Effects of combined menaquinone-4 and PTH 1–34 treatment on osetogenesis and angiogenesis in calvarial defect in osteopenic rats

Purpose The aim of this study was to evaluate the effect of combining human parathyroid hormone (1–34) (PTH 1–34 ; PTH) and menaquinone - 4 (MK-4) on calvarial bone defect repair in osteopenic rats. Methods Fourteen week olds were subject to craniotomy for the establishment of osteopenic animal models fed through a chronically low-protein diet. After that, critical calvarial defect model was established and all rats were randomly divided into four groups: sham, MK-4, PTH, and PTH + MK-4. The animals received MK-4 (30 mg/kg/day), PTH 1–34 (60 μg/kg, three times a week), or PTH 1–34 (60 μg/kg, three times a week) plus MK-4 (30 mg/kg/day) for 8 weeks, respectively. Serum γ-carboxylated osteocalcin (Gla-OC) levels, histological and immunofluorescent labeling were employed to evaluate the bone formation and mineralization in calvarial bone defect. In addition, Microfil perfusion, immunohistochemical, and micro-CT suggested enhanced angiogenesis and bone formation in calvarial bone healing. Results In this study, treatment with either PTH 1–34 or MK-4 promoted bone formation and vascular formation in calvarial bone defects compared with the sham group. In addition, combined treatment of PTH 1–34 plus MK-4 increased serum level of Gla-OC, improved vascular number and vascular density, and enhanced bone formation in calvarial bone defect in osteopenic conditions as compared with monotherapy. Conclusions In summary, this study indicated that PTH 1–34 plus MK-4 combination therapy accelerated bone formation and angiogenesis in calvarial bone defects in presence of osteopenia.