Hyperbilirubinemia-induced pro-angiogenic activity of infantile endothelial progenitor cells

Objectives: Bilirubin, a by-product of heme degradation, is suggested to have a role for vascular protection. There is increasing evidence that bilirubin may directly affect the function and secretory activity of endothelial cells. In this study, potential effect of hyperbilirubinemia on biological features of circulation endothelial progenitor cells (cEPCs) isolated from infants was investigated. Methods: Circulation concentration, differentiation and migratory activity of cEPCs isolated from infants with (n = 111) or without (n = 73) hyperbilirubinemia were analyzed. Then, the potential beneficial effect of conditioned medium of cEPCs from infants with or without hyperbilirubinemia was examined on experimental mouse wounds. Results: Our results revealed significantly higher percentages of cEPCs in infants with hyperbilirubinemia. Cell proliferation, and migratory properties of cEPCs isolated and expanded from infants with hyperbilirubinemia were significantly improved. Also, the conditioned medium of cEPCs from hyperbilirubinemic infants possessed a superior beneficial effect on wound healing, which was associated with increased protein levels of VEGF, IL-10, and Pho-ERIVERK, and decreased TNF-alpha in the wound tissues. Conclusions: Our results showed that hyperbilirubinemia can activate migration, proliferating and angiogenic properties of cEPCs. Hyperbilirubinemia can promote the proangiogenic secretory activity of cEPCs, thereby resulting in enhancement of their regenerative wound healing properties.