Figure 5. Intra-articular injection of senescent MSCs induces OA-like cartilage degradation. (A) p16INK4A, p19ARF, p21cdkn1a, TGF-β, MMP-13, IL-1β and IL-6 mRNA expression in MSCs derived from bone marrow (BM) of 6-month-old SAMP8 or SAMR1 mice by RT-qPCR. Data are the mean ± SEM (n=3 for each conditions); *=p<0.05. (B) Beta-galactosidase staining in MSCs derived from BM of SAMP8 or SAMR1 mice. Data are the mean ± SEM (n=5); ****=p<0.0001. (C) Experimental design of BM-MSC injection in the knee of 2-month-old C57BL/6JRj mice. (D) Cartilage degradation (OA modified score according to van den Berg, from 0 to 30, after Safranin-O/Fast Green staining) at day 42 after SAMP8 or SAMR1 BM-MSC intra-articular injection. Data are the mean ± SEM (n = 5 for both conditions); *=p<0.05. (E) Representative images of cartilage degradation in a C57BL/6JRj mouse after SAMP8 or SAMR-1 BM-MSC injection. (F) Histo-morphometric analyses by micro-CT of the left knee (medial and lateral compartment) at day 42 after injection of SAMR1 or SAMP8 BM-MSCs. Data are the mean ± SEM (n = 5 for each condition).