TISSUE ENGINEERING PERICARDIUM

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Various vascular grafts am commonly used in the reconstruction of cardiovascular tissues. However, cunently used prosthelic or bioprosthetic materials lack giowth potential and, therefore, subsequently requie replacement in pediatric Talients as they matrure. Tissue engineering (YE) isa new discipline that offers the potential to create replacement structures ficm autologous cells and bkxlegiadable polymer scaffolds. Because Th constructs contain living cells, they may have the potential to grow, self-repair, and self-remodel, Tissue Engineered Vascular Autografts (TEVAs) were made by seeding 4-6 x 10^6 of mixed cells obtained fiom femoral veins of mongiel dogs onto tube-shaped biodegradable polymer scaffolds composed of a polyglyecolic acid (PGA) non-woven fabric sheet and a co-polymer of l-lactide andcapolactone (N=4). After 7 days, the inferior vena cavas (IVCs) of the same dogs were replaced with TEVAs. After 3,4. 5 and 6 months, angiographies were perfomed, and the dogs were sacii … More ficed. The implanted TEVAs were examined both grossly and immunohistologically. The implanted TEVAs showed no evidence of stenosis or dilatation. No thrombus was found inside the TEVAs. even without any anticoagulation therapy. Remnants of the polymer scaffolds weie not observed in all specimens, and the overall gross appearance appeared similar to that of native IVCs. Inimunohistological staining revealed the presence of Factor VIII positive nudcated cells at the luminal surface of the TEVAs. In addition, lesions were observed where α-smooth muscle actin and desmin positive cells existed. Implanted TEVAs contained a sufficient aniotnit of extracellular matrix, and showed neither occlusion nor anetuysmal formation. In addition. endothelial cells were found to line the luminal surface of each TEVA. These results strongly suggest that 'ideal' venous grafts with anti-thrombogenicity can be produced. Using theTEtedmique, a peripheral pulmonary artery was successfully reconstructed in a 4 year-old girl using autologous venous cells. The occluded pulmonary artery was reconstructed with the TEvessel graft No postojemtive complications occurred On follow-up angiography, the transplanted vessels were noted to be completely patent. In the same manner, autologous pericardium using biodegadable polymer sheet was examined in an animal model. Pericardial adhesion was relatively mild companing to the prosthetic materials. Because both our laboratory and clinical experiences are quite encouraging, we suggest that the TE approach may play an important ole as an alternative metohd to transplantation and to the use of artificial organs in the fldd of pediatric cardiovasucular surgery. Less