Dibutyryl cAMP influences endothelial progenitor cell recruitment during wound neovascularization

Delayed wound healing is one of the major complications of diabetes, and is caused by delayed cellular infiltration, reduced angiogenesis, and decreased formation and organization of collagen fibers. Recently, endothelial progenitor cells (EPC) isolated from peripheral blood were shown to accumulate at sites of neovascularization during wound healing. The present study tested the hypothesis that sodium N-6,2'-O-dibutyryl adenosine-30,50-cyclic phosphate (DBcAMP), which has been shown to accelerate wound healing, promotes recruitment of EPC into wounds and contributes to the stimulation of neovascularization in genetically diabetic mice. Topical application of DBcAMP resulted in significant acceleration of wound healing and wound vascularization partly via enhanced recruitment of EPC. EPC in DBcAMP-treated wounds were mainly localized to cell clusters at the border of the granulation tissue, a site where blood supply is most insufficient. DBcAMP treatment increased the mRNA expression of angiogenic cytokines vascular endothelial growth factor (VEGF) and stromal cell-derived factor-1 alpha (SDF-1 alpha) in vivo in wound tissue and in cultured fibroblasts and macrophages, in vitro. Culture supernatants of DBcAMP-treated cells enhanced EPC migration. Taken together, these results indicate that DBcAMP promotes neovascularization in wound healing, at least partly by increasing the accumulation of EPC at wound sites.