Figure 2.

Necrotic area of the femoral head has enhanced osteoclast activity and decreased expression of antioxidant enzymes. (A) Hematoxylin & Eosin (HE) staining showing the necrotic bone is featured by the presence of empty osteocyte lacunae (green arrows) and tartrate-resistant acid phosphatase (TRAP) staining showing the distributions of osteoclasts on trabecular bone surface (red arrows) in the HR and NR. The accumulation of fat tissue (asterisk) is also notable in the NR. (B) Quantitative analyses of N.OC/BS. (C) qPCR results showing the genes' expression of osteoclast-specific markers and antioxidant enzymes relative to the ACTB expression. TNFSF11, encoding receptor activator of nuclear factor kappa-Β ligand (RANKL); TNFRSF11B, encoding osteoprotegerin (OPG); CTSK, encoding cathepsin K; ACP5, encoding TRAP; CAT, encoding catalase; NQO1, encoding NAD(P)H quinone dehydrogenase 1; HMOX1, encoding heme oxygenase 1 (HO1). (D) Western blot analysis showing the protein expression level of osteoclast-related markers including RANKL and cathepsin K, as well as anti-oxidant enzymes including catalase, γ-glutamylcysteine synthetase (γ-GCSc), and superoxide dismutase 1 (SOD1). All bar graphs are presented as mean ± SD (n=3 in each group). *P<0.05, **P<0.01 compared with control group (HR). HR, Healthy region; NR, Necrotic region; N.Oc/BS, osteoclast number/bone surface