Fig. 6

Immunohistochemical expression of type II and X collagen in femoral condyle cartilage. (A) Immunohistochemical expression of type II and X collagen in the femoral articular cartilage of normal sheep and in a sheep model of knee osteoarthritis surgically induced by anterior cruciate ligament transection and medial meniscectomy, followed by the intra-articular injection of sterile saline (NC) or haMSCs into the right knee joint at 6 weeks (one dose) and 9 weeks (one dose) after surgery. Scale bars: 1000, 500, and 50 μm. (B) Area stained positive for type II collagen (three animals per group). *p < 0.05. (C) Number of hypertrophic chondrocytes expressing type X collagen per field. The red squares are magnified images (three animals per group). **p < 0.01. Abbreviations: NC, negative control; haMSCs, human adipose-derived mesenchymal stem cells