STRUCTURAL STUDIES ON BOVINE BIOPROSTHETIC TISSUES AND THEIR IN-VIVO CALCIFICATION - PREVENTION VIA DRUG-DELIVERY

Cardiovascular calcification, the formation of calcium phosphate depos its in cardiovascular tissue, is a common end-stage phenomenon affecti ng a wide variety of bioprostheses. To study the process of calcificat ion in tissue prosthetics, glutaraldehyde-treated bovine pericardium, dura mater and fascialata were implanted subcutaneously in rats and re trieved 21 days later and thereby morphological findings were correlat ed with biochemically determined levels of calcium. Transmission elect ron microscopy showed that calcification primarily involved the surfac e of collagen fibrils and the interfibrillar spaces. The deposition of calcium was higher with dura and fascia prostheses compared to perica rdium. However, the release of Fe3+ ions from chitosan matrix had subs tantially inhibited the deposits of calcium in all implanted tissues. It seems that the structural and anatomical features of the tissue is one of the important factors for tissue-associated calcification. It i s also confirmed that glutaraldehyde-preserved pericardium is the most suitable material for the development of cardiac prosthesis, with an appropriate drug combination therapy for prevention of pathological ca lcification.