The present invention relates a wire stent, and more particularly, to a wire stent capable of allowing connection portions in a stent consisting of wires to come in surface contact with each other to reinforce a radial strength.
Also, the present invention relates to a wire stent having a structure in which endothelial cellularization is easily performed during a vascular regeneration process after the stent is mounted at a blood wall upon surgical implantation of the stent.
Generally, balloon catheters and stents are medical apparatuses which are surgically implanted inside a vascular lumen or a blood vessel to expand the vascular lumen or the blood vessel when the vascular lumen in the human body is narrowed by various diseases developed in the human body, resulting in degraded innate functions of the vascular lumen, or when diseases such as poor blood circulation caused by the narrowed blood vessel occur.
Among such stents, a wire stent is manufactured by winding wires in a predetermined form of a frame to shape the wires and welding connection portions using laser beams. Korean Unexamined Patent Application Publication Nos. 10-2008-0044323 and 10-2011-0051849 disclose one example of such a wire stent.
In the case of conventional wire stents, however, connection portions between unit wires are formed so that the unit wires come in point contact with each other. When such wire stents have the connection portions formed to come in point contact with each other, the wire stents have an advantage in flexibility, but have a problem in that the unwelded portions do not come in close contact with a curbed shape of a blood vessel as the stent swells, which makes it easy to deform the wire stents. Also, the conventional wire stents have a problem in that a recoiling or shortening phenomenon in which the stents are shortened due to plastic deformation after swelling.
Meanwhile, referring to
Therefore, the present invention is designed to solve the problems of the prior art, and therefore it is an object of the present invention to provide a wire stent capable of enhancing the strength of the wire stent in a radial direction while maintaining the unique flexibility of the wire stent intact.
Also, it is another object of the present invention to provide a wire stent capable of promoting endothelial cellularization by designing both cross-sectional structures of the wire stent so as to promote the endothelial cellularization during a vascular regeneration process after the wire stent is mounted on a blood wall upon surgical implantation of the wire stent.
To solve the above problems, according to an aspect of the present invention, there is provided a wire stent comprising a plurality of unit wires to treat angiostenosis. Here, connection portions of the plurality of unit wires come in surface contact with each other in an axial direction.
According to one exemplary embodiment of the present invention, the plurality of unit wires may be connected to each other using at least one method selected from the group consisting of welding, and adhesion.
According to another exemplary embodiment of the present invention, the unit wires having a predetermined pattern may be configured to be connected with each other.
According to still another exemplary embodiment of the present invention, each of the unit wires may include a cell wire configured to form a cell with another adjacent unit wire; and a connection unit extending from one end of the cell wire to be connected with another unit wire.
According to still another exemplary embodiment of the present invention, the cell wire may have a zigzag shape in an axial direction.
According to still another exemplary embodiment of the present invention, connection portions of the connection units come in surface contact with each other.
According to still another exemplary embodiment of the present invention, the connection units may extend in opposite directions from both ends of the cell wire.
According to still another exemplary embodiment of the present invention, the stent may be made of at least one selected from the group consisting of a metal, a biodegradable polymer, a metal coated with the biodegradable polymer, a mixture of the metal and the biodegradable polymer, and a combination thereof.
According to still another exemplary embodiment of the present invention, in struts constituting the stent, the struts extending in an axial direction may be formed of a biodegradable polymer, and the struts extending in a circumferential direction may be formed of a metal.
According to still another exemplary embodiment of the present invention, the plurality of unit wires may be combined to form closed cells.
According to still another exemplary embodiment of the present invention, each of the struts constituting the stent may be formed so that the width of the strut increases toward the inner wall of a blood vessel.
According to still another exemplary embodiment of the present invention, both lateral surfaces of each of the struts are formed so that a slope of the strut increases toward the center thereof.
According to still another exemplary embodiment of the present invention, both lateral portions of each of the struts may be formed so that the lateral portions of the strut are symmetric to each other.
According to still another exemplary embodiment of the present invention, a cross section of each of the struts may be in a trapezoidal shape.
According to still another exemplary embodiment of the present invention, the cross section of each of the struts may be in a semicircular shape.
According to still another exemplary embodiment of the present invention, the cross section of each of the struts may be in triangular shape.
According to still another exemplary embodiment of the present invention, each of the struts may have a height of 30 to 120 μm.
According to still another exemplary embodiment of the present invention, a drug-carrying groove configured to carry a drug may be formed at one surface of each of the struts.
According to yet another exemplary embodiment of the present invention, both lateral surface portions of each of the struts constituting the wire stent are formed so that the both lateral surface portions of the strut are inclined in a straight or curved line.
According to one exemplary embodiment of the present invention, the wire stent including the wires can be useful in enhancing the strength of the wire stent in a radial direction while maintaining the unique flexibility of the wire stent intact by connecting the wires by means of welding and/or adhesion so that the connection portions of the wires in the stent do not come in point contact but come in surface contact with each other, thereby minimizing the recoiling and shortening phenomena.
According to one exemplary embodiment of the present invention, the wire stent can also be useful in being more firmly fixed in the inner wall of a blood vessel and more effectively treating angiostenosis by forming both lateral portions of each of struts constituting the wire stent so that the width of each of the struts increases toward the inner wall of the blood vessel so as to promote endothelial cellularization in a state in which the wire stent is mounted at the inner wall of the blood vessel.
a and 3b are enlarged cross-sectional views of the connection portion as shown in
a and 8b are configuration views schematically showing the cross section of a strut in a conventional wire stent.
In the present invention, the “wire stent” may refer to a stent including a plurality of unit wires.
In the present invention, the term “wires” may refer to strands constituting the stent.
In the present invention, the term “struts” may refer to individual strands constituting the stent.
In the present invention, the term “cell” may refer to a void space formed by the wires.
In the present invention, the term “closed cell” may refer to a closed cell completely surrounded by the wires.
In the present invention, the term “open cell” may refer to a cell which is not completely surrounded by the wires but partially opened.
Hereinafter, the wire stent according to one exemplary embodiment of the present invention will be described in detail with reference to the accompanying drawings.
The wire stent is inserted into a blood vessel, and closely attached to the inner wall of the blood vessel upon surgical implantation of the wire stent. The wire stent closely attached to the inner wall of the blood vessel serves to expand the blood vessel so as to promote blood circulation. The wire stent may be made of a material having predetermined rigidity and elasticity.
In the present invention, the wire stent may be made of a metal and/or a biodegradable polymer. Specifically, for example, the wire stent may be made of 1) a metal alone, 2) a biodegradable polymer alone, 3) a metal coated with the biodegradable polymer, 4) a mixture of the metal and the biodegradable polymer, or 5) a combination of two or more of the components 1) to 4).
When the metal and the biodegradable polymer are used together, the wire stent has an advantage in that it is possible to enhance radiopacity.
At least one selected from the group consisting of stainless steel, cobalt, titanium, platinum, nickel, iridium, niobium, tantalum, gold, silver, copper, aluminum, chromium, manganese, magnesium, and an alloy thereof may be selected and used as the metal.
By way of example, nitinol may be used as the alloy. In this case, nitinol is a kind of a Ni—Ti alloy and an alloy having shape memory behavior. The most common alloy is 55-nitinol which includes Ni at 54 to 56% by weight and the balance of Ti. The nitinol alloy has good corrosion resistance, no magnetism, and a relatively low density of 0.234 lb/in3.
The biodegradable polymer generally encompasses all types of polymers which are autonomously decomposed in a living body or a natural environment. In the present invention, for example, a copolymer or homopolymer of lactic acid and glycolic acid; a polymer including a carbohydrate-derived monomer such as a glucose derivative as a constituent element; a biodegradable hydrogel such as alginic acid; or a natural polymer such as a polypeptide, a polysaccharide, or a polynucleotide may be used as the biodegradable polymer. Examples of the biodegradable polymer may include polylactide (PLA), poly-L-lactide (PLLA), polyglicolide (PGA), polylactide-co-glicolide (PLGA), poly-ε-caprolactone (PCL), polylactide-co-caprolactone (PLCL), polydioxanone (PDO), poly-β-hydroxybutyrate (PHB), and the like, which may be used alone or in combination.
Meanwhile, in the struts constituting the wire stent, the struts extending in an axial direction (in a left/right direction as shown in
Meanwhile, the wire stent may have a two-layer structure including an inner stent and an outer stent. In this case, a polymer fiber may be inserted between the inner stent and the outer stent. Here, the polymer may be a biodegradable polymer, and may be stacked in the form of a fiber sheet.
The connection between the wires may be performed using a welding and/or adhesion method. The welding may be performed using a typical welding method, and the adhesion may also be performed using a typical adhesive.
In the case of the adhesion, when the biodegradable polymer is used as a stent material, the polymer may be melted, and may be used for attachment. The same polymers as the biodegradable polymer constituting the wire stent may be used as the polymer used for adhesion, or the same or similar types of polymers may also be used as the polymer used for adhesion. When the polymer is melted, the polymer may be melted using a solvent, or melted using a method such as heating.
Also, the wires may also be connected using an adhesive. For example, bioadhesives such as a cyanoacrylate-based glue, a fibrin glue, and a protein gelatin glue may be used as the adhesive.
Referring to
In the configuration of the unit wires 100, the first unit wire 110 will be specifically described by way of example. The first unit wire 110 includes a first cell wire 112 configured to form a cell 150 with other unit wires 120 and 130, and connection units 114 extending from both ends of the first cell wire 112.
The first cell wire 112 may be used to form the entire backbone of the wire stent, and thus may have a zigzag shape in a circumferential direction, as specifically shown in
The cell 150 may be a closed cell, or an open cell. The closed cell may have a better radial force than the open cell, and thus the closed cell may be advantageous in terms of minimization of the recoiling and shortening phenomena. As shown in
Also, the connection unit 114 extending from one end of the first cell wire 112 may be connected to other unit wires 120 and 130. More particularly, the connection units 114 may extend in opposite directions, that is, extend upward and downward from the first cell wire 112, based on the wire stent as shown in
As shown in
In the present invention, the connection between the unit wires 110, 120 and 130 whose connection portions come in surface contact with each other may include all connection between the cell wires 112, 122 and 132, connection between the connection units 114, 124 and 134, connection between the cell wires 112, 122 and 132 and the connection units 114, 124 and 134.
As shown in
a and 3b are diagrams showing the connection portion 140, as viewed from the cross section of a wire,
As shown in
In the plurality of unit wires 100 as described above, the connection portions 140 preferably come in surface contact in an axial direction. As the connection portions 140 come in surface contact, the strength of the wire stent may increase in a radial direction. Specifically, when the connection portions 140 come in point contact, the wire stent may be deformed when swelled since the wire stent does not match with the curved shape of a blood vessel.
As described in this exemplary embodiment, however, when the connection portions 140 of the unit wires 100 come in surface contact with each other, the strength of the wire stent increase in a radial direction (a vertical direction as shown in
According to this exemplary embodiment, the connection units 114, 124, and 134 are provided at both ends of the unit wires 100, as described above. As the connection portions 140 come in surface contact, the connection units 114, 124, and 134 may serve to reinforce degraded flexibility of the wire stent.
That is, since the connection units 114, 124, and 134 connect the respective unit wires 100 at predetermined intervals in a circumferential direction of the wire stent, the wire stent may also secure flexibility while maintaining a predetermined strength in a radial direction. When the flexibility of the wire stent is secured as described above, the wire stent may be easily swelled to match with the shape of the blood vessel.
The connection portions 140 of the above-described unit wires 100 may be properly selected according to the material and thickness of the wire stent. That is, the rigidity of the wire stent may also be enhanced by lengthening the connection portions 140. Also, when the flexibility of the wire stent needs to be further enhanced, it is possible to design the connection portions 140 to be short.
Hereinafter, the performance of the closed cell stent and the open cell stent was tested for comparison. For this purpose, one closed cell stent (
As shown in
Hereinafter, one exemplary embodiment of the wire stent capable of promoting endothelial cellularization according to the present invention will be described in further detail with reference to the accompanying drawings.
That is, the strut 10 may be formed so that the width of the strut 10 increases, as shown in
On the other hand, both lateral surface portions of the strut 10 may be formed aslant in a straight or curved line. That is, the both lateral surface portions of the strut 10 may be formed aslant so that the endothelial cells easily climb over the strut 10.
Referring to the shape shown in
Since the conventional strut as shown in
Also, both lateral surface portions of the strut 10 are preferably formed symmetrically to each other with respect to the center thereof, as shown in
Meanwhile, the height H of the strut 10 may be in a range of 30 to 120 μm, particularly preferably less than or equal to 70 μm. In the prior art, the strut 10 was generally designed to have a height of 85 to 90 μm. According to this exemplary embodiment, however, the strut 10 was designed so that the endothelial cells more easily climb over the strut 10 by reducing the height of the strut 10.
Also, a drug-carrying groove 14 configured to carry a drug 20 may be formed on one surface of the strut 10, that is, one surface of the strut 10 which is closely attached to the inner wall of a blood vessel. When the drug-carrying groove 14 is formed as described above, it is possible to deliver a drug capable of suppressing the excessive growth of neointimal cells. For reference, the drug-carrying groove 14 may have protrusions 12 formed on one surface of the strut 10 to extend from both sides thereof.
Next, hereinafter, another exemplary embodiment of the wire stent capable of promoting endothelial cellularization according to the present invention will be described in further detail with reference to the accompanying drawings.
As shown in
In addition to the exemplary embodiment as shown in
As described above, according to the above-described above exemplary embodiments, both lateral surface portions of the strut are configured to promote endothelial cellularization in a state in which the wire stent is mounted at the inner wall of a blood vessel. Therefore, the wire stent may be more firmly fixed in the inner wall of a blood vessel, and thus may be more effective in treating angiostenosis.
Hereinafter, a cell migration assay according to an angle formed between the strut and the inner wall of a blood vessel was performed. Specifically, a total of four types of stents were used. A first stent whose reverse slope is formed at an angle of approximately 30° as shown in
Human umbilical vein endothelial cells (HUVEC) were seeded in a 12-well cell culture plate at a density of 2×105 per well, and incubated at 37° C. until the cells adhered to the bottom of the plate.
To form a cell-free zone, a HUVEC monolayer was scraped using a P10 pipette tip.
The cells were washed with a medium to remove the free cells and cell debris.
An embryo germination medium (EGM)-2 medium was added, and each stent was positioned on the cell-free zone.
The cells were incubated for 7 days, and the respective stents were then recovered, and transferred to 1.5 ml tubes.
The stents were washed twice with phosphate buffered saline (PBS), and trypsin-ethylenediaminetetraacetic acid (EDTA) was added at an amount of 0.3 ml (an amount at which the wire stent was immersed). Thereafter, the cells were incubated at 37° C. for 2 minutes to detach the cells from the stents.
The stent were removed, and the cells were centrifuged at 1,000 rpm for 2 minutes to remove 0.25 ml of a supernatant.
A pellet was re-suspended, and the cells were counted.
As shown in
The present invention has been described in detail. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the scope of the invention will become apparent to those skilled in the art from this detailed description.
Number | Date | Country | Kind |
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10-2012-0093175 | Aug 2012 | KR | national |
10-2012-0094322 | Aug 2012 | KR | national |
Filing Document | Filing Date | Country | Kind |
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PCT/KR2013/007618 | 8/26/2013 | WO | 00 |