Circulating endothelial progenitor cell levels are higher during childhood than in adult life.

Age-related vascular dysfunction contributes to the increased cardiovascular risk in elderly. Endothelial progenitor cells (EPC), a hematopoietic stem cell (HSC) subtype, can improve vascular repair. Therefore, it is hypothesized that a decrease in these circulating progenitor cells during aging plays a role in the enhanced cardiovascular risk. Until now, research has focused on EPC and HSC in the aging adult, but no studies have been conducted in children whereas animal studies specifically suggest a benefit of juvenile bone marrow. We investigated CD34(+)/KDR(+) EPC and CD34(+) HSC numbers by flow cytometry in healthy humans aged 1- to 81-years old. An inverse relation with age was observed for EPC counts [r=-0.37, p=0.007] as well as for HSC counts [r=-0.37, p=0.008]. During childhood significantly higher levels of EPC [p<0.0001] and HSC [p=0.001] were found compared to adults. These findings may have great clinical relevance since increasing circulating EPC levels is a promising therapeutic target to enhance the endogenous regenerative capacity. Better insight in the mechanisms underlying the higher EPC levels in children may provide options to increase EPC counts in adults, thereby potentiating endothelial repair mechanisms.