Degradable vascular stent and preparation method thereof

Abstract

The application relates to a degradable vascular stent and a preparation method thereof, and belongs to the technical field of medical devices. The vascular stent comprises an inner layer and an outer layer. The inner layer is provided with a plurality of first grooves which are distributed in a grid shape. The outer layer is provided with a plurality of second grooves which are distributed along the length direction of the vascular stent at intervals. The second grooves are in a groove shape and are arranged around the central axis of the vascular stent. The first grooves arranged on the inner layer in a grid shape can specifically regulate the migration, adhesion and proliferation of endothelial cells, and rapidly complete endothelialization. Meanwhile, the second grooves arranged on the outer layer in a groove shape and distributed along the length direction of the vascular stent at intervals can effectively regulate the proliferation and directional arrangement of smooth muscle cells. The selective regulation of different cells is beneficial to the rapid formation of a continuous endothelial monolayer and a circumferentially arranged smooth muscle layer in the vascular stent in the body, thereby promoting the functional regeneration of the blood vessel and maintaining the long-term patency of the blood vessel.

Description

Technical Field

[0001] This application relates to the field of medical device technology, and in particular to a biodegradable vascular stent and its preparation method. Background Technology

[0002] With the continued severity of population aging and the increasing prevalence of cardiovascular disease, the clinical demand for artificial vascular grafts for replacement or bypass surgery of coronary and peripheral vascular diseases continues to grow. Despite the huge clinical demand for artificial vascular grafts, there are also significant challenges such as poor immune receptivity, low tissue integration and remodeling, thrombotic potential, mismatched tissue mechanics, and the inability to "on-demand" supply, which limit the selection of artificial vascular grafts.

[0003] Due to limitations such as vascular occlusion, intimal hyperplasia, thrombosis, and low patency rates, there are currently no clinically available small-diameter (<6mm) artificial vascular grafts. Common artificial vascular graft products include autologous vessels, xenogeneic vessels, commercially available artificial vessels, and tissue-engineered vessels. Using autologous vessels is currently the clinical gold standard for small-diameter vessel replacement; however, the source of autologous vessels is limited, and their usability is complicated by pre-existing diseases, trauma, anatomical abnormalities, and size mismatches, and can also cause secondary damage. Xenogeneic vessels are often subject to immune rejection. Commercially available artificial vascular graft materials (such as expanded polytetrafluoroethylene) are non-degradable, have poor compliance, lack tissue regeneration capacity, and lack the ability to integrate with the host, making them unsuitable for small-diameter vessel replacement. Tissue-engineered vascular grafts have the advantages of promoting tissue regeneration, host-graft integration, and rapid vascular function, overcoming the shortcomings of the above grafts and representing the most promising vascular replacement solution.

[0004] Natural blood vessels are orderly assembled from multiple layers of extracellular matrix and various cells, exhibiting anisotropic structure and mechanical properties. A continuous, fused endothelial layer maintains unobstructed blood flow. The intima of a normal blood vessel consists of a continuous monolayer of endothelial cells to ensure luminal patency, while the media contains densely packed, circumferentially oriented smooth muscle cells to ensure mechanical strength. Research in vascular tissue engineering primarily focuses on reconstructing the structures of the intima and media to create biomimetic multilayered scaffolds. Specifically, vascular scaffolds must guide the formation of a fused monolayer of endothelial cells within the lumen (endothelialization) to mimic the intima and should also reproduce the directional accumulation of vascular smooth muscle cells to mimic the media. In addition to meeting these basic design goals, for vascular scaffolds to function successfully in vivo, they also need to possess the following conditions: sufficient mechanical properties, such as tensile strength, suture strength, and rupture strength; good immune receptivity, minimizing the risks of inflammatory responses, foreign body reactions, and immune recognition; good bioactivity, with the potential to be remodeled, reconstructed, and renewed by the host; and a suitable non-thrombotic luminal surface.

[0005] Currently, strategies for regulating cell behavior are mainly divided into biochemical and biophysical inducements. Using biochemical signals (such as growth factors, chemokines, and hormones) to guide cell biological functions has many limitations, such as complex preparation processes, poor stability of soluble factors, unsatisfactory long-term effects, and the potential for side effects. Topological structure, as an important biophysical feature, determines cell behavior and function through a "mechanical transduction" mechanism, exhibiting good controllability and scalability. Therefore, researchers favor using the topological structure of scaffold materials to guide cell behavior (adhesion, proliferation, migration), as this regulatory approach is simple and effective.

[0006] Existing technologies have proposed using electrospun fiber materials as vascular scaffolds. Electrospun fiber materials are widely used in tissue engineering and drug delivery due to their controllable fiber orientation, structure, and morphology, diverse fiber composition, simple preparation process, large specific surface area, high porosity, and ability to mimic the extracellular matrix structure. However, the single micro / nanoscale fiber topology makes it difficult to simulate the complex physical microstructure of vascular tissue, resulting in limited bioactivity and an inability to achieve functional regeneration of damaged vascular tissue. Summary of the Invention

[0007] This application provides a biodegradable vascular stent and its preparation method to improve the functional regeneration of damaged vascular tissue that cannot be achieved by currently using electrospun fiber materials.

[0008] In a first aspect, this application provides a biodegradable vascular stent, the vascular stent comprising an inner layer and an outer layer, the inner layer having a plurality of first grooves distributed in a grid pattern; the outer layer having a plurality of second grooves distributed at intervals along the length direction of the vascular stent, the second grooves being groove-shaped, and the second grooves being circumferentially disposed around the central axis of the vascular stent on the outer layer.

[0009] As an optional implementation, the first groove is rectangular; and / or

[0010] The side length of the first groove is 20–100 μm; and / or

[0011] The distance between two adjacent first grooves is 5 to 30 μm.

[0012] As an optional implementation, the width of the second groove is 20–100 μm; and / or

[0013] The distance between two adjacent second grooves is 20 to 100 μm.

[0014] As an optional implementation, the outer layer includes a plurality of stacked sub-layers, the surfaces of which are provided with the second groove; and / or

[0015] The thickness of the outer layer is 3 to 5 times the thickness of the inner layer.

[0016] As an optional implementation, the vascular stent is an electrospun fiber membrane of a biodegradable polymer material.

[0017] As an optional implementation, the biodegradable polymeric material includes at least one of polyurethane, polylactic acid and its derivatives, and polycaprolactone and its derivatives; and / or

[0018] The biodegradable polymer material further includes gelatin; and / or

[0019] The polylactic acid derivatives include at least one of polylactic acid-glycolic acid copolymer and polylactic acid-polyethylene glycol copolymer; and / or

[0020] The derivatives of polycaprolactone include: polyethylene glycol-polycaprolactone copolymer.

[0021] As an optional implementation, the diameter of the electrospun fiber membrane is 0.15 to 1 μm.

[0022] As an optional implementation, the diameter of the vascular stent is 1 to 6 mm.

[0023] Secondly, this application provides a method for preparing a biodegradable vascular stent, wherein the vascular stent is the vascular stent described in the first aspect, and the method includes:

[0024] A substrate having multiple first grooves and multiple second grooves is obtained, wherein the multiple first groove layers are distributed in a grid pattern and the second grooves are in a trench pattern;

[0025] The substrate is rolled into a tubular structure to obtain a vascular stent.

[0026] As an optional implementation, obtaining the substrate having a plurality of first grooves and a plurality of second grooves includes:

[0027] Electrospun fibers are deposited on a template with a preset pattern using an electrospinning method to obtain a first substrate with multiple first grooves on its surface and a second substrate with multiple second grooves on its surface.

[0028] The first substrate and the second substrate are connected to obtain two substrates, each having multiple first grooves and multiple second grooves respectively.

[0029] The technical solutions provided in this application have the following advantages compared with the prior art:

[0030] The vascular stent provided in this application embodiment, by setting a first groove in a grid-like distribution in the inner layer, can specifically regulate the migration, adhesion, and proliferation of endothelial cells, rapidly completing endothelialization. Simultaneously, by setting a second groove in a groove-like distribution along the length of the vascular stent in the outer layer, it can effectively regulate the proliferation and directional alignment of smooth muscle cells. This selective regulation of different cells facilitates the rapid formation of a continuous endothelial monolayer and a circumferentially arranged smooth muscle layer in vivo, thereby promoting functional regeneration of blood vessels and maintaining their long-term patency. Attached Figure Description

[0031] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0032] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 A flowchart illustrating the method provided in the embodiments of this application;

[0034] Figure 2 This is a fluorescent image of the first groove on the inner surface of the vascular stent provided in Embodiment 1 of this application;

[0035] Figure 3 This is a fluorescent image of the second groove on the outer surface of the vascular stent provided in Embodiment 1 of this application;

[0036] Figure 4 This is a scanning electron microscope image of the first groove on the inner surface of the vascular stent provided in Embodiment 1 of this application;

[0037] Figure 5 This is a scanning electron microscope image of the second groove on the outer surface of the vascular stent provided in Embodiment 1 of this application;

[0038] Figure 6 A chromosomal image of the cytoskeleton after endothelial cells were co-cultured with the first groove on the inner surface of the vascular stent provided in Example 1 of this application for 3 days;

[0039] Figure 7 A chromosomal image of the cytoskeleton after endothelial cells were co-cultured with the first groove on the inner surface of the vascular stent provided in Example 1 of this application for 6 days;

[0040] Figure 8 A chromatogram of the cytoskeleton of smooth muscle cells after co-culturing with the second groove on the outer surface of the vascular scaffold provided in Example 1 of this application for 3 days;

[0041] Figure 9 A statistical comparison of the average blood flow velocity of the vascular stents provided in Example 1 and Comparative Example 1 of this application after 6 weeks of in vivo implantation with natural blood vessels;

[0042] Figure 10 These are stereomicroscopic images taken 6 weeks after the vascular stent was implanted in vivo, as provided in Embodiment 1 of this application.

[0043] Figure 11 A stereomicroscopic image of the vascular stent implanted in vivo 6 weeks after comparative example 1 of this application;

[0044] Figure 12 An image showing the immunofluorescence staining results of natural blood vessels provided in an embodiment of this application;

[0045] Figure 13 This is an image showing the immunofluorescence staining results of the vascular stent implanted in vivo 6 weeks after embodiment 1 of this application;

[0046] Figure 14 This is an image showing the immunofluorescence staining results of the vascular stent implanted in vivo 6 weeks after Comparative Example 1 of this application. Detailed Implementation

[0047] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0048] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0049] like Figure 1 As shown, this application provides a biodegradable vascular stent, which includes an inner layer and an outer layer. The inner layer has a plurality of first grooves, which are distributed in a grid pattern. The outer layer has a plurality of second grooves, which are spaced apart along the length of the vascular stent. The second grooves are groove-shaped and are arranged around the central axis of the vascular stent in the outer layer.

[0050] This vascular scaffold, with its inner layer featuring a grid-like distribution of first grooves, specifically regulates the migration, adhesion, and proliferation of endothelial cells, rapidly achieving endothelialization. Simultaneously, the outer layer, with its intermittently distributed grooves along the length of the scaffold, effectively regulates the proliferation and directional alignment of smooth muscle cells. This selective regulation of different cell types facilitates the rapid formation of a continuous endothelial monolayer and a circumferentially arranged smooth muscle layer within the scaffold in vivo, thereby promoting functional vascular regeneration and maintaining long-term patency.

[0051] As an optional implementation, the first groove is rectangular. It should be noted that "rectangular" means that the shape of the first groove projected onto the inner surface after the vascular stent is unfolded is rectangular. For example, the first groove can be square, rectangular, etc. The side length of the first groove is 20–100 μm; the distance between two adjacent first grooves is 5–30 μm. Controlling the side length and spacing of the first grooves facilitates cell migration and allows for rapid coverage of the entire material surface.

[0052] As an optional implementation, the width of the second groove is 20–100 μm; the spacing between two adjacent second grooves is 20–100 μm. Controlling the width and spacing of the second grooves is beneficial for cell proliferation and functional regulation, fully leveraging the advantages of the micro / nanoscale fiber topology, thereby enabling smooth muscle cells to have better orientation and alignment.

[0053] As an optional implementation, the outer layer comprises multiple stacked sublayers, each sublayer having the second groove on its surface. Generally, the outer layer comprises 3 to 5 sublayers. Further, the thickness of the outer layer is 3 to 5 times the thickness of the inner layer. Controlling the thickness of the outer layer to 3 to 5 times that of the inner layer better simulates the structure of the intima and media in real blood vessels. Simultaneously, this gives the vascular stent better mechanical properties, facilitating in vivo implantation. It also helps control the degradation time of the vascular stent, allowing smooth muscle cells to better penetrate the vessel wall, resulting in better vascular remodeling and regeneration effects.

[0054] Electrospun fiber materials, due to their controllable fiber orientation, structure, and morphology, large specific surface area, and high porosity, can simulate the structure of the extracellular matrix. As an optional implementation method, the vascular scaffold is an electrospun fiber membrane of a biodegradable polymer material. By employing the micro / nanoscale fiber topology of the electrospun fiber material in conjunction with the micropatterns of the first and second grooves, better biological effects are observed. The biodegradable polymer material includes at least one of polyurethane, polylactic acid and its derivatives, and polycaprolactone and its derivatives; exemplarily, the biodegradable polymer material can be selected from at least one of biocompatible polycaprolactone, polylactic acid, polylactic acid-glycolic acid copolymer, polyethylene glycol-polycaprolactone copolymer, polylactic acid-polyethylene glycol copolymer, other derivatives of polycaprolactone, and other derivatives of polylactic acid. The biodegradable polymer material also includes gelatin. Exemplarily, the biodegradable polymer material can be selected from a mixture of polylactic acid derivatives / polycaprolactone derivatives and gelatin. It should be noted that the above-mentioned biodegradable polymer materials can be commercially available or obtained through preparation. These biodegradable polymer materials are particularly suitable as fiber substrates for electrospinning, where the electrospun fiber membrane has a fiber diameter of 0.15–1 μm. Controlling the fiber diameter of the electrospun fiber membrane to 0.15–1 μm allows for better matching of micro / nanoscale fiber topologies, which complements the nanoscale structure in the natural extracellular matrix. This biomimics the nanoscale structure of the extracellular matrix, promoting cell adhesion and spreading. The resulting fiber membrane has good pore size and porosity, which is beneficial for nutrient penetration and cell proliferation.

[0055] The vascular stents provided above are particularly suitable for small-diameter vascular transplantation, such as the transplantation of vessels with a diameter of less than 6 mm. As an optional implementation method, the diameter of the vascular stent is 1 to 6 mm.

[0056] like Figure 1 As shown, based on a general inventive concept, this application also provides a method for preparing a biodegradable vascular stent, wherein the vascular stent is the vascular stent described in the first aspect, and the method includes:

[0057] S1. Obtain a substrate having a plurality of first grooves and a plurality of second grooves, wherein the plurality of first groove layers are distributed in a grid pattern and the second grooves are groove-shaped.

[0058] In some embodiments, obtaining a substrate having a plurality of first grooves and a plurality of second grooves includes: electrospinning fibers on a template with a preset pattern by electrospinning to obtain a first substrate having a plurality of first grooves on its surface and a second substrate having a plurality of second grooves on its surface; and connecting the first substrate and the second substrate to obtain two layers of substrate having a plurality of first grooves and a plurality of second grooves respectively.

[0059] Specifically, in this embodiment, a template with a preset pattern is fixed on a stainless steel plate or roller as a receiving device. Electrospinning is used to deposit electrospun fibers onto the surface of the template with the preset pattern to obtain a patterned fiber membrane. After electrospinning is completed, the patterned electrospun fiber membrane is separated from the template and stored in a vacuum drying oven for drying and later use, resulting in a first substrate with multiple first grooves on its surface and a second substrate with multiple second grooves on its surface. The patterned fiber membrane prepared above is connected with the first grooves in the inner layer and the second grooves in the outer layer using spinning liquid as an adhesive to obtain two substrates with multiple first grooves and multiple second grooves respectively. The electrospun fibers have a diameter of 0.15–1 μm; biodegradable polymer materials are selected to prepare the electrospinning solution; trifluoroethanol is used as a solvent to prepare a 10–20% (w / v) polymer solution, which is stirred overnight at room temperature to completely dissolve the polymer material; the electrospinning parameters are as follows: push speed is 0.3–0.8 mL / h, voltage is 16–20 kV, receiving distance is 16–22 cm, roller speed is 200–2200 rpm, temperature is controlled at 20–25 °C, and humidity is 50–70%; the direction of the grooves in the conductive patterned template can be parallel or perpendicular to the direction of roller rotation to control the orientation of local fibers in the groove micropattern.

[0060] The method for preparing a template with a preset pattern can be as follows: using a laser marking machine or a laser engraving machine to engrave a pre-designed grid micro-pattern corresponding to the first groove (for example, the grid side length can be 30-50μm and the spacing between adjacent grids can be 10-20μm) and a groove micro-pattern corresponding to the second groove (for example, the groove width is 25-50μm and the spacing between adjacent grooves is 25-50μm) on a plastic pad paper, and then performing a gold spraying pretreatment on the engraved patterned template to make it conductive.

[0061] S2. Roll the substrate into a tubular structure to obtain a vascular stent.

[0062] Specifically, in this embodiment, a tubular mold can be used to roll the substrate into a tubular structure to obtain a vascular stent. The size of the tubular mold can be selected according to the size of the blood vessel to be replaced.

[0063] The above method uses biodegradable polymer materials as the substrate for vascular scaffolds, preparing a biodegradable polymer fiber vascular scaffold with an inner layer of mesh micropatterned fibers and an outer layer of grooved micropatterned fibers. The mesh micropatterned fiber structure can specifically regulate the migration, adhesion, and proliferation of endothelial cells, rapidly completing endothelialization; the grooved micropatterned fiber structure can effectively regulate the proliferation and directional alignment of smooth muscle cells. The selective regulatory effects of the two micropatterned fiber structures on different cells facilitate the rapid formation of a continuous endothelial monolayer and a circumferentially arranged smooth muscle layer in vivo, thereby promoting functional regeneration of blood vessels and maintaining their long-term patency.

[0064] The vascular stent material possesses excellent mechanical properties to meet the mechanical requirements of artificial blood vessels, good in vitro degradability, blood compatibility, biocompatibility, and low foreign body reaction. Compared with traditional electrospun vascular stents, the vascular stent of this invention has a biomimetic micro-nano composite topology, thereby exhibiting better biological effects, such as faster endothelialization.

[0065] The present application is further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the application. Experimental methods in the following embodiments that do not specify specific conditions are generally determined according to national standards. If there is no corresponding national standard, then general international standards, conventional conditions, or conditions recommended by the manufacturer are followed.

[0066] Example 1

[0067] A method for preparing a biodegradable vascular stent, the method comprising:

[0068] 1) Preparation of patterned templates: Use a laser marking machine to engrave pre-designed grid micro-patterns (grid side length 50μm, spacing between adjacent grids 10μm) and groove micro-patterns (groove width 50μm, spacing between adjacent grooves 50μm) on plastic pad paper. Then, perform gold spraying pretreatment on the engraved patterned templates to make them conductive.

[0069] 2) Preparation of patterned fiber membrane: The conductive patterned template prepared in 1) was fixed on a stainless steel plate as a receiving device. Electrospinning was used to deposit electrospun fibers onto the surface of the conductive patterned template to obtain a patterned fiber membrane. A 20% (w / v) polylactic acid and gelatin mixed spinning solution was prepared using trifluoroethanol as a solvent, with a mass ratio of polylactic acid to gelatin of 6:1. The electrospinning parameters were as follows: pushing speed of 0.5 mL / h, voltage of 18 kV, receiving distance of 20 cm, temperature controlled at 25 ℃, and humidity of 60%. After electrospinning, the patterned electrospun fiber membrane was separated from the template and stored in a vacuum drying oven for later use.

[0070] 3) Preparation of vascular stent: The patterned fiber membrane prepared above was rolled into a tubular structure with a grid micro-pattern on the inner layer and a groove micro-pattern on the outer layer using a stainless steel shaft with a diameter of 2 mm. The length of the groove pattern area was 3 times that of the grid pattern area. The spinning solution was used as a binder to obtain the target product, a biodegradable polymer fiber vascular stent with a micro-pattern structure. The vascular stent had an inner diameter of 2 mm, a wall thickness of 0.2 mm, and a length of 8 mm.

[0071] Example 2

[0072] Except for the following descriptions, all other contents of this embodiment are the same as those of Embodiment 1.

[0073] 1) Preparation of patterned templates: Use a laser marking machine to engrave pre-designed grid micro-patterns (grid side length 30μm, spacing between adjacent grids 20μm) and groove micro-patterns (groove width 25μm, spacing between adjacent grooves 25μm) on plastic pad paper. Then, perform gold spraying pretreatment on the engraved patterned templates to make them conductive.

[0074] Example 3

[0075] Except for the following descriptions, all other contents of this embodiment are the same as those of Embodiment 1.

[0076] 1) Preparation of patterned template: Use a laser marking machine to engrave pre-designed grid micro-patterns (grid side length 40μm, spacing between adjacent grids 15μm) and groove micro-patterns (groove width 35μm, spacing between adjacent grooves 35μm) on plastic pad paper. Then, perform gold spraying pretreatment on the engraved patterned template to make it conductive.

[0077] Example 4

[0078] Except for the following descriptions, all other contents of this embodiment are the same as those of Embodiment 1.

[0079] 1) Preparation of patterned template: Use a laser marking machine to engrave pre-designed grid micro-patterns (grid side length 15μm, spacing between adjacent grids 5μm) and groove micro-patterns (groove width 15μm, spacing between adjacent grooves 15μm) on plastic pad paper. Then, perform gold spraying pretreatment on the engraved patterned template to make it conductive.

[0080] Example 5

[0081] Except for the following descriptions, all other contents of this embodiment are the same as those of Embodiment 1.

[0082] 1) Preparation of patterned templates: Use a laser marking machine to engrave pre-designed grid micro-patterns (grid side length 120μm, spacing between adjacent grids 40μm) and groove micro-patterns (groove width 150μm, spacing between adjacent grooves 150μm) on plastic pad paper. Then, perform gold spraying pretreatment on the engraved patterned templates to make them conductive.

[0083] Comparative Example 1

[0084] Except for the contents described below, the contents of this comparative example are the same as those of Example 1.

[0085] The patterned template was replaced with a patternless template; the grid micropattern and groove micropattern fiber membranes were replaced with patternless random fiber membranes to obtain a biodegradable polymer fiber vascular stent with a patternless structure.

[0086] To verify that this method can effectively enhance angiogenesis and maintain patency, the following tests were conducted to demonstrate its effectiveness.

[0087] 1. The surface micropattern morphology of the vascular stents provided in Examples 1 to 5 was characterized using fluorescence fiber microscopy and scanning electron microscopy. Since the results are similar, the following description uses only the results obtained in Example 1. Figures 2 to 5 As shown, Figure 2 and Figure 3 The images shown are fluorescent images of the first groove on the inner surface and the second groove on the outer surface of the vascular stent provided in Example 1 (green fluorescence is due to coumarin staining). Figure 4 and Figure 5 Scanning electron microscope (SEM) images of the first groove on the inner surface and the second groove on the outer surface of the vascular stent provided in Example 1 show that the mesh micropatterned fiber membrane in the vascular stent has a periodic mesh micropattern structure, with a mesh side length of approximately 50 μm and a spacing of approximately 12 μm. The groove micropatterned fiber membrane in the vascular stent has a distinct micropattern structure of alternating grooves and ridges, with a groove width of approximately 52 μm and a spacing of approximately 47 μm. The dimensions of the mesh and grooves are basically consistent with the dimensions of the designed pattern template. Furthermore, the diameter difference between the mesh micropatterned fiber membrane and the groove micropatterned fiber membrane is not significant (approximately 400 nm). These results indicate that the polymer fiber vascular stent in Example 1 possesses a biomimetic micro / nano composite topology.

[0088] 2. Mechanical performance tests were conducted on the vascular stents provided in Examples 1 to 5. The test steps included: characterizing the tensile properties of the vascular stents using a uniaxial tensile test; cutting the vascular stents into tubular samples with a length of 3 cm and a diameter of 2 mm, measuring the stent thickness using a micrometer, setting the tensile rate to 0.5 mm / min, and setting at least 3 parallel samples for each group of samples; and statistically analyzing the elastic modulus, breaking strength, and elongation at break based on the stress-strain curve.

[0089] The suture strength of the vascular stents provided in Examples 1 to 5 was tested. The test steps included: clamping one end of the vascular stent with the clamp of the universal tensile testing machine, passing a single-needle 7-0 suture through the stent 2 mm from the port on the other side of the stent, tying the suture knot and connecting it to the clamp, and stretching the suture at a speed of 10 mm / min until the stent ruptured, and recording the strength at the time of rupture.

[0090] The rupture pressure test was performed on the vascular stents provided in Examples 1 to 5. The test procedure included fixing the vascular stent in the rupture chamber, pumping phosphate buffered saline (PBS) at a constant rate of 0.5 mL / min to gradually increase the pressure in the rupture chamber until the stent ruptured, and recording the highest pressure value.

[0091] In addition, the diameter of the vascular stent was measured in the burst pressure test at pressures of 80 mmHg and 120 mmHg. The formula for calculating the compliance of the vascular stent is as follows:

[0092]

[0093] Among them, D 120 and D 80 These represent the diameters at 120 mmHg and 80 mmHg, respectively.

[0094] The results are shown in the table below:

[0095]

[0096] As shown in the table above, the vascular stents fabricated using the method provided in this application meet the mechanical requirements for implantation (elastic modulus: 2-20 MPa, tensile strength > 2 MPa, elongation at break > 60%). Furthermore, the vascular stents possess sufficient suture strength for direct anastomosis; the burst pressure of the vascular stents is significantly higher than normal human blood pressure (approximately 16 kPa); and the compliance of the vascular stents is within the same range as that of the human saphenous vein (0.7-1.5%). These results indicate that the vascular stents fabricated using the method provided in this application have excellent conditions for vascular transplantation.

[0097] 3. Cell morphology tests on the vascular scaffolds provided in Examples 1 to 5: The effects of grid and groove micropatterns in the vascular scaffolds on the adhesion and morphology of endothelial cells and smooth muscle cells were investigated using fluorescence microscopy. After co-culturing cells with the vascular scaffolds for 3 and 6 days, the culture medium was removed, the cells were washed three times with PBS, fixed overnight at 4°C with 2.5% glutaraldehyde solution, the fixative was removed, the cells were washed three times with PBS, treated with 0.1% Trion X-100 solution at room temperature for 10 minutes, then treated with 2% bovine serum albumin solution at room temperature for 2 hours (to block non-specific binding sites), washed three times with PBS, stained with rhodamine-labeled phalloidin at 37°C for 1 hour, washed three times with PBS, and finally counterstained with 4',6-diamidinyl-2-phenylindole (DAPI) solution for 10 minutes. After staining, the scaffold samples were placed between a slide and a coverslip, keeping the samples flat, mounted with 75% glycerol, and the cytoskeleton was observed and photographed using a fluorescence microscope (the cytoskeleton showed red fluorescence, and the cell nuclei showed blue fluorescence). Since the results of the various embodiments are similar, the following description will only use the results obtained in Embodiment 1 as an example. Figure 6 and 7 As shown, Figure 6 and Figure 7 The images show cytoskeleton staining after 3 and 6 days of co-culturing endothelial cells with the first groove on the inner surface of the vascular scaffold provided in Example 1. It can be seen that at 3 days, endothelial cells preferentially aggregate at the raised areas of the grid micropattern and exhibit a grid-patterned distribution. Most of the endothelial cells on the raised areas are elongated, which facilitates cell migration and allows them to quickly spread across the entire material surface. At 6 days, endothelial cells almost completely cover the pattern surface, are tightly packed, and have abundant filamentous pseudopodia. Endothelial cells in the recessed areas exhibit a typical cobblestone morphology. These results demonstrate that the grid micropattern in the vascular scaffold enables endothelial cells to grow in a grid-patterned pattern; that is, cells first aggregate at the raised areas of the grid and then rapidly spread across the entire pattern surface. This growth pattern promotes the rapid formation of a complete, fused monolayer of endothelial cells within the vascular scaffold. Figure 8 As shown, Figure 8 The cytoskeleton staining image of smooth muscle cells after co-culturing with the second groove on the outer surface of the vascular scaffold provided in Example 1 for 3 days demonstrates that the groove micropattern fiber structure in the vascular scaffold enables smooth muscle cells to align in a direction along the groove.

[0098] 4. In vivo regenerative performance testing of the vascular stents provided in Examples 1 to 5 and Comparative Example 1: A rat abdominal aortic replacement model was established to evaluate the in vivo vascular regeneration effect of the vascular stents. After anesthetizing rats with chloral hydrate and gas, the rats were fixed on the operating table. Abdominal hair was shaved, and after alcohol disinfection, the abdominal skin and muscles were cut along the midline. The abdominal organs were separated by gauze to allow for operation. The abdominal aorta located below the renal artery was carefully dissected using blunt forceps. During dissection, small branches of the artery were ligated, and both ends of the artery were clamped with hemostatic clips to block blood flow. The dissected abdominal aorta was transversely cut, and under a microscope, a sterile vascular graft was anastomosed end-to-end to the abdominal aorta using 8-0 needle-loaded sutures. Interrupted sutures were used, with 8-10 stitches at each end. After suturing, the distal and proximal hemostatic clips were slowly removed to restore blood flow, and the patency and bleeding of the vascular stent were checked. The abdominal muscle and skin openings were closed with 3-0 sutures, disinfected with povidone-iodine, and penicillin was injected intramuscularly at a dose of 200,000 units per animal. No anticoagulants were used before or after the procedure. Six weeks after implantation, the patency and blood flow of the vascular stent were observed using a small animal high-frequency ultrasound system. Since the results of the various examples are similar, the following descriptions only use the results obtained in Example 1 and Comparative Example 1. Figure 9 As shown, Figure 9 The statistical comparison chart of the average blood flow velocity of the vascular stent provided in Example 1 and Comparative Example 1 after 6 weeks of implantation with natural blood vessels shows that the average blood flow velocity of the vascular stent provided in Example 1 is close to that of natural blood vessels, indicating that it has good patency.

[0099] After ultrasound imaging, the mice were euthanized with an overdose of anesthetic, the vascular stent was removed, and the patency of the lumen was observed using a stereomicroscope. Since the results of each embodiment are similar, the following description will only use the results obtained in Example 1 and Comparative Example 1 for specific illustration. Figure 10 and 11 As shown, Figure 10 and 11 The images shown are stereomicroscopic images of the vascular stents provided in Example 1 and Comparative Example 1, taken 6 weeks after implantation. In Comparative Example 1, the stent lumen surface shows narrowing and significant thrombus formation. In Example 1, the stent lumen is covered by a layer of new tissue, the lumen surface is clean and smooth, and there is no visible intimal hyperplasia or thrombus formation, indicating good vascular remodeling capacity.

[0100] Then, the sections of the vascular stent were subjected to double immunofluorescence staining for platelet-endothelial cell adhesion molecule (CD31) and α-smooth muscle actin (α-SMA) to determine the type, distribution, and arrangement of vascular cells. Since the results of each embodiment are similar, the following description only uses the results obtained in Example 1 and Comparative Example 1 for specific illustration. Figures 12 to 14 As shown, Figure 12The image shows the immunofluorescence staining results of natural blood vessels provided in the example. Figure 13 and 14 The images show the immunofluorescence staining results of the vascular stents provided in Example 1 and Comparative Example 1 6 weeks after in vivo implantation. It can be seen that the endothelialization effect and the regeneration of the newly formed smooth muscle layer of the vascular stent in Comparative Example 1 are poor. In Example 1, the regenerated endothelial cell layer and smooth muscle cell layer of the vascular stent are similar in structure to those of the natural artery, indicating that it has a faster endothelialization rate and better vascular remodeling and regeneration capacity.

[0101] Various embodiments of this application may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a hard limitation on the scope of this application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Furthermore, whenever a numerical range is referred to herein, it means including any referenced number (fraction or integer) within the referred range.

[0102] In this application, unless otherwise stated, directional terms such as "upper" and "lower" specifically refer to the drawing directions in the accompanying drawings. Furthermore, in the description of this application, terms such as "comprising" and "including" mean "including but not limited to." In this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. In this document, "and / or" describes the relationship between related objects, indicating that three relationships can exist; for example, A and / or B can represent: A alone, A and B simultaneously, or B alone. A and B can be singular or plural. In this document, "at least one" means one or more, and "more than one" means two or more. "At least one," "at least one of the following," or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, "at least one of a, b, or c" or "at least one of a, b, and c" can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be a single or multiple.

[0103] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A biodegradable vascular stent, characterized in that, The vascular stent includes an inner layer and an outer layer. The inner layer has a plurality of first grooves, which are distributed in a grid pattern. The outer layer has a plurality of second grooves, which are spaced apart along the length of the vascular stent. The second grooves are groove-shaped and are arranged around the central axis of the vascular stent in the outer layer. The first groove is rectangular in shape; the side length is 20-100μm; the distance between two adjacent first grooves is 5-30μm. The first groove is rectangular in shape, which means that the shape of the first groove projected onto the inner surface after the vascular stent is unfolded is rectangular. The width of the second groove is 20–100 μm; the distance between two adjacent second grooves is 20–100 μm; The outer layer includes multiple stacked sub-layers, and the surface of each sub-layer is provided with the second groove; the thickness of the outer layer is 3 to 5 times the thickness of the inner layer.

2. The biodegradable vascular stent according to claim 1, characterized in that, The vascular stent is an electrospun fiber membrane made of biodegradable polymer material.

3. The biodegradable vascular stent according to claim 2, characterized in that, The biodegradable polymer material includes at least one of polyurethane, polylactic acid and its derivatives, and polycaprolactone and its derivatives; and / or The biodegradable polymer material further includes gelatin; and / or The polylactic acid derivatives include at least one of polylactic acid-glycolic acid copolymer and polylactic acid-polyethylene glycol copolymer; and / or The derivatives of polycaprolactone include: polyethylene glycol-polycaprolactone copolymer.

4. The biodegradable vascular stent according to claim 3, characterized in that, The diameter of the electrospun fiber membrane is 0.15 to 1 μm.

5. The biodegradable vascular stent according to claim 1, characterized in that, The diameter of the vascular stent is 1–6 mm.

6. A method for preparing a biodegradable vascular stent, characterized in that, The vascular stent is the vascular stent according to any one of claims 1 to 5, and the method includes: A substrate having multiple first grooves and multiple second grooves is obtained, wherein the multiple first groove layers are distributed in a grid pattern and the second grooves are in a trench pattern; The substrate is rolled into a tubular structure to obtain a vascular stent.

7. The method for preparing a biodegradable vascular stent according to claim 6, characterized in that, The substrate having a plurality of first grooves and a plurality of second grooves includes: Electrospun fibers are deposited on a template with a preset pattern using an electrospinning method to obtain a first substrate with multiple first grooves on its surface and a second substrate with multiple second grooves on its surface. The first substrate and the second substrate are connected to obtain two substrates, each having multiple first grooves and multiple second grooves respectively.

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