AimTo explore the potential mechanism of endothelial progenitor cells (EPC) on the regulation of AngⅡ-induced phenotype transformation of vascular smooth muscle cell (VSMC).MethodsEPC were obtained by isolating mononuclear cells using Ficoll density-gradient centrifugation and were identified by morphology, fluorescence double-staining and flow cytometry according to previous methods.ELISA were performed to analyze the secretion of calcitonin gene-related peptide (CGRP) in EPC and HUVEC.Early endothelial progenitor cells conditioned medium (E-EPC-CM) was pre-incubated with functional blocking antibodies against CGRP for 1h or VSMC was preteated with CGRP837(CGRP receptor antagonist) for 1 h before VSMC were pretreated with CM for 30 min, RT-PCR and Western-blot were performed to analyze the effect of E-EPC-CM on AngⅡ-induced the expression of α-SM-actin, calponin and phosphorylation of ERK, NF-κB(p65) in VSMC.ResultsThe level of CGRP was higher than that observed in the L-EPC-CM and HUVEC-CM groups.After stimulation with angiotensin Ⅱfor 48h, the expression of the α-SM-actin mRNA and protein significantly decreased and the osteopontin mRNA and protein markerly increased compared with control group, suggesting that VSMC was changed from contractile to synthesize type by angiotensinⅡ.But treatments with E-EPC-CM could up-regulate the expression of the α-SM-actin and down-regulate the expression of the osteopontin, suggesting that E-EPC-CM could inhibit the phenotype of VSMC from contractile to synthesize type induced by angiotensin Ⅱ.Moreover, we demonstrated that treatments with CGRP837 or anti-CGRP antibody could partly reverse the inbibiton effect of phenotype transformation of E-EPC-CM on the Ang II-stimulated VSMC.Likewise, we also demonstrated that treatment with anti-CGRP antibody or CGRP837 could partly reverse AngⅡ-induced phosphorylation of ERK, NF-κB(p65).ConclusionIt is showed that the inhibitory effect of EPCs on phenotype transformation of VSMC is associated at least partly with release of CGRP, which inactivates ERK and NF-κB signaling pathway.