Figure 6

MiR-9 is involved in pathogenesis of OA. Articular chondrocytes were isolated form cartilage (upper panel) that was divided into 3 classes depending on the progression of OA pathology (A: healthy zone, B: intermediate zone, and C: severe zone). (A) Images of the cultures were captured using light microscopy and human cartilages were stained with safranin O and Alcian blue. (B) The expressions of MMP-2, MMP-9, MMP-12, and MMP-13 were measured with real-time PCR. (C) Cell viability (right panel) and caspase-3/7 activity (left panel) were analyzed. (D) Changes in the protein level of Type II collagen and PRTG were analyzed by Western blotting. GAPDH was used as control (upper left panel). PRTG expression was analyzed by immunocytochemisty (upper right panel). The expressions of type II collagen (Col II), PRTG, and miR-9 were analyzed by real-time PCR (lower panel). (E) Mouse cartilages with OA induced by destabilization of the medial meniscus (DMM), were infected with miR-9 or si-miR-9 lentiviruses and stained with safranin O, propium iodide, and Tunnel. PRTG level was analyzed by immunohistochemistry (left panel). Inserted number in safranin-O photomicrographs indicated the averages of semi-quantitative score for the degree of cartilage destruction in MFC (first score) and MTP (second score) view. Each histological score for the degree of cartilage destruction (n = 5 mice/group) in MFC (first score) and MTP (second score) view were graphed (right panel). Sham-operated (Sham) cartilage was used as control. *, statistically different from control cells (p < 0.001). The error bars represent average of data from each human sample. Scale bar, 200 μm.