Fig. 2.

Pathological features of MSCs and osteocytes in OA femoral heads

(A) Safranin O staining of OA FH showing S and NS regions used for IHC and percentages of bone area occupied in FH from three OA donors (empty boxes: NS; grey boxes: S regions); arrow: remaining area of tidemark. (B) Abundance of CD271⁺cells in S regions dominated by OPG⁺ dense fibrovascular tissue (indicated as *) adjacent to E11⁺ osteocytes. (C) High-magnification images of CD271 and E11 IHC in S (upper panels) and NS (lower panels) regions of OA FHs and quantification of CD271-stained area and proportions of E11⁺ osteocytes. CD271 area and E11 quantification was performed based on DAB+ staining (brown), within selected bone areas (dashed lines) above negative control threshold (red colour). (D) Gene expression in sorted CD45^-CD271⁺MSCs from healthy and OA bone. *P <0.05; **P <0.01; ****P <0.0001. (E) Tri-lineage differentiation ability of OA CD45^-CD271⁺ MSCs following culture-expansion. Empty arrow heads: E11⁺ osteocytes; full arrow heads: osteoblasts; arrow: CD271⁺MSCs. FH: femoral head; S: sclerotic; NS: non: sclerotic; IHC: immunohistochemistry; DAB: diaminobenzidine.