ENDOTHELIAL PROGENITOR CELLS

Endothelial progenitor cells participate in processes linked with tissue regeneration and growth especially in situations associated with changes in distribution of EPCs. Circulating endothelial progenitor cells (cEPCs, i.e. those occurring in the peripheral blood) (circulating EPCs) home actively to sites of neovascularization; cEPCs are recruited to tumours and participate in tumour angiogenesis. Recent studies provided evidence that cEPCs are mobilized in response to tissue ischemia, e.g. in acute myocardial infarction, coronary artery bypass grafting, burns etc.

A decrease in circulating endothelial progenitor cells was observed in patients with coronary artery disease (impaired vascularization) and also in old, diabetic and hypercholesterolemic patients. A drop in cEPCs reflects endothelial dysfunction.

Above mentioned examples document active participation of endothelial progenitor cells in process of endothelial lining renewal in blood vessels. For that reason EPCs are promising candidates for cell therapy to support tissue vascularization. In experiments aimed at utilization of EPCs in therapy of lower limb ischemia transplantation of these cells improved limb perfusion whereas administration of endothelial (i.e. differentiated) cells failed. Infusion of endothelial progenitor cells in myocardial infarction preserved left ventricular function, enhanced neovascularization and inhibited myocardial fibrosis. Bone marrow-derived EPCs control the angiogenic switch in mouse lung metastasis.

Another possible implication can be seen in anti-angiogenic therapy focused on eradication of endothelial progenitor cells under conditions where angiogenesis should be suppressed (e.g. to suppress nourishment of a growing tumour).