Osteoporosis: On the Cutting Edge of Bone Health
Advances in research are changing the way osteoporosis experts think about this widespread disease.
Understanding Bone Remodeling continued...
Now that they understand the importance of bone remodeling, osteoporosis experts are trying to use that knowledge to help predict osteoporosis risk factors. They're developing tools known as biomarkers, which are chemical measures of the rate of bone remodeling that can be found in secretions from blood or urine. There are already biomarkers for the rate of bone remodeling that work very well in large population studies, says Heaney, but they do not yet have markers that work well in the doctor's office, on an individual patient level. Once more accurate biomarkers are developed, these and advanced imaging techniques may enormously improve our understanding of who is at greatest risk from osteoporosis.
"This allows us to focus on where the problem really lies: the excess remodeling that's making bone fragile," Heaney says.
New Osteoporosis Treatments
A few years ago, Heaney saw an 18-year-old girl who'd been in a serious car accident. She'd escaped with only a few bruises, and X-rays revealed that she had unusually high bone density. It turned out that her mother, too, had bone density well above the average. Heaney and his colleagues at Creighton began studying the entire family -- over 150 people -- and eventually identified what they call the "high bone mass gene."
A particular mutation in this gene causes the body to make abnormally high amounts of a protein called LRP5 (low density lipoprotein receptor-related protein 5). LRP5 influences how much bone is formed and maintained. "None of the people with the high bone mass gene had ever broken anything, even if they'd fallen off the barn roof," says Heaney.
The identification of the high bone mass gene and the chemical signaling pathway it involves has opened up a wide range of new possibilities for osteoporosis treatment. "The prospect here is to build an osteoporosis drug or drugs that cause the body to act as if it has that mutation, building up more bone," says Heaney. He believes that drugs aimed at this pathway are already in human testing, but it may take some time before they can come to market. "Because this pathway acts on other areas of the body besides bone, you have to be sure that your drug isn't producing unintended results elsewhere."