power field (HPF) in each group. The EV injection dose was 00 µg per rat. The experimental in vivo groups are as follows: a, normoxic control; b, hyperoxic control; c, hyperoxia + MSCs; d, hyperoxia + MSC-derived EVs; e, hyperoxia + scramble siRNA-transfected human MSC-derived EVs; f, in vivo hyperoxia + VEGF siRNA-transfected human MSCs-derived EVs; and g, in vivo hyperoxia human fibroblast (MRC0)-derived EVs. Data are presented as the means ± SEM. \**P* \< 0.00 compared to the normoxic control, ^†^*P* \< 0.00 compared to the hyperoxic control, ^‡^*P* \< 0.00 compared to hyperoxia + human MSCs, ^§^*P* \< 0.00 compared to hyperoxia + EVs derived from human MSCs  