PPS-MS reduce knee damage in PTOA. Mice were mechanically loaded (ML) unilaterally in the left knee and then optically imaged in vivo for binding of MabCII680 and evaluation of MMP activity 2 weeks post-initiation of injury. (A) Optical imaging of normal control mice and unilateral PTOA mice treated with PBS or PPS-MS (RK, right knee; LK, left knee). (B, C) Quantitative optical imaging of MabCII bound to damaged cartilage and MMP activity in left knee joint shows significant decreases with PPS-MS treatment. (D) PPS-MS have an inhibitory effect on total NO production in the PTOA mouse model, as shown by levels of total NO measured in sera of treated mice 2 weeks postinitiation of injury. (Data are expressed as mean ± SD, *p < 0.05, n = 6/group.)