Bioabsorbable stent and method of making the same

• US 5,527,337 A
• Filed: 02/22/1994
• Issued: 06/18/1996
• Est. Priority Date: 06/25/1987
• Status: Expired due to Term

• Current Assignee: Duke University
• Original Assignee: Duke University
• Inventors: Walker, William F., Clark, Howard G., McElhaney, James H., Stack, Richard S.
• Primary Examiner(s): Thaler, Michael H.
• Application Number:
  US08/200,556
• Time in Patent Office: 847 Days
• Field of Search: 606/108, 606/198, 606/191, 606/151, 606/153-156, 623/1, 623/12, 623/901
• US Class Current: 606/198
• CPC Class Codes: A61F 2/90 characterised by a net-like or mesh-like structure
• CPC Class Codes: A61F 2/92 Stents in the form of a rolled-up sheet expanding after insertion into the vessel , e.g. with a spiral shape in cross-section
• CPC Class Codes: A61F 2/958 Inflatable balloons for placing stents or stent-grafts
• CPC Class Codes: A61F 2210/0004 bioabsorbable
• CPC Class Codes: A61F 2250/0067 Means for introducing or releasing pharmaceutical products into the body
• CPC Class Codes: A61L 31/148 Materials at least partially resorbable by the body
• CPC Class Codes: Y10S 623/901 Method of manufacturing prosthetic device

Abstract

A bioabsorbable stent for placement at the locus of a stenotic portion of a body passage, such as a blood vessel, which is flexible and compliant for safe and effective delivery to the site of the stenotic portion of, for example, a blood vessel, and so as to avoid the disadvantages of chronic implantation, such as arterial rupture or aneurism formation while exposed to the continuous stresses of a beating heart. The stent is formed from a bioabsorbable material and is porous or has apertures defined there through to facilitate tissue ingrowth and encapsulation of the stent. The stent is encapsulated and biodegrades or bioabsorbs within a period of days, weeks or months as desired following encapsulation to thereby minimize the likelihood of embolization or other risks of the dissolved material and to avoid the disadvantages of chronic implantation.

Claims

1. A method of forming pores on the surface of a stent, the stent including a tubular main body portion having a first end, a second end, and a flow passage defined therethrough from said first end to said second end, said tubular main body portion being sized for intraluminal placement within a body passage, said main body portion being one of porous and apertured, at least in part, said main body portion being one of expandable and self-expanding from a first, reduced cross-sectional dimension to a second enlarged cross-sectional dimension whereby said main body portion can be transported intraluminally to a targeted portion of a body passage and expanded to a second enlarged diameter so as to engage and support said targeted portion of said body passage, the method comprising the steps of:

i) contacting material from which said stent is formed with a solvent that swells said material under conditions such that swelling of an outer layer of said material is effected; and

ii) contacting said material resulting from step (i) with an agent that is a nonsolvent for said material, which agent forms a solution with said solvent, under conditions such that said agent diffuses into said swollen outer layer of said material thereby causing phase separation and pore formation in said outer layer of said material.

2. The method according to claim 1, wherein said pores are formed in said outer layer of said material prior to formation of said stent from said material.

3. The method according to claim 1, wherein said pores are formed in said outer layer of said material after formation of said stent from said material.

4. The method according to claim 1, wherein said main body portion is formed at least in part from a bioabsorbable material.

5. A method of incorporating a drug into a stent, the stent including a tubular main body portion having a first end, a second end, and a flow passage defined therethrough from said first end to said second end, said tubular main body portion being sized for intraluminal placement within a body passage, said main body portion being one of porous and apertured, at least in part, said main body portion being one of expandable and self-expanding from a first, reduced cross-sectional dimension to a second enlarged cross-sectional dimension whereby said main body portion can be transported intraluminally to a targeted portion of a body passage and expanded to a second enlarged diameter so as to engage and support said targeted portion of said body passage, said stent having a therapeutically effective amount of a drug coated thereon or incorporated therewithin, the method comprising the steps of:

i) forming pores in an outer layer of material from which said stent is formed;

ii) introducing into said pores a composition comprising said drug and a gel forming agent; and

iii) effecting setting of said composition as a gel.

6. The method according to claim 5, wherein said main body portion is formed at least in part from a bioabsorbable material.

7. An intraluminal stent comprising a tubular main body portion having a first end, a second end, and a flow passage defined therethrough from said first end to said second end, said tubular main body portion being sized for intraluminal placement within a body passage, said main body portion being formed at least in part from a material which has been rolled into a substantially cylindrical configuration and thereby said main body portion has a central axis, said main body portion being one of porous and apertured with a plurality of apertures, at least in part, said main body portion being expandable from a first, reduced cross-sectional dimension to a second enlarged cross-sectional dimension whereby said main body portion can be transported intraluminally to a targeted portion of a body passage and then can be expanded to said second enlarged cross-sectional dimension so as to engage and support said targeted portion of said body passage, said main body portion including means for retaining said main body portion in said reduced cross-sectional configuration and means for retaining said main body portion in said enlarged cross-sectional configuration, said main body portion being in the form of at least one strip of material, said means for retaining comprising an elongated connector element provided adjacent a first end of said strip of material, said connector element having a radially inner wall and a radially outer wall defining therebetween a strip receiving passage extending in a first direction from a first open end to a second end thereof, said strip receiving passage extending in said first direction at least part circumferentially of said main body portion, said strip of material being slidably disposed in said strip receiving passage whereby sliding movement of said strip of material in said first direction decreases a diameter of said main body portion and sliding movement of said strip of material in a second direction, opposite to said first direction, increases a diameter of said main body portion, at least a portion of said strip of material being disposed in said passage when said main body portion has said first cross-sectional dimension and at least a portion of said strip of material being disposed in said passage when said main body portion has said second cross-sectional dimension, wherein said second end of said passage is open, and said strip of material extends through said passage to selectively protrude from said first and second open ends thereof.

8. A stent as in claim 7, wherein said means for retaining comprises frictional engagement between said strip of material and said connector element.

9. A stent as in claim 7, wherein first and second connector elements are provided, one of said connector elements being fixedly secured to said first end of said strip of material.

10. A stent as in claim 9, wherein each of said connector elements includes means for slidably receiving said strip of material.

11. A stent as in claim 7, wherein a plurality of strips of material are provided.

12. The stent according to claim 7, wherein said main body portion is formed at least in part from a bioabsorbable material.

13. The stent according to claim 7, wherein said main body portion has a therapeutically effective amount of a drug coated thereon or incorporated therewithin.

14. An intraluminal stent comprising a tubular main body portion having a first end, a second end, and a flow passage defined therethrough from said first end to said second end, said tubular main body portion being sized for intraluminal placement within a body passage, said main body portion being formed at least in part from a material which has been rolled into a substantially cylindrical configuration and thereby said main body portion has a central axis, said main body portion being one of porous and apertured, at least in part, said main body portion being expandable from a first, reduced cross-sectional dimension to a second enlarged cross-sectional dimension whereby said main body portion can be transported intraluminally to a targeted portion of a body passage and then can be expanded to a second enlarged diameter so as to engage and support said targeted portion of said body passage, said main body portion including means for retaining said main body portion in said reduced diameter configuration and means for retaining said main body portion in said enlarged diameter configuration,

said main body portion including a plurality of tine receiving cavities and a plurality of tine elements, said tine receiving cavities each extending in a first direction at least part circumferentially of said main body portion from a first open end to a second end thereof, said tine elements being slidable in respective tine receiving cavities whereby sliding movement of said tine elements in said first direction in said tine receiving cavities selectively increases or decreases a diameter of said main body portion.