Estudo experimental com heteroenxertos valvares descelularizados: a prótese do futuro

Objective: To make a comparative evaluation of the behavior of cryopreserved homografts and decellularized porcine heterografts implanted in the right ventricular outflow tract of juvenile sheep as well as to report on the initial clinical experience with decellularized pulmonary homografts in patients submitted to the Ross procedure. Method: In group A, four cryopreserved homografts were implanted and in group B four heterografts decellularized with deoxycholic acid were used. In each group, two animals were sacrificed at 90 days and the other two at 150 days. The explants were evaluated macroscopically, and radiologically, as well as undergoing a histological examination with HE, Gomori and Sirius Red staining. We also report our initial clinical experience with decellularized pulmonary homografts in four patients submitted to the Ross procedure. Results: All the animals survived. Echocardiograms evidenced that all the implanted valves had normal function. Although the cusps had normal appearance in both groups, calcium content was higher in the cryopreserved valves, radiologically there were traces of calcification in the cryopreserved valves but no traces were observed in the decellularized valves. Cryopreserved homografts lost their cellularity while decellularized heterografts were progressively repopulated by fibroblasts and were partially re-endothelialized. Four patients submitted to a Ross operation with decellularized homografts had a good clinical outcome with normal function in their right-sided homografts. Conclusions: Decellularized heterografts were progressively repopulated by autologous cells and exhibited minimal tendency to calcification in this model. These results suggest that decellularized heterografts may have some regenerative capacity and thus potentially greater durability than conventional cryopreserved homografts.