VEGFA and chronic obstructive pulmonary disease: Therapeutic effect of MSCs in COPD include secretion of epithelial growth factor (EGF), hepatocyte growth factor (HGF), keratinocyte growth factor (KGF), vascular endothelial growth factor (VEGF) to inhibit alveolar epithelial cell damage and apoptosis and release of EVs containing miR-100, miR-146a and miR-146-5b [39].