Circulating endothelial progenitor cells in premature infants: is there an association with premature birth complications?

Background: The most common morbidities in preterm infants are associated with vascular pathology. Endothelial progenitor cells (EPCs) have been implicated in repair of the vasculature, but their role in the pathogenesis of prematurity complications is not clear. Objectives: We prospectively investigated an association between the number of EPCs circulating in blood during delivery as well as 2 and 6 weeks afterwards, the level of growth factors regulating their migration/homing, and the incidence of premature birth complications. Patients and methods: The study groups consisted of 90 preterm and 52 full-term infants. Early-EPCs (CD133(+)CD34(+)CD144(+)) and late-EPCs (CD133(-)CD34(+)CD144(+)) were analysed in cord blood (CB) and peripheral blood (PB). Results: We found higher early-and late-EPC counts in the CB of premature infants compared with full-term babies. The number of circulating early-and late-EPCs was inversely associated with the Apgar score of preterm infants. A positive association between the early-EPC count and the risk of respiratory distress syndrome, retinopathy of prematurity, bronchopulmonary dysplasia, and infections was found. Nevertheless, multivariate analysis revealed that a higher number of EPCs was not an independent predictor of prematurity complications, which were directly related to lower gestational age. The EPC count in full-term infants maintained a constant, relatively low level over the 6-week follow-up, whereas the EPC population in preterm infants gradually decreased during this period. Furthermore, the number of CB late-EPCs in preterm infants positively correlated with VEGF concentration. Conclusions: EPCs may play a considerable role in vascular development in preterm infants.