In Vitro Cultivation and Immunogenicity of Human Cardiac Valve Endothelium

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Abstract
Endothelial cells were derived from aortic and mitral valves (n = 17) by collagenase digestion and subsequently cultivated in RPMI medium supplemented with 20% fetal calf serum. The cells were stained in an alkaline phosphatase-anti-alkaline phosphatase stain for the expression of MHC Class I and Class II antigens, ICAM-1, ELAM-1, F VIII, and H/Y. The endothelium showed a strong expression of Class I, H/Y, and ICAM-1 molecules, and weak expression of MHC Class II molecules. In contrast to vascular endothelium that is known to express F VIII constitutively, cardiac valve endothelium was found to be negative. F VIII and ELAM-1 were only expressed after stimulation with recombinant interferon-gamma. To analyze the immunogenicity of valve endothelium, cells were used as stimulator cells in a mixed cell culture reaction using lymphocytes as responder cells. Endothelial cells had a 2 to 3 times higher stimulatory effect than peripheral blood lymphocytes. These data allow speculation on whether the observed degeneration of homografts can be reduced if HLA matching is performed prior to valve implantation.