Scientists at the University of Hong Kong have uncovered a protein that acts as an exercise sensor in bones, explaining how movement prevents age-related bone loss. This discovery could lead to drugs mimicking exercise benefits for those unable to stay active. The findings highlight potential new treatments for osteoporosis affecting millions worldwide.
Researchers from the Department of Medicine at the University of Hong Kong's School of Clinical Medicine have pinpointed a key biological mechanism behind exercise's role in maintaining bone strength. Their study reveals that a protein called Piezo1, located on mesenchymal stem cells in bone marrow, detects physical forces from movement and directs these cells to form bone tissue rather than fat.
As people age, bones lose density, with stem cells increasingly turning into fat cells, which weakens the structure and accelerates osteoporosis. According to the World Health Organization, one in three women and one in five men over 50 will suffer a fracture due to weakened bones. In Hong Kong, 45% of women and 13% of men aged 65 and older are affected, leading to pain, reduced mobility, and healthcare burdens.
Experiments on mouse models and human stem cells showed that activating Piezo1 reduces fat accumulation and boosts bone formation. Without it, inflammatory signals like Ccl2 and lipocalin-2 promote fat production and hinder bone growth; blocking these signals helped restore balance.
"Osteoporosis and age-related bone loss affect millions worldwide, often leaving elderly and bedridden patients vulnerable to fractures and loss of independence," said Professor Xu Aimin, who led the study. He added, "We have essentially decoded how the body converts movement into stronger bones."
Co-leader Dr. Wang Baile noted the implications for frail individuals: "This discovery is especially meaningful for older individuals and patients who cannot exercise due to frailty, injury or chronic illness." Professor Eric Honoré, from France's CNRS, emphasized, "This offers a promising strategy beyond traditional physical therapy."
The research, published in Signal Transduction and Targeted Therapy in 2025, was supported by various grants and involved international collaboration. The team now aims to develop 'exercise mimetics' to target Piezo1 and combat bone loss in vulnerable groups.
