[Method of expansion of late endothelial progenitor cells]

To validate a novel method of expanding late endothelial progenitor cells (EPC) in vitro.

We cultured mononuclear cells (MNC) from human peripheral blood on the plate with the feeder layer cells, i.e. irradiated late EPC or human umbilical vein endothelial cells. After 21 days, the numbers of late EPC colonies were counted separately. And the surface antigen of late EPC was detected by fluorescence-activated cell sorter (FACS) and their in vitro ability of forming vascular structure examined by matrigel.

Both colony numbers of late EPC with feeder layer cell culturing were over 20 times than those without (40.0 ± 3.9, 39.3 ± 3.1 vs 2.0 ± 1.3, both P < 0.05). And the former's late EPC colony appeared earlier. The late EPC expressed CD31, CD34, eNOS, Flt-1, P1H12, Sendo, VE cadherin and CD117. And vascular structures were discerned.

The method of feeder layer cells may vastly expand the quantity of late EPC. And microenvironment plays an important role in its expansion.