Figure 2. BMMSCs from old mice express higher levels of senescence markers and lower osteoblast markers compared to young ones. Statistically analyzed values show the mean ± SD (n=10). * p < 0.05. (A) In vitro staining of the senescence-related marker ß-galactosidase in BMMSCs cultures derived from young and old mice. Quantitative analysis of the total number of positively stained cells. (B-C) Real-time PCR analyses on whole bone tissue extracts (B) and on BMMSCs (C) for the senescence-related genes p16, p21 and p53. Normalization to ß-actin. (D) The western blot showed that the protein level changed as the mRNA. (E) Alizarin red staining of BMMSCs from young and old mice osteogenically induced for 14 d. Cont = Control, OS = osteogenically induced. (F-G) Real-time PCR and western blot analyses on BMMSCs for the osteogenic markers Runx2, ALP, osterix. Normalization to ß-actin.