Your skeleton isn't a fixed framework bolted together at birth. It turns out your body completely rebuilds its entire set of bones roughly every 10 years. But scientists have never fully understood which tiny workers—cells and genes—control this constant renovation. Until now.
A team of Australian and British researchers has created the most detailed map ever made of the cells and genes that govern how our bones form, break down, and repair themselves. Their findings, published in the journal Nature Genetics, could lead to entirely new treatments for bone diseases that affect millions.
The research was led by Professor Peter Croucher and Dr. Ryan Chai from the Garvan Institute of Medical Research in Sydney, along with Associate Professor John Kemp from Mater Research and scientists from Imperial College London.
The team used a powerful technique called single-cell RNA sequencing to examine individual cells at the place where hard bone meets bone marrow—the exact site where bones are constantly being built and torn down. What they found surprised them.
They identified 34 different groups of cells controlling bone health, and more than half of the genes active in these cells had never been linked to bones before. "To our surprise, more than half of the genes identified have never before been shown to play a role in maintaining bone health," Dr. Chai said.
One of the most surprising discoveries was the role of blood vessel cells. The researchers found that cells surrounding blood vessels play a critical part in repairing bone—a function scientists had largely overlooked until now.
To connect their discoveries to human disease, the team analyzed genetic data from half a million people taking part in the UK Biobank, one of the world's largest collections of health information. This allowed them to pinpoint exactly which cells go wrong in conditions like osteoporosis, a disease that weakens bones and affects nearly half of all people over 50.
Currently, most bone disease drugs only slow down bone loss rather than rebuild what has been lost. "Most of the drugs now available focus only on halting bone disease, rather than rebuilding lost bone, which is really important for reversing damage," Professor Croucher explained.
The findings may also help fight cancer. Because bone is a common hiding place for cancer cells that have spread from other parts of the body, understanding bone's cellular machinery could lead to new ways to prevent relapse.
The researchers have made their entire dataset freely available to scientists around the world through an open-access platform, hoping this will speed up the development of new medicines. The team is now continuing to study these newly discovered cells and genes, working toward treatments that could not just slow bone disease but actually reverse the damage.