Biologic properties of endothelial progenitor cells and their potential for cell therapy

Abstract

Recent studies indicate that portions of ischemic and tumor neovasculature are derived by neovasculogenesis, whereby bone marrow (BM)-derived circulating endothelial progenitor cells (EPCs) home to sites of regenerative or malignant growth and contribute to blood vessel formation. Recent data from animal models suggest that a variety of cell types, including unfractionated BM mononuclear cells and those obtained by ex vivo expansion of human peripheral blood or enriched progenitors, can function as EPCs to promote tissue vasculogenesis, regeneration, and repair when introduced in vivo. The promising preclinical results have led to several human clinical trials using BM as a potential source of EPCs in cardiac repair as well as ongoing basic research on using EPCs in tissue engineering or as cell therapy to target tumor growth.

Figure 1.

Model of characterized culture-expanded EPC populations. Early outgrowth EPCs co-express myeloid/pan-leukocyte and endothelial markers and cannot be expanded with serial passage in contrast to late outgrowth EPCs. Despite the heterogeneity in the origin and differentiation of these cell types, the in vivo vasculogenic and therapeutic efficacy appears similar.