Extracellular matrix scaffolds for tissue engineering heart valves

Currently available heart valve substitutes fail to emulate the sophisticated functions of the native aortic valve, a factor that contributes to their eventual failure. One possible strategy to generate a valve substitute that reproduces the function of the native valve would be to apply the principals of tissue engineering. A crucial step in this process will be the choice of scaffold, which serves as an initial support on which to seed the cells. Successful scaffold materials should be amenable to modification, have a controlled degradation, be compatible with the cells, lack cytotoxicity and not elicit an immune or inflammatory response. Importantly the ideal scaffold should possess cell attachment and signalling molecules that will promote cell population and function, resulting in remodelling of the scaffold into a tissue construct, which can mimic the function of the native valve, possessing the mechanical strength and integrity to withstand aortic pressures. Such molecules are naturally present in biological scaffolds to varying degrees. This chapter discusses the various biological scaffolds that have been considered and are being studied for use in tissue engineering a heart valve and primarily focuses on the aortic valve. Strategies to optimize the physical parameters of the scaffold and to introduce biological signals into synthetic scaffolds or augment biological scaffolds are also discussed.