Matrix metalloproteinase-13 expression during osteoarthritis development. Immunohistochemical findings for matrix metalloproteinase (MMP)-13 in the medial femoral condylar cartilage from (A) a control knee, (B) a collagen tripeptide (Ctp)-treated knee, (C) a hyaluronan (HA)-treated knee and (D) a Ctp/HA-treated knee 5 weeks after surgery (original magnification ×400). (E) Appearance of the MMP-13 (×400) staining in the medial femoral condylar cartilage from a normal rabbit knee. (F) Population of MMP-13-positive chondrocytes in medial femoral condylar cartilage of each group 5, 10 and 15 weeks after surgery. Counted area was 6.76 × 104 μm2. Data presented as mean ± standard deviation (*P <0.05).
Naraoka et al. Arthritis Research & Therapy 2013 15:R32 doi:10.1186/ar4181