Effect of Synthetic Bone Mineral (SBM) on the Quality of the Tibia Bone in Ovariectomized Rats: Histomorphometric and Imaging Analyses.

Abstract

Osteoporosis is a skeletal disease characterized by loss of bone strength, decrease in density, thinning cortical bone and disorganized trabecular microarchitecture leading to bone fragility and susceptibility to fracture. The condition affects both men and women but especially 45% of women over the age of 50. Current therapies (e.g., estrogen, bisphosphonate-based drugs) are proved effective. However, studies show that they also cause serious side effects (e.g., breast cancer, jaw osteonecrosis, delayed bone healing, unexplained fracture). A calcium phosphate-based compound (described as synthetic bone mineral, SBM) has been shown to minimize bone loss when administered by injection or orally using a rat model. Objective: The aim of this study was to determine two effects of SBM in (1) preventing bone loss (therapeutic effect) and (2) restoring bone loss (recovery effect). The focus of the study is on the effect of SBM on the quality of the rat tibia: microarachitecture, degree of mineralization (DOM), mineral apposition rate, bone mineral density (BMD). Method: The tibias were separated from Sprague-Dawley rats belonging to the following groups (10 per group): (A) Therapeutic effect: P1, sham operated on low mineral diet (LMD); P2, ovariectomized (OVX) on LMD; and P3 and P4, OVX on LMD supplemented with SBM (with and without fluoride, F, respectively). Study period, 3 months. (B) Recovery effect: R1, sham operated on LMD; R2, R3, and R4 OVX on LMD. After 3 months, R3 and R4 diets were supplemented with SBM (+/-F, respectively) for 2 months. The cleaned tibias were characterized using Micro-CT, back-scattered electron (BSE-SEM), Microscopy, DEXA and femurs were tested for mechanical properties. Results: Results of this study demonstrated that the synthetic bone mineral (SBM) with or without fluoride was effective in minimizing bone loss and recovering bone loss induced by estrogen deficiency accelerated by low mineral diet and the therapeutic and recovery effects between SBM with or SBM without fluoride were not significantly different. Significance: SBM may have a potential use for osteoporosis therapy and restoration of bone loss without any adverse side effects.