Bone regeneration with systemic administration of lactoferrin in non-critical-sized rat calvarial bone defects

Using in vivo microfocus computed tomography (micro-CT) and tissue sections, we evaluated bone regeneration in non-critical-sized rat calvarial flat bone defects during systemic administration of lactoferrin (LF). Ten 11-week-old male Fischer rats were used. Non-critical-sized calvarial bone defects (diameter, 2.7 mm) were trephined into the dorsal parietal bone on both sides of the midsagittal suture, and a collagen sponge soaked in saline was placed on each side. LF was injected intraperitoneally every day, starting on the day of the operation (day 0; groups: control, 10 mg/kg LF, 100 mg/kg LF). Micro-CT imaging was performed repeatedly from 1 to 4 weeks after surgery. The defect sites were then removed, along with surrounding bone and soft tissues, and stained with hematoxylin and eosin. During weeks 1-4, micro-CT showed a significant difference in reossification ratio between the controls and the 100 mg/kg LF group. Histological analysis revealed that there were more osteoblast-like cells around the bony rim in the 100 mg/kg group than in the control group. In summary, micro-CT and histological analyses showed that systemic administration of LF accelerated bone regeneration in non-critical-sized rat calvarial bone defects.