Bone breakthrough could reverse osteoporosis
Scientists have uncovered a mechanism that could lead to treatments aimed at reversing osteoporosis rather than only slowing its progression.
The finding involves a cell receptor called GPR133, also known as ADGRD1, which regulates osteoblasts – the cells that build new bone tissue.
When triggered by a compound called AP503, this receptor increased bone strength in both healthy and osteoporotic mice.
Researchers from the University of Leipzig in Germany and Shandong University in China tested mice lacking the GPR133 gene.
These animals developed weak bones resembling osteoporosis. But when the receptor was present and activated with AP503, bone growth and strength improved.
University of Leipzig biochemist Ines Liebscher said: “Using the substance AP503, which was only recently identified via a computer-assisted screen as a stimulator of GPR133, we were able to significantly increase bone strength in both healthy and osteoporotic mice.”
AP503 acts as a biological switch, prompting osteoblasts to build bone more actively.
The team also showed that it could work in combination with exercise to strengthen bones further.
Although the results are based on animal models, the underlying biological processes are likely similar in humans.
Earlier studies had already linked variations in the GPR133 gene to bone density in people, which led researchers to study the protein it produces.
Liebscher said: “If this receptor is impaired by genetic changes, mice show signs of loss of bone density at an early age – similar to osteoporosis in humans.”
The researchers suggest future treatments could not only protect bone health but also rebuild degraded bone, potentially benefiting women who develop osteoporosis during menopause.
Osteoporosis is a serious condition affecting millions worldwide.
While existing therapies can slow the disease, they cannot reverse or cure it. Many also carry side effects, such as increased risk of other conditions, or lose effectiveness over time.
Molecular biologist Juliane Lehmann from the University of Leipzig said: “The newly demonstrated parallel strengthening of bone once again highlights the great potential this receptor holds for medical applications in an ageing population.”
