In vitro endothelialization of photooxidatively stabilized xenogeneic pericardium

The possibility of improving the performance of heart valve bioprostheses and vascular biografts by means of preendothelialization with cultured autologous cells has been suggested. Such culture techniques are available, but the glutaraldehyde-preserved heart valve prostheses used clinically appear cytotoxic. Recently, dye-mediated photooxidation has been reported to stabilize pericardial tissue, possibly through the cross-linking of collagen fibrils. We have seeded cultured adult human saphenous vein endothelial cells (HSVECs) onto photooxidatively stabilized tissue and investigated the morphologic characteristics 7 days later. A confluent lining of cultured HSVECs similar to native endothelium was demonstrated by scanning electron microscopy. The presence of von Willebrand's factor, an integrin located at the interendothelial cell contacts (PECAM/CD 31), and the basement membrane component collagen type IV was demonstrated using monoclonal antibodies. The results were similar for the HSVECs seeded onto both bovine and porcine pericardial tissues. The results clearly indicate that the dye-mediated photooxidation technique produces a tissue that is cell compatible. Provided the HSVECs remain attached and retain antithrombotic and antiinflammatory properties, this appears to be a feasible way of endothelializing bioprosthetic heart valves before implantation.