Bleaching and dyeing; fluid treatment and chemical modification – Treatment of hides – skins – feathers and animal tissues – Internal tissues
Patent
1996-09-24
1998-03-31
Diamond, Alan
Bleaching and dyeing; fluid treatment and chemical modification
Treatment of hides, skins, feathers and animal tissues
Internal tissues
8 9433, 530356, 623 1, 623 2, 623 3, 623 11, 623 12, 523113, A61F 202
Patent
active
057333394
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a process for fixing human or animal tissue prior to implantation into humans or animals, and more particularly to a fixation process that forms links within and between the proteinaceous molecules of the tissue by covalently binding the reactive amine groups and/or the reactive carboxyl groups on the tissue either directly in the presence of a coupling agent and preferably of a coupling enhancer, or through bridges formed by one or more cross-linking agent(s) in the presence of a coupling agent and preferably of a coupling enhancer.
BACKGROUND OF THE INVENTION
The surgical implantation of prosthetic devices (prostheses) into humans and other animals has been carried out with increasing frequency. Such prostheses include, by way of illustration only, heart valves, vascular grafts, urinary bladders, left ventricular-assist devices, hips, breast implants, tendons, and the like. The prosthesis can be entirely or partially made of biological tissue(s) from humans or from animals. To prevent degeneration and/or foreign body reactions, the bioprosthetic tissue must be stabilized before implantation in a human or in an animal. The stabilization process, known by those skilled in the art as fixation, consists of blocking the reactive moieties of the tissue. After it was found in 1968 that collagen, a major component of bioprostheses, was (1968)!, that, of various aldehydes tested, glutaraldehyde best retarded degeneration of implanted heart valves, and that glutaraldehyde-fixed heart valves were minimally thrombogenic and had excellent biophysical and 3:309-318 (1975)!, the process of glutaraldehyde-fixation has been and continues to be applied to most varieties of experimental and clinical bioprostheses. This process of fixation with glutaraldehyde consists of blocking the reactive amines of the tissue through formation of an aldehyde-amine bond known by the skilled in the art as a Schiff-base.
Of all glutaraldehyde-fixed bioprostheses, the heart valve has been one of the most widely studied, and its clinical application and pathology are Heart valve bioprostheses are generally fabricated either from glutaraldehyde-fixed porcine aortic or pulmonic valves or from glutaraldehyde-fixed bovine pericardium, which may be sewn, although not necessarily, onto a cloth-covered metallic or polymeric stent and sewing ring. These bioprostheses may be preferred over the mechanical heart valve prostheses (which typically are composed of rigid materials such as polymers, pyrocarbons and metals, and employ one or more occluders which respond passively with changes in intracardial pressure or flow) because of certain significant clinical advantages. For example, heart valve bioprostheses do not require permanent anticoagulation therapy, while mechanical heart valves do. Also, should a bioprosthesis fail, it typically first exhibits a gradual deterioration which can extend over a period of months, or even years, while a mechanical heart valve may occasionally undergo catastrophic failure. On the other hand, glutaraldehyde-fixed heart valve bioprostheses are generally less durable than mechanical heart valves mostly because they calcify.
Calcification has been recognized for more than 20 years as the main cause of failure of most bioprostheses. For example, more than 50 percent of heart valve bioprostheses fail within 10 years of implantation because of the cuspal tears and stenosis that result from calcification, which failure occurs substantially more rapidly in children than in adults pathogenesis of heart valve calcification (which involves not only the donor tissue, but also host factors such as blood components, and the stress to which the valve is submitted when implanted) is as yet not completely understood, glutaraldehyde has been identified as an important (1991)!. Multiple approaches to eradicate calcification of glutaraldehyde-fixed bioprostheses have been taken.
The techniques resulting from these efforts may be broadly divided into two categories: those involving the treatment of glu
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patent: 4383832 (1983-05-01), Fraefel et al.
patent: 5104405 (1992-04-01), Nimni
patent: 5118791 (1992-06-01), Burnier et al.
patent: 5447536 (1995-09-01), Girardot et al.
Girardot Jean-Marie
Girardot Marie-Nadia
Biomedical Design, Inc.
Diamond Alan
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