Fig. 6
a Representative immunohistochemistry of VEGF and b representative western blots and quantitative data determined with densitometry for VEGF protein expression in 14-day-old rats exposed to postnatal RA or hyperoxia and treated with NS or surfactant on postnatal day 4 and NS or hUC-MSCs (3 × 104 or 3 × 105 cells) on postnatal day 5. The black arrows indicated the VEGF positively stained endothelium of the blood vessel. The rats reared in hyperoxia and treated with NS exhibited significantly lower levels of VEGF protein expression than did those reared in RA and treated with NS or surfactant. Treatment with surfactant and hUC-MSCs (3 × 104 or 3 × 105 cells) more significantly augmented the hyperoxia-induced decrease in the VEGF protein expression levels than the treatment with NS. Data are shown as box-and-whisker plots. *P < 0.05, **P < 0.01, and ***P < 0.001. MSCs mesenchymal stem cells, NS normal saline, O2 oxygen-enriched atmosphere, RA room air, S surfactant, VEGF vascular endothelial growth factor