CXCL5 and acute respiratory distress syndrome: In the present study, pFUS appears to have facilitated the activation and migration steps in the homing of hUC-MSCs by modulating homing-associated factors SDF-1, ICAM-1, CXCL5 and IGF-1, thereby promoting their lung homing, which in turn induced significant histological and cytokine improvements in ARDS.