Research Paper Volume 14, Issue 14 pp 5669—5680

Figure 4. Effect of M1 macrophages on chondrocyte injury. (A) Flow cytometry (n=3): Chondrocytes co-cultured with M1 macrophages and those cultured with culture medium exhibited obvious apoptosis, macrophages with KLF4 overexpression induced more severe chondrocyte apoptosis than ordinary macrophages, and the apoptosis rate was up-regulated. (B, C) Cell viability detection (n=3) results suggested that, cells in Control group did not show obvious apoptosis, while chondrocytes co-cultured with M1 macrophage/cultured with culture medium had markedly decreased viability. **P<0.01 between groups. (D, E) Expression of MMP13 (n=3). The expression level of MMP13 in Control was lower, while in L/I, both co-culture and medium could increase the expression of MMP13 in chondrocytes, After KLF4 overexpression, the level of MMP13 was further increased, with a significant difference compared with L/I, **P<0.01 between groups.