Senescence and apoptosis assays. Acid β-galactosidase and Annexin V assays were carried out to detect senescent and apoptotic cells in MSC samples treated with HS and OS. The picture shows representative fields of acid β-galactosidase (left) and Annexin staining (right). Arrowheads indicate senescent cells. Annexin-positive cells are green. Cells were counterstained with DAPI (blue). Mean expression values for senescent and apoptotic cells are indicated in the corresponding table (± SD, number of experiment replicates: three). DAPI, 4',6-diamidino-2-phenylindole; HS, healthy weight sera; MSCs, mesenchymal stem cells; OS, overweight sera.