Fig. 1

Loss of hepatic ApoE expression increases bone deposition in aged fracture callus. a Schematic diagram of the tibia fracture model in 24-month-old control (ApoE^fl/fl, Ctrl) mice and liver-specific ApoE knockout (ApoE^Alb, ΔApoE) mice. b ELISA was used to measure ApoE concentration in the plasma of mice (Ctrl, n = 10; ΔApoE, n = 15). c 21-day fracture calluses were assessed using micro-CT analysis to determine (d) total volume (TV), (e) bone volume (BV), and (f) bone ratio (BV/TV) (Ctrl, n = 9; ΔApoE, n = 13). g Safranin O/fast green/hematoxylin staining was used to stain the fracture calluses and (h) histomorphometric analysis was used to quantify the amount of bone within the fracture callus (Ctrl, n = 6; ΔApoE, n = 6). i Schematic diagram of tibial drill hole defect in 24-month-old control (ApoE^fl/fl, Ctrl) mice and liver-specific ApoE knockout (ApoE^Alb, ΔApoE) mice. j Healing was assessed 14 days after defect using micro-CT and (k) bone ratio (BV/TV) in the defect region was determined (Ctrl, n = 9; ΔApoE, n = 9). Data are presented as mean ± 95% confidence interval. *P < 0.05