BDNF and acute lung injury: It was reported that cytokines such as basic fibroblast growth factor (bFGF), nerve growth factor (NGF), stem cell factor (SCF), hepatocyte growth factors (HGF), vascular endothelial growth factor (VEGF), insulin‐like growth factor (IGF‐1) and brain derived neurotrophic factor (BDNF), which were secreted in the medium by cultured stem cells, could encourage the growth of cells.16, 17, 18 Li et al11 reported that induced pluripotent stem cell‐derived conditioned medium (iPS‐CM) potentially restored the bronchial microstructure in acute lung injury (ALI).