Stent and method of manufacturing the same

Abstract

To provide a stent capable of accelerating the complete cure of cerebral aneurysm.SOLUTION: An aspect of the present invention is a stent 20 that is indwelled so as to be in pressure contact with a blood vessel wall and straddle a cerebral aneurysm 21, the stent 20 having a function of promoting endothelialization prior to complete occlusion of the cerebral aneurysm in a state of being in pressure contact with the blood vessel wall. The stent 20 is formed of a cylindrical braided body obtained by braiding wire rods. The wire material is obtained by coating the surface of an element wire, the element wire contains a magnesium alloy containing 90 atom% or more of Mg or pure magnesium, and the function is to promote neointima formation at the neck of the cerebral aneurysm.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a stent for an aneurysm and a method for manufacturing the same. [Background technology]

[0002] A cerebral aneurysm is a swelling of a cerebral artery. A cerebral aneurysm usually forms when a branching part of a large blood vessel in the brain is pushed by cerebral blood flow and gradually expands. If a cerebral aneurysm ruptures, it can cause subarachnoid hemorrhage, making it a very frightening disease.

[0003] To prevent subarachnoid hemorrhage, it is necessary to treat cerebral aneurysms before they rupture. Treatment options include either craniotomy (clipping) or endovascular treatment using a cerebral aneurysm stent.

[0004] Treatment using a stent for cerebral aneurysms is as follows: A doctor inserts a tube through the femoral artery at the base of the leg and guides it to the cerebral aneurysm. A flow diverter stent is then deployed from the catheter so that it spans the cerebral aneurysm and is then placed in the blood vessel. This slows the blood flow to the cerebral aneurysm, causing it to gradually become thrombosed. Subsequently, as the thrombus is absorbed, the cerebral aneurysm gradually shrinks, eventually completely curing the aneurysm. Patent Document 1 discloses a flow diverter stent made of a NiTi alloy as a stent for cerebral aneurysms. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-135794 Summary of the Invention [Problem to be solved by the invention]

[0006] As mentioned above, placing a flow diverter stent in a blood vessel slows blood flow to the cerebral aneurysm, causing the aneurysm to gradually thrombose. Specifically, it is believed that neointima first forms gradually around the neck of the aneurysm, causing the aneurysm to gradually thrombose. Therefore, by developing a flow diverter stent that promotes endothelialization, which creates neointima more quickly before thrombosis occurs in the aneurysm, it is believed that the aneurysm can be cured more quickly. This also reduces the burden on the patient.

[0007] An object of various aspects of the present invention is to provide a stent that can hasten the complete healing of cerebral aneurysms and a method for manufacturing the same. [Means for solving the problem]

[0008] Various aspects of the present invention are described below.

[0009] [1] A stent that is placed across a cerebral aneurysm by pressing against the blood vessel wall, A stent characterized in that, when pressed against the blood vessel wall, it has the function of promoting endothelialization prior to complete occlusion of the cerebral aneurysm.

[0010] [2] In [1] above, The stent is characterized in that it is composed of a tubular braided body made of wire material.

[0011] [3] In [2] above, The wire material has a coated surface, The wire contains a magnesium alloy containing 90 atomic % or more of Mg or pure magnesium, A stent characterized in that its function is to promote neointima formation in the neck of the cerebral aneurysm.

[0012] [4] In [3] above, The stent is characterized in that the wire material has a surface coated with a bioabsorbable polymer material, a parylene coating, or an MPC polymer coating.

[0013] [5] In paragraph [4] above, A stent characterized in that each of the bioabsorbable polymer material coating, the parylene coating, and the MPC polymer coating contains a drug.

[0014] [6] In any one of paragraphs [3] to [5] above, A stent characterized in that the above function is achieved by forming a skeleton in the braided body that serves as a scaffold for endothelial formation during the process of absorption of the magnesium alloy or pure magnesium into the body, and this skeleton remaining for a certain period of time.

[0015] [7] In paragraph [6] above, A stent characterized in that the framework is a structure formed along the wire material of the braided body.

[0016] [8] In any one of paragraphs [3] to [5] above, The stent contains 50% to 96% of all wires of the braided body of a magnesium alloy or pure magnesium, A stent characterized in that the outer diameter of each of the wire materials is 80 μm or less.

[0017] [9] In paragraphs [4] or [5] above, The stent is characterized in that the wire of the wire material has a 0.2% yield strength of 300 MPa or more and a ductility of 3% or more.

[0018]

[10] In any one of paragraphs [3] to [5] above, The stent is characterized in that the magnesium alloy is an alloy having a crystalline structure having an α-Mg phase or an α-Mg phase and a long-period stacking ordered structure phase.

[0019]

[11] In paragraphs [4] or [5] above, A stent characterized in that the thickness of each of the bioabsorbable polymer material coating, the parylene coating, and the MPC polymer coating is 10 μm or less.

[0020]

[12] In paragraph [1] above, The stent is composed of a tubular braided body braided with wires, The stent is characterized in that the wire material is a wire whose surface is covered with a coating containing a magnesium-containing compound, a magnesium alloy, or pure magnesium.

[0021]

[13] In paragraph

[12] above, A stent characterized in that the wires are made of a bioabsorbable material or an X-ray opaque metal material.

[0022]

[14] In any one of paragraphs [2] to [5],

[12] and

[13] above: The stent is characterized in that the tubular braided body is braided with two or more types of wire materials.

[0023]

[15] In any one of paragraphs [1] to [5],

[12] and

[13] above: A stent characterized in that the vessel wall in the function is a human vessel wall.

[0024]

[16] A step (a) of preparing a wire made of a magnesium alloy containing 90 atomic % or more of Mg or pure magnesium; (b) applying a coating to the wire by electrospinning a positively charged polymer jet onto the wire surface while rotating a counter electrode around the wire; (c) forming a wire by performing a heat treatment to smooth the coating film; (d) a step of forming a tubular braided body by braiding the wire around a core material using a braiding machine with a winding mechanism; A method for manufacturing a stent, comprising:

[0025]

[17] In paragraph

[16] above: A method for manufacturing a stent, characterized in that it comprises, after step (d), a step of performing a heat treatment to increase the crystallinity of the coating film of step (c) and to give the braided body shape memory and self-expandability. [Effects of the Invention]

[0026] According to various aspects of the present invention, it is possible to provide a stent that can hasten the complete healing of cerebral aneurysms and a method for manufacturing the same. [Brief explanation of the drawings]

[0027] [Figure 1] FIG. 1 is a diagram showing a schematic diagram of a flow diverter stent 20 according to one embodiment of the present invention placed in a blood vessel 22 so as to straddle a cerebral aneurysm 21. [Figure 2] (A) is a schematic diagram showing how a cerebral aneurysm 21 thrombustes and progresses to complete healing when a flow diverter stent (Co / Cr-FD) 120 containing Co / Cr as a comparative example is placed in a blood vessel 22 so as to straddle the cerebral aneurysm 21, and (B) is a schematic diagram showing how a cerebral aneurysm 21 thrombustes and progresses to complete healing when a flow diverter stent (Mg-FD) 20 containing a magnesium alloy containing 90 atomic % or more of Mg or pure magnesium is placed in a blood vessel 22 so as to straddle the cerebral aneurysm 21. [Figure 3] A flow diverter stent (MgFD PLLA-coated), which uses a magnesium alloy wire with a PLLA coating on its surface, and a flow diverter stent (MgFD Bare), which uses a magnesium alloy wire without a coating, were placed in the abdominal aorta of a rabbit, and the neointima on the surface of each flow diverter stent was evaluated 14 days later in SEM images. [Figure 4] Photographs of experimental results showing the process of formation of a framework that serves as a scaffold for endothelial formation in the braided body of an Mg-FD stent at the neck of a cerebral aneurysm. [Figure 5] Figure 4 shows part of the test system used to obtain the experimental results. [Figure 6] 1A and 1B are schematic diagrams illustrating a method of applying a coating to a wire 12 based on an electrospinning method. [Figure 7] (A) is a photograph showing the state in which a film has been coated on a wire using the method shown in Figure 6, and (B) is a photograph showing the state after heat treatment has been performed to smooth the film coated on the wire shown in (A). [Figure 8] FIG. 1 is a schematic diagram showing a braiding machine with a winding mechanism. DETAILED DESCRIPTION OF THE INVENTION

[0028] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the following description, and it will be readily understood by those skilled in the art that various changes in form and details can be made without departing from the spirit and scope of the present invention. Therefore, the present invention should not be interpreted as being limited to the description of the embodiments shown below.

[0029] (First embodiment) FIG. 1 is a diagram schematically illustrating a state in which a flow diverter stent 20 according to one embodiment of the present invention is placed in a blood vessel 22 so as to straddle a cerebral aneurysm 21.

[0030] The flow diverter stent 20 shown in Figure 1 is a stent that is placed so as to straddle a cerebral aneurysm 21 by being pressed against a blood vessel wall 22, and has the function of promoting endothelialization prior to complete occlusion of the cerebral aneurysm 21 while pressed against the blood vessel wall 22. The blood vessel wall in this function is preferably a human blood vessel wall.

[0031] The stent 20 is composed of a cylindrical braided body made of wire. The stent 20 has self-expanding properties and is placed by being pressed against the blood vessel wall 22. Although the present embodiment uses a self-expanding flow diverter stent 20, a non-self-expanding stent that is placed in the blood vessel wall by being expanded with a balloon may also be used.

[0032] The wire material of the stent 20 may preferably have a surface coating. The wire may preferably contain a magnesium alloy containing 90 atomic % or more of Mg or pure magnesium. The above function may preferably be to promote neointima formation in the neck of a cerebral aneurysm.

[0033] The above-mentioned cylindrical braided body may be braided with one type of wire material, or may be braided with two or more types of wire materials.

[0034] 2(A) is a schematic diagram showing the process of thrombosis and complete healing of a cerebral aneurysm 21 when a flow diverter stent (Co / Cr-FD) 120 containing Co / Cr is placed in a blood vessel 22 so as to straddle the cerebral aneurysm 21 as a comparative example. Note that the cerebral aneurysm 21 shown in FIGS. 2(A) and 2(B) was derived from the results of an experiment using an aneurysm in the abdominal aorta of a rabbit.

[0035] As shown in Figure 2(A), in the case of a Co / Cr-containing flow diverter stent 120, thrombus formation begins within the cerebral aneurysm 21 from three months (3M~), the cerebral aneurysm 21 thrombusizes within six months (6M~), and after six months (6M~), the cerebral aneurysm gradually shrinks as the thrombus is absorbed, eventually leading to complete healing. Here, neointima 31 forms to cover the neck of the cerebral aneurysm 21 six months (6M~) after the cerebral aneurysm 21 thrombusizes. In other words, the cerebral aneurysm 21 thrombusizes as the neointima 31 forms around the neck of the cerebral aneurysm 21. However, even when the entire cerebral aneurysm 21 thrombusizes, the neointima 31 does not completely cover the neck. As the cerebral aneurysm gradually shrinks with the absorption of the thrombus, the neointima 31 forms to completely cover the neck. This flow diverter stent 120 is not bioabsorbed and remains within the blood vessel 22.

[0036] Figure 2(B) is a schematic diagram showing how a cerebral aneurysm 21 thrombustes and progresses to complete healing when a flow diverter stent (Mg-FD) 20 containing a magnesium alloy containing 90 atomic % or more of Mg or pure magnesium is placed in a blood vessel 22 across the cerebral aneurysm 21.

[0037] As shown in Figure 2(B), before a thrombus forms in the cerebral aneurysm 21 within two weeks to one month (2W-1M), a neointima 31 is formed to cover the neck of the cerebral aneurysm 21. In contrast, in the flow diverter stent 120 containing Co / Cr shown in Figure 2(A), the neointima 31 is not yet formed at the neck of the cerebral aneurysm 21.

[0038] As shown in Figure 2(B), between one and three months (1M to 3M), neointima 31 almost completely covers the neck of cerebral aneurysm 21. After three months (3M), neointima 31 completely covers the neck of cerebral aneurysm 21. In contrast, in the flow diverter stent 120 containing Co / Cr shown in Figure 2(A), neointima 31 has not yet formed much at the neck of cerebral aneurysm 21.

[0039] As shown in Figure 2(B), after three months (3M or more), the cerebral aneurysm becomes thrombotic, and as the thrombus is absorbed, the cerebral aneurysm gradually shrinks and eventually heals completely. In contrast, with the Co / Cr-containing flow diverter stent 120 shown in Figure 2(A), after three months (3M to 6M), neointima 31 begins to form at the neck of the cerebral aneurysm 21, and a thrombus begins to form within the cerebral aneurysm 21. From these findings, it can be said that the earlier the neointima 31 forms at the neck of the cerebral aneurysm 21, the earlier the cerebral aneurysm becomes thrombotic, and the earlier the cerebral aneurysm heals.

[0040] As described above, the stent 20 is a tubular braided structure made of wires. The wires may be coated with a bioabsorbable polymer material, a parylene coating (paraxylylene resin coating), or an MPC (2-methacryloyloxyethyl phosphorylcholine) polymer coating. In this embodiment, however, wires coated with a bioabsorbable PLLA (polylactic acid) are used. Specific examples of bioabsorbable polymer materials for the bioabsorbable polymer coating include polycaprolactone, polyglycolic acid (PGA), copolymer of glycolic acid and L-lactic acid (PGLA), copolymer of glycolic acid and DL-lactic acid (PGDLLA), poly-L-lactic acid (PLLA), poly-D-lactic acid (PDLA), poly-DL-lactic acid (PDLLA), copolymer of L-lactic acid and ε-caprolactone (LCL), and poly-p-dioxanone (PDO).

[0041] The thickness of each of the bioabsorbable polymer coating, parylene coating, and MPC polymer coating is preferably 10 μm or less.

[0042] Furthermore, the stent 20 preferably contains 50% to 96% of all wires in the braided body of the stent 20. The magnesium alloy is preferably an alloy having a crystalline structure having an α-Mg phase or an α-Mg phase and a long-period stacking ordered structure phase. The long-period stacking ordered structure phase is an LPSO (Long Period Stacking Order) structure phase. The outer diameter of each of the wires is preferably 80 μm or less. The lower limit of the outer diameter of each of the wires is preferably 30 μm. The wire strands of the wire preferably have a 0.2% yield strength of 300 MPa or more and a ductility of 3% or more.

[0043] As mentioned above, the wires are preferably made of a magnesium alloy containing 90 atomic % or more of Mg or pure magnesium, but in this embodiment, wires made of a magnesium alloy of Mg-0.9Zn-2.05Y-0.15Al-0.1Yb (at. %) are used.

[0044] Figure 3 shows SEM images of neointima formation on the surface of a flow diverter stent (MgFD PLLA-coated) made from a magnesium alloy wire with the above composition coated with PLLA, and a flow diverter stent (MgFD Bare) made from a magnesium alloy wire with the above composition but without any coating, placed in the abdominal aorta of a rabbit 14 days later. Figure 2(B) shows the result of the use of the above flow diverter stent (MgFD PLLA-coated).

[0045] As shown in Figure 3, the neointima was completely covered in both stents within two weeks, and a thick neointima was formed that was so thick that the irregularities of the stent were not visible, confirming high biocompatibility. This corresponds to 2W shown in Figure 2(B). This also confirms that, as shown in Figure 2(B), between two weeks and one month (2W-1M), the neointima 31 forms to cover the neck of the cerebral aneurysm 21 prior to thrombus formation. Note that the results shown in Figures 2(A), (B), and 3 are from animal (rabbit) experiments, but it is believed that similar tendencies in the effects can be obtained in humans.

[0046] Furthermore, the bioabsorbable polymer coating, parylene coating, or MPC polymer coating may each contain a drug, which may regulate endothelialization, for example, promote endothelialization.

[0047] The function of the stent to promote endothelialization prior to the complete occlusion of the cerebral aneurysm 21 is realized by forming a framework in the braided body that serves as a scaffold for endothelialization during the absorption process of the magnesium alloy or pure magnesium into the body, and the framework remaining for a certain period of time. The framework is preferably a structure formed along the wires of the braided body.

[0048] It has been confirmed that the Mg-FD shown in Figure 2(B) has a higher probability of occluding the aneurysm earlier than the Co / Cr-FD shown in Figure 2(A) because the neointima grows and covers the aneurysm neck earlier. This is thought to be because the Mg-FD shown in Figure 2(B) forms a framework in the braided stent that serves as a scaffold for endothelial formation earlier than the Co / Cr-FD shown in Figure 2(A).

[0049] Figure 4 is a photograph of the experimental results showing the process of the formation of a framework that serves as a scaffold for endothelialization in the braided body of the above-mentioned Mg-FD stent at the neck of a cerebral aneurysm. Figure 5 is a diagram showing part of the test system used to obtain the experimental results shown in Figure 4. The system reproduces a human cerebral artery and cerebral aneurysm, and an Mg-FD stent is placed in the vascular wall so that it straddles the cerebral aneurysm, thereby recreating an environment similar to that of a human cerebral artery, thereby evaluating the degradation performance of the Mg-FD stent over time. The wire material of the Mg-FD stent shown in Figure 4 is an uncoated wire made of a magnesium alloy of Mg-0.9Zn-2.05Y-0.15Al-0.1Yb (at.%).

[0050] An experiment was conducted in which an Mg-FD stent (not shown) shown in Figure 2(B) was placed in a blood vessel 42 of a cerebral artery 41 in a test system shown in Figure 5, and blood with the chemical components and concentrations shown in Table 1 was flowed through the blood vessel 42 in the direction of arrow 43 at the flow rate, pressure, and temperature shown in Table 2, to observe the changes in the Mg-FD stent over time. The results of the experiment are shown in Figure 4.

[0051] [Table 1]

[0052] [Table 2]

[0053] As shown in Figure 4, after 20 days, a skeletal structure begins to form along the braided wires (dark wires) of the Mg-FD stent in the neck area of ​​the cerebral aneurysm. Next, after 23 days, the stent wires begin to dissolve (absorb) in the blood, decompose, and decrease, and the skeletal structure increases. Next, after 25 days, the stent wires decrease further, and the skeletal structure increases accordingly. Finally, after 30 days, most of the stent wires are absorbed by the blood, and a skeletal structure is formed along the braided wires of the stent. Although not shown, there was no significant change (decomposition) in the Mg-FD stent in the neck area until 15 days.

[0054] Considering the results of Figures 2(A), (B), 3, and 4 described above, the reason why neointima 31 forms more quickly in the neck of cerebral aneurysm 21 in the Mg-containing flow diverter stent (Mg-FD) 20 shown in Figure 2(B) compared to the Co / Cr-containing flow diverter stent 120 shown in Figure 2(A) is thought to be as follows.

[0055] As the Mg in the braided wires of the stent shown in Figure 4 dissolves in the blood, a skeleton-like structure is formed along the braided wires, which remains for a certain period of time and serves as a scaffold for endothelial formation, promoting neointima formation at the neck of the cerebral aneurysm as shown in Figure 3. Note that the results shown in Figure 3 are from an experiment on an animal (rabbit), while the results shown in Figure 4 are a reproduction of the blood vessels and cerebral aneurysms of a human cerebral artery, but these results suggest that similar tendencies in the effects can be obtained in humans as well.

[0056] According to this embodiment, it is possible to realize a flow diverter stent 20 that promotes endothelialization, which generates neointima 31 more quickly prior to thrombosis of the cerebral aneurysm 21, thereby hastening the complete cure of the cerebral aneurysm and reducing the burden on the patient.

[0057] (Second embodiment) The stent of this embodiment is a flow diverter stent that is crimped against the blood vessel wall and placed across a cerebral aneurysm. When crimped against the blood vessel wall, it has the function of promoting endothelialization prior to complete occlusion of the cerebral aneurysm, and is similar to the first embodiment in that the stent is made of a tubular braided body woven with wire.

[0058] The following describes the parts that are different from the first embodiment, and a description of the same parts will be omitted. The wire material of the stent is a wire whose surface is covered with a coating containing a magnesium-containing compound, a magnesium alloy, or pure magnesium.

[0059] The wires are preferably made of a bioabsorbable material or a radiopaque metal material. Using a radiopaque metal material makes it easier to observe the state of the stent placed in the patient's blood vessel. Examples of bioabsorbable materials include bioabsorbable polymeric materials (e.g., polycaprolactone, polyglycolic acid (PGA), copolymer of glycolic acid and L-lactic acid (PGLA), copolymer of glycolic acid and DL-lactic acid (PGDLLA), poly-L-lactic acid (PLLA), poly-D-lactic acid (PDLA), poly-DL-lactic acid (PDLLA), copolymer of L-lactic acid and ε-caprolactone (LCL), and poly-p-dioxanone (PDO)). Examples of radiopaque metal materials include platinum-tungsten (e.g., Pt-8 wt% W) and Nitinol (nickel-titanium) shape-memory alloys.

[0060] In this embodiment, the same effects as in the first embodiment can be obtained.

[0061] (Third embodiment) In this embodiment, a method for manufacturing the stent according to the first embodiment will be described. Fig. 6 is a schematic diagram illustrating a method for coating wire 12 based on the electrospinning method. Fig. 7(A) is a photograph showing the wire coated with a film by the method shown in Fig. 6, and Fig. 7(B) is a photograph showing the wire after heat treatment to smooth the film coated on the wire shown in Fig. 7(A). Fig. 8 is a schematic diagram 61 showing a braiding machine with a winding mechanism 62.

[0062] A wire 12 made of a magnesium alloy containing 90 atomic % or more of Mg or pure magnesium is prepared (step (a)).

[0063] Next, as shown in FIG. 6, a coating is applied to the wire 12 by depositing a positively charged polymer jet onto the surface of the wire 12 while rotating a counter electrode 14 around the wire 12 based on the electrospinning method (step (b)).

[0064] Step (b) will be described in detail below. As shown in Figure 6, the wire 12 is moved at a predetermined speed in the direction indicated by arrow AR4. A counter electrode 14 is disposed so as to surround the wire 12, and is supported by a support 13. The counter electrode 14 and support 13 are configured to be rotated around the wire 12 at a preset rotational speed in the direction indicated by arrow AR3 by a rotation drive unit (not shown). While the counter electrode 14 is rotating around the wire 12, a positively charged polymer jet is discharged onto the surface of the wire 12 by a polymer discharge unit 11, causing the polymer jet to adhere to the surface of the wire 12. This results in a coating being applied to the wire 12.

[0065] The support part 13 has a funnel shape and includes a bowl-shaped main part 131 with an opening 131a at the bottom, and a cylindrical part 132 whose inside is in communication with the inside of the main part 131 via the opening 131a. The counter electrode 14 is bowl-shaped and disposed so as to cover the inner wall of the main part 131 of the support part 13. The counter electrode 14 is grounded via a ground wire (not shown). The polymer discharge part 11 includes a cylindrical syringe 111 that stores a polymer liquid inside, a nozzle 112 attached to the tip of the syringe 111, a plunger 113 inserted on the side of the syringe 111 opposite the nozzle 112 side, and a voltage application part 114 that applies a DC voltage to the nozzle 112. Here, the voltage application part 114 is a DC voltage source that applies a predetermined DC voltage to the nozzle 112. The polymer discharge unit 11 also has a pressing mechanism (not shown) that pneumatically presses the plunger 113 into the syringe 111. The polymer discharge unit 11 is configured to discharge the polymer liquid from the nozzle 112 toward the portion of the wire 12 facing the counter electrode 14 while maintaining the nozzle 112 at a higher potential than the counter electrode 14. Preferably, the tip 112a of the nozzle 112, where the nozzle outlet is provided, is located within a projection area A1 of the counter electrode 14 in the direction of the rotation axis of the counter electrode 14. The polymer liquid is a liquid in which a polymer is dissolved in an organic solvent. A highly bioabsorbable polymer, such as PLLA (polylactic acid), can be used as the polymer. Examples of organic solvents include dichloromethane, trichloromethane (CHCl3), dichloroethane, N,N-dimethylformamide, tetrahydrofuran, toluene, pyridine, acetonitrile, formamide, benzene, dimethylacetamide, N-methylpyrrolidone, hexane, 1,4-dioxane, acetone, methanol, and ethanol.

[0066] Next, a heat treatment is carried out to smooth the coating film, thereby forming a wire (step (c)).

[0067] Step (c) will be described in detail below. In the above step (b), the film coated on the wire 12 (see FIG. 7(A)) is heat-treated to form a wire with a smoothed film (see FIG. 7(B)). This heat treatment melts the polymer and smooths the film. The heat treatment here is preferably performed at a temperature of 30°C or higher and 250°C or lower for a time of 1 second or higher and 10 minutes or shorter.

[0068] 8, the wire is braided around the core material using a braiding machine 61 with a winding mechanism 62 to form a tubular braided body 51 (step (d)). The core material is preferably a low-friction core material.

[0069] This may be followed by a step of heat treatment to increase the crystallinity of the coating film of step (c) and to impart shape memory and self-expandability to the braided body 61. The heat treatment here may be performed at a temperature of 30°C or higher and 180°C or lower for a time period of 1 second or higher and 10 hours or shorter.

[0070] A method of using the flow diverter stent manufactured as described above will be described with reference to FIG.

[0071] A physician guides a catheter into the skull via the femoral artery at the base of the leg. The flow diverter stent 20 is then inserted into the blood vessel 22 across the cerebral aneurysm 21. Its self-expanding properties allow it to be deployed by crimping against the vascular wall. When the flow diverter stent 20 is placed in the parent vessel 22 containing the cerebral aneurysm 21, the mesh structure of the flow diverter stent 20 restricts blood flow (not shown) into the cerebral aneurysm 21, gradually promoting thrombosis within the cerebral aneurysm. The neck of the aneurysm 21 is then covered with a stent neointima, resulting in complete occlusion of the cerebral aneurysm 21 after several months. The flow diverter stent 20 itself gradually decomposes over the course of several months, eventually disappearing without leaving any foreign matter behind. However, if a non-bioabsorbable wire or other material is used in a portion of the flow diverter stent 20 to ensure visibility, the wire or other material may remain. [Explanation of symbols]

[0072] 12 wire 14 Counter electrode 20 Stents 21 Cerebral aneurysm 22 Blood vessels 31 Neointima 41 Cerebral arteries 42 Blood vessels 43 Arrow 51 Braid body 61 Braiding Machine 62 Winding mechanism

Claims

1. A stent that is placed across a cerebral aneurysm by being pressed against the blood vessel wall, A stent characterized in that, when pressed against the blood vessel wall, it has the function of promoting endothelialization prior to complete occlusion of the cerebral aneurysm.

2. In claim 1, The stent is characterized in that it is composed of a tubular braided body made of wire material.

3. In claim 2, The wire material has a coated surface, the wires contain a magnesium alloy containing 90 atomic % or more of Mg or pure magnesium, A stent characterized in that its function is to promote neointima formation in the neck of the cerebral aneurysm.

4. In claim 3, The wire has a surface coated with a bioabsorbable polymer material, a parylene coating, or an MPC polymer coating, The stent is characterized in that the wires are made of a magnesium alloy containing 90 atomic % or more of Mg or pure magnesium.

5. In claim 4, A stent characterized in that each of the bioabsorbable polymer material coating, the parylene coating, and the MPC polymer coating contains a drug.

6. In any one of claims 3 to 5, A stent characterized in that the above function is achieved by forming a skeleton in the braided body that serves as a scaffold for endothelial formation during the process of absorption of the magnesium alloy or pure magnesium into the body, and this skeleton remaining for a certain period of time.

7. In claim 6, A stent characterized in that the framework is a structure formed along the wire material of the braided body.

8. In any one of claims 3 to 5, the stent contains 50% to 96% of all wires of the braided body of a magnesium alloy or pure magnesium, A stent characterized in that the outer diameter of each of the wire materials is 80 μm or less.

9. In claim 4 or 5, The stent is characterized in that the wire of the wire material has a 0.2% yield strength of 300 MPa or more and a ductility of 3% or more.

10. In any one of claims 3 to 5, The stent is characterized in that the magnesium alloy is an alloy having a crystalline structure having an α-Mg phase or an α-Mg phase and a long-period stacking ordered structure phase.

11. In claim 4 or 5, A stent characterized in that the thickness of each of the bioabsorbable polymer material coating, the parylene coating, and the MPC polymer coating is 10 μm or less.

12. In claim 1, The stent is composed of a tubular braided body braided with wires, The stent is characterized in that the wire material is a wire whose surface is covered with a coating containing a magnesium-containing compound, a magnesium alloy, or pure magnesium.

13. In claim 12, A stent characterized in that the wires are made of a bioabsorbable material or an X-ray opaque metal material.

14. In any one of claims 2 to 5, 12 and 13, The stent is characterized in that the tubular braided body is braided with two or more types of wire materials.

15. In any one of claims 1 to 5, 12 and 13, A stent characterized in that the vessel wall in the function is a human vessel wall.

16. A step (a) of preparing a wire made of a magnesium alloy containing 90 atomic % or more of Mg or pure magnesium; (b) applying a coating to the wire by electrospinning a positively charged polymer jet onto the wire surface while rotating a counter electrode around the wire; (c) forming a wire by performing a heat treatment to smooth the coating film; (d) a step of braiding the wire around a core material using a braiding machine with a winding mechanism to form a tubular braided body; A method for manufacturing a stent, comprising:

17. In claim 16, A method for manufacturing a stent, characterized in that after step (d), a step of performing heat treatment to increase the crystallinity of the coating film of step (c) and to give the braided body shape memory and self-expandability.

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