Potential of baboon endothelial progenitor cells for tissue engineered vascular grafts

Thrombosis and intimal hyperplasia limit the usefulness of small caliber vascular grafts. While some improvements have been reported for grafts seeded with mature endothelial cells (EC), the harvesting of ECs from autologous sources, for example, veins or adipose tissue, remains problematic. More recently, endothelial progenitor cells (EPCs) have been considered a promising source of ECs because EPCs can be readily isolated from whole blood then rapidly expanded in vitro. Additionally, EPCs are increasingly recognized to play important roles in hemostasis, angiogenesis, and arterial injury repair. However, the characterization of EPCs in relevant animal models remains poorly defined. Accordingly, we have characterized the isolation, growth, and functional characteristics of Baboon EPCs (BaEPCs) to evaluate their potential for an autologous cell source for tissue engineered vascular grafts. BaEPCs were successfully cultured from the peripheral blood with an average population doubling time of 1.17 +/- 0.43 days. While the BaEPCs were positive for typical EC markers of vWF, CD31, VE-cadherin, VEGF-R2, Thrombomodulin, and E-selectin, there was reduced eNOS expression. The BaEPCs cell body and actin filaments align in the direction of flow typical of mature ECs. Thus while the lack of eNOS expression is worthy of investigation, EPCs are an attractive cell source for tissue engineered vascular grafts and the baboon model has great potential for continuing evaluations of these cells.