Fig. 3.

Pharmacological inhibition of Fap ameliorates joint symptoms after the onset of OA. a–c Safranin O/Fast Green staining in wild-type mice treated with FAPi or vehicle after DMM surgery. Weekly intra-articular administration of FAPi (40 μg·kg⁻¹ body weight) or vehicle (PBS) was performed 4 weeks after DMM surgery in 10-week-old mice and continued for 8 weeks before paraffin sectioning and safranin O/fast green staining of the knee joints. Representative cartilage erosion (a, top: femur, bottom: tibia), subchondral bone thickening (b) and synovitis (c) images are shown (n = 6 mice per group). Yellow dotted lines indicate the subchondral bone plate. Arrows indicate the synovium. Scale bars: 100 μm. d–f Quantification of the OARSI score (d), subchondral bone thickness (e) and synovitis score (f). g, h Immunostaining of Col II in the knee joints (g) with quantification (h) (n = 6 mice per group). DAPI staining indicates the nucleus. Scale bars: 100 μm. The statistical significance was assessed using one-way ANOVAs with Tukey’s multiple comparison tests. Data are presented as the mean ± SD (*P < 0.05, **P < 0.01, ***P < 0.001)