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.