JP2002355316A - Stent cover and stent - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a stent cover which suppresses a restenosis by continuing a lumen open state of a biolumen for a long period when the stent cover is used as a cover of a stent body for indwelling in the biolumen such as a vessel interior. SOLUTION: The cylindrical stent cover comprises openings opened at both distal ends, and the cylindrical stent body extended in the longitudinal direction between the two openings in such a manner that the stent cover coats an outside face and/or an inside face of the body. The stent cover further comprises non- porous films formed at a central part of the cover and formed at the distal ends.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a stent and a stent cover used for the stent. More specifically, when used as a stent to be placed in a living body lumen such as a blood vessel including a blood vessel or a bile duct, the stent has a stent cover that can maintain the lumen patency of the living body lumen for a long time. The present invention relates to a stent and a stent cover used for the stent.

[0002]

2. Description of the Related Art Conventionally, in the treatment of angina pectoris, myocardial infarction and the like, percutaneous coronary artery reconstruction (PTC) is performed on a stenotic part of a coronary artery.
A) To prevent a high rate of restenosis after treatment according to (A) etc., or to apply it to a lesion form where PTCA does not provide good dilatation, a metal stent is permanently applied to coronary arteries and other vessels. Implanting and securing blood flow are performed. Such a stent is generally mesh-like made of a metal wire, has a tubular structure that can be reduced in diameter, such as a coil, and is inserted into a vessel by a catheter in a reduced-diameter state,
The diameter is expanded and indwelled so as to mechanically support the vessel lumen at the stenosis. However, it has been reported that even with the placement of such an intravascular stent, restenosis occurs due to the proliferation and thickening of the luminal tissue from the gaps between the metal wires constituting the stent.

[0003] In order to solve this problem, for example, as disclosed in Japanese Patent Application Laid-Open No. Hei 7-24072, a porous membrane is placed over the inside / outside of the stent and fixed to provide a cover. Attempts have been made to suppress the proliferation and thickening of tissue in the lumen. However, at the end of the cover, turbulence is likely to occur in the body fluid flowing in the vessel,
When this bodily fluid is blood, turbulence in the blood facilitates the formation of thrombus, and when a stent covered with a cover is placed in a blood vessel, the thrombus generated at the end of the cover is caused to grow. Thrombus occlusion is a problem in using stents.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and an object thereof is to provide a method for indwelling in a body lumen such as a blood vessel.
An object of the present invention is to provide a stent having a stent cover that maintains a lumen patency state of a living body lumen for a long period of time and suppresses restenosis, and a stent cover used therefor.

[0005]

The above object is achieved by the present invention described below. (1) A cylindrical stent cover which is open at both ends and covers an outer surface and / or an inner surface of a cylindrical stent body extending longitudinally between the two terminal openings, A stent cover wherein a central portion of the cover is formed of a non-porous membrane and a terminal portion is formed of a porous membrane. (2) The stent cover according to (1), wherein the porous membrane at the end of the cover is a nonwoven fabric. (3) The stent cover according to (1) or (2), wherein the non-porous membrane at the center and the porous membrane at the end of the cover have biocompatibility. (4) The stent cover according to any one of (1) to (3), wherein the non-porous membrane at the center and the porous membrane at the end of the cover have biodegradability or bioabsorbability. (5) The stent cover according to any of (1) to (4), wherein a drug for preventing restenosis of a living body lumen in which the stent is placed or for promoting endothelialization at the end of the stent is added to the cover. . (6) The stent cover according to (5), wherein the drug has at least one of an antithrombotic effect, a cell migration suppression, a cell growth suppression, and an endothelial cell growth promotion. (7) The stent cover according to (5) or (6), wherein the drug is added while being contained in a gel. (8) The stent cover according to (7), wherein the gel is inert to a living body. (9) The stent cover according to (7) or (8), wherein the gel has biodegradability or bioabsorbability. (10) a cylindrical stent body that is open at both ends and extends longitudinally between the two end openings;
A stent comprising the stent cover according to any one of (1) to (9). (11) Both ends are open, and a cylindrical stent body extending longitudinally between the two end openings, and covering the outer surface of the stent body (1) to (9). A stent comprising: a stent cover; and a porous membrane covering both end portions of the inner surface of the stent body and not covering a central portion.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a stent cover according to the present invention and a stent using the stent cover will be described in more detail with reference to the drawings. The overall shape of the stent cover of the present invention is a hollow cylindrical membrane to cover the outer surface and / or the inner surface of the stent body. Here, the stent body is a cylindrical body that is open at both ends and extends longitudinally between the two terminal openings, and the side surface of the cylindrical body communicates the outer surface and the inner surface. The notch has a structure that can be expanded and contracted in the radial direction of the cylindrical body by deforming the notch. In the stent cover of the present invention, the central portion in the major axis direction is formed of a non-porous membrane, and both end portions, that is, portions on the opening side of the stent body are formed of the porous membrane. In the stent cover of the present invention, since the central portion is formed of a non-porous membrane, water permeability of the central portion is low, infiltration of cells from the living body lumen to the stent lumen side is suppressed, and Proliferation and thickening of tissue to the cavity side are prevented. On the other hand, in the stent cover of the present invention, since both ends are formed of a porous membrane, the water permeability of both ends is high, and the stent lumen of the stent cover extends from the inner wall of the living body lumen near the stent cover. The formation of a smooth endothelial surface (endothelialization) is promoted toward the side surface, and the stent is excellently fixed to the tissue.

Here, the ratio of the length of the cylindrical stent cover between the central portion and both ends is usually 100: 74.
00 to 100: 2, preferably 100: 200 to
100: 5, more preferably 100: 100 to 1
00:10, most preferably 100: 50 to 10
0:20. When the ratio of the length of the central portion to the length of both ends is within such a range, when used as a cover for a stent to be placed in a living body lumen, the growth and thickening of tissue into the stent lumen can be prevented. And sufficiently promote endothelialization at the end of the cover. As an example, in the case of a stent cover used for a normal intravascular stent having a length in the major axis direction of the cylindrical body of 10 to 150 mm, the length of each of the two end portions is 1 mm or more, and the length of the central portion is If the thickness is 3 mm or more, the object of the present invention can be sufficiently achieved.
Here, the lengths of the two end portions are generally the same,
It is not necessarily limited, and the length of both ends may be different depending on the use.

[0008] The non-porous membrane forming the central portion of the stent cover of the present invention has elasticity, can be easily expanded even with a small stress, and undergoes plastic deformation without hindering the expansion of the stent body. It is made from a material that does In addition, from the use of the present invention, it is preferable that the non-porous membrane is made of a biocompatible material. Examples of such materials include polyolefin, polyester, fluororesin, silicone, polyurethane, polyamide, polysulfone,
Examples include polyether, polyglycolic acid, polylactic acid, polycaprolactone, polyglactin, polyhydroxybutyric acid, chondroitin sulfate gel, hyaluronic acid gel, fibrin, cellulose, polyorthoester, polyhydroxybutyrate valeric acid, and the like. It may be a product, a copolymer, or a mixture.

[0009] More preferably, the non-porous membrane is made of a biodegradable or bioabsorbable material. Such materials include, among the above-mentioned materials, polylactic acid, polycaprolactone, polyglycolic acid, polyglactin, polyhydroxybutyric acid, chondroitin sulfate gel, hyaluronic acid gel, fibrin, cellulose, polyorthoester, polyhydroxybutyrate. Examples thereof include folic acid and the like, which may be a single substance, a copolymer, or a mixture.
The non-porous membrane can be suitably produced by a method usually used for producing a film or a sheet from the above-mentioned materials.

[0010] The porous membrane forming the end of the stent cover of the present invention has elasticity and can be easily expanded with a small stress, similarly to the non-porous membrane forming the center of the stent cover. It is preferable that the film be made of a film that is plastically deformed without hindering the expansion of the diameter of the stent body. Such a porous membrane is, for example, a porous membrane obtained by foaming a polymer film such as polyolefin or polyurethane, a nonwoven fabric produced by melt-blowing the same polymer material, and a woven fabric produced from cellulose fibers and the like. Is exemplified. These porous membranes can be suitably obtained by preparing a foam, a nonwoven fabric or a woven fabric of a polymer film from a material exemplified for the nonporous membrane forming the central portion of the stent cover by a known method. it can.

The porous film is a foam of the polymer film.
, The porosity of the membrane is 1 × 10 ¹~ 1 × 10^FivePieces/
cm^TwoIs preferably 1 × 10¹~ 1 × 10^Four
Pieces / cm^TwoIs particularly preferred. It also has a porous structure
Is preferably 0.1 to 100 μm.
And more preferably 0.1 to 60 μm.
1 to 40 μm, more preferably 1 to 20 μm.
m is particularly preferred. Porosity and porous structure
If the pore size of the cover is within the above range, the endothelium at the end of the cover
Can be sufficiently promoted, and sufficient strength can be obtained as a cover.
Can be When the porous membrane is made of the nonwoven fabric or woven fabric
In this case, the water permeability of the porous membrane is 1 × 10 ¹~ 1 × 10^Fiveml /
cm^Two/ Min, preferably 1 × 10^Two~ 1
× 10^Fourml / cm^Two/ Min is particularly preferred.
No. If the water permeability of the porous membrane is within the above range, the cover
Endothelialization at the end can be sufficiently promoted.

The porous membrane is preferably made of a biocompatible material, like the non-porous membrane forming the central portion. Further, the biodegradable or bioabsorbable material is preferably used. More preferably, it is produced. As such a material, those exemplified above for the non-porous film can be suitably used.

In the stent cover of the present invention, the central portion formed of the non-porous film and the terminal portion formed of the porous film may be made of the same material or different materials. You may. However, when both are made of different materials, it is necessary that they can be joined to each other. In an example of a preferred configuration of the stent cover of the present invention, the central portion is formed of a non-porous film of a silicone elastomer, and the terminal portion is formed of a nonwoven fabric of polyester. When the stent cover has the above-described configuration, the junction between the central portion and the terminal portion is excellent, the endothelialization at the cover terminal portion is sufficiently promoted, and the biocompatibility is also excellent.

In the stent cover of the present invention, the nonporous membrane at the center and the porous membrane at the end are joined by a method usually used for joining membranes, that is, fusion, bonding with an adhesive, fixation, and the like. It can be preferably carried out by suturing with a thread or the like, and which method to use may be appropriately selected depending on the material of the membrane. In addition, when joining the center part and the end part of the stent cover, it is preferable to join them so that they overlap each other at the boundary part. If the central portion and the terminal portion of the stent cover are joined in this way, no gap is generated at the joining portion, and the central portion and the terminal portion can be securely joined. Here, the order of the overlapping is such that the central portion of the stent cover is overlapped with the terminal portion (that is, the terminal portion of the stent cover is on the side closer to the stent body to be covered) as in the embodiment described later. It is preferable that the two are joined together in a state where the ends overlap with the center. Alternatively, when joining the center portion and the end portion of the stent cover, the ends may be joined by bonding with an adhesive, sewing with a thread, or the like without overlapping the boundary portion.

[0015] A drug may be added to the stent cover of the present invention for the purpose of preventing restenosis of the body lumen and promoting endothelialization at the end of the stent. Such a drug is not particularly limited and can be appropriately selected as necessary, but is preferably a drug having an antithrombotic action, a cell migration inhibitory action, a cell growth inhibitory action, or an endothelial cell growth promoting action. . Drugs having such effects, specifically, for example, anticancer drugs such as paclitaxel, immunosuppressants such as sirolimus, antiplatelet drugs such as abciximab,
Phosphorylcholine, steroids, angiopeptin, forskolin, hirudin, iloprost, viral vectors and DNA (bFGF, VEGF, HGF, TF
PI etc.), which may be added as a single substance or as a mixture of a plurality of drugs.

A method for adding a drug to the stent cover is as follows.
Although not particularly limited, from the viewpoint of handleability, the drug is preferably contained in a gel and added as a mixture or in an encapsulated state. The gel used for such a purpose is preferably inert to a living body. As such a gel, specifically, for example, gelatin,
Examples thereof include poly (2-methoxyethyl acrylate), chondroitin sulfate, hyaluronic acid, and fibrin. These may be used as a single substance, or may be a gel of a mixture of two or more kinds. More preferably, such gels have biodegradability or bioabsorbability. In the stent cover of the present invention, the end portion is formed of a porous membrane, so that when a drug is added, the pores of the porous or the voids of the woven or non-woven fabric are filled with the gel, and the non-porous There is an advantage that the amount of loaded drug can be increased as compared with a stent cover formed of a membrane.

In the stent cover of the present invention, the site to which a drug is added is appropriately selected according to the efficacy of the drug to be added. The agent that has the action of proliferating endothelial cells, that is, the agent for promoting endothelialization, covers the entire stent cover that covers the inner surface of the stent body, that is, the non-porous membrane at the center of such a stent cover and the end of the stent cover. Add to any of the porous membranes. Thereby, endothelialization is promoted on the entire surface of the stent cover on the lumen side of the stent. On the other hand, in the case of a drug having an action of suppressing thickening or forming a thrombus, it is preferable to add the drug to the end of the stent cover since thickening and formation of a thrombus easily occur at the end of the stent.

The stent of the present invention comprises a stent body and a stent cover. In the stent of the present invention, the stent body is a cylindrical body that is open at both ends and extends longitudinally between the two terminal openings, and the side surface of the cylindrical body has an outer surface and an inner surface. And a large number of notches communicating with the cylindrical body, and the notch is deformed to have a structure capable of expanding and contracting in the radial direction of the cylindrical body. In the stent according to the first embodiment of the present invention, the outer surface and / or the inner surface of such a stent body is covered with the stent cover of the present invention. The notch may be actually notched or may be an opening formed of a linear body. FIG. 1 is a side perspective view showing one aspect of the configuration of the stent of the first embodiment of the present invention, and FIG. 2 is a cross-sectional view of the stent of FIG. 1 taken along line 20-20. , FIG. 3 is a cross-sectional view of the stent of FIG. 1 taken along line 30-30. FIG.
FIG. 2 is a perspective view showing an example of a stent body. In FIG. 1, a stent body 2 constituting a stent 1 of the present invention is shown.
Is a cylindrical body having both ends opened as in the case of the stent body shown in FIG. 4, and the outer surface and the inner surface thereof are covered with the stent cover 100 of the present invention. In the figure, a central portion 5 of the stent cover 100 is formed of a non-porous film, and both end portions 3 are formed of a porous film. Reference numeral 4 denotes a joint between the central portion 5 formed of a non-porous film and the terminal portion 3 formed of a porous film. As shown in FIG. 2, the outer surface and the inner surface of the stent body 2 are covered with a non-porous membrane 5 at the center of the stent 1. As shown in FIG. 3, at both ends of the stent 1, the outer surface and the inner surface of the stent body 2 are covered with a porous membrane.

The stent body 2 is a cylindrical body that is open at both ends and extends longitudinally between the two terminal openings, and the side surface of the cylindrical body is the outer surface and the inner surface. The notch has a plurality of notches, and the notch is deformed, so that the cylindrical body can be expanded and contracted in the radial direction, and can be inserted into a biological lumen such as a blood vessel such as a blood vessel or a bile duct. Detained and maintain its shape. In FIG. 1, the notch communicating with the outer surface of the inside of the cylinder has a substantially rhombic shape and has a mesh-like structure as a whole. When a stress is applied, the rhombic shape is deformed and deformed in the radial direction of the cylinder. A possible stent body 2 is shown. A specific example of a cylindrical structure having a notch on the side surface and capable of expanding and contracting in the radial direction of the cylindrical body by deforming the shape of the notch will be described below. FIG.
FIG. 4 is a perspective view of a stent body 15 in which a plurality of elastic wires 16 are bent into a coil shape and connected to each other to form a cylindrical shape, and a gap between the elastic wires 16 forms a cutout portion.
A stent body similar to the stent body shown in FIG. 4 is disclosed in, for example, JP-A-9-215575 and JP-A-7-529. As another example of the stent body, for example, Japanese Patent Publication No. Hei 8-502428 and Japanese Patent Publication No. Hei 7-500272 disclose a method of bending an elastic wire in a zigzag shape and connecting a plurality of the elastic wires to a cylindrical shape. Yes,
A stent body in which a gap between elastic wires forms a cutout portion is disclosed. Japanese Unexamined Patent Publication No. 2000-501328 discloses that an elastic wire is bent into the shape of a serpentine flat ribbon, wound around a mandrel in a helical shape, and formed into a cylindrical shape. A stent body is disclosed. A stent body having a structure similar to that of the stent body disclosed in JP-T-2000-501328 is also disclosed in JP-A-11-222288. Japanese Patent Application Laid-Open No. 10-503676 discloses a stent body having a mesh-like structure in which the shape of a notch is different from that in FIG. 1 of the present specification and which has a meander pattern. . Tokiohei 8-50
No. 7243 discloses a stent body in which a plate-like member is bent into a coil shape to have a cylindrical shape, and a gap between adjacent coil portions forms a cutout portion. Also,
In Japanese Patent Publication No. 4-68939, an elastic plate-like member is formed into a cylindrical shape by spirally forming an elastic plate-shaped member. A cylindrical stent body having a plurality of different structures including a stent body in which a gap between elastic wires forms a notch is disclosed. In addition, the shape may be a leaf spring coil shape, a multiple spiral shape, an irregularly shaped tube, or the like. FIG. 2 of Japanese Patent Publication No. 4-68939
(A) and (b) describe a stent main body in which an elastic plate-like member is spirally bent into a cylindrical shape. As described above, the cylindrical main body does not have a cutout on the side surface, but the cylindrical main body has a notch. A cylindrical stent main body configured to be expandable / contractible in the radial direction can also be used as the stent main body of the present invention.
All of the above references and patent applications are incorporated herein by reference.

The means for expanding the stent main body after being placed is not particularly limited, and is self-expandable, that is, by expanding the radial direction with its own restoring force by removing the force holding the thin and small folded stent main body. The balloon may be of a balloon-expandable type, that is, a type in which the balloon is expanded from the inside of the stent body in the radial direction by an external force. Furthermore, the stent body is not limited to one that is placed in a vessel such as a blood vessel, and may be a part that is to be placed in any site where a stenotic body lumen such as a bile duct needs to be expanded and its shape maintained. Good.

The material of the stent body may be a polymer material or a metal material, and is not particularly limited as long as it has a certain degree of rigidity and elasticity, but is preferably a biocompatible material. Specifically, examples of the polymer material include polyolefins such as polyethylene and polypropylene, polyesters such as polyethylene terephthalate, and fluorine-containing polymers such as polytetrafluoroethylene and tetrafluoroethylene-ethylene copolymer. Examples thereof include stainless steel, tantalum, titanium, nickel titanium alloy, tantalum titanium alloy, nickel aluminum alloy and the like. Among these, a super-elastic alloy such as titanium nickel is preferable because a restoring force to the original shape is required as the self-expanding type, and it is preferable that the balloon does not easily return to the shape after expansion as the balloon-expandable type. From stainless steel. The method of manufacturing the stent body is not particularly limited, and may be appropriately selected from commonly used manufacturing methods according to the structure and material of the stent. For example, in the case of a mesh-like structure made of a metal material shown in FIG. 1, a pipe made of a metal material having a required dimension is cut out, and a side surface of the pipe is partially removed by cutting, chemical etching, laser cutting, or the like. To form a plurality of notches.

In the stent according to the first embodiment of the present invention,
The material and manufacturing method of the stent cover 100 are as described above. 1 to 3,
Although the aspect in which both the outer surface and the inner surface of the stent body 1 are covered with the stent cover 100 of the present invention is shown,
The stent of the present invention is not limited to this. That is, in the stent of the present invention, only one of the outer surface and the inner surface of the stent body may be covered with the stent cover of the present invention. On the other side, the entire prior art may or may not be covered by a cover formed of a porous membrane. In the stent of the present invention,
Preferably, both the outer and inner surfaces of the stent body are covered with the stent cover of the present invention. The stent in which both the outer surface and the inner surface of the stent body are covered with the stent cover of the present invention has a structure in which the stent cover covering the outer surface reduces irritation to the wall of a living body body in which the stent is placed, and reduces The stent cover, which covers the inner surface, prevents thickening of the cavity tissue, prevents the body fluid in the living body lumen from directly contacting the stent body, and particularly when the body fluid is blood, forms a thrombus. prevent. Furthermore, the porous membrane at the end of the stent cover that covers the inner surface provides an excellent scaffold for promoting endothelialization. On the other hand, a stent in which only one of the outer surface and the inner surface of the stent body is covered with the stent cover of the present invention can reduce the wall thickness of the entire stent, and the living lumen in which the stent is placed Large lumen can be secured. When only one of the outer surface and the inner surface of the stent body is covered with the stent cover of the present invention, the outer surface of the stent body is preferably covered with the stent cover of the present invention. Thereby, the proliferation and thickening of the tissue in the lumen of the stent can be suppressed, and the lumen at the site where the stent is placed can be secured large.

In FIG. 1, the end of the stent body 2 is exposed from the stent cover 100. However, the stent of the present invention is not limited to this, and the entire stent body (up to the end) is the stent cover. It may be coated. A stent in which the end of the stent body is exposed from the stent cover is advantageous in promoting endothelialization at the end of the stent, and is excellent in fixing the stent to tissue.
On the other hand, a stent in which the entire stent body is covered with the stent cover is excellent in preventing the occurrence of thickening in the stent lumen. In a mode in which the end of the stent body is exposed from the stent cover, the ratio of the exposed portion to the non-exposed portion in the length of the stent body in the longitudinal direction is 50:50 to 1: 1.
The ratio is preferably 0: 100, more preferably 3
0:70 to 10: 100, more preferably 2
0:80 to 10: 100. When the proportion of the exposed portion of the stent body is in the above range, it is advantageous in promoting endothelialization at the end of the stent, and is excellent in fixing the stent to the tissue.

A drug may be added to the stent cover 100 for the purpose of preventing restenosis of a body lumen and promoting endothelialization at the end of the stent. As you did. An outer surface and / or an inner surface of the stent body 2 is covered with a stent cover 10.
The method of covering with the stent body 100 is as follows: when the stent body 2 expands and contracts in the radial direction,
Any known method may be used as long as it does not exfoliate, can appropriately maintain the coated state, and does not adversely affect the living body. For example, after applying a solution having an adhesive action such as a fluoroelastomer solution, the solvent may be evaporated and then adhered to the outer surface and / or the inner surface of the stent body 2 so as to be adhered and fixed. When the stent cover is made of a thermoplastic material, the stent cover may be placed in close contact with the outer surface and / or the inner surface of the stent body, and then the stent cover may be thermally fused to the stent body by heating. .

In the stent according to the second embodiment of the present invention, the outer surface of the stent body is covered with the stent cover of the present invention, but the inner surface of the stent body is covered only with the porous membrane at the end. And the central part is not covered. In the stent according to the second embodiment of the present invention, the outer surface of the stent main body is covered with the stent of the present invention in which the central portion is formed of a non-porous membrane. Infiltration of cells from the lumen to the lumen side of the stent is suppressed, and proliferation and thickening of tissue toward the lumen side of the stent are prevented. On the other hand, since both ends of the outer surface and the inner surface of the main body of the stent are covered with the porous membrane, the water permeability of both ends is high, and the stent of the stent cover extends from the inner wall of the living body lumen near the cover. The formation of a smooth endothelial surface (endothelialization) is promoted over the surface on the lumen side, and the stent is excellently fixed to a tissue. Further, the porous membrane covering the end portion of the inner surface of the stent body becomes an excellent scaffold for promoting endothelialization.

In the stent of the second embodiment, the ratio of the length of the central portion to the both ends of the stent cover that covers the outer surface of the stent body is as described in the stent of the first embodiment. Further, the length of the porous membrane covering the end portion of the inner side surface, the ratio of the length of the uncoated portion of the central part of the stent body and the portion covered with the porous membrane of both end portions is the above-mentioned ratio. The length is the same as the ratio of the length of the center portion to the both end portions of the stent cover in the first embodiment. In the stent of the second embodiment, the porous membrane covering the inner surface of the stent body is
The end of the stent body may be completely covered, or may be covered with the end of the stent body exposed. In the case where the porous membrane covers the inner surface with the end of the stent body exposed, the ratio of the length of the exposed portion to the non-exposed portion of the stent end is determined according to the stent of the first embodiment of the present invention. Is as shown in FIG. In the stent of the second embodiment, the structure, material and manufacturing method of the stent body, the material and manufacturing method of the non-porous film and the porous film, the method of joining the non-porous film and the porous film, and the method of covering the stent body with the stent cover Alternatively, the method of coating with a porous membrane is as described for the stent cover of the present invention or the stent of the first embodiment of the present invention. Also for the stent of the second embodiment, the drug may be added to the stent cover covering the outer surface of the stent body and / or the porous membrane covering the terminal portion of the inner surface. And the stent cover of the present invention.

Hereinafter, the present invention will be further described with reference to examples. (Embodiment 1) In the embodiment, the diameter of both ends is 1.
5mm, 20mm long, about 120μm thick cylindrical body,
A central portion 5 is formed of a non-porous membrane on the outer surface and the inner surface of the stent body 2 having a mesh structure as a whole having a plurality of substantially rhombic notches communicating the inner and outer surfaces with the side surface of the cylindrical body, Both ends 3 are porous membranes (water permeability: 1100
(Ml / cm ² / min))
The stent 1 according to the first embodiment of the present invention shown in FIGS. 1 to 3 was manufactured by covering and bonding and fixing the stent cover 100 which is a μm cylindrical film. In the figure,
The central portion 5 of the stent cover 100 is made of a non-porous film made of a silicone elastomer having a length of about 10 mm, and both end portions 3 of the stent cover 100 have a length of about 5 mm.
mm polyolefin non-woven fabric
At the border 4 of the two covers, the two overlap by about 2 mm, with the silicone elastomer film overlying the polyolefin nonwoven (the polyolefin nonwoven is closer to the stent body 2 to be coated). Using the prepared stent, an implantation test into the rabbit abdominal aorta was performed. FIG. 7 is a diagram showing a state of implanting a stent into the rabbit abdominal aorta. In the figure, a stent 9 placed on a balloon 8 of a balloon catheter 7 is inserted from a rabbit right common carotid artery 12, delivered to a rabbit abdominal aorta 11, and a water pressure of 10 atm is applied to the balloon 8 so as to have a diameter of about 3 mm.
The stent 9 was implanted in the rabbit abdominal aorta 11 after being expanded to mm. Necropsy was performed 4 weeks after implantation and pathological evaluation was performed.
As a result of the pathological evaluation, no thrombus was found to adhere to the cover,
It was observed that smooth endothelialization progressed over the surface of the stent cover on the lumen side of the stent.

(Example 2) The procedure is the same as that of Example 1, but instead of covering the entire inner surface of the stent body with the stent cover, only the both ends are covered with a porous membrane, The stent of the second embodiment was prepared without coating, and the stent was implanted into the rabbit abdominal aorta, and the pathology was evaluated. The stent cover covering the outer cavity wall of the stent body is the same as the stent cover of the first embodiment. The porous membrane covering both ends of the lumen wall of the stent body is a porous nonwoven fabric made of polyolefin having a length of about 5 mm and a thickness of about 100 μm (water permeability: 1100 (ml)
/ Cm ² / min). FIG. 8 is a histopathological image of a cross section of the rabbit abdominal aorta 11 in which the intravascular stent 9 of the example is embedded and the vicinity of the end of the stent cut perpendicularly to the axis of the stent, viewed from the upstream side. It was taken at 20x. From the figure, thrombus was not adhered to the cover, and it was observed that smooth endothelialization was progressing on the surface of the stent cover on the lumen side of the stent.

(Comparative Example 1) As in Example 2, the diameter was 1.5
A stent having a thickness of about 100 μm was covered as a cover on the outer surface of the stent body 2 having a thickness of about 120 μm, a length of about 20 mm, and a thickness of about 120 μm to produce a stent shown in FIG. However, unlike the second embodiment, the cover 5 having a length of about 20 mm is entirely formed of a non-porous film made of silicone elastomer.
The prepared stent was implanted in the rabbit abdominal aorta as in the example. Necropsy was performed 4 weeks after implantation and pathological evaluation was performed. FIG. 9 is a histopathological view of a cross section obtained by cutting the vicinity of the stent end of the rabbit abdominal aorta in which the stent of Comparative Example 1 is embedded perpendicularly to the axis of the stent as viewed from the upstream side,
The photograph was taken at a magnification of 20 times. According to the figure, no cells invading the lumen through the cover were observed, but cells were infiltrated into the lumen at the end of the cover, and a thrombus was formed in the area. The condition was also observed.

(Comparative Example 2) The same 1.5 mm diameter as in the example.
m, length of 20 mm, thickness of about 80 μm outside the stent body
A film with a total thickness of about 200 μm on the side and inside surfaces
Cover as a cover and glue and fix
Produced. In the same figure, a cover 3 having a length of about 20 mm
Is a polyolefin porous membrane (water permeability: 350
(Ml / cm ^Two/ Min)). Made
Implanted stent into rabbit abdominal aorta as in Example
I do. Necropsy 4 weeks after implantation and pathological evaluation
In a state where cells have infiltrated the lumen through the cover
Was observed.

[0031]

According to the stent cover of the present invention, the central portion of the cover is formed of a non-porous membrane. Infiltration of cells from the lumen to the lumen side of the cover is suppressed. In addition, since the end portion of the cover is formed of a porous membrane, the formation of a smooth endothelialized surface from the wall of the living body near the cover to the inner surface of the cover covering the inner surface of the stent body is promoted. In addition, disturbance of blood flow at the end of the cover is eliminated. The stent according to the present invention has an outer surface and / or an inner surface of the stent body covered with the stent cover according to the present invention, or the outer surface of the stent body is covered with the cover according to the present invention, and the stent body has Since the end of the inner surface is covered with the porous membrane, the formation of a thrombus at the end can be suppressed, and the lumen patency can be maintained for a long time.

[Brief description of the drawings]

FIG. 1 is a side perspective view showing one embodiment of the configuration of the stent of the present invention.

FIG. 2 is a cross-sectional view of the stent of FIG. 1 taken along line 20-20.

FIG. 3 is a cross-sectional view of the stent of FIG. 1 taken along line 30-30.

FIG. 4 is a perspective view showing a stent main body in a form different from that of FIG. 1;

FIG. 5 is a side perspective view showing the configuration of the stent of Comparative Example 1.

FIG. 6 is a side perspective view showing a configuration of a stent of Comparative Example 2.

FIG. 7 is a view showing a state of implanting a stent into the abdominal aorta of a rabbit.

FIG. 8 is a pathological tissue diagram of a cross section of the abdominal aorta of a rabbit in which the stent of Example 2 is embedded, which is cut perpendicular to the axis of the stent near the end of the stent.

FIG. 9 is a pathological tissue diagram of a cross section of a rabbit abdominal aorta in which the stent of Comparative Example 1 has been implanted, which is cut perpendicular to the axis of the stent near the end of the stent.

[Explanation of symbols]

 1, 6: stent 2, 15: stent body 3: end of stent cover (cover of porous membrane) 4: boundary between end and center of stent cover 5: center of stent cover (non-porous) 7: balloon catheter 8: balloon 9: stent 10: rabbit 11: abdominal aorta 12: right common carotid artery 16: elastic wire 20, 30: cutting line 100: stent cover

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4C167 AA42 AA44 AA45 AA46 AA50 AA55 BB05 BB13 BB32 CC09 DD01 FF05 GG02 GG03 GG04 GG05 GG06 GG07 GG08 GG11 GG14 GG16 GG21 GG22 GG23 GG42 GG42H43

Claims (11)

[Claims] 1. A cylindrical stent cover having an open end at both ends and covering an outer surface and / or an inner surface of a cylindrical stent extending longitudinally between the two end openings. A central portion of the cover is formed of a non-porous membrane,
A stent cover, wherein a terminal portion is formed of a porous membrane. 2. The stent cover according to claim 1, wherein the porous membrane at the end of the cover is a nonwoven fabric. 3. The stent cover according to claim 1, wherein the non-porous membrane at the center and the porous membrane at the end of the cover have biocompatibility. 4. The stent cover according to claim 1, wherein the non-porous membrane at the center and the porous membrane at the end of the cover have biodegradability or bioabsorbability. 5. An agent for preventing restenosis of a living body lumen in which a stent is placed, or for promoting endothelialization at the end of the stent, is further added to the cover.
5. The stent cover according to any one of items 4 to 4. 6. The method according to claim 1, wherein the drug has an antithrombotic effect, suppresses cell migration,
The stent cover according to claim 5, wherein the stent cover has at least one effect of cell growth suppression or endothelial cell growth promotion. 7. The stent cover according to claim 5, wherein the drug is added while being contained in a gel. 8. The stent cover according to claim 7, wherein the gel is inert to a living body. 9. The stent cover according to claim 7, wherein the gel has biodegradability or bioabsorbability. 10. A stent body according to claim 1, wherein both ends are open, and a cylindrical stent body extending in a longitudinal direction between the two end openings is provided. Stent. 11. An open end at both ends thereof, a cylindrical stent body extending longitudinally between the two end openings, and covering an outer surface of the stent body.
And a stent comprising a porous membrane covering both end portions of the inner surface of the stent body and not covering the central portion.