Functional small-diameter neovessels created using endothelial progenitor cells expanded ex vivo

Arterial conduits are increasingly preferred for surgical bypass because of inherent functional properties conferred by arterial endothelial cells, es pecially nitric oxide production in response to physiologic stimuli. Here w e tested whether endothelial progenitor cells (EPCs) can replace arterial e ndothelial cells and promote patency in tissue-engineered small-diameter bl ood vessels (4 mm). We isolated EPCs from peripheral blood of sheep, expand ed them ex vivo and then seeded them on decellularized porcine iliac vessel s. EPC-seeded grafts remained patent for 130 days as a carotid interpositio n graft in sheep, whereas non-seeded grafts occluded within 15 days. The EP C-explanted grafts exhibited contractile activity and nitric-oxide-mediated vascular relaxation that were similar to native carotid arteries. These re sults indicate that EPCs can function similarly to arterial endothelial cel ls and thereby confer longer vascular-graft survival. Due to their unique p roperties, EPCs might have other general applications for tissue-engineered structures and in treating vascular diseases.