Bioprosthetic tissue preparation with synthetic hydrogels

• US 20050119736A1
• Filed: 10/18/2004
• Published: 06/02/2005
• Est. Priority Date: 10/30/2003
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Bezuidenhout, Deon, Oostheysen, Anel, Human, Paul, Zilla, Peter
• Granted Patent: US 7,955,788 B2
• Time in Patent Office: Days
• US Class Current: 623/2.420
• CPC Class Codes: A61L 27/3687 characterised by the use of chemical agents in the treatment, e.g. specific enzymes, detergents, capping agents, crosslinkers, anticalcification agents
• CPC Class Codes: A61L 27/507 for artificial blood vessels apparatus for applying cells on a blood vessel prosthesis A61F2/062
• CPC Class Codes: A61L 27/52 Hydrogels or hydrocolloids

Abstract

Methods for treating xenogenic tissue for implantation into a human body including in-situ polymerization of a hydrogel polymer in tissue, and tissue treated according to those methods, where the polymerization takes place in tissue that has not been fixed with glutaraldehyde. The polymerization may only fill the tissue, bind the polymer to the tissue, or cross-link the tissue through the polymer, depending on the embodiment. One method includes free radical polymerization of a first vinylic compound, and can include cross-linking through use of a second compound having at least two vinyl groups. Another method utilizes nucleophilic addition polymerization of two compounds, one of which can include PEG and can further include hydrolytically degradable regions. In one embodiment, applicants believe the in-situ polymerization inhibits calcification, and that the polymerization of tissue un-fixed by glutaraldehyde allows for improved penetration of the polymer. The methods find one use in the treatment of porcine heart valve tissue, intended to extend the useful life of the valves by inhibiting calcification. The incorporation of degradable hydrogel regions may initially fill the tissue and reduce any initial inflammatory response, but allow for later infiltration by cells to remodel the tissue.

Claims

1. A method for treating a tissue for implantation into a human body, the method comprising:

providing the tissue, wherein the tissue has unreacted amino groups;

providing a first compound having at least one vinyl moiety;

introducing the first compound into the tissue; and

polymerizing the compound in the tissue to form a hydrogel polymer, wherein the polymerizing includes reacting the vinyl moiety with the tissue amino groups to bind at least some of the polymer to the tissue amino groups.

2. The method of claim 1, further comprising providing a second compound that is different from the first compound, wherein the polymerizing includes reacting the second compound to cross-link the polymer.

3. The method of claim 1, wherein a majority of the tissue amino groups are not cross-linked with glutaraldehyde.

4. The method of claim 1, wherein essentially none of the tissue amino groups are cross-linked with glutaraldehyde.

5. The method of claim 1, wherein the first compound has the formula R₁R₂C═

CR₃R₄, wherein R₁, R₂, and R₃ are selected from the group consisting of H and CH₃, and wherein R₄ is selected from the group consisting of alkyl, aryl, ethers, esters, alcohols and amines, and any combination thereof.

6. The method of claim 5, wherein R₄ is selected from the group consisting of —

COOH, —

COOR₅, —

CONH₂, and —

CONHR₆, wherein R₅ is an alcohol, and wherein R₆ is an alkyl.

7. The method of claim 5, wherein R4 is selected from the group consisting of —

COOH, —

COOR₅, —

CONH₂, and —

CONHR₆, wherein R₅ has the formula -(—

CH₂—

)_n—

OH and n=1 or greater, and wherein R₆ has the formula -(—

CH₂—

)_p—

CH₃ and p is 0 or greater.

8. The method of claim 1, in which the first compound is selected from the group consisting of acrylamide, 2-hydroxy ethyl methacrylate, methyl crotonate, methyl acrylate, ethyl acrylate, N(hydroxymethyl) methacrylamide, methyl methacrylate, methacrylamide, and N(hydroxymethyl) acrylamide and any combinations thereof.

9. The method of claim 1, in which the first compound has at least two vinyl moieties.

10. The method of claim 9, in which the first compound includes PEG.

11. The method of claim 10, in which the first compound includes PEG in a compound backbone.

12. The method of claim 10, in which the first compound includes PEG in a compound sidearm.

13. The method of claim 2, in which the second compound has at least two vinyl moieties.

14. The method of claim 13, in which the second compound includes PEG.

15. The method of claim 14, in which the second compound includes PEG in a compound backbone.

16. The method of claim 14, in which the second compound includes PEG in a compound sidearm.

17. The method of claim 2, in which the second compound is selected from the group consisting of N, N′

-methylenebisacrylamide, N, N′

-(1,2-dihydroxyethylene)bisacrylamide, polyethyleneglycol divinyl ether, and R7-O-PEG-O—

C(—

C—

O-PEG-O—

R₇)CO[C(—

C—

O-PEG-O—

R₇)CO—

]_nC(—

C—

O-PEG-O—

R₇)CO-PEG-OR₇, where R₇ contains a vinyl group and n is an integer 1 or greater.

18. The method of claim 1, wherein at least some of the tissue amino groups have been capped with a blocking capping agent, leaving essentially non-reactive groups coupled to the tissue.

19. The method of claim 18, in which the blocking capping agent non-reactive groups are selected from the group consisting of alkyl, aryl, ether and alcohol groups.

20. The method of claim 18, in which the capping agent is selected from the group consisting of glycidyl ether (PGE), glyceral, propional, CHO(CH₂)_nCH₃, and CH₃CHO(CH₂)_nCH₃, where n is an integer having a value or 0 or greater, and any combinations thereof.

21. The method of claim 1, wherein at least some of the tissue carboxyl groups have been capped with a capping agent, leaving essentially non-reactive groups.

22. The method of claim 21, in which the non-reactive groups are selected from the group consisting of alkyl, aryl, ether and alcohol groups.

23. The method of claim 1, wherein at least some of the tissue amino groups have been capped with an activation capping agent, leaving essentially reactive groups covalently bonded to the tissue amino groups.

24. The method of claim 23, in which the activation capping agent is selected from the group consisting of allyl glycidyl ether, butadiene monoxide, 1,2-epoxy-5-hexene, and glycidyl methacrylate, and any combinations thereof.

25. The method of claim 1, in which the providing tissue provides porcine heart valve tissue.

26. A method for treating a tissue for implantation into a human body, the method comprising:

providing the tissue;

providing a first compound having at least two α

, β

unsaturated moieties;

providing a second compound having at least two nucleophilic moieties;

introducing the first and second compounds into the tissue; and

polymerizing the first and second compounds in the tissue through conjugate nucleophilic addition, to form a hydrogel polymer.

27. The method of claim 26, wherein the first compound has the formula R₉-(X)_n, where n is an integer having a value of at least 2, and where X represents an α

, β

unsaturated compound, selected from the group consisting of -Z-C═

C, where Z is selected from the group consisting of CHO, COR, COOR, CONH2, CN, SOR, SO2R, where R is selected from the group consisting of hydrogen, alkyl, aryl, ethers, esters, alcohols and amines, and any combination thereof, and where R₉ represents a water soluble polymer.

28. The method of claim 26, wherein the second compound has the formula R₈-(Nu)_m, where Nu is a nucleophile, and where m is an integer having a value of at least 2, and wherein R₈ represents a water soluble polymer.

29. The method of claim 28, wherein the nucleophile is selected from the group consisting of amino (—

NH₂) and thiol (—

SH) groups.

30. The method of claim 28, wherein R8 is selected from the group consisting of water soluble polymers, polyethylene glycol (PEG), polyvinyl alcohol (PVAL), polyvinylpyrrolidone (PVP), polyacrylamide (PAM), polyacrylic acid (PAA) and any combinations thereof, and random, graft, and block copolymers formed thereof.

31. The method of claim 28, wherein R8 is selected from the group consisting of hydrolytically degradable polymers, polyesters, polyglycolic acid, polylactic acid, polycaprolactone, polyhydroxybuterate, polyortoesters, polyanhydrides, poly (sebasic acid-hexadecanoic acid anhydride), polyiminocarbonates and any combinations thereof, and random, graft, and block copolymers formed thereof.

32. The method of claim 28, wherein R8 includes polymers selected from the group consisting of enzymatically degradable polymers, polyamino acids, and polysaccharides and any combinations thereof, and random, graft, and block copolymers formed thereof.

33. The method of claim 27, wherein R9 is selected from the group consisting of water soluble polymers, polyethylene glycol (PEG), polyvinyl alcohol (PVAL), polyvinylpyrrolidone (PVP), polyacrylamide (PAM), and polyacrylic acid (PAA) and any combinations thereof, and random, graft, and block copolymers formed thereof.

34. The method of claim 27, wherein R9 is selected from the group consisting of hydrolytically degradable polymers, polyesters, polyglycolic acid, polylactic acid, polycaprolactone, polyhydroxybuterate, polyortoesters, polyanhydrides, poly (sebasic acid-hexadecanoic acid anhydride), polyiminocarbonates and any combinations thereof, and random, graft, and block copolymers formed thereof.

35. The method of claim 28, wherein R9 includes polymers selected from the group consisting of enzymatically degradable polymers, polyamino acids, and polysaccharides and any combinations thereof, and random, graft, and block copolymers formed thereof.

36. The method of claim 26, in which the tissue has unreacted nucleophilic moieties, wherein the polymerizing includes reacting the α

, β

unsaturated moieties with the tissue nucleophilic moieties to bind at least some of the polymer to the tissue nucleophilic moieties.

37. The method of claim 26, wherein the tissue includes amino groups, and essentially none of the tissue amino groups are cross-linked with glutaraldehyde prior to polymerization.

38. The method of claim 26, wherein the tissue includes amino groups, and a majority of the tissue amino groups are not cross-linked with glutaraldehyde prior to polymerization.

39. The method of claim 26, the tissue includes amino groups, wherein at least some of the tissue amino groups have been capped with a blocking capping agent, leaving essentially non-reactive groups bonded to the amino groups.

40. The method of claim 39, in which the non-reactive groups are selected from the group consisting of alkyl, aryl, ether and alcohol groups.

41. The method of claim 39, in which the blocking capping agent is selected from the group consisting of glycidyl ether (PGE), glyceral, propional, CHO(CH₂)_nCH₃, and CH₃CHO(CH₂)_nCH₃, where n is an integer having a value or 0 or greater, and any combinations thereof.

42. The method of claim 26, wherein the tissue includes carboxyl groups, wherein at least some of the tissue carboxyl groups have been capped with a blocking capping agent, having essentially non-reactive groups bonded to the carboxyl groups.

43. The method of claim 42, in which the non-reactive groups are selected from the group consisting of alkyl, aryl, ether and alcohol groups.

44. The method of claim 42, in which the capping agent is selected from the group consisting of glycidyl ether (PGE), glyceral, propional, CHO(CH₂)_nCH₃, and CH₃CHO(CH₂)_nCH₃, where n is an integer having a value or 0 or greater, and any combinations thereof.

45. The method of claim 26, in which the providing tissue provides porcine heart valve tissue.

46. The method of claim 26, further comprising fixing the tissue with glutaraldehyde after the polymerization.

47. The method of claim 26, wherein at least some of the first compound α

, β

unsaturated moiety include acrylate groups, and wherein the first compound has at least three acrylate groups.

48. The method of claim 26, wherein at least some of the first compound α

, β

unsaturated moieties include vinyl sulfone groups and wherein the first compound has between 2 and 8 arms including polyethylene glycol.

49. The method of claim 26, wherein at least some of the first compound α

, β

unsaturated moieties include acrylate groups and wherein the first compound has between 2 and 8 arms including polyethylene glycol.

50. The method of claim 26, further comprising decellularizing the tissue prior to the polymerization.

51. The method of claim 50, further comprising decellularizing the tissue by rupturing cell membranes with a surfactant and rinsing the tissue.

52. A method for treating a tissue for implantation into a human body, the method comprising:

providing the tissue, wherein the tissue has unreacted amino groups;

providing a first blocking capping agent;

introducing the first agent into the tissue;

reacting the capping agent with amino groups in the tissue to form a covalent bond with the amino groups, wherein the reacting leaves an essentially unreactive compound coupled to the amino group; and

forming a hydrogel in the tissue through in-situ polymerization.

53. The method of claim 52, wherein the capping agent reacts with the amino groups through either aldehyde or epoxide moieties.

54. The method of claim 52, wherein the capping agent reacts with the amino groups through a vinyl moiety.

55. The method of claim 52, wherein the capping agent is selected from the group consisting of glycidyl ether (PGE), glyceral, propional, and CH₃CHO(CH₂)_nCH₃, where n is an integer having a value or 0 or greater, and any combinations thereof.

56. The method of claim 52, wherein the capping agent includes an acrylate moiety.

57. The method of claim 52, wherein some amino groups remain unreacted after the capping, where the in-situ polymerization includes bonding the hydrogel polymer to the tissue amino groups.

58. The method of claim 52, wherein some amino groups remain unreacted after the capping, where the in-situ polymerization includes bonding the hydrogel polymer to the tissue amino groups at more than one polymer site to cross-link the tissue.

59. The method of claim 52, wherein some amino groups remain unreacted after the capping, where the in-situ polymerization forms the hydrogel covalently bonded to the tissue amino groups, such that some tissue amino groups are cross-linked through the hydrogel while other tissue amino groups are capped with the capping agent.

60. The method of claim 52,wherein the in-situ polymerization is performed after the reacting of the block capping agent.

61. A method for treating a tissue for implantation into a human body, the method comprising:

providing the tissue, wherein the tissue has unreacted carboxyl groups;

providing a first blocking capping agent;

introducing the first agent into the tissue;

reacting the capping agent with carboxyl groups in the tissue to form a covalent bond with the carboxyl groups, wherein the reacting leaves an essentially unreactive compound coupled to the carboxyl group; and

forming a hydrogel in the tissue through in-situ polymerization.

62. The method of claim 61, wherein the capping agent reacts with the carboxyl groups through an epoxide moiety.

63. The method of claim 61, wherein the capping agent is glycidyl ether (PGE).

64. The method of claim 61, further comprising filling the tissue through in-situ polymerization of a hydrogel polymer.

65. The method of claim 61,wherein the in-situ polymerization is performed after the reacting of the block capping agent.

66. A method for treating a tissue for implantation into a human body, the method comprising:

providing the tissue, wherein the tissue has unreacted amino groups;

providing an activation capping agent, wherein the activation capping agent has an epoxy moiety and a vinyl moiety;

introducing the activation capping agent into the tissue; and

reacting the activation capping agent epoxy moiety with the tissue amino groups to form a covalent bond with the amino groups.

67. The method of claim 66, in which the activation capping agent is selected from the group consisting of AGE, BMO, EH and GMA and any combinations thereof.

68. The method of claim 66, in which the activation capping agent has the formula H₂C═

CRCHCH₂O, where R is selected from the group consisting of hydrogen, alkyl, aryl, ethers, esters, alcohols and amines, and any combination thereof.

69. A method for treating a tissue for implantation into a human body, the method comprising:

providing the tissue, wherein the tissue includes native, unreacted amino groups;

providing a compound, wherein the compound includes at least two vinyl groups, at least two alpha, beta unsaturated groups, and at least one polyethylene glycol group;

introducing the compound into the tissue; and

polymerizing the compound in the tissue to form a hydrogel polymer.

70. The method of claim 69, in the polymerizing includes forming at least one covalent bond between the hydrogel and the tissue amino group.

71. The method of claim 69, in the polymerizing includes cross-linking at least two tissue amino groups through the hydrogel by forming at least two covalent bonds between one hydrogel polymer and the tissue amino groups.

72. The method of claim 69, wherein the polymerization includes forming more than one covalent bond with tissue free amino groups to cross-link the tissue.

73. The method of claim 69, wherein the polymerization utilizes free radical polymerization.

74. The method of claim 69, wherein the polymerization utilizes nucleophilic conjugate addition.

75. The method of claim 74, wherein at least some of the compound vinyl groups are disposed within acrylate groups.

76. The method of claim 74, wherein at least some of the compound vinyl groups are disposed within vinyl sulfone groups.

77. A method for treating a tissue for implantation in a foreign body, the method comprising in-situ polymerization of a hydrogel in the tissue where the tissue has not been fixed with glutaraldehyde.

78. The method of claim 77, wherein the polymerization includes introducing a first compound into the tissue and initiating polymerization of the first compound in the tissue, wherein the first compound is selected from the group consisting of monomers and polymers and any combinations thereof.

79. The method of claim 78, wherein the first compound has at least one vinyl group and the polymerization includes free radical polymerization of the first compound using the vinyl group.

80. The method of claim 78, wherein the first compound has at least two vinyl groups and the polymerization includes free radical polymerization of the first compound using the two vinyl groups.

81. The method of claim 77, wherein the polymerization includes introducing a first compound and a second compound into the tissue, wherein the second compound is a cross-linking compound, wherein the second compound is selected from the group consisting of monomers and polymers and any combinations thereof, further including initiating polymerization of the first compound and second compound in the tissue.

82. The method of claim 81, wherein the polymerization includes free radical polymerization.

83. The method of claim 77, wherein the in-situ polymerization includes introducing a first compound having at least two nucleophilic moieties and introducing a second compound having at least two alpha, beta unsaturated moieties, and wherein the polymerization includes nucleophilic addition polymerization between the first compound and the second compound.

84. The method of claim 83, wherein the nucleophilic moiety is selected from the group consisting of thiol (SH) and amino(NH2) groups.

85. The method of claim 83, wherein the alpha, beta unsaturated moiety has the formula -Z-C═

C, wherein Z is selected from the group consisting of CHO, COR, COOR, CONH₂, CN, SOR, and SO₂R.

86. The method of claim 83, wherein the first or second compound includes polyethylene glycol (PEG).

87. The method of claim 77, in which the in-situ polymerization includes covalently bonding at least some of the polymers to at least one tissue site per polymer.

88. The method of claim 77, in which the in-situ polymerization includes covalently bonding at least some of the polymers to at least two tissue sites per polymer.

89. The method of claim 77, further comprising fixing the tissue with glutaraldehyde after the polymerization.

90. The method of claim 77, further comprising decellularizing the tissue prior to the in-situ polymerization.

91. A heart valve including xenogenic tissue, wherein the tissue has native amino groups, the tissue comprising a plurality of hydrogel polymers disposed within the tissue, wherein at least some of the polymers are directly covalently bonded to the native amino groups.

92. The heart valve of claim 91, wherein the polymer is formed from monomers or prepolymers including vinyl groups, wherein the covalent bond between the polymer and the tissue amino group is a reaction product of a free radical polymerization between the vinyl group and the tissue amino group.

93. The heart valve of claim 91, wherein the native tissue and amino groups are represented by T-NH2, where T represents the tissue, where the polymer is represented by P, wherein the covalent bond of the polymer to the tissue is represented by T-NH—

CR₁R₂CR₃R₄—

P, where R₁, R₂, R₃, and R₄ are selected from the group consisting of hydrogen, alkyl, aryl, ethers, esters, alcohols and amines, and any combination thereof.

94. The heart valve of claim 91, wherein the polymer is formed from monomers or prepolymers including alpha, beta unsaturated groups, wherein the covalent bond between the polymer and the tissue amino group is a reaction product of a nucleophilic addition polymerization between the alpha, beta unsaturated groups and the tissue amino group.

95. The heart valve of claim 91, wherein the native tissue and amino groups are represented by T-NH2, where T represents the tissue, where the polymer is represented by P, wherein the covalent bond of the polymer to the tissue is represented by T-NH—

CR₁R₂CR₃R₄—

P, where R₁, R₂, R₃, and R₄ are selected from the group consisting of hydrogen, alkyl, aryl, ethers, esters, alcohols and amines, and any combination thereof.

96. The heart valve of claim 91, in which at least some of the polymers are directly covalently bonded to at least two native amino groups.

97. The heart valve of claim 91, in which the hydrogel includes enzymatically degradable regions covalently bonded at each end of the region.

98. The heart valve of claim 91, in which the tissue is not fixed with glutaraldehyde.

99. The heart valve of claim 91, in which the tissue includes amino groups, in which the amino groups have been capped with essentially non-reactive groups.

100. The heart valve of claim 91, in which the tissue includes carboxyl groups, in which the carboxyl groups have been capped with essentially non-reactive groups.

101. The heart valve of claim 91, in which the polymer has regions including polyethylene glycol.

102. The heart valve of claim 91, in which the polymer is a reaction product of free radical polymerization of at least one monomer or pre-polymer having at least one vinyl group.

103. The heart valve of claim 91, in which the polymer is a reaction product of nucleophilic addition polymerization of at least a first compound having at least two alpha, beta unsaturated moieties, and a second compound having at least two nucleophilic moieties.