Figure 3. Chondroprotective effect of CD38 deficiency in mice.

DMM surgery was performed on WT (C57BL/6) and CD38KO (A, n=10/group), as well as WT mice with and without apigenin treatment (n=9/group). Sham surgeries performed on separate groups of mice were used as controls. All mice were sacrificed at 10 weeks post-DMM surgery, and knee sections of these mice were subjected to histological and IHC analyses. The OARSI scores and the representative images of safranin-O staining of the DMM knees with medial compartment enlarged were shown in A and B. Representative IHC images of expression of CD38 and SIRT1 in articular cartilage and percentage of cells with positive staining for CD38 and SIRT1 relative to all cells present in the non-calcified regions of femoral and tibial cartilage indicated by hematoxylin staining were shown in C and D (n=4/group). Statistical analysis was performed using unpaired Student t-test in A and B (WT vs. CD38KO and non-treated vs. apigenin-treated), one-way ANOVA with Tukey multiple comparison test in D. The data were expressed as mean±95% CI (A, B) or mean±SD (D). p values with significance were indicated in the figures.