CA2181522A1

CA2181522A1 - Method of covering a stent with acellular matrix

Info

Publication number: CA2181522A1
Application number: CA 2181522
Authority: CA
Inventors: Allan Adelman; Malcolm Rawlings
Original assignee: Individual
Current assignee: Individual
Priority date: 1995-10-03
Filing date: 1996-07-18
Publication date: 1997-04-04
Also published as: WO1997012563A1

Abstract

A stent having an inner tubular lining of a biomaterial. The inner lining has open ends for rolling about the ends of the stent. The ends of the tube enclose the ends of the stent and are attached to the tube. A method of covering a stent includes mounting a tube of biomaterial on a distal end of a catheter, mounting the stent over the biomaterial, and rolling the open ends of the biomaterial over the distal and proximal ends of the stent.

Description

2181~22 METHOD OF COVERING A STENT WITH ACELLULARMATRIX
FIELD OF INVENTION
This invention relates to a method of covering a stent with biomaterial. In particular, this invention relates to a method of covering a stent with acellular matrix.
S BACKGROUND OF INVENTION
Stents, concicting of an "open" metal scaffolding, are now widely used for supporting l~lvwed or stenotic blood vessels that have been opened or e~r~nrled by balloon angioplasty. The stent is deployed to its target location within a vessel by threading the stent-c~, j~g c~ r through the vessel from an irlcision or 10 p~l~;uL~euus l~u~ ule some ~ e away. The stent isthen exrqn~led either on its own accord or by ballooning the c.~ll.r~ l for supportive engagement with the interior of the vessel wall to mqintqin vessel enl~eme~
Balloon çxp~qn-lqble stents are typically metal mesh that are mounted on balloon c~thPt~rs and delivered to the target location. When the balloon is expqntl~d, 15 the stent ~ AI~rlc to the desired ~ , to support the interior of the vessel.
Examples of such stents are described in United States Patent Nos.: 5,059,211;
5,282,824; 5,306,286; and 5,334,201.
Self-~l.An~ stents are made of an alloy having a "memory" that expand to the desired size after being placed at the target site of the vessel. Examples of such 20 stents are described in United States Patent Nos.: 4,800,882; 5,282,824; and 5,342,387.
In United States Patent No. 5,342,387,Summers, a wire double helix stent design is illustrated. The double helix is advantageous because by l~luwing and widening the gaps bc;L~en the parallel struts, it can be contracted and e~r-qn-le-l in 21~52~

tii~ml-ter willwul chA .~gi 1~ its length.
~lthou~h balloon s~Al~A~ Ahle stents of the prior art have been very successful in treating ~ ow~d or occl~lded blood vessels, these stents still suffer from a serious drawback.
All intravascular stents consist of an open metal scaffolding. The ratio of open space to stent material varies from 80t20 to about 90/10. When the vessel is stretched by balloon angioplasty and a stent is e~pan~f d in place across a now dilated lesion, a healing response is triggered. The healing response is a proliferation of smooth ml-scles cells from the area of vessel wall which has been injured by the procedure.
10 Although the scaffolding effect of the stent serves to restrict the build up of scar tissue (smooth muscle sell proliferation) and subseq~ent ,~ whlg, the gaps in the metal provide an OppOlLul~ily for en~l~ing smooth muscle cell proliferation to grow through the open spaces of the stent. As a result, about 30% of p,qtifnt~ will e~e~;f .re resten~ si~ of the vessel. The stent and the expqn~ion of the vessel ;~ t~
15 a reaction which causes tissue hlglowlll (intimal hyperplasia) which eventually leads to ~~ whlg or l~s~ si~, which may l~oces-~ te a revascularization prosedure to reopen the llallvwcd area inside the stent. This additional h~l~t;lllion is costly and, more iu~ol~llly, exposes the patient to further risk.
Attempts have been made to ...i.~ these complications. In United States 20 Patent No. 5,282,824,C~idllLulco, a stent assembly is disclosed which has a flexible nylon sleeve Attq-rll~od to the outside cil.;~llfel.~ ial surface of a stent. On implantation of the stent, the sleeved stent is allowed to e~pq-n~ ~tl~ssing the flexible sleeve against the walls of the blood vessel. The sleeve is intf n-lf d to pl. ~ tissue growth belWc;ell the gaps defined by the stent. However, nylon and other ~ylllll~lic 2~ s~

m~tPri~l~ probably will not provide a long term solution as such materials can cause massive infl~.. ~lol~ or thrombogenic lca.;Lions.
Recently, investigators have developed materials which are not associated with thrombosis or infl~.. ~lc,ly reactions. Acell~ r matrix is a biolllatelial derived from 5 tissue extracted from -~ n.~ which isprocessed to remove all cells and soluble proteins. This bio..l~ l has been shown to be non-thrombogenic and non-infl~.. ~o~ rPllul~r matrix cc,lll~lises a framework of largely insoluble collagen and elastin, which are very stable pl'Ot~inS. EA~lhllellL~l studies with this matrix have been sllGces~rul in a variety of cardiovascular applications. (CoulLIllan et al.:
10 "Development of ~licaç~ial .Are~ r Matrix Bio...~ Biochpnlir~l and Mech~nir~l Effects of Cell Extraction" Journal of Biom~o~ir~l Materials Research, Vol. 28, 655-666 (1994), and Wilson et al. ".Are~ r Matrix Allograft Small Caliber Vascular Protheses", Vol. XXXVI Trans. AM. Soc. Artif. Intern Organs, (1990), and see also United States Patent nos. 4,776,853and 4,801,299) Hel~lofole, acellular .. -l. ;res have been surgically implanted during eAl,clillltll~l studies. ~rPlllll~r matrix prothesis have not been incorporated as an integral part of stents.
Summary of the Invention The disadvantages of the prior art may be o~._lcollle by providing a method 20 of pr~aling a stent for impl~nt~tion by hs~ ulg an open ended tube of acellular matrix through a stent when in a co..l.~çted or collapsed condition, and rolling the open ends of the tube back over itself. The combination tube and stent is capable of being tr~n~lllmin~lly or surgically insell~d to a target site.
It is desirable to provide a bi-....~t~ l CO~'~.li~ for a stent, whel~ul the covering is non-thrombogenic and inhibits tissue i~ wl~- when deployed inside a blood vessel, duct, or conduit.
It is desirable to provide a biom~t~n~l covering which can form a barrier b~lween an implanted stent and the wall of the host blood vessel, duct, or conduit.
It is further desirable to provide a biomaterial covering which provides a smooth inner surface through which fluid flows.
It is further desirable to provide a biollla~lial co~"hl~ to encourage o~ rd gro-wth from the an&slolllosis sites inward.
It is further desirable to provide a plurality of stents covered with biomaterial 10 on a single c,,~ t- I for multiple deployment of the stents.
It is still further desirable to provide a stent co.rel~,d with biomaterial for use as a vascular graft for bylJassillg stenotic or occh~clecl blood vessels.
It is still further desirable to provide a stent covered with acellular matrix or biomaterial for use as a stent or graft for other ducts or col~luils within a living body.
It is still a further object of the invention to provide a stent lined with ~rPllnl~r matrix that resllic~ tissue ingrowth for co~gP~ l vascular defects such as pulmonary artery stenosis, portacaval shunts, arterio-venous shunts, deterioration of sll.h- .~o~s vein grafts for colul~y artery by-pass grafts and peripheral arteries and endohlmin~
grafting.
According to one aspect of the invention, a method of l,~a~illg occlusion and stenosis of a blood vessel, duct, or conduit is provided. The method colll~lises the steps of: providing a c~th~ter having a distal end; mrllntin~ a tube of ~cell~ r matrix or other biolllat,lial on the distal end of the c~thrtrr; sliding a stent over the bi.~ t~ l; rolling,l~ e~;lively,thedistalandpl(~ullalendsofthebiGllla~lial over - S -the distal and proximal ends of the stent; delivering the stent and bi~ at~lial to a target site; ç~ n~ g the stent; and withdlawiilg the c~ ter.
According to one aspect of the invention, a mPthorl of treating occlusion and stenosis of a blood vessel is provided. The method c~ p~ises the steps of: providing 5 a c"l-~l~,r having a distal end and an internal release wire; muulllhlg a tubular acellular matrix on the distal end of the c~ , sliding a self-exp~n-lin~ stent over the matrix, the self-e~ "~ stent having a ~ûlt:~;live sheath; ~ the distal and proximal ends of the stent through the acellular matrix to engage the release wire, contr~^tin~ the stent into an implantable condition; willl~awhlg the sheath;
10 rolling, l~,s~e~;lively, the distal and proximal ends of the tubular acellular matrix over the distal and l"o~il,lal ends of the stent; joining the distal and proximal ends of the tubular acellular matrix to the matrix, illse.lillg the c~l.rl~l distal end into the blood vessel; guiding the c~thf~tçr distal end to a targeted portion of the blood vessel;
withdlawing the release wire, allowing the stent to çxp~nf1 and withdlawhlg the C~7~llf tl from the blood vessel.
According to another aspect of the invention, a stent with an inner tubular lining of acelhll~r matrix or other bio"la~lial is provided. The inner lining has open ends for rolling about the ends of the stent. The ends of the tube enclose the ends of the stent and are ~tt~rhf d to the tube.
Acco,ding to another aspect of the invention, a stent with an inner tubular lining of acellular matrix or other biGllldl~lial is provided. The inner lining has open ends for rolling about ends of the stent. The open ends of the tube are ~tt^^hf~A to each other.

2~81522 Description of the D. ,.~. il~ iJ
In dlawing~ which illustrate embo ~ of the invention:
Figure 1 is a pc.~ecliv~ view of the present invention in an ullvvla~ed condition and mounted on a dual release wire CAI~ tt~
Figure 2 is a side sectional view of the self~ stent and acellular matrix mounted on a single release wire c~thPter;
Figure 3 is a section~l view of the self~ p stent partially covered with an ~ r matrix;
Figure 4 is a sectional view of the self~ n~ stent fully covered with an ac~lllll~r matrix; and Figure 5 is a pc,~c.,li~.~e view of al~ller self-ç~ u~ g stent which can be incol~lal~d into the present invention.
D~h;le~ Description of the Invention The pl~f~,.l.d stent to be used with the present invention is illu~lla~d in 15 Figure 1. Stent 12 is more particularly described in United States Patent no.
S,342,387, the contents of which are illcol~olaled herein by l~fc.~.lce. In the pler~,.l~ embotlim~nt~ stent 12 is self-~ an~il-g. However, the present invention also conLellll)lates lltili7in_ any self-e~l-AI-~lAble or balloon ~"l-A~-A~ble stent.
Ref~.ling to Figure 2, the stent 12 is illllstrAt~l mounted on a CA~ t~l 14.
20 Acellular matrix 16 is mounted belweell the c~th~ter 14 and the stent 12, pre~..l;.
an inner lining for the stent 12.
Acellular matrix 16 of the ple~ ,d embodiment is derived from ",~...,..~liAn preferably a human vessel, in~ j~ blood vessels, namely arteries and veins, ducts, or conlui~, and are ~ .erol~, tubular in shape having open ends. The size of the 2~8~522 vessel to be hal~csled is r1irtq-t~d by the size and type of stent to be implanted in the patient. Preferably, acellular matrix 16 is t~ c~d from human sources. However, bovine, ~ ciuc, canine or similar ~ lqliqn sources may also be suitable. Further, cryo-preserved human veins or other ducts or col~ui~ are contemplated as being a 5 suitable source for the bio...~ q-l .
The method of e~llacli~g and ~le~h~ the matrix 16 is fully described in Courtman et al.: "Development of Pelical.lial ~relllllqr Matrix Biomaterial:
Bioch.omirql and Mech~nir~l Effects of Cell F.~ l;on" Journal of Biom~lirq-l l~qt~riql~ Research, Vol. 28, 655-666 (1994), and Wilson et al. "Acellular Matrix 10 Allograft Small Caliber Vascular ~ollleses", Vol. XXXVI Trans. AM. Soc. Artif.
Intern Organs, (1990), and United States Patent nos. 4,776,853and 4,801,299,all of which are incorporated herein by ler~,lellce.
Stent 12 may have an int~rnql plolcclive sleeve 18. Sleeve 18 has a longit~ inqlly ek~ slot 20. Slot 20 allows access for distal end 22 and proximal 15 end 24 of the stent to be inserted into notches 26 and 28 in the cqth~ter 14. Notches 26 and 28 receive, lc~c~,lively, the distal end 22 and proximal end 24 of stent 12 to retain the stent for deployment. Proximal end 24 is first engaged with the release wire 30 and then the distal end 22 is wound down to compact the stent 12. The distal end 22 is then looped through with the release wire 30. Release wire 30 e.~lr~ s 20 intçrnqlly within the c~lh~ l 14 through loops formed in each the distal end 22 and proximal end 24 of the stent 12 to retain the stent 12 on the c-q-th~ter 14 in a compq-cte~ condition.
Once the stent 12 engdges the release wire 30, the protective sleeve 18 can be withdrawn by sliding it along the c~ e, to~alds the proximal end thereof. After 2181~22 the protective sleeve 18 is withdrawn, the distal end 32 of acellular matrix 16 is rolled back over itself to cover the distal end of stent 22. Similarly, the proximal end 34 is rolled over itself to cover the proximal end 24 of stent 12.
Referring to Figure 3, the distal end 32 is rolled back to cover only a portion 5 of the distal end region of the stent 12. Similarly, the proximal end 34 is rolled back a portion of the length of stent 12 to cover the pl~hl~al end region thereof.
The distal end 32 and the p~ illlal end 34 are Att~h~d to the inner tubular body of the acellular matrix 16 by sululill~, surgical stapling, gluing, taping, or any other method for qttqrhin~ biolllat~ ~ial to itself.
The stent 12 and acellular matrix 16 can now be deployed using t~chniques and m~thotl~ well known in the art.
~ lths)ugh the ~lcf~,l.,d embodiment has desclil,ed the acellular matrix 16 being mounted an a cath~ter for cov. .hlg the stent 12, it is now readily understood that similar cylin~rir-q-l a~alus could be used. The stent 12 and acellular matrix 16 15 of the present invention could be mounted on such cylinder and later llal~Ç~ d to a stent for imp!qntqtion.
Refe.li~ to Figure 4, the distal end 32 and the ~ hllâl end 34 of acellular matrix 16 are fully retracted until the ends 32 and 34 abut. A continuous suture line may be used around the ch.;ulllfe~.llial seam for joining the ends 32 and 34 together.
20 In this embo~lim~ont the stent 12 is fully covered, both int~rnqlly and ext~rnqlly and may be deployed using techni~ es and m.oth~s well known in the art.
It is noted that the distal end 22 and proximal end 24 of stent 12 extend through the acellular matrix 16 when in the ready for deployment condition. Once the release wire 30 is retracted, the distal end 22 and the proximal end 24 of stent 12 will retract back through the pul~ ulcd ~c,~ing in ace~ r matrix 16 which will close, fully covering stent 12.
The stent 12 and acell~ r matrix 16 are also useful in grafting. The stent 12 5 and acellular matrix 16 may be implanted on ends of a blood vessel which are to be joined. The stent 12 will provide ~rovcd structural support for the vessel over conventional prior art grafts. This i~ loved support will reduce the risk of al~cu~y~llls.
Additionally, the stent 12 and acelllll~r matrix 16 can be made of a larger 10 ~ m~ter to operate as a graft for larger ducts within the human body. For example, the stent 12 and acellular matrix 16 of the present invention has applications as a proll,esis for the trachea, oesophagus, ali,.,~ canal, geniluuli-~y or other similar bodily ducts.
Referring to Figure 5, a second embodiment of a self-e~ stent 112 15 which could be covered and implanted by the present invention is illustrated.
It will be obvious to those skilled in the art that various mo-lifir~tions and changes can be made to the method wi~,uul dcp~~ g from the spirit and scope of this invention.

Claims

1. A method of preparing a stent for implantation, the method comprising the steps of placing an open ended tube of biomaterial relatively inside of a stent and rolling open ends of the tube back over itself.

2. A method as claimed in claim 1 including a first preliminary step of coaxially mounting the tube onto a distal end of a catheter.

3. A method as claimed in claim 2 including after said rolling step, attaching said ends of the tube to itself.

4. A method as claimed in claim 3 wherein said attachment step includes suturing, surgical stapling, gluing, or taping.

5. A method as claimed in claim 1 wherein said ends of the tube are attached to each other.

6. A method as claimed in claim 1 wherein said implantation is for free grafting ends of a vessel in a patient.

7. A method of treating occlusion and stenosis of a blood vessel comprising the steps of:
providing a catheter having a distal end;
mounting a tube of biomaterial on the distal end of said catheter sliding a stent over the biomaterial;
rolling distal and proximal ends of the biomaterial over distal and proximal ends of the stent;
delivering the stent and biomaterial to a target site;
expanding the stent; and withdrawing said catheter.

8. A method as claimed in claim 7 wherein said biomaterial is an acellular matrix.

9. A method as claimed in claim 8 wherein said acellular matrix is derived from a vessel selected from a group comprising of human, bovine, canine, or porcine sources.

10. A method as claimed in claim 7 wherein said acellular matrix is derived from human bodily vessels.

11. A method of preventing occlusion and stenosis of a blood vessel comprising the steps of:
providing a catheter having a distal end and an internal release wire;
mounting a tubular acellular matrix on the distal end of said catheter;
sliding a self-expanding stent over the matrix, said self-expanding stent having a protective sheath;
extending distal and proximal ends of said stent to engage said release wire for contracting said stent into an implantable condition;
withdrawing said sheath;
rolling distal and proximal ends of said tubular acellular matrix over distal and proximal ends of said stent;
joining said distal and proximal ends of said tubular acellular matrix to itself;
inserting said catheter distal end into said blood vessel;
guiding said catheter distal end to a targeted portion of said blood vessel;
withdrawing said release wire allowing said self-expanding stent to expand; and withdrawing said catheter from said blood vessel.

12. A method as claimed in claim 11 wherein said acellular matrix is derived from a vessel selected from a group comprising of human, bovine, canine, or porcine sources.

13. A method as claimed in claim 11 wherein said acellular matrix is derived from human bodily vessels.

14. A stent covered with a biomaterial.

15. A stent as claimed in claim 14 wherein said biomaterial is an acellular matrix.

16. A stent as claimed in claim 15 wherein said acellular matrix is derived from a vessel selected from a group comprising of human, bovine, canine, or porcine sources.

17. A stent as claimed in claim 15 wherein said acellular matrix is derived from human bodily vessels.

18. A stent having an inner tubular lining of a biomaterial said inner lining having open ends for rolling about ends of said stent.

19. A stent as claimed in claim 18 wherein said biomaterial is an acellular matrix.

20. A stent as claimed in claim 19 wherein said acellular matrix is derived from a vessel selected from a group comprising of human, bovine, canine, or porcine sources.

21. A stent as claimed in claim 19 wherein said acellular matrix is derived from human bodily vessels.

22. A stent as claimed in claim 19 wherein said open ends of the tube enclose said ends of said stent and are attached to said tube.

23. A stent as claimed in claim 19 wherein said open ends of the tube are attached to each other.