Increased circulation mobilization of endothelial progenitor cells in preterm infants with retinopathy of prematurity.

Retinopathy of prematurity (ROP) is a result of increased pathological neoangiogenesis of the retina in preterm infants. Cells responsible for the pathogenesis of ROP are unclear, but some evidence indicates that bone marrow derived cells are involved in this disorder. Endothelial progenitor cells (EPCs), play a role in angiogenesis in response to tissue ischemia or endothelial damage. In this study, the number of cEPCs in preterm infants with ROP was determined to identify whether the circulation mobilization of EPCs is associated with ROP. We evaluated 99 participants in this study: 22 preterm infants with ROP, 35 preterm infants without ROP, and 42 full-term infants. The release of EPCs in the circulation was first quantified. Thereafter, cEPCs were harvested and cultivated, then the biological features of these cells including migratory, proliferative, and tubulogenic activities were analyzed. The mRNA levels of some proangiogenic factors were also measured in preterm infants. Our results showed greater numbers of cEPCs in infants with ROP, which was associated with increased serum concentrations of angiogenic factors and with augmented proliferative, migratory, and tubulogenic activity of these cells. Western blotting showed increased protein levels of VEGF and HIF-α in cEPCs harvested from ROP infants. This study showed that ROP in preterm infants is associated with increased mobilization of EPCs into the circulation. Therefore, increased cEPCs along with elevated levels of angiogenic factors and tubulogenesis suggest that these cells may play a role in the development and progression of ROP.