Characterization of porcine circulating progenitor cells: Toward a functional endothelium

The lack of available healthy vessels, significant patient morbidity, and high costs hinders the successful clinical utilization of autologous endothelial cells (ECs). Herein we assess the feasibility of using endothelial progenitor cells (EPC) found in circulating blood to engineer a functional endothelium on poly(1,8-octanediol-co-citrate) (POC), a hemocompatible and biodegradable elastomer used in vascular tissue engineering. EPCs were isolated from porcine blood and biochemically differentiated into porcine endothelial (PE)-like cells in vitro. Once differentiated, EC phenotype and function on POC were assessed according to the presence of the EC-specific markers von Willebrand factor, platelet EC adhesion molecule, and vascular endothelial cadherin; metabolism of acetylated low-density lipoprotein; secretion of the anti-thrombogenic factors nitric oxide and prostacyclin; and inhibition of platelet adhesion and clotting processes in vitro. The effects of PE-like cells on porcine aortic smooth muscle cells (PASMCs) were also investigated via co-culture. PE-like cells on POC had phenotype, function, and clotting responses similar to those of primary aortic ECs. The presence of PE-like cells resulted in a 71 +/- 20% decrease in PASMC proliferation; a 52 +/- 2% decrease in the protein: deoxyribonucleic acid ratio; and an elongated, spindle-shaped morphology indicative of a shift from the proliferative to the contractile phenotype. These data suggest that EPCs and POC can provide the basis for a functional tissue-engineered endothelium.