It could be used for patients suffering fromOsteoporosis, women treated for breast cancer with hormonal therapy (in whom the bones are more fragile) or even young high-level athletes. All people whose bones, made fragile, need to be solidified. This brand new hormone, called CCN3, discovered in breastfeeding women, has just been described in the journal Nature.
More than 200 million people suffer from osteoporosis worldwide
Worldwide, more than 200 million people suffer from osteoporosis. This disease causes severe weakening of the bones which can lead to frequent fractures. Women are part of the populations at risk after menopause, when estrogen levels decline in the body. It is this sex hormone that normally stimulates bone production.
However, estrogen levels are also low during breastfeeding. Yet osteoporosis and bone fractures are not common in breastfeeding women. What in the body could possibly maintain good bone health in these women? It is this scientific mystery that led a team from the University of California in San Diego on the trail of CCN3.
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The “maternal brain hormone”, poorly understood but already effective
Working on female mice, the team had already observed that blocking an estrogen receptor in a small area of the brain led to significant bone mass gain. This time, while looking for which hormone was involved, they put their finger on CCN3.
Produced by neurons in the same brain region in all mice, this hormone has been shown to be crucial for the health of the mother and her young. The experiments showed that without CCN3, mothers and their offspring began to lose weight, confirming the key role of this brand new hormone. Renamed “Maternal Brain Hormone”, it shows very promising results.
In young or senior mice, increasing CCN3 showed a rapid improvement in bone strength and mass within a few weeks. And this even in older females lacking estrogen. “ The strength of a bone depends on several parameters, not only its mass but also its mineral density and its microarchitecture. Using X-ray microtomography (a scanner on a microscopic scale, editor’s note), we can know the mineral composition of the bones as well as the bone volume in general.“, explains Science and Future Dr. Thomas Ambrosi, researcher at UC Davis and co-author of the article. Strength tests can also help determine how much force a bone can withstand before breaking.
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In patch or injection
Freshly discovered, the hormone still retains an element of mystery. “ At present, little is known about the mode of action of CCN3. It is known to directly stimulate bone formation by activating bone stem cells. These cells are therefore more numerous and differentiate to create bone more quickly. And finally, the spongy mass of the bone increases“, explains the researcher.
But a direct link with calcium has not yet been observed. “ The hormone is only expressed in the neurons of the hypothalamus during lactation. Its production stops when the demand for milk stops. But how this actually happens remains a scientific enigma. What activates it and what deactivates it? We know it has to do with estrogen, but the answer is probably much more complex.“, adds Professor Holly Ingraham, specializing in cellular and molecular pharmacology and co-author of the article.
Although it still conceals secrets, this hormone has already proven itself therapeutically. To supplement the body with CCN3, the team developed a patch based on hydrogel, capable of delivering the molecule directly to the bones. To do this, simply apply it to the level of the fracture, where the release of CCN3 occurs gradually over two weeks.
The device proved convincing in senior mice, stimulating bone production at the fracture site and contributing to its healing. “ We could therefore imagine strategies of CCN3 supplementation or injections. Before that, we still need to understand by what mechanism the brain triggers its production“, suggests Dr. Ambrosi. Only then can new therapeutic approaches be offered to patients.
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