Endothelialization of mechanical heart valves in vitro with cultured adult human cells.

Previous studies have shown that in vitro endothelialization of synthetic vascular prostheses with cultured autologous cells leads to a reduction in their thrombogenicity. It is possible that pre-endothelialization of mechanical heart valve prostheses would have a similarly advantageous effect. In this study we have therefore investigated the possibility of creating an endothelium layer on mechanical heart valve prostheses by seeding in vitro with cultured adult human endothelial cells. After harvest, endothelial cells were cultured for two to three weeks before seeding of six valves (three Monostrut, three CarboMedics bileaflet) with 1.5-2 x 10(5) cells/cm2. The valves were then kept under culture conditions for seven days. A confluent lining of cultured endothelial cells was observed in the scanning electron microscope on the parts covered with pyrolitic carbon, e.g. disc, leaflet, flange, and on carbon coated sewing rings. Untreated sewing rings showed a discontinuous endothelial lining. On the metallic surface only a few scattered cells were observed. Two endothelialized bileaflet valves were implanted in the mitral position in pig and permitted to perform physiologic work for one hour. A mainly continuous endothelium remained on the carbon covered sewing rings but the endothelium detached from the leaflets and flanges. This study demonstrates that mechanical heart valves do not contain cytotoxic compounds. It also demonstrates that cultured adult human endothelial cells are able to form a monolayer when seeded on monostrut and bileaflet valve prostheses. A significant number of cells remain on the sewing ring after pulsatile flow in the mitral position but not on the polished pyrolitic carbon surfaces.(ABSTRACT TRUNCATED AT 250 WORDS)