PBX1 and hydrops fetalis: To further confirm whether PBX1 could attenuate HF-MSCs senescence and apoptosis by upregulating SIRT1, and whether PBX1 could rescue SIRT1 knockdown-mediated HF-MSCs senescence and apoptosis, we overexpressed PBX1 and knocked down SIRT1 in HF-MSCs.