Scientists suggest possible solution to space-induced bone loss

One of the foremost health risks for astronauts may have a cure en route. A specially-formulated medication has been shown to prevent bone loss in mice, and perhaps humans, aboard the International Space Station.

According to the team from the University of California Los Angeles (UCLA) and the Forsyth Institute in Cambridge, Massachusetts, microgravity causes a one percent drop in bone mineral density (BMD) per month of exposure. To counteract that loss, they turned to a nearly 30-year old discovery and earlier associated research to develop a new drug that they said not only prevented bone loss in the ISS' rodent residents, but even increased bone density.

"Our findings hold tremendous promise for the future of space exploration, particularly for missions involving extended stays in microgravity," said UCLA professor of plastic and reconstructive surgery Dr Chia Soo this week. 

The drug used in the experiment was a modified version of NELL-1, a protein that is used to regulate bone growth. NELL-1 was discovered by UCLA chair of orthodontics Dr Kang Ting in 1996, who found it associated with a birth defect involving overactive bone growth. A 2015 study by Ting and others, including Dr Soo, found that NELL-1 was effective in stimulating bone growth both in stem cells in lab environments and animals. 

For this latest study, a the version of NELL-1 was necessary to simplify the treatment process. The team developed a form of NELL-1 bound to bisphosphate called BP-NELL-PEG that "specifically targets bone tissues without the common deleterious effects of [biphosphate]," per UCLA, and it appears to have been a resounding success.

Mice who spent nine weeks aboard the ISS that were given BP-NELL-PEG "showed a significantly increased BMD in all bones compared to control," the team said in their paper. Both the ground and flight groups treated with the experimental medication showed increased BMD, as one may expect from prior NELL-1 experiments. 

"We conclude that BP-NELL-PEG successfully reverses osteoporitic bone loss and is a viable pharmacologic countermeasure for use in spaceflight," the researchers conclude.

When can we expect human tests of NELL-1?

The next step in the study, Soo told UCLA, was analysis of live animal data, and how it relates to humans - mice not being prime targets for interplanetary travel.

"We hope this will provide some insight on how to help future astronauts recover from longer duration space missions," Soo told UCLA. That doesn't answer the most pressing question about this discovery, though: When can we expect human trials of what could be a life-changing treatment for astronauts, much less those suffering from bone density diseases?

We reached out to Dr Soo, who didn't immediately respond to our questions. Without her input suggesting otherwise, it looks like NELL-1 is nowhere near the commercialization stage. 

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Just one company - Burlington, Massachusetts-based Bone Biologics - appears to have reached the point of doing human clinical trials using NELL-1 to treat degenerative disk disease in a pilot program in Australia. It's unclear what the status of that study is, however - first announced in 2019, the company said again in April of this year that it was still working on starting the same 30-person study. 

Without knowing when human trials of any NELL-1 treatment could begin, astronauts will probably be forced to maintain regular treadmill sessions for the foreseeable future. No word on when treatment for brain changes and other detrimental health effects of space exposure are any closer to being addressed, either. ®