Histological analysis of surgically-induced osteoarthritis (OA) in the knee joints of mice after administering B3 or the vehicle control.

<p>OA was surgically induced in 12-week-old mice, and the knee joints were harvested 4 weeks later. B3 or the vehicle alone (control) was orally administered 5 times a week beginning 5 days after surgery and continuing until the end of the experiment (n = 10). A, Representative histologic features (a−d, Safranin O staining; e and f, H&E staining) of the knee joints of control (a, c, e) and B3-treated (b, d, f) mice. Degenerative changes in the articular cartilage were ameliorated in B3-treated mice (b, d) as compared to controls (a, c). Note the thicker medial pseudocapsule in the control group (a, b, arrows), and the ectopic cartilage formation in the pseudocapsule (a, asterisk). e, f, High magnification images of the pseudocapsules. Note that the control pseudocapsule is occupied with hypertrophic chondrocyte-like cells (e), whereas only thin fibrous cells are observed in B3-treated mice (f). B, Histological scoring of cartilage destruction according to Mankin’s score, * <i>p</i><0.05. C, The thickness of the pseudocapsule was significantly reduced in the B3-treated group. Values represent the mean ± SD of 10 samples per group. *<i>p</i><0.05. D, The incidence of ectopic cartilage formation at the medial pseudocapsule was reduced by B3 treatment.