Collagen structures in pericardium and aortic heart valves and their significance for tissue engineering

Biological prostheses of human heart valves are prepared from autologous heart valves and from xenogeneic heart valves or pericardium. Xenogenous and allogenous biological prostheses are associated with adverse immune reactions, thrombosis and degeneration, and thus they have a high rate of reoperation. An optimum autologous tissue for heart valve grafts therefore needs to be found. Human pericardium was assessed as a potential source, and was compared with native human heart valves and porcine and bovine pericardium and heart valves. The tissues were evaluated for their mechanical properties, their collagen content and structure, and their histological structure. We observed differences in mechanical properties, collagen fibre orientation, the shape of the collagen bundles, and the collagen content among the pericardium samples and heart valves of different origin.