Endothelialized biological heart valve prostheses in the non-human primate model

OBJECTIVE: The main disadvantage of implanted cardiac valve bioprostheses remains primarily tissue failure due to calcification. Coating of bioprostheses with viable autologous endothelial cells may delay or even eliminate tissue calcification and subsequent cardiac dysfunction. METHODS: Glutaraldehyde-preserved Hancock bioprostheses (n = 5), pretreated with glutamic acid (8%) and cryopreserved allografts (n = 5) were lined, using endothelial cells harvested from the external jugular vein. Coated specimens were cultivated for 9 days in Medium 199 supplemented with 20% fetal calf serum and basic fibroblast growth factor. Endothelialized grafts were anastomosed into the descending thoracal aorta of adult Chacma baboons. Untreated valve bioprostheses (n = 4) served as controls. Forty days after implantation the prostheses were examined morphologically and immunohistochemically. RESULTS: After implantation endothelialized prostheses showed a positive Factor VIII related antigen reaction by immunohistochemistry on all valve surfaces. Scanning electron microscopy showed confluently lined leaflets with transplanted endothelial cells and displayed cobblestone morphology on all coated allografts. In contrast, the surface of pretreated xenograft valves revealed uncoated areas with platelet and leucocyte aggregates. No endothelium was observed on the leaflets of untreated controls 40 days after implantation. CONCLUSION: In vitro endothelialization of cardiac valve bioprostheses with autologous endothelial cells is possible. The newly created endothelium is shear stress resistant and the antithrombotic as well as the antiaggregatory capacity of the transplanted cells were retained. Lining with autologous endothelial cells could improve the durability and clinical outcome of biological valve prostheses.