Blood donor white blood cell reduction filters as a source of human peripheral blood–derived endothelial progenitor cells

Abstract

Neovascularization in tumors, wounds, and sites of ischemic injury occurs by both angiogenesis (proliferation from existing vessels) and by vasculogenesis (differentiation into endothelial cells from circulating endothelial progenitor cells [EPCs]). EPCs can be obtained from marrow, from cord blood, or by ex vivo expansion of human peripheral blood (PB). The ease of obtaining human PB EPCs has led many recent studies to utilize PB EPCs. The ability to obtain large numbers of PB EPCs would greatly facilitate characterization to further our understanding of EPC biology and their application in cellular gene therapy. Peripheral blood mononuclear cells (PBMNCs) from whole blood or from the material obtained from white blood cell (WBC) reduction filters were isolated. The cells from both sources were then cultured separately under defined conditions to quantify EPC yield from each source. The yield of EPCs per million PBMNCs plated was approximately 3.5-fold higher from fresh PB. Because greater numbers of PBMNCs were obtained from each filter, however, the mean yield of EPCs from one filter versus fresh blood was 5.4 million versus 0.4 million, respectively (approx. 14-fold increased yield). The use of WBC reduction filters provides a safe, inexpensive, and readily available source for large numbers of PBMNCs from which culture-expanded EPCs can be generated for further study.