[Heart valve and myocardial tissue engineering]

Cardiac function, including the heart muscle and valves, can be severely altered by congenital and acquired heart diseases. Several graft materials are currently used to replace diseased cardiac tissue and valvular segments. Implantable grafts are either non-vital or can trigger an immune response which leads to graft calcification and degeneration. None of the existing grafts have the ability to remodel and grow in tandem with the physiological growth of a child and therefore require re-operation. Novel approaches such as tissue engineering have emerged as possible alternatives for cardiac reconstruction. The main concept of tissue engineering includes the use of biological and artificial scaffolds that form the shape of the organ structures for subsequent tissue replacement, which will provide absolute biocompatibility, no thrombogenicity, no teratogenicity, long-term durability and growth.Heart valve tissue engineering represents an important field especially in pediatric patients with valve pathologies. In order to create an autologous valve equivalent myofibroblasts and/or endothelial cells are seeded on specially designed scaffolds. Here we describe the different types of cell sources and different types of matrices currently used in heart valve tissue engineering. Valve manufacture is carried out in specially designed bioreactors providing physiological conditions. The number of clinical studies using tissue engineered valves is still limited; however, several promising results have already demonstrated their durability and ability to grow.Myocardial tissue engineering aims to repair, replace and regenerate damaged cardiac tissue using tissue constructs created ex vivo. Conceivable indications for clinical application of tissue engineered myocardial-implant substitutes include ischemic cardiomyopathies, as well as right ventricular outflow tract reconstruction in patients with congenital heart diseases. Therapeutic application of functional (contractile) tissue engineered heart muscle appears feasible once key issues such as identification of the suitable human cell source, large scale expansion and suitable scaffolds are solved. In addition, the present article discusses the importance of vascularization as an important prerequisite for successful bio-artificial myocardial tissue.Further experimental and clinical research on cardiovascular tissue engineering is felt to be of great importance for others as well as for us in order to create an ideal heart valve/myocardial substitute and help our patients with advanced cardiac pathologies.