of contrast media across the biological organ 8.

[0030] For purposes of the present invention, a vascular graft is defined as a blood vessel of animal origin, such as a blood vessel harvested from a pig, cow, sheep, or other animal, or a blood vessel of human origin, which has been previously harvested from a human or animal body as part of the practice of a method according to the present invention and which has not been connected to the human or animal body.

[0031] Preferably, such vessels have been previously decellularized, i.e., cells and foreign DNA have been removed to eliminate potential tissue incompatibility with the recipient. Even more preferably, following decellularization, such vessels are loaded with recipient cells. Decellularization can be achieved using any method known in the art, such as using a flow method or a static system in which the vessel is placed in a detergent solution within the vessel on a shaker.

[0032] The term "bionic organ" or "artificial organ" refers to an artificially obtained three-dimensional structure that mimics an organ such as the pancreas, lung, heart, or liver. Preferably, the biological organ is obtained using 3D bioprinting. The biological organ is equipped with a vascular system that terminates in vascular ports.

[0033] The method according to the present invention provides a rapid, tight and permanent connection between a living organ and a vascular graft.

[0034] The vascular graft thus connected together with the living organ may then be connected to the recipient's vasculature, for example by vascular sutures (indirect connection using the vascular graft).

[0035] The connection method according to the invention can also be used to directly connect a biological organ to the recipient's vasculature by using an in vivo stent to connect the organ directly to the recipient's blood vessel. More specifically, such a connection is made by incising the recipient's blood vessel upstream of the connection point with the biological organ and inserting and expanding the stent therein to secure the connection. The following options are possible for connecting a biological organ to the recipient's vasculature in situ: - In situ isolated arterial and venous vessels of the recipient Steps a) to c) of the method according to the invention are now replaced by the following: the recipient's terminal vessels (cut at one end) (e.g. epigastric vein and artery, internal iliac vein and artery) isolated over a distance of at least 30 mm are temporarily closed, preferably with a vascular clamp, and an incision is made near the closure site in order to introduce the system according to the invention through an opening made towards the cut end.

[0036] Further steps of connecting the vessel to the vascular port of the living organ are similar to the ex vivo method according to the invention: Once the mandrel is removed, the vascular opening is closed with vascular sutures. - In situ isolated arterial and venous vessels of the recipient Steps a) to c) of the method according to the invention are now replaced as follows: the recipient's terminal vessels (e.g., epigastric vein and artery, internal iliac vein and artery), isolated over a distance of at least 30 mm, are temporarily closed, preferably with vascular clamps, and a central incision is made. An incision is then made in the vessel, preferably near both clamps, in order to introduce the system according to the invention through the resulting opening towards the cut end. The further steps of connecting the vessels to the vascular ports of the living organ (here with vascular ports located at both ends) are similar to the ex vivo method according to the invention. Once the mandrel is removed, the vascular opening is closed with vascular sutures.

[0037] Systems for connecting living organs to vascular grafts have undergone various modifications with respect to commercially available stents in order to allow them to be used in the method according to the present invention.

[0038] The stents described in this application are housed within a casing that maintains the stent in a compressed (contracted) state until removed from the casing, and include a mandrel that allows the stent to be removed from the casing, at which point the stent expands to its expanded state.

[0039] Such a stent may further comprise depth indicators on its casing to allow accurate positioning during insertion, especially during insertion into the vasculature of a living organism, which allow for accurate implantation of the stent with the vascular graft within the inlet / outlet openings (vascular ports) of the living organism to optimize insertion.

[0040] The stents described herein may be provided with loops at each end that extend beyond the stent casing. These loops are used to secure the stent to a vascular graft using surgical thread. Compared to commercially available systems, the system disclosed herein is characterized by a reduced length of the assembled casing and mandrel, which ranges from 20 to 40 cm and is preferably equal to 30 cm. This reduced length facilitates handling of the stent under laminar chamber conditions.

[0041] Stents are also available in a variety of diameters and lengths. The diameter of the stent when fully expanded (fully expanded means the maximum expansion of the stent outside the vascular graft and vascular port) ranges from 0.2 to 50 mm, preferably from 1 to 20 mm, and is appropriately selected so that the diameter of the stent before expansion is smaller than the diameter of the vascular graft and the stent expands to a diameter equal to or greater than the diameter of the vascular port. Preferably, the diameter of the stent after expansion is between 100% and 150% of the diameter of the vascular port. Examples of stents with various diameters are shown in Figure 4. The length of the stent ranges from 10 to 40 mm, preferably equal to 20 mm. This range of available stent diameters and lengths offers a wide range of adaptability depending on the type of organ to be implanted and the diameter of the vascular graft and vascular port.

[0042] Furthermore, the system according to the invention comprises a mandrel with a breakable tip. This mandrel can be provided with a notch along its circumference at the level of the outer end of the stent, so that the mandrel tip can be broken off in place. The breakable mandrel tip prevents damage to the living organ or vascular port when inserting the vascular graft together with the stent into the living organ or vascular port. This solution also eliminates the need to design the living organ's vessel in a straight line relative to the vascular port. The breakable tip prevents the mandrel from abutting against the living organ's vessel wall when the stent is pushed out, preventing the mandrel from compressing the vessel wall.

[0043] The modification of existing solutions as described above makes the system according to the invention a unique and currently unavailable product that may play an important role in the field of transplantation, especially in the case of living organ transplantation.

[0044] Preferably, the system according to the invention comprises a set of samplers that allow the diameter of the stent to be precisely matched to the vascular graft. Such a set of samplers may include the following samplers with diameters ranging from 0.2 to 50 mm, preferably from 1 to 20 mm; preferably, the set includes the full range of samplers with diameters from 1 to 20 mm in 0.5 mm increments. [Example]

[0045] Example 1 - Preparation of a stent for use in a method according to the present invention based on a commercially available stent

[0046] To obtain a stent (2) suitable for use in the method according to the invention, the following modifications were made to a commercially available stent having a size of 6 mm x 20 mm. The mandrel (1) and casing (3) set of the stent (2) is shortened to a length of 30 cm, allowing it to be handled ex vivo in a laminar flow chamber. For comparison, commercially available mandrel and casing sets have a length of, for example, 125 cm. - A slit of about 5 mm in length is made in the casing (3) of the stent (2) to allow placement of a surgical thread in the first loop of the stent without opening the stent. - Create two fixation loops (6) on the outer edge of the stent (2), one at each end of the stent (2). - Creating a circumferential notch in the mandrel (1) near the point where it retracts into the casing (3) to facilitate subsequent breaking or twisting. - Creating a depth indicator (5) on the casing (3) of the stent (2).

[0047] Example 2 - Implementation of the connection between the vascular graft and the artificial pancreas (ex vivo stage of artificial pancreas implantation)

[0048] 1) Vascular graft creation

[0049] Grafts (4) were prepared using porcine splenic arteries obtained from a local slaughterhouse. Using a gauge, vessels measuring 3.5–4 mm in diameter and approximately 60 mm in length were selected. The vessels were then subjected to flow decellularization in a closed system at a constant flow rate of 40 mL / min. The decellularization process consisted of the following steps: - 1% Triton X-100 + 0.1% NH4OH solution in 1x PBS was allowed to flow for 48 hours at 4°C. -1xPBS solution containing 0.01% streptomycin was allowed to flow for 48 hours at 4°C. -0.0002% DNase I, 0.12 mM Ca 2+ and Mg 2+ Flow the 1xPBS solution containing HCl at 37°C for 8 hours. - Allow to flow for 48 hours at 4 °C with 1x PBS solution containing 0.01% streptomycin.

[0050] The blood vessels were then stored in 1x PBS containing 0.01% streptomycin and sterilized with radiation at a dose of 25 kGy. Finally, the blood vessels were repopulated with recipient cells (using recipient endothelial cells).

[0051] 2) Stent selection

[0052] A self-expanding stent (2) with a diameter of 6 mm and a length of 20 mm, obtained as described in Example 1, was used in the experiment.

[0053] 3) An artificial pancreas connected to a vascular graft

[0054] A bioprinted organ, the artificial pancreas (8), was used in the experiments. The organ (8) was obtained by extrusion bioprinting technology using bioink, which is the subject of another patent application by the same applicant, EP19218191.5, still pending at the filing date of this application. The organ housing components (8) were printed using SLA technology with a photocurable polymer. The inlet and outlet vascular ports (7) of the artificial pancreas (8) had identical diameters of 4 mm.

[0055] 4) Experimental flow

[0056] This method is shown schematically in Figures 1-3. Figure 1 shows the stent (2) in a compressed state before insertion into the vascular graft (4). In its compressed form, the stent (2) was located inside a casing (3). The casing was fitted with a mandrel (1), the rounded, tapered tip of which allowed for easy and damage-free insertion of the stent (2) into the vascular graft (4).

[0057] As shown in Figure 2, in the first step of connecting a living organ (8) to a vascular graft (4), a stent (2) in a compressed form placed in a casing (3) was inserted into the vascular graft (4) to an appropriate depth. The stent in the casing (3) was inserted into the graft so that it was completely inside the graft.

[0058] After inserting the stent (2) together with the casing (3) into the vascular graft (4), the stent (2) was gently removed from the casing (3) without fully unfolding the stent (2) so that it could be secured to the vascular graft (4) via the fixation loops (6) at both ends of the stent (2). This was achieved by suturing the loops (6) to the vascular graft (4) with surgical thread to secure the stent (2) within the graft (4). The stent (2) was then sutured to the vascular graft (4) using a single vascular suture (Prolen 4-0) at both ends of the stent (2). At the appropriate circumferential notched points, the tip of the mandrel (1) protruding beyond the contours of the casing (3) was broken off. At this stage, the tip had already fulfilled its function, i.e., it allowed the vascular graft (4) to slide over the casing (3). This tip was no longer necessary and even prevented the execution of subsequent steps of the method.Two such structures were prepared for connecting a vascular graft (4) to a stent (2).

[0059] In the next step shown in Figure 3, the vascular graft (4) with the stent (2) sutured within the casing (3) was inserted into the vascular port (7). The resulting structure connecting the vascular graft (4) and stent (2) was inserted into the arterial vascular port (7) and venous vascular port (7) of the artificial pancreas (8) to a depth of 20 mm. This depth also corresponded to the length of the stent (2) used. The latter value was particularly important because it ensured proper fixation without excessively expanding the entire organ. The inner diameter of the vascular graft (4) was selected to be 0.0 to 0.5 mm larger than the inner diameter of the vascular port (7). In this step, the insertion depth was controlled using a depth indicator (5).

[0060] In the next step, each of the two self-expandable stents (2) was removed from the casing (3) using a mandrel (1*) and the stents (2) were expanded to their expanded state.

[0061] The casing 3 and mandrel 1* of the stent 2 were then removed from both vascular ports 7 of the artificial pancreas 8, causing the stent 2 to expand to its expanded state, i.e., the diameter of the inlet and outlet of the artificial pancreas 8, i.e., 4 mm. This expanded vascular graft 4 and secured the stent 2 together with the vascular graft 4 to the lumen of each vascular port 7. In this process, the connection was achieved by the expansion force of the stent 2, which not only secured the connection but also secured the vascular graft 4 within the vascular port 7, preventing stenosis along the length of the stent 2. When the stent 2 was opened, the proximal portion of the stent 2 expanded slightly (by approximately 2 mm) beyond the contour of the vascular graft 4 to be implanted. The exposed portion of the stent (2) located on the outside of the graft (4) secured the artificial pancreas (8) to the vascular port (7), and the tapered funnel-shaped portion further sealed the vascular port (7).

[0062] 5) Results

[0063] The artificial pancreas (8) obtained in this experiment is shown in Figure 5. This figure shows the flow of contrast agent through the pancreas (8) from the inlet vascular graft to the outlet vascular graft. The fixation of the vascular graft (4) by the stent (2) is marked in black.

[0064] Ex vivo tests performed demonstrated that the connection was robust at pressures up to 180 mmHg. Above this value, a loss of tightness was observed in the artificial pancreas (8), but this only involved dissection of the functional part of the artificial pancreas (8), and not the vascular port (7).

[0065] The artificial pancreas (8) connected to the vascular graft (4) obtained as in Example 2 was implanted into a live pig by dissecting each of the pig's iliac vessels and connecting the venous and arterial vascular ports (7) of the artificial pancreas (8) to the vascular graft (4) located therein using end-to-side Carrel sutures. After 14 days, the artificial pancreas (8) was again removed and dissected for visual inspection.

[0066] In vivo experiments confirmed that the resulting vascular graft (4) and artificial organ (8) connection was durable and strong.

Claims

1. A system for connecting a living organ to a vascular graft, comprising a self-expanding stent (2), a casing (3), and a mandrel (1) with a breakable tip, wherein, when the system is assembled, the stent (2) is placed in a compressed state within the casing (3), the casing (3) holds the stent (2) in a compressed state until the stent (2) is removed, and the mandrel (1) removes the stent (2) from the casing (3). and a stent (2) is placed inside the casing (3) to compress the vascular graft (4), the length of the casing (3) and the mandrel (1) being in the range of 20-40 cm and the length of the stent (2) being in the range of 10-40 mm in the assembled state, the diameter of the stent (2) being selected so that in the compressed state the diameter of the stent (2) is smaller than the diameter of the vascular graft (4), and the diameter of the stent (2) is equal to or greater than the diameter of the vascular port (7) of the biological organ (8) when expanded. A system characterized by:

2. The system according to claim 1, characterized in that in the expanded state, the diameter of the stent (2) is in the range of 0.2 mm to 50 mm.

3. 3. The system according to claim 1 or 2, characterized in that in the assembled state, the length of the casing (3) and the mandrel (1) is 30 cm and the length of the stent (2) is 20 mm.

4. 4. A system according to any one of claims 1 to 3, characterized in that the mandrel (1) is provided with a circumferential notch that allows the breakable tip of the mandrel (1) to be broken off.

5. 5. A system according to any one of claims 1 to 4, characterized in that the breakable tip of the mandrel (1) has a conical shape with a rounded end.

6. 6. The system according to any one of claims 1 to 5, characterized in that the stent (2) comprises at least one fixation loop (6).

7. 7. System according to any one of the preceding claims, characterized in that the casing (3) is provided with a depth indicator (5).

8. 8. The system according to claim 1, further comprising a set of at least two samplers that allow the diameter of the stent (2) to be selected to match the diameter of the vascular port (7), the samplers having different diameter sizes ranging from 0.2 mm to 50 mm.

9. 9. A method for connecting a living organ to a vascular graft under ex vivo conditions, said connection being achieved by a system according to any one of claims 1 to 8, said method comprising: a) inserting the assembled system into the vascular graft (4); b) partially removing the stent (2) from the casing (3) and attaching the stent (2) to the vascular graft (4); c) cutting off the tip of the mandrel (1); d) inserting the vascular graft (4) with the stent (2) mounted in the casing (3) into the vascular port (7) of the living organ (8); e) removing the stent (2) from the casing (3) using the mandrel (1*); f) removing the casing (3) and the mandrel (1*) from the vascular port (7) of the living organ (8); A method comprising:

10. 10. The method according to claim 9, characterized in that as the vascular graft (4) there is used: - decellularized or recellularized blood vessels of animal origin, or - preserved blood vessels of animal origin, or - Autologous blood vessels, or - Vessels harvested and preserved from deceased donors, or - Non-preserved blood vessels taken from deceased donors, or - Artificial blood vessels.

11. 11. The method according to claim 9 or 10, characterized in that before carrying out step a), the vascular graft (4) is decellularized and then implanted with endothelial cells.

12. 12. The method according to any one of claims 9 to 11, characterized in that the biological organ (8) is prepared using 3D bioprinting technology.

13. 13. The method according to any one of claims 9 to 12, characterized in that the insertion depth in step d) is controlled by a depth indicator (5) and corresponds to the length of the stent (2) used.

14. A method according to claim 13, characterized in that in step d) the stent (2) is inserted to a depth of 10 to 40 mm.

15. 15. The method according to any one of claims 9 to 14, characterized in that the sequence of steps a) to f) is performed for each of the vascular ports (7) of the living organ (8).

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