Abstract

Various vascular and valvular grafts are commonly used in the reconstruction of cardiovascular disease. Current prosthetic or bioprosthetic materials lack growth potentials, therefore, subsequent replacement further defeats the concept of primary repair early in pediatric cardiac patients. Tissue engineering (TE) is a new discipline that offefs the potential to create replacement structures from autologous cells and biodegradable polymer scaffold. Because TE constructs contain living cells, they may have potentials for growth, self-repair, and self-remodeling. Cardiac valve leaflets and large conduits in the pulmonary circulation have been made with this TE approach in a lamb mode. Venous conduits were also created in a dog model. Mixed cell populations of endothelial cells and fibroblasts were isolated from explanted peripheral arteries or veins. A synthetic biodegradable scaffold consisted of polyglactin and polyglycolic acid fibers was seeded in vitro with mixed cultured cells. After one week, these autologous cell/polymer constructs were re-implanted in animals. Each animal was then followed periodically by echocardiography and angiography. The animals were sacrificed and the implanted tissues were examined histologically, biochemically and biomechanically. A 4-hydroxyproline assay was performed to evaluate the collagen content. The implanted conduit diameters increased as the animals grew during the study period. Histologically the biodegradable polymer scaffold was completely degraded. Collagen analysis of the constructs showed the development of an extracellular matrix. Immunohistochemical staining demonstrated elastin fiber in the matrix and Factor VIII on the inner surface of the conduits. In conclusion, tissue engineering approach to construct cardiovascular structure is feasible using either arterial or venous cell origin. In these tissue-engineered autografts, transplanted autologous cells generated proper matrix over the polymer scaffold under physiologic condition. (Presented at the 1184th Meeting, November 9, 2000. )

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