Immunohistochemical analysis for MMP-1 and TNF-α in menisci. Photomicrographs of representative specimens evaluated for MMP-1 (A) and TNF-α (B) in medial menisci of OA, 4% RSA and ASC-treated groups. Data are reported as mean ± SD. Scale bars = 100 μm. Statistical values of at least P < 0.01 were observed in all the comparisons.