Estrogen-deficient bone loss prevented by calcium phosphate-based compound (MZF-CaP)

We developed synthetic bone mineral (MZF-CaP) incorporating magnesium (Mg), zinc (Zn) and fluoride (F) in carbonate apatite matrix that when used as a supplement was shown to prevent bone loss induced by mineral deficiency in rats (AADR IADR 2006). Objective: This study aimed to investigate the effect of MZF-CaP in preventing bone loss induced by estrogen-deficiency (ovariectomy) in rats. Methods: MZF-CaP (#74) was prepared and characterized using x-ray diffraction (XRD), FT-IR and chemical analyses. Purina basic diets and supplemented diets (2.0 wt% of total diet) were prepared by Purina Test Labs. Ovariectomized (OVX) and non-OVX 3-month old Sprague-Dawley rats, ave wt. 225 g (Charles Laboratories) were randomly divided into the following groups (10 in each group): G1: control (non-OVX) on basic diet (BD); G2: control on BD + MZF-CaP; G3: OVX on BD; G4: OVX on BD + MZF-CaP for a period of 5 months then sacrificed by CO2 inhalation. The bones were cleaned of extraneous soft tissues and stored in alcohol. Mechanical strength was determined using 3-point bending (Instron). Bone density was determined using radiography; bone volume, using micro-CT (µCT, Scanco); bone composition by TGA, FT-IR, XRD and chemical analyses. Dissolution properties were determined in acidic buffer. Results: MZF-CaP showed similar XRD profile and FT-IR spectra as bone mineral. Comparing bones G3 and G4 rats, G4 showed significantly (p<0.05) higher mineral/organic ratio, higher fracture load, higher bone volume/total volume (BV/TV) ratio, higher Mg, Zn and F contents, and lower dissolution rate in acidic buffer. Conclusion: MZF-CaP administered as diet supplement effectively prevented bone loss induced by estrogen-deficiency (ovariectomy) in rats and improved bone properties. MZF-CaP has potential for osteoporosis therapy. [Supported by research grant 1RO1 EB 003070 from NIBIB/NIH].