Tissue Engineering of Heart Valves

Abstract

Valvular heart disease is an important cause of morbidity and mortality worldwide. Valve replacement represents the most common surgical therapy for end-stage valvular heart disease. Currently, 300,000 procedures are performed annually worldwide. Furthermore, eight of 1000 children are born with congenital cardiac defects. Every fifth of these needs a heart valve replacement. Currently, clinically available cardiovascular prosthetic substitutes, including xenografts, mechanical prostheses, and homografts, function well but have some disadvantages in common [1–3]. They consist of foreign, nonviable materials which entail the risk of thromboembolism and the lack of ability to repair, remodel, and grow, which leads to multiple reoperations. Pediatric patients are of particular interest in this context because they “outgrow” the prostheses so that multiple reoperations and considerable suffering for the patients and their families are the consequence [4]. Tissue engineering could be an alternative in overcoming these disadvantages. The interdisciplinary approach of tissue engineering combines principles of engineering and materials science with biology and vascular surgery to fabricate viable and functional prostheses from autologous, living cells with the aim of long-lasting replacement or reconstruction of the dysfunctional native tissue. Using autologous cells, these viable prostheses should have the potential to integrate, grow, remodel, and repair and therefore to conceivably make reoperations unnecessary. There are three major requirements for a successful tissue engineered cardiovascular substitute: (a) isolation of a suitable cell source, if possible of an autologous origin; (b) a suitable 3-D scaffold; and (c) in vitro culture conditions conducive to fabrication of the construct before implantation.