Guiding endothelial progenitor cell tube formation using patterned fibronectin surfaces

Engineering vascular networks is a key initiative in regenerative medicine. Moreover, control over the formation of organized vascular networks in vitro may facilitate their rapid and functional integration with the host vasculature after implantation. The extracellular matrix provides a structural platform for endothelial progenitor cells (EPCs) to differentiate and assemble into a tubular structure. We demonstrate that optimized, patterned fibronectin surfaces guide the ordered adhesion of human EPCs, maintain EPC responsiveness to tumor necrosis factor-alpha, support their elongation along the culture period, and enhance von Willebrand factor expression. Using fibrin gel as the three-dimensional milieu allows the assembly of unidirectional chains and formation of tubular structures. High-resolution analysis shows a distinctive lumen, as well as numerous Weibel Palade bodies and caveolae, all indicating a typical progression in vascular morphogenesis and the angiogenic process. Altogether, this approach allows us to engineer the formation of well-organized vascular structures in vitro.