Degradable stent for promoting artificial blood vessel tissue regeneration and preparation method thereof

Abstract

The invention provides a degradable stent for promoting artificial blood vessel tissue regeneration and a preparation method thereof.The degradable stent is a three-layer tubular stent constructed by degradable polymers, the middle layer is a nanofiber layer, a large number of micropores exist in the tube wall of the inner layer and the tube wall of the outer layer, and the micropores are evenly distributed in the tube wall of the inner layer and the tube wall of the outer layer. And the micropores are mutually communicated in series and extend from inside to outside to form a bead structure. The bead structure extends to the outer surface from the interior of the tube cavity and becomes a micro-channel for cells to migrate inwards, and the cells can endocrine extracellular matrix on the tube wall, so that the purpose of promoting regeneration of new tissues is achieved; meanwhile, the nanofiber layer can separate micropore channels of the inner layer and the outer layer, different cells can grow on the inner layer and the outer layer respectively, and then pores in the nanofiber layer do not allow the cells to pass through but allow nutrient substances and growth factors secreted by the cells to pass through, so that information exchange of the cells on the two sides is promoted, and cell behaviors are adjusted; the vascular remodeling is further accelerated.

Description

Technical Field

[0001] The present invention relates to the technical field of medical devices, and in particular to a degradable stent for promoting the regeneration of artificial blood vessel tissue and a preparation method thereof. Background Art

[0002] Cardiovascular disease (CDV) has become one of the diseases with the highest mortality rate in the world. It is estimated that by 2025, the number of people suffering from cardiovascular disease in the world will reach 4 million. Artificial blood vessels can replace and reshape damaged natural blood vessels for vascular replacement, vascular bypass and vascular fistula. At present, the large-caliber (inner diameter>6mm) artificial blood vessel stents used in clinical practice are polyester (PET) and polytetrafluoroethylene (ePTFE) artificial blood vessels, which are mainly used to treat aortic aneurysm repair and aortic coarctation. However, due to the poor biocompatibility of polymer materials, it is easy to activate coagulation reactions to form thrombi, thereby causing vascular blockage. The hard polymer material is also not compatible with the mechanical energy of natural blood vessels, resulting in blood confusion at the suture site, further increasing the risk of vascular blockage. Due to thrombosis, these two stents showed poor patency in the early and middle stages of implantation and are not suitable for the preparation of small-caliber artificial blood vessel stents. Autologous transplanted blood vessels are soft and have good biocompatibility, but they have not been widely promoted due to limited sources. In order to obtain an artificial vascular stent with good biocompatibility to meet the demand for small-caliber artificial blood vessels, more and more researchers have turned their attention to degradable materials.

[0003] Degradable materials include degradable natural materials and degradable synthetic materials. They are widely used to make implantable stents for heart valves, organs, muscles, etc. due to their excellent biocompatibility. Degradable vascular stents are usually formed by electrospinning, phase separation and other methods to obtain a uniform hollow tubular structure, but the endothelialization effect of the dense wall structure is not ideal. This is because it is difficult for cells to grow inside the stent, and the smooth inner wall is also very unfavorable for cell adhesion. Although electrospinning can produce a dense fiber mesh, the micron-level pores do not allow cell infiltration. This single-structure stent delays the rate of tissue regeneration and may trigger a series of inflammatory reactions, increasing the risk of stent blockage. Therefore, it is necessary to design a degradable stent that promotes the regeneration of artificial vascular tissue. Summary of the invention

[0004] The present invention provides a degradable stent for promoting the regeneration of artificial blood vessel tissue and a preparation method thereof. The degradable stent is a three-layer tubular stent structure. A large number of micropores are present in the inner and outer tube walls. The micropores are interconnected to form a beaded structure. The beaded structure extends from the tube cavity to the outer surface and becomes a microchannel for cells to migrate inward. The cells can secrete extracellular matrix in the tube wall, thereby achieving the purpose of promoting the regeneration of new tissue. At the same time, the middle layer of the degradable stent is a nanofiber layer with certain pores, which functions to block but not block. First, the microporous channels of the inner and outer layers can be separated, and different cells can be grown in the inner layer and the outer layer respectively, which makes up for the defect of slow growth and proliferation of single cells and accelerates vascular remodeling. Secondly, the pores on the nanofiber layer do not allow cells to pass through, but allow nutrients and growth factors secreted by cells, such as NO and various enzymes, to pass through, thereby promoting information exchange between cells on both sides, regulating cell behavior, and further accelerating vascular remodeling.

[0005] In order to solve the above technical problems, the technical solution of the present invention is:

[0006] A degradable stent for promoting the regeneration of artificial vascular tissue. The degradable stent is a three-layer tubular stent constructed of a degradable polymer, the middle layer is a nanofiber layer, and a large number of micropores exist in the tube walls of the inner and outer layers. The micropores are connected in series and extend from the inside to the outside to form a beaded structure.

[0007] The degradable polymer of each layer in the three-layer tubular stent is one or more of polycaprolactone (PCL), polylactic acid (PLA), polyglycolide (PGA), polylactic acid-glycolic acid (PGLA) and polyglycolide-lactide (PLGA), and the molecular weight of the degradable polymer is 5000-20000MW.

[0008] The three-layer tubular stent has an inner layer with a wall thickness of 0.2-0.4 mm, a middle layer with a wall thickness of 0.1-0.2 mm, and an outer layer with a wall thickness of 0.2-0.4 mm.

[0009] The length of the degradable stent is 6-20 cm, and the inner diameter of the degradable stent is 0.1-3.0 cm.

[0010] The maximum diameter of the micropores in the beaded structure of the outer layer and the inner layer of the three-layer tubular stent is 400-600 μm, the minimum diameter of the micropores is 300-400 μm, the diameter of the serially connected micropores is 100-300 μm, the porosity of the micropores is 30-60%, the pore diameter of the nanofiber layer is 10-20 μm, and the porosity of the nanofiber layer is 10-15%.

[0011] The nanofiber layer is prepared by an electrospinning process, and the technical parameters of the electrospinning process include: an extrusion speed of 2.5.0-3.0 mL / h, a voltage of +12-20 kV, a distance between the needle and the bracket of 15-20 cm, a rotation speed of 700-1000 rpm, and a spinning temperature of room temperature.

[0012] The shape of the micropores is one or more combinations of circular, elliptical, square and triangular.

[0013] The present invention also provides a method for preparing a degradable stent for promoting the regeneration of artificial vascular tissue, comprising the following steps: S1, preparing a set of molds; the mold comprises a round tube, a round rod, a lower end cover, an upper conversion joint and a lower conversion joint, the lower end cover is detachably connected to the lower end of the round tube, a round hole groove is arranged at the center of one side of the round tube near the lower end cover, the diameter of the round hole groove matches the outer diameter of the round rod, the round rod is inserted into the round tube and connected to the round hole groove of the lower end cover; one end of the upper conversion joint and the lower conversion joint can be detachably connected to the upper and lower ends of the round tube, and the other ends of the upper conversion joint and the lower conversion joint are detachably connected to a syringe and a vacuum pump respectively;

[0014] S2, connect the lower end cover of the mold to the lower end of the round tube, insert the round rod into the round tube and connect it to the round hole groove of the lower end cover, then fill the gap between the round rod and the round tube with gelatin microspheres with a diameter of 10-20 μm, then place the round tube in an environment with a humidity of 60-70% and a temperature of 24-26°C for 6-12 hours, and then place it in an environment with a humidity of 40-60% and a temperature of 26-28°C for drying for 6-12 hours, so that the gelatin microspheres are bonded to each other;

[0015] S3. Prepare a degradable polymer solution with a mass fraction of 5-10% by using an organic solvent, and pour the degradable polymer solution into a syringe; connect the upper conversion joint and the lower conversion joint to the upper and lower ends of the round tube respectively, and then connect the upper conversion joint and the lower conversion joint to the syringe and the vacuum pump respectively, turn on the vacuum pump to evacuate, and introduce the degradable polymer solution into the gaps of the gelatin microspheres under negative pressure;

[0016] S4, connecting the lower end cap to the lower end of the round tube, placing the round tube in an environment with a humidity of 60-70% and a temperature of 24-26° C. for curing for 24-48 hours, and then soaking the round tube in distilled water for 1-3 days to remove the gelatin microspheres and residual organic solvent, and obtaining a single-layer tubular scaffold with micropores of a beaded structure;

[0017] S5, taking out the single-layer tubular scaffold with micropores of beaded structure obtained in S4 from the round rod and the round tube, preparing a degradable polymer solution with a mass fraction of 20% by organic solvent, and electrospinning a nanofiber layer on the surface thereof to obtain a double-layer tubular scaffold;

[0018] S6. Insert the double-layer tubular stent wrapped in S5 back into the round rod and the round tube, and repeat the process of S2-S4 to obtain a three-layer tubular stent.

[0019] The organic solvent is one or more of hexafluoroisopropanol, dioxane, dimethylformamide, dimethylacetamide and tetrahydrofuran.

[0020] The gelatin microspheres are prepared from a gelatin aqueous solution with a mass fraction of 2-4% by microfluidic technology.

[0021] Compared with the prior art, the present invention has the following beneficial effects: (1) The degradable stent for promoting the regeneration of artificial vascular tissue provided by the present invention is a three-layer tubular stent structure, with a large number of micropores in the inner and outer tube walls, which are interconnected to form a beaded structure. The beaded structure extends from the lumen to the outer surface and becomes a microchannel for cells to migrate inward. Cells can secrete extracellular matrix in the tube wall, thereby achieving the purpose of promoting the regeneration of new tissue.

[0022] (2) The middle layer of the degradable stent in the present invention is a nanofiber layer with certain pores, which can separate the microporous channels of the inner and outer layers, so that different cells can grow in the inner and outer layers respectively, making up for the defect of slow growth and proliferation of single cells and further accelerating vascular remodeling. Secondly, the pores on the nanofiber layer allow information exchange between cells, further regulating cell behavior and accelerating vascular remodeling.

[0023] (3) In the present invention, gelatin microspheres are adhered to each other to form channels with a beaded structure in the degradable polymer. Gelatin can be dissolved at 30°C, which is convenient for pore formation. In addition, gelatin has good biocompatibility, is non-toxic, and is degradable. Even if gelatin cannot be completely removed during the preparation of the stent, the gelatin will degrade over time after the stent is implanted.

[0024] (4) The present invention prepares the degradable stent through a special mold, the preparation method is simple, the mold structure is simple, and the manufacturing cost is low. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A schematic diagram of the structure of a degradable stent for promoting the regeneration of artificial vascular tissue provided by the present invention;

[0026] Figure 2 A flow chart of a method for preparing a degradable stent for promoting regeneration of artificial vascular tissue provided by the present invention;

[0027] Figure 3 An electron microscope image of the degradable stent for promoting the regeneration of artificial vascular tissue provided by the present invention;

[0028] Figure 4 This is a confocal staining image of the degradable scaffold in this embodiment;

[0029] In the figure: 1-round tube, 2-round rod, 3-lower end cover, 4-upper conversion joint, 5-lower conversion joint, 6-syringe. DETAILED DESCRIPTION

[0030] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0031] The structure of the degradable stent for promoting the regeneration of artificial vascular tissue provided by the present invention is as follows: Figure 1 As shown, the degradable stent is a three-layer tubular stent constructed of degradable polymers. Specifically, the degradable polymers of each layer in the three-layer tubular stent are one or more of polycaprolactone, polylactic acid, polyglycolide, polylactic acid-glycolic acid and polyglycolide lactide, and the molecular weight of the degradable polymer is 5000-20000MW. Further, the length of the degradable stent is 6-20cm, and the inner diameter of the degradable stent is 0.1-3.0cm. The inner layer wall thickness of the three-layer tubular stent is 0.2-0.4mm, the middle layer wall thickness is 0.1-0.2mm, and the outer layer wall thickness is 0.2-0.4mm.

[0032] In this embodiment, the middle layer of the three-layer tubular stent is a nanofiber layer, and there are a large number of micropores in the tube walls of the inner and outer layers, and the micropores are connected in series and extend from the inside to the outside to form a beaded structure. Figure 1 . This structure can promote the inward migration of cells and secrete extracellular matrix in the lumen, thereby accelerating tissue regeneration; the nanofiber layer can separate the inner and outer porous structures, allowing different cells to grow in the inner and outer layers respectively. The multi-cell growth of the scaffold further promotes vascular remodeling. Secondly, the pores on the nanofiber layer allow information exchange between cells, further regulating cell behavior and accelerating vascular remodeling. Specifically, the multi-cells are one or more of endothelial cells (HUVEC cells), smooth muscle cells (SMC cells), fibroblasts (Fibroblast), and mesenchymal stem cells (MSC). Figure 1 The inner layer of the tube wall is mainly composed of endothelial cells, while the outer layer of the tube wall is mainly composed of smooth muscle cells.

[0033] Specifically, the shape of the micropores is one or more combinations of circular, elliptical, square and triangular. Further, the porosity of the micropores in the tube wall of the outer layer and the inner layer of the three-layer tubular stent is 30-60%, and the porosity of the nanofiber layer is 10-15%. Preferably, the maximum diameter of the micropores at the beaded structure of the outer layer and the inner layer of the three-layer tubular stent is 400-600 μm, the minimum diameter of the micropores is 300-400 μm, the diameter of the serial connection between the micropores is 100-300 μm, and the pore diameter of the nanofiber layer is 10-20 μm.

[0034] The present invention also provides a method for preparing a degradable stent for promoting the regeneration of artificial vascular tissue, such as Figure 2 As shown, the following steps are included: S1, preparing a set of molds;

[0035] Mould structure Figure 2 The mold includes a round tube 1, a round rod 2, a lower end cover 3, an upper conversion joint 4 and a lower conversion joint 5. The lower end cover is detachably connected to the lower end of the round tube. In actual setting, the lower end cover is connected to the lower end of the round tube by interference fit or threading; a circular hole groove (not shown in the figure) is provided at the center of one side of the round tube near the lower end cover. The diameter of the circular hole groove matches the outer diameter of the round rod. The round rod is inserted into the round tube and connected to the circular hole groove of the lower end cover. Figure 2 , so that the round rod is coaxially connected to the round tube; one end of the upper conversion joint and the lower conversion joint can be detachably connected to the upper and lower ends of the round tube. In actual settings, the upper conversion joint and the lower conversion joint can also be connected to the upper and lower ends of the round tube by interference fit or threading; the other ends of the upper conversion joint and the lower conversion joint are respectively detachably connected to the syringe 6 and the vacuum pump; specifically, the round tube is a stainless steel tube, and the round rod is made of polytetrafluoroethylene material.

[0036] S2, connect the lower end cover of the mold to the lower end of the round tube, insert the round rod into the round tube and connect it to the round hole groove of the lower end cover, then fill the gap between the round rod and the round tube with gelatin microspheres with a diameter of 10-20 μm, and then place the round tube in an environment with a humidity of 60-70% and a temperature of 24-26°C (high humidity environment) for 6-12 hours, and use the moisture in the air to make the gelatin microspheres adhere to each other; then place it in an environment with a humidity of 40-60% and a temperature of 26-28°C for drying for 6-12 hours, so that the gelatin microspheres adhere to each other;

[0037] Specifically, the gelatin microspheres are prepared by microfluidics technology using a gelatin aqueous solution with a mass fraction of 2-4%.

[0038] S3. Prepare a degradable polymer solution with a mass fraction of 5-10% by organic solvent, and pour the degradable polymer solution into a syringe; remove the lower end cap, connect the upper conversion joint and the lower conversion joint to the upper and lower ends of the round tube respectively, and then connect the upper conversion joint and the lower conversion joint to the syringe and the vacuum pump respectively, turn on the vacuum pump to evacuate, and introduce the degradable polymer solution into the gaps of the gelatin microspheres under negative pressure;

[0039] Specifically, the organic solvent is one or more of hexafluoroisopropanol, dioxane, dimethylformamide, dimethylacetamide, and tetrahydrofuran;

[0040] S4, remove the upper conversion joint and the lower conversion joint, connect the lower end cap to the lower end of the round tube, place the round tube in an environment with a humidity of 60-70% and a temperature of 24-26°C for curing for 24-48 hours, and then soak the round tube in distilled water for 1-3 days to remove the gelatin microspheres and residual organic solvent, and obtain a single-layer tubular scaffold with micropores of a beaded structure;

[0041] S5, taking out the single-layer tubular scaffold with micropores of beaded structure obtained in S4 from the round rod and the round tube, preparing a degradable polymer solution with a mass fraction of 20% by organic solvent, and electrospinning a nanofiber layer on the surface thereof to obtain a double-layer tubular scaffold;

[0042] Specifically, the technical parameters of the nanofiber layer include: extrusion speed of 2.5.0-3.0 mL / h, voltage of +12-20 kV, distance between the needle and the support of 15-20 cm, rotation speed of 700-1000 rpm, and spinning temperature of room temperature;

[0043] S6, insert the double-layer tubular stent wrapped in S5 back into the round rod and the round tube, and repeat the process of S2-S4 to obtain a three-layer tubular stent. The diameter of the round tube used in this step is larger than the diameter of the round tube in step S2, and the sizes of the matching lower end cap, upper conversion joint and lower conversion joint are also different, so as to obtain a three-layer tubular stent of the required thickness.

[0044] The electron microscopy image of the degradable stent prepared in this example is as follows: Figure 3 As shown, it can be observed that the pores inside the scaffold are evenly distributed and of appropriate size.

[0045] The degradable stent prepared in this example was used in an in vitro experiment, and the experimental steps were as follows:

[0046] 1. Seeding cells: Cut the biodegradable scaffold into 3 cm pieces, sterilize with alcohol overnight, and wash with PBS; culture the cells in a culture dish, and digest them with 0.25% trypsin after the fusion rate reaches more than 80%, resuspend in culture medium, and plate at 1*10 7 The density of cells / ml was seeded on the surface and lumen of the degradable scaffold;

[0047] 2. Perfusion culture: After the cells adhered to the wall for 4 hours, the samples were connected to the perfusion system, and the scaffolds were cultured in a dynamic environment for 7 days. The perfusion liquid flow rate was 1000 μl / min (i.e., the speed of the culture fluid flowing in the scaffold) to simulate the real human vascular microenvironment;

[0048] 3. Sample fixation and dehydration: After the 7th day of dynamic culture, the scaffold was removed from the perfusion system and fixed overnight in paraformaldehyde; then dehydrated overnight in 30% sucrose solution; and then dehydrated overnight in 40% sucrose solution;

[0049] 4. Cryosectioning: After the water on the surface of the sample is absorbed, OCT embedding is performed, and a 100 μm thick slice is cut using a cryostat (note that the cross section of the sample is cut at this time), and the sample is taken with a slide for subsequent staining and sealing;

[0050] 5. Cell staining: Use an immunohistochemistry pen to circle the sample range on the slide to prevent the dye from leaking out during the staining process. Add 0.3% Triton to permeabilize the cell membrane, discard after 15 minutes of treatment, and wash with PBS; prepare RFITC staining working solution (10μl stock solution + 2ml 3% BSA), drop it on the sample, incubate in the incubator in the dark for 30 minutes, discard, and wash with PBS; incubate DAPI working solution in the dark for 5 minutes, discard, and wash with PBS; add anti-fluorescence quencher, cover a slide, and add nail polish around to seal the slide;

[0051] 6. Confocal imaging: Place the slide upside down in a fluorescence microscope, adjust the focus and brightness, select the required field of view and magnification to shoot and save. The results are as follows: Figure 4 shown.

[0052] The cells used in the present embodiment are endothelial cells, and the cell size is about 60 μm, and the serial pores in the support vary from 100 to 300 um. Confocal staining pictures prove that cells adhere and spread on the inner wall of the pores, substantially covering the entire pore surface, and the migration degree is deeper, which is the result of the inward migration of cells adhered to the surface, proving that cells can grow on the support surface and migrate inward. In the early stage of seeding, cells only adhere to the surface of the support lumen, and after 7 days of dynamic cultivation, under the action of the osmotic pressure of the tube wall, the cells are pushed by the pressure to grow inside the support, and the pores on the support surface also have suitable space and microenvironment to accommodate the migrated cells, and the serial structure of the pores in the tube wall further accelerates the overall cellization of the support, because cells can infiltrate deeper into the support. And in the process of cell infiltration, it is not necessary for the support to degrade and produce pores with other special treatments, and the mechanical properties of the support after long-term implantation will not be reduced.

Claims

1. A degradable stent for promoting regeneration of artificial vascular tissue, characterized in that: The degradable stent is a three-layer tubular stent constructed of degradable polymers, wherein the middle layer is a nanofiber layer, and a large number of micropores exist in the tube walls of the inner and outer layers, and the micropores are interconnected in series and extend from the inside to the outside to form a beaded structure.

2. The degradable stent for promoting artificial vascular tissue regeneration according to claim 1, characterized in that: The degradable polymer of each layer in the three-layer tubular stent is one or more of polycaprolactone, polylactic acid, polyglycolide, polylactic acid-glycolic acid and polyglycolide-lactide, and the molecular weight of the degradable polymer is 5000-20000MW.

3. The degradable stent for promoting artificial vascular tissue regeneration according to claim 1, characterized in that: The three-layer tubular stent has an inner layer with a wall thickness of 0.2-0.4 mm, a middle layer with a wall thickness of 0.1-0.2 mm, and an outer layer with a wall thickness of 0.2-0.4 mm.

4. The degradable stent for promoting artificial vascular tissue regeneration according to claim 1, characterized in that: The length of the degradable stent is 6-20 cm, and the inner diameter of the degradable stent is 0.1-3.0 cm.

5. The degradable stent for promoting artificial vascular tissue regeneration according to claim 1, characterized in that: The maximum diameter of the micropores in the beaded structure of the outer layer and the inner layer of the three-layer tubular stent is 400-600 μm, the minimum diameter of the micropores is 300-400 μm, the diameter of the serially connected micropores is 100-300 μm, the porosity of the micropores is 30-60%, the pore diameter of the nanofiber layer is 10-20 μm, and the porosity of the nanofiber layer is 10-15%.

6. The degradable stent for promoting artificial vascular tissue regeneration according to claim 1, characterized in that: The nanofiber layer is prepared by an electrospinning process, and the technical parameters of the electrospinning process include: an extrusion speed of 2.5.0-3.0 mL / h, a voltage of +12-20 kV, a distance between the needle and the bracket of 15-20 cm, a rotation speed of 700-1000 rpm, and a spinning temperature of room temperature.

7. The degradable stent for promoting artificial vascular tissue regeneration according to claim 1, characterized in that: The shape of the micropores is one or more combinations of circular, elliptical, square and triangular.

8. A method for preparing a degradable stent for promoting regeneration of artificial vascular tissue according to any one of claims 1 to 7, characterized in that The following steps are involved: S1. Prepare a set of molds; the mold comprises a round tube, a round rod, a lower end cover, an upper conversion joint and a lower conversion joint, the lower end cover is detachably connected to the lower end of the round tube, a round hole groove is arranged at the center of one side of the round tube near the lower end cover, the diameter of the round hole groove matches the outer diameter of the round rod, the round rod is inserted into the round tube and connected to the round hole groove of the lower end cover; one end of the upper conversion joint and the lower conversion joint can be detachably connected to the upper and lower ends of the round tube, and the other ends of the upper conversion joint and the lower conversion joint are detachably connected to a syringe and a vacuum pump respectively; S2, connect the lower end cover of the mold to the lower end of the round tube, insert the round rod into the round tube and connect it to the round hole groove of the lower end cover, then fill the gap between the round rod and the round tube with gelatin microspheres with a diameter of 10-20 μm, then place the round tube in an environment with a humidity of 60-70% and a temperature of 24-26°C for 6-12 hours, and then place it in an environment with a humidity of 40-60% and a temperature of 26-28°C for drying for 6-12 hours, so that the gelatin microspheres are bonded to each other; S3. Prepare a degradable polymer solution with a mass fraction of 5-10% by using an organic solvent, and pour the degradable polymer solution into a syringe; connect the upper conversion joint and the lower conversion joint to the upper and lower ends of the round tube respectively, and then connect the upper conversion joint and the lower conversion joint to the syringe and the vacuum pump respectively, turn on the vacuum pump to evacuate, and introduce the degradable polymer solution into the gaps of the gelatin microspheres under negative pressure; S4, connecting the lower end cap to the lower end of the round tube, placing the round tube in an environment with a humidity of 60-70% and a temperature of 24-26° C. for curing for 24-48 hours, and then soaking the round tube in distilled water for 1-3 days to remove the gelatin microspheres and residual organic solvent, and obtaining a single-layer tubular scaffold with micropores of a beaded structure; S5, taking out the single-layer tubular scaffold with micropores of beaded structure obtained in S4 from the round rod and the round tube, preparing a degradable polymer solution with a mass fraction of 20% by organic solvent, and electrospinning a nanofiber layer on the surface thereof to obtain a double-layer tubular scaffold; S6. Insert the double-layer tubular stent wrapped in S5 back into the round rod and the round tube, and repeat the process of S2-S4 to obtain a three-layer tubular stent.

9. The method for preparing a degradable stent for promoting regeneration of artificial vascular tissue according to claim 8, characterized in that: The organic solvent is one or more of hexafluoroisopropanol, dioxane, dimethylformamide, dimethylacetamide and tetrahydrofuran.

10. The method for preparing a degradable stent for promoting regeneration of artificial vascular tissue according to claim 8, characterized in that: The gelatin microspheres are prepared from a gelatin aqueous solution with a mass fraction of 2-4% by microfluidic technology.

Images