Heart valve tissue engineering.
Tissue-engineered heart valves have been proposed by physicians and scientists alike to be the ultimate solution for treating valvular heart disease. Rather than replacing a diseased or defective native valve with a mechanical or animal tissue-derived artificial valve, a tissue-engineered valve would be a living organ, able to respond to growth and physiological forces in the same way that the native aortic valve does. Two main approaches have been attempted over the past 10 to 15 years: regeneration and repopulation. Regeneration involves the implantation of a resorbable matrix that is expected to remodel in vivo and yield a functional valve composed of the cells and connective tissue proteins of the patient. Repopulation involves implanting a whole porcine aortic valve that has been previously cleaned of all pig cells, leaving an intact, mechanically sound connective tissue matrix. The cells of the patients are expected to repopulate and revitalize the acellular matrix, creating living tissue that already has the complex microstructure necessary for proper function and durability. Regrettably, neither of the 2 approaches has fared well in animal experiments, and the only clinical experience with tissue-engineered valves resulted in a number of early failures and patient death. This article reviews the technological details of the 2 main approaches, their rationale, their strengths and weaknesses, and the likely mechanisms for their failure. Alternative approaches to valvular tissue engineering, as well as the role of industry in shaping this field in the future, are also reviewed.
Vesely
Ivan
I
The Saban Research Institute of Children's Hospital Los Angeles, Keck School of Medicine, University of Southern CaliforniaLos Angeles, CA 90027, USA. ivesely@chla.usc.edu
D000818:Animals; D001705:Bioprosthesis; D003094:Collagen / Q000378:metabolism; D006349:Heart Valve Diseases / Q000628:therapy*; D006350:Heart Valve Prosthesis; D006351:Heart Valves / Q000166:cytology*; D006801:Humans; D011475:Prosthesis Failure; D013234:Stem Cells / Q000166:cytology; D023822:Tissue Engineering / Q000379:methods*; D014183:Transplantation, Heterologous
D003094:Collagen