Tonsil-Derived Mesenchymal Stem Cells Promote Bone Mineralization and Reduce Marrow and Visceral Adiposity in a Mouse Model of Senile Osteoporosis

Osteoporosis is a disease that affects 35% women and 20% men aged more than 65 years. Reduction in bone formation and increased bone resorption are known factors that drive osteoporosis, but recent studies suggest a positive correlation between bone marrow adipose tissue (MAT) and osteoporosis. Previously, we have observed that tonsil-derived mesenchymal stem cells (T-MSCs) reduce MAT in a mouse model of bone marrow depletion. That prompted us to investigate on the senile osteoporosis to characterize the bone-forming effect, as well as MAT-reducing effect of T-MSCs. In a mouse model of senescence-accelerated mouse prone 6 (SAMP6), we injected T-MSCs or T-MSC conditioned medium (CM) through tail vein and examined changes in bone microstructure using micro-CT scan and hematoxylin & eosin (H&E) staining. Biochemical markers of osteoporosis, deoxypyridinoline (DPD) and osteocalcin, were examined by ELISA. Results demonstrated attenuation in the progression of osteoporosis, in part, by sustaining osteocalcin production and by blocking MAT accumulation. Increase in matrix mineralization was determined using in vitro culture of murine preosteoblast cell line by treatment of T-MSC CM. Interestingly, T-MSC CM induced continuous weight loss and selectively reduced visceral adipose tissue mass. Finally, antiadipogenic effects of T-MSC CM were determined in vitro. In conclusion, regulation of bone together with MAT could be considered as a new therapeutic option for the treatment of senile osteoporosis and this report may provide a framework for future cell therapy using T-MSCs.