Naringin enhances endothelial progenitor cell (EPC) proliferation and tube formation capacity through the CXCL12/CXCR4/PI3K/Akt signaling pathway.

Endothelial progenitor cells (EPCs) have been shown to be involved in the process of physiological neovascularization in vivo. Because increasing evidence has indicated that naringin, a major active ingredient in the Chinese herb Drynaria fortunei, can promote angiogenesis and inhibit endothelial cell apoptosis, our study was designed to determine the role of naringin in EPC proliferation and tube formation capacity and examine the potential mechanism for these effects. EPCs were isolated from bone marrow and treated with naringin. An MTT assay was used to investigate EPC proliferation and the tube formation capacity of these EPCs, which were seeded on Matrigel. The protein levels of CXCL12, its receptor (chemokine receptor 4 (CXCR4)) and a downstream signaling molecule (Akt and phosphorylated Akt (pAkt)) were examined using Western blotting. A CXCR4 antagonist (AMD3100) and a phosphatidylinositol 3-kinase (PI3K) antagonist (LY294002) were used to characterize the underlying mechanisms. The results showed that naringin-induced EPC proliferation reached a maximum at day 3 and that the optimal dose of naringin was 500 ng/ml. Treatment with naringin facilitated the EPC tube formation capacity and increased the levels of CXCL12, CXCR4 and pAkt (P < 0.05) relative to those in the control group. Moreover, the naringin-induced EPC tube formation capacity was significantly attenuated by AMD3100 or LY294002. In conclusion, we showed here that the naringin-enhanced EPC proliferation and tube formation were mediated by the activation of the PI3K/Akt signaling pathway via the CXCL12/CXCR4 axis, which suggests that naringin could serve as a new therapeutic medicine and has the potential to be applied for the treatment of ischemic disease.