Fig. 4

MSCs enhanced the cell proliferation of melanocytes and rescued melanocytes from oxidative stress. a Schematic diagrams of the Transwell coculture system, phase-contrast diagram and dopa staining of melanocytes; magnification, × 100; scale bar, 200 μm. b–k Cell proliferation of 10 primary melanocyte pools. Statistical data were analyzed by Student’s t test, and a P value < 0.05 was considered significant. l Phase-contrast microscopy analysis of primary melanocyte cell proliferation after treatment with 1 mM H₂O₂ for 30 min and coculture with MSCs for 24 h or 48 h; magnification, × 100; scale bar, 200 μm. m Hoechst staining of melanocytes; magnification, × 100; scale bar, 200 μm. n Statistical analysis of Hoechst staining with SPSS 20.0. o Primary melanocytes cocultured with MSCs for 0 h, 4 h, 8 h, or 12 h and analyzed by immunoblotting for Nrf2. p Melanocytes treated as described in l. Immunoblotting was used to evaluate Nrf2 expression. q, r Melanocytes treated as described in l. Flow cytometry was used to detect the cell death rate of each group. s, t Melanocytes pretreated with 1 mM H₂O₂ for 30 min and then cocultured with keratinocytes for 12 h, flow cytometry assay was used to detect the apoptosis rate. ns represents no statistical significance, and ** represents P value < 0.01