Endothelialization of Cardiac Valve Bioprostheses

Abstract

The main disadvantage of implanted xenograft valves used in cardiac surgery is their poor clinical long-term result, due to early tissue degeneration. In order to improve the performance of such glutaraldehyde fixed bioprostheses, a biological coating with viable endothelial cells was suggested. Therefore, glutaraldehyde preserved bovine pericard patches, as well as commercially available xenograft valves, were lined using human venous endothelial cells or microvascular cells from the subcutaneous fat tissue. Before cells were transplanted into their new environment, grafts were treated with an amino acid solution in order to neutralize the cytotoxic effect of free aldehydes, and precoated with fibronectin-heparin and basic fibroblast growth factor (bFGF) or endothelial cell growth supplement (ECGS) in order to enhance cell proliferation. Coated specimens were kept in culture conditions for a further seven days. Proliferation of transplanted cells was verified by an increase of activation following 3H-thymidine incorporation, while the maintained metabolic cell activity was demonstrated via Prostacycline (PGI2) measurement. Morphology was evaluated by means of scanning electron microscopy (SEM). As evaluated by the beta-Counter, 7 ng/ml bFGF (288,727 +/- 39,668 counts on day 4) substantially enhanced cell proliferation after seeding, opposed to the stimulation with 30,000 ng/ml ECGS (91,924 +/- 1129 counts on day 4), (p < 0.001). The PGI2 release of transplanted cells was stimulated with 25 microM Na arachidonic acid by the factor 2.6 +/- 0.3 and inhibited with 5 mM acetylsalicylic acid by the factor 0.7 +/- 0.2 on day 4 when compared with the basic level.(ABSTRACT TRUNCATED AT 250 WORDS)