Dental Tissue-Derived Mesenchymal Stem Cells Modulate Mitochondrial and OPG/RANKL Signaling in Obesity-Associated Osteoporosis Under Estrogen-Deficient and Intact Conditions.

Background/

Objectives

Obesity and menopause are major determinants of skeletal deterioration; however, their combined effects on bone remodeling and associated cellular bioenergetics remain incompletely understood. This study aimed to determine whether obesity induces osteoporotic alterations under both estrogen-replete and estrogen-deficient conditions and to evaluate the therapeutic potential of dental tissue-derived mesenchymal stem cells (D-MSCs).

Methods

Female mice were subjected to ovariectomy (OVX) and/or high-fat diet (HFD) feeding for 16 weeks to establish obesity-associated osteoporosis models. D-MSCs were administered intraperitoneally at defined intervals. Body weight and serum leptin levels were measured to assess metabolic status. Femoral tissues were analyzed by quantitative real-time PCR for estrogen receptors (ERα, ERβ), inflammatory markers (Il-1β, Tnf-α), mitochondrial regulators (Pgc1α, Pgc1β), and the OPG/RANKL ratio. Histological analysis was performed to evaluate bone marrow adiposity.

Results

HFD significantly increased body weight and serum leptin levels in both intact and OVX mice. Obesity was associated with reduced expression of ERα and ERβ, decreased Pgc1α levels, and a lower OPG/RANKL ratio, accompanied by increased Il-1β, Tnf-α, and Pgc1β expression. D-MSC administration attenuated body weight gain and reduced leptin levels, particularly in OVX mice. In femoral tissue, D-MSC treatment restored estrogen receptor expression, increased Pgc1α, decreased Pgc1β, and normalized the OPG/RANKL ratio. In addition, inflammatory marker expression and bone marrow adiposity were reduced following MSC administration.

Conclusions

Obesity induces bone remodeling dysregulation under both intact and estrogen-deficient conditions, characterized by altered estrogen signaling, inflammatory activation, and mitochondrial imbalance. D-MSC administration was associated with partial restoration of these alterations, suggesting a potential role in modulating metabolic and skeletal homeostasis in obesity-associated bone loss.