Fig. 4

Quantification of the amount of a PDGF-A, b VEGF, and c BMP2 released by both co-cultured cells and monocultured EpSlKCs and DP cells by ELISA (n = 3). Data shown are mean ± SEM. *p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001; ∙ p < 0.05, ·· p < 0.01, ··· p < 0.001, ···· p < 0.0001 vs. day 5; ^#p < 0.05 vs. day 9. bd, bellow detection level; BMP2, bone morphogenetic protein 2; PDGF-A, platelet-derived growth factor A; VEGF, vascular endothelial growth factor