Full-thickness cartilage explants (n=64 explants) were used to study the effect of rapamycin on mechanical injury-induced sulfated glycosaminoglycan (sGAG) release into supernatants based on the dimethylmethylene blue method. Explants were subjected to mechanical injury, treated with rapamycin (Rapa; 1 μM) and analyzed at 24, 48, 96 hours. A, Safranin O staining of control explants and after mechanical injury at 48 hours. Original magnification x40. B, Quantitative analysis of sGAG release into supernatants. Values are mean ± SD. * = P < 0.05 vs injury; ** = P < 0.001 vs control. Values represent mean ± SD of four separate experiments each in duplicate.