Improved calcification resistance and biocompatibility of tissue patch grafted with sulfonated PEO or heparin after glutaraldehyde fixation

Abstract

A novel chemical modification of biological tissues was developed aimed at improving biocompatibility and calcification resistance. This method involved the additional grafting of sulfonated PEG (PEO-SO3,) or heparin after conventional glutaraldehyde (GA) fixation of bovine pericardium (BP). The amino groups of PEG-SO, or heparin were utilized to react to the GA residues to block them. The PEG-SO, or heparin grafted tissues demonstrated a slightly higher shrinkage temperature and tensile strength, but greater resistance to collagenase digestion, than GA treated ones. These results suggest that modified tissues have improved durability due to the grafting and filling effect of PEG-SO, or heparin in addition to the GA cross-linking, At the direct contact cytotoxicity test in vitro, PEG-SO, or heparin grafted tissue was shown to be nontoxic, while relatively significant cytotoxicity was observed for the GA treated tissues, possibly due to the release of GA, From the in vivo calcification study, calcium contents deposited on the modified tissues were much less than those on GA treated tissues. Such a decreased calcification might be explained hy the decrease of residual GA groups during the additional treatment, and the space-filling effect and the nonadhesive property and/or the blood compatiblility of PEG-SO, or heparin grafted covalently, The newly modified tissue patch was observed to show improved pathological assessibility including less inflammation and tissue reactions, This simple modification method may be useful for calcification-resistant and blood-compatible tissue patches for cardiovascular implants. (C) 2000 John Wiley & Sons. Inc. J Biomed Mater Res (Appl Biomater) 58: 27-35. 2001.