Fig. 4
a Representative histology and b MLI in 14-day-old rats exposed to either postnatal RA or hyperoxia and treated with either NS or surfactant on postnatal day 4 and either NS or hUC-MSCs (3 × 104 or 3 × 105 cells) on postnatal day 5. The rats reared in hyperoxia and treated with NS yielded a significantly higher MLI than did those reared in RA and treated with NS or surfactant. Treatment with surfactant and treatment with surfactant and hUC-MSCs (3 × 104 cells) significantly diminished the hyperoxia-induced increase in the MLI. The O2 + surfactant + hUC-MSCs (3 × 105 cells) group exhibited a significantly lower MLI than the O2 + surfactant + NS and the O2 + surfactant + hUC-MSCs (3 × 104 cells) groups. Data are shown as box-and-whisker plots. ***P < 0.001. MSCs mesenchymal stem cells, NS normal saline, O2 oxygen-enriched atmosphere, RA room air, S surfactant