Aged bone matrix-derived extracellular vesicles as a messenger for calcification paradox.

Area of Science:

• Biomedical Science
• Cell Biology
• Bone Biology

Background:

• Bone marrow mesenchymal stem/stromal cells (BMSCs) differentiate into adipocytes, leading to marrow adiposity and osteoporosis, particularly with aging and menopause.
• Osteoporosis is paradoxically associated with vascular calcification, termed the 'calcification paradox'.

Purpose of the Study:

• To investigate the role of extracellular vesicles derived from aged bone matrix (AB-EVs) in BMSC differentiation and vascular calcification.
• To elucidate the mechanism by which AB-EVs contribute to the calcification paradox.

Main Methods:

• Characterization of AB-EVs and their effect on BMSC differentiation and vascular smooth muscle cell calcification in vitro.
• In vivo studies using mouse models to assess the impact of AB-EVs injection and alendronate treatment on bone-fat balance and vascular calcification.
• MicroRNA analysis of AB-EVs and functional studies involving miR-483-5p and miR-2861.

Main Results:

• AB-EVs promote BMSC adipogenesis over osteogenesis and augment vascular smooth muscle cell calcification.
• Administration of AB-EVs exacerbates bone-fat imbalance and vascular calcification in mice.
• Alendronate treatment reduces AB-EVs release and mitigates these effects.
• MiR-483-5p and miR-2861 within AB-EVs are crucial for the observed phenotypes.

Conclusions:

• AB-EVs act as key mediators in the calcification paradox by promoting adipogenesis and vascular calcification.
• Targeting AB-EVs or their microRNA cargo may offer therapeutic strategies for osteoporosis and vascular calcification.