Getting older brings with it a mixed bag of items. If you are lucky you can get wiser. If you are not so lucky you can get osteoporosis. But while scientists don’t know how to make you wiser, they have gained some new insights into what makes bones weak and so they might be able to help with the osteoporosis.

Around 200 million people worldwide suffer from osteoporosis, a disease that causes bones to become so brittle that in extreme cases even coughing can lead to a fracture.

Scientists have known for some time that the cells that form the building blocks of our skeletons are found in the bone marrow. They are called mesenchymal stem cells (MSCs) and they have the ability to turn into a number of different kinds of cells, including bone or fat. The keys to deciding which direction the MSCs take are things called epigenetic factors, these basically control which genes are switched on or off and in what order. Now researchers from the UCLA School of Dentistry have identified an enzyme that plays a critical role in that process.

The team found that when the enzyme KDM4B is missing in MSCs those cells are more likely to become fat cells rather than bone cells. Over time that leads to weaker bones and more fractures.

In a news release Dr. Cun-Yu Wang, the lead researcher, said: “We know that bone loss comes with age, but the mechanisms behind extreme cases such as osteoporosis have, up until recently, been very vague.”

To see if they were on the right track the team created a mouse model that lacked KDM4B. Just as they predicted the MSCs in the mouse created more fat than bone, leading to weaker skeletons.

They also looked at mice who were placed on a high fat diet – something known to increase bone loss and weaker bones in people – and found that the diet seemed to reduce KDM4B which in turn produced weaker bones.

In the news release Dr. Paul Krebsbach, Dean of the UCLA School of Dentistry, said the implications for the research are enormous. “The work of Dr. Wang, his lab members and collaborators provides new molecular insight into the changes associated with skeletal aging. These findings are an important step towards what may lead to more effective treatment for the millions of people who suffer from bone loss and osteoporosis.”

The study is published in the journal Cell Stem Cell.