Milk extracellular vesicles accelerate osteoblastogenesis but impair bone matrix formation

Area of Science:

• Biochemistry
• Cell Biology
• Bone Biology

Background:

• The skeletal benefits of milk consumption remain debated.
• Extracellular vesicles (EVs) in milk, containing proteins and RNA, are newly discovered.
• The specific impact of bovine milk-derived EVs (BMEVs) on bone formation is unknown.

Purpose of the Study:

• To investigate the effect of BMEVs on osteogenesis in mice and human mesenchymal stem cells (hMSCs).

Main Methods:

• Oral administration of BMEVs to DBA/1J mice for 7 weeks.
• In vitro exposure of hMSCs to BMEVs for 21-28 days.
• Analysis of bone parameters, cell proliferation, mineralization, gene expression, and protein production.

Main Results:

• BMEVs increased osteocyte numbers and woven bone in mice, but did not alter tibia trabecular bone area.
• In hMSCs, BMEVs initially upregulated osteogenic genes but later reduced collagen production.
• Prolonged BMEV exposure led to increased proliferation and mineralization, with altered expression of sclerostin and osteonectin.

Conclusions:

• BMEVs influence bone formation, affecting osteoblast differentiation and bone matrix composition.
• The findings suggest BMEVs may contribute to the complex and contradictory effects of milk on bone health.
• Further research is needed to elucidate the precise mechanisms and long-term implications of BMEVs on skeletal integrity.