MSCs influence C2C12 myoblast proliferation through the release of VEGF.

<p>A) Cytokine and growth factor secretion profiles by MSCs grown in C2C12 differentiation medium (MSC-CM). B) Western Blotting analysis of VEGFR2 expression in C2C12 cells in single culture (C2C12) or exposed to MSC-CM (C2C12/MSC-CM), in the presence or absence of VEGFR2 inhibitor, KRN633. C) Superimposed DIC and fluorescence image showing cellular localization of VEGFR2 in C2C12 cells; the staining (green) is mainly localized at the cell surface. D) VEGFR2 phosphorylation in C2C12 cells in the noted experimental conditions, assayed by Western Blotting analysis performed on the immunoprecipitated VEGFR2 protein. Note that VEGFR2 expression and phosphorylation levels increase in the cells exposed to MSC-CM as compared with control. E) Superimposed DIC and fluorescence image showing nuclear EdU (green) staining and corresponding quantitative analysis. (F,G) Notch-1 expression by (F) Western blotting and (G) confocal immunofluorescence in C2C12 cells in the indicated experimental conditions. The quantitative analyses are reported in the histograms. Note that EdU staining and Notch-1 expression are significantly affected by treatment with the VEGFR2 inhibitor, KRN633. Data represent the results of at least three independent experiments with similar results. * <i>p<0.05.</i>