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Figure 2 | BMC Musculoskeletal Disorders

Figure 2

From: Molecular changes in articular cartilage and subchondral bone in the rat anterior cruciate ligament transection and meniscectomized models of osteoarthritis

Figure 2

Up-regulation of matrix degradation markers as an early gene regulation event in the surgically-induced models of osteoarthritis. (A) Up-regulation of matrix degradation markers was seen as early as one week following surgery. (a) Aggrecanase-1 demonstrated early increases of 3-4 fold in ACLT+MMx and ACLT models, respectively. High levels of expression were maintained throughout the 10 wks of study duration. (b) MMP-13 levels were elevated 2-fold at wk 1 post-surgery. Levels progressively increased by 3 to 5-fold relative to Sham through wk 10. (c, d) Expression levels of both markers were unaffected in contra-lateral joints over entire time course. (B) No changes in MMP-13 mRNA expression were observed in deep tissue slice 2 (a) or slice 3 (b). Similar results were observed for aggrecanase-1. All values are shown as mean ± SD. (C) Frontal section of medial tibial plateau and growth plate were stained with anti-MMP-13 (a, b, d, e, and f) or toluidine blue-O (c). Articular cartilage, including growth plate, at wk 2 (a and b) and at wk 10 (c, d, e, and f) post-surgery are shown. (a) ACLT+MMx OA joint highly expressed MMP-13 in differentiated chondrocytes (closed arrowheads) and synovial cells on cartilage surface (arrow). (b) In sham joint, few cells are MMP-13 positive in deep zone (arrows). (c) Arrows indicate osteophyte formation in periarticular region of the medial tibial plateau of ACLT-MMx. (d) MMP-13 immunostaining of semi-serial section of (c). (e) Higher magnification of osteophyte region (inset in d) shows many MMP-13 positive chondrocytes are found in proximity to vascular invasion (open arrowheads). (f) In growth plate, as a positive control, MMP-13 was intensely stained in hypertrophic chondrocytes. C: articular cartilage. B: bone. V: vascular invasion. GP: growth plate. PS: primary spongiosa. Bar = 100 μm in (a, b), 500 μm (c, d), 50 μm (e), 200 μm (f).

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