Fig. 3.

CXCR4−/− macrophages demonstrate increased proliferation and accelerated OC differentiation. (A) BrdU incorporation was measured in FLM from CXCR4−/− and WT cells. *, P = 0.03, two-tailed t test. (B) DNA fragmentation was measured from day-5 and -6 OC cultures from CXCR4−/− and WT cells. P = 0.64 day 5 and P = 0.34 day 6, two-tailed t test. (C) CXCR4 mRNA levels decreased as WT macrophages differentiated into OCs. Levels of TRAP and Cathepsin K were elevated in CXCR4−/− fetal liver-derived pre-OCs and OCs compared with WT (P < 0.005 day 2 and day 4 TRAP levels, P = 0.02 day 4 Cathepsin K levels; two-tailed t test). (D) Actin ring formation was evaluated in CXCR4−/− (Lower) and WT (Upper) FLM plated on bone in M-CSF and RANKL in triplicate. Representative images of cultures from days 3 (Left), 5 (Center), and 7 (Right) are shown. (Scale bars: 120 μm.)