Microvascular dysfunction plays a key role in the pathology of sepsis, leading to multi-organ failure, and death. Circulating endothelial progenitor cells (cEPCs) are critically involved in the maintenance of the vascular homeostasis in both physiological and pathological contexts. In this study, concentration of cEPCs in preterm infants with sepsis was determined to recognize whether the EPC mobilization would affect the clinical outcome of infantile sepsis. One hundred and thirty-three preterm infants (81 with sepsis and 52 without sepsis) were enrolled in this study. The release of EPCs in circulation was first quantified. Thereafter, these cells were cultivated and biological features of these cells such as, proliferation and colony forming efficiency were analyzed. The levels of chemoattractant cytokines were also measured in infants. In mouse models of sepsis, effects of VEGF and SDF-1 as well as anti-VEGF and anti-SDF-1 were evaluated in order to shed light upon the role which the EPC mobilization plays in the overall survival of septic animals. Circulating EPCs were significantly higher in preterm infants with sepsis than in the non-sepsis group. Serum levels of VEGF, SDF-1, and Angiopoietin-2 were also higher in preterm infants with sepsis than in control non-sepsis. In the animal experiments, injection of VEGF and SDF-1 prompted the mobilization of EPCs, leading to an improvement in survival whereas injection of anti-VEGF and anti-SDF-1 was associated with significant deterioration of survival. Overall, our results demonstrated the beneficial effects of EPC release in preterm infants with sepsis, with increased mobilization of these cells was associated with improved survival. J. Cell. Biochem. 118: 3299-3307, 2017. © 2017 Wiley Periodicals, Inc.

Many infants who develop bronchopulmonary dysplasia (BPD) are born with serious respiratory distress syndrome (RDS), which is associated with impaired vascular and alveolar growth. RDS is a breathing disorder that mostly affects preterm infants and occurs in infants whose lungs have not yet been fully developed. The use of surfactant in RDS treatment does not necessarily prevent BPD. Endothelial progenitor cells (EPCs) may contribute to lung angiogenesis for the prevention and treatment of BPD. The aim of this study was to evaluate the therapeutic efficacy of phototherapy for EPC release in preterm infants born with RDS. Seventy-five RDS preterm infants were divided into two groups: RDS with phototherapy and RDS without phototherapy. Respiratory indices were recorded for each patient. Circulating EPCs were isolated before and after phototherapy and colony forming efficiency, chemotactic, tubulogenic, proliferative, and functional properties of these cells were analyzed. Our results showed that phototherapy increased the release of EPCs into the circulation in RDS preterm infants, with augmentation of cell proliferation, tubulogenic, chemotactic, and proliferative properties of EPCs. Phototherapy-induced EPC release was associated with improved lung function as was recorded by significantly decrease in continuous positive airway pressure (CPAP) days, CPAP plus ventilator days, and PCO along with a significant increase in PO and PaO /FiO , resulting in markedly decreased rate of BPD occurrence in preterm infants with RDS. Overall, phototherapy is touted as a promising modality for the amelioration of respiratory performance and prohibition of BPD occurrence in RDS preterm infants. J. Cell. Biochem. 118: 594-604, 2017. © 2016 Wiley Periodicals, Inc.