Fig. 6
Therapeutic effects of B2M-CuS NPs in a surgery-induced OA mouse model. (a) Schematic diagram of the experimental design. B2M-CuS NPs, CuS NPs, and PBS were intra-articularly injected into the knee joints of OA mice every 2 weeks beginning at 4 weeks post-surgery. Knee joints were collected at 8 weeks post-surgery. (b) OARSI scores were measured from histological sections. (c) Representative images of Safranin O/fast green staining of the knee joints after treatment. Cartilage lesions are highlighted by red arrows. (d–g) Immunofluorescence staining of knee joints at 8 weeks post-surgery. The expression of Col-2 (d) was higher while the expression of MMP-13 (e) was lower in the B2M-CuS group relative to the CuS and PBS groups. Senescence marker p16ink4a(f) was highly expressed while HMGB-1 expression (g) was negligible in the PBS group. The expression of p16ink4a and HMGB-1 were similar between B2M-CuS and sham groups, indicating that B2M-CuS NPs effectively eliminated senescent chondrocytes. Cartilage areas are highlighted by white dotted lines. Data are presented as mean ± SD (n = 6). *p<0.05, **p<0.01, ***p<0.001, and ****p<0.0001