[The role of circulating endothelial progenitor cells in the progression of retinopathy of prematurity--a prospective study].

Retinopathy of prematurity (ROP) is the primary cause of visual impairment in preterm infants. There are available data confirming that circulating endothelial progenitor cells (EPCs) are involved in forming the growing network of blood vessels in the developing retina. In this study we sought to explore potential relationship between concentration of circulating bone marrow-derived EPCs and development of ROP in prospective study.The study groups consisted of 90 preterm (23-36 weeks of gestational age), and 52 full-term control infants. EPCs were analyzed in cord blood (CB) and subsequently in peripheral blood (PB) in second and sixth week since delivery. The incidence and stage of ROP was prospectively documented in the preterm infants.EPC concentration in CB was considerably higher in the preterm infants developing ROP. In the preterm infants a noticeable decrease in PB EPC concentration within six weeks of the follow up was found, whereas in full-term infants EPC concentration was maintained at invariable level. Of note, in the sixth week since delivery, EPC concentration in preterm infants with ROP was lower compared to preterm infants without ROP.Increase in CB EPC concentration in preterm infants, including those developing ROP, indicates that the circulating EPC cells contribute to the process of blood vessel formation, and their number in CB reflects the degree of prematurity. Impaired blood vessel formation within retina in the course of ROP may result from decrease in circulating EPC number observed at the sixth week since delivery.