Blood outgrowth endothelial cells from cord blood and peripheral blood: angiogenesis-related characteristics in vitro

Blood outgrowth endothelial cells (BOEC) are good candidates for vascular (re-) generating cell therapy. Although cord blood (CB) BOEC have been reported as more proliferative than peripheral blood (PB) BOEC, not much is known about their functional properties.

We have studied the following determinants in BOEC expanded from CB and PB: endothelial phenotype, in vitro adhesion, migration, proliferation, and angiogenic tube forming capacity.

Endothelial phenotype of BOEC was evaluated by fluorescence activated cell sorting (FACS) analysis and confirmed the presence of endothelial markers including CD31, CD105, CD144, CD146, KDR/VEGFR-2, Tie-2, and TNF-alpha-induced VCAM-1 and ICAM-1. Evaluation of cell proliferation revealed a higher basal proliferation of CB-BOEC, which increased after exposure to bFGF but not VEGF. The lower basal proliferation of PB-BOEC increased with VEGF or bFGF addition. Array analysis of angiogenic genes showed many comparable expressions in both BOEC, and a slightly more pronounced pro-angiogenic profile in CB-BOEC than PB-BOEC. Both BOEC were able to form tubular structures in a three-dimensional fibrin matrix. Tube formation in CB-BOEC was markedly induced by TNF-alpha only and inhibited by anti-urokinase antibodies. It was comparable to that induced by combined addition of TNF-alpha and VEGF or bFGF, while maximal tube formation in PB-BOEC required simultaneous exposure to TNF-alpha/VEGF or TNF-alpha/bFGF.

The endothelial phenotype and characteristics for homing, adhesion, migration, inflammation, and angiogenic tube formation are almost equal for BOEC from CB and PB. A slightly more angiogenic phenotype favors CB-BOEC. However, addition of VEGF to PB-BOEC induces equal proliferation and tube formation.