(A) Schematic of direct and indirect coculture of HUVECs and NRCMs. (B) Images and quantitative analysis of von Willebrand factor (vWF) staining for the tube formation ability of cocultured HUVECs with control medium and Sr ion–containing medium (10 pictures for each group). An unpaired t test was used for statistical analyses. *P < 0.05. (C) qRT-PCR analysis of the expression levels of angiogenesis-related genes [VEGF, KDR, vascular endothelial–cadherin (VE-cad), eNOS, bFGF, and bFGFR] in HUVECs and NRCMs that were acquired from monocultured cells or cocultured cells in each treatment group. Experiments were conducted in triplicate. An unpaired t test was used for statistical analyses. All data are presented as means ± SEM. *P < 0.05 was considered statistically significant. Mo, monocultured; Co, cocultured. (D) qRT-PCR analysis of the angiogenic gene (VEGF, KDR, VE-cad,
eNOS, bFGF, and bFGFR) expression in HUVECs treated with normal medium and conditioned medium from NRCMs, which were treated with Sr ions or not, as well as in NRCMs treated with normal medium and conditioned medium from HUVECs, which were treated with Sr ions or not. Experiments were conducted in triplicate. One-way ANOVA was used for statistical analyses. All data are presented as means ± SEM. *P < 0.05, **P < 0.01, and ***P < 0.001.