Figure 2. Vascular density and apoptosis detection by immunohistochemistry and qRT-PCR in vivo. (A) PECAM-1 staining of microvascular endothelial cells (×100 magnification). (B) Comparative analysis of vascular density in lung tissue. (C) TUNEL analysis of pulmonary vascular cells apoptosis in lung tissue. (D) Comparative analysis of the OD value of TUNEL-positive cells in each group. Data are presented as the mean ± SD. *P < 0.05 compared with the control group; #P < 0.05 compared with the BPD group; △P<0.05 compared with the EPO; ▲P<0.05 compared with the MSCs group.