Sildenafil induces in vitro angiogenesis, DRG neurite outgrowth and Schwann cell migration.
Representative microscopic images (A to D) and quantitative data (I) show capillary-like tube formation of endothelial cells under regular glucose (RG), high glucose (HG), high glucose with sildenafil (HG+sil, 300 nM), and high glucose with sildenafil in the presence of a neutralizing antibody against Tie2 (+Tie2, 5 μg/ml). Panels E to H show NFH immunoreactive DRG neuron cultured in conditional medium derived from endothelial cells treated with regular glucose (RG), high glucose (HG), high glucose with sildenafil (HG+sil, 300 nM), and high glucose with sildenafil in the presence of a neutralizing antibody against Tie2 (+Tie2, 5 μg/ml). Panels J and K show quantitative data of neurite outgrowth from DRG neurons and the percentage of Schwann cell migration under different conditions listed above. Panel L shows ELISA data of Ang1 levels in conditional medium harvested from endothelial cells cultured with regular glucose (RG), high glucose (HG), high glucose with sildenafil (+sil, 300 nM). *p<0.05 versus regular glucose (RG), and #p<0.05 versus high glucose (HG), respectively. n = 6/group. Bar in D = 50 μm and Bar in H = 20 μm.