Fig 2: FGF7 regulated bone remodeling during OA progression. A, B Schematic of the treatment regimen (n = 3). C Knee articular cartilage safranin O/Fast Green staining in various treatment groups. Scale bar, 100 μm. D Representative images of COL II IHC in the articular cartilage and subchondral bone of various treatment groups. Scale bar, 100 μm. E Representative fluorescence images of Sp7-Cre/ERT2-Td knee joints with DAPI staining. F TRAP staining image of tibial subchondral bone and trabecular bone. Scale bar, 100 μm. G OARSI grade of the knee articular cartilage. H Quantitative analysis of the COL II area in articular cartilage and subchondral bone. I, J qPCR analysis of the expression levels of FGF7, RUNX2, SP7, Cx43, COL1a1, and SPP1 in various treatment groups. K Micro-CT scans of knee joints from various treatment groups after ALCT surgery. L, M Microarchitectures of tibial subchondral bones showing BV/TV (L) and Tb.Sp (M). Quantitative analyses were conducted using the IHC Profiler plug-in for ImageJ. All data are presented as the mean ± S.D. *P < 0.05; **P < 0.01; ***P < 0.001; ns, not significant

Fig 3: The expression of STAT3 and FGF7 in SSCs increased during OA progression. A Schematic of the protein interaction diagram related to Lepr. B mRNA levels of STAT3 in SSCs at different time points after ALCT. C, D QPCR analysis of the expression levels of STAT3 in OA mouse (C) and human (D) samples. The N side represents the less severely diseased side of the s source joint, whereas the O side represents the more severely diseased side of the joint. E CellChat analysis was performed to investigate the cell‒cell communication patterns between clusters in articular cartilage. The overall outgoing and incoming signal strengths of each cluster were visualized in a scatter plot. F The relative strength of all enriched signals (outgoing and incoming) across various clusters was visualized in a heatmap. G Violin plot showing the expression of canonical markers in the FGF signal. H FGF signaling pathway-associated ligand‒receptor. I Circle plots showing the dynamic alterations in the interaction networks between Fgf7 and Fgfr1 as well as between Fgf7 and Fgfr2. J, L Representative images of FGF7 IHC in articular cartilage and subchondral bone in OA mouse (J) (n = 3) and human (L) (n = 2) samples. Scale bar, 100 μm. K, M Quantitative analysis of the FGF7 area in articular cartilage and subchondral bone in OA mouse (K) and human (M) samples. N, O QPCR analysis of the expression levels of FGF7 in OA mouse (N) and human (O) samples. Quantitative analyses were conducted using the IHC Profiler plug-in for ImageJ. All data are presented as the mean ± S.D. *P < 0.05; **P < 0.01; ***P < 0.001; ns, not significant