Scientists have developed a new, rapid test that may offer near real-time monitoring of bone diseases, such as osteoporosis and multiple myeloma, using blood samples from NASA space shuttle astronauts.
The functionality of the test, which measures changes in calcium isotope ratios, has been validated on blood samples from NASA astronauts. Our bones are largely built of calcium, and the turnover of calcium can indicate the development of bone diseases such as osteoporosis and the cancer multiple myeloma.
A group of US geochemists, biologists and clinicians, from Arizona State University and the Mayo Clinic, worked with NASA to develop the new, rapid test of bone health. These methods, using mass spectrometry, can discern the relative ratios of the calcium isotopes 42Ca and 44Ca in bone. The researchers found that lighter calcium isotopes, such as 42Ca, are absorbed from the blood into the bone during bone formation.
Conversely, these light isotopes tend to be released into the bloodstream when bones break down. By measuring the ratios of the two isotopes in blood or urine scientists can calculate the rate of change of bone mass.
"The big advantage of these measurements is that they show what is happening in the bone, whereas traditional bone health measurements, such as DXA scans, show what has happened," said lead researcher, Ariel Anbar from the Arizona State University. "This means that we can have a real near-time view of what is happening in the bone, rather than comparing before and after, when damage may have already been done," said Anbar.
"Our goal is that these measurements will allow us to see bone breakdown in osteoporosis, but also can show us the progress of certain bone cancers, such as multiple myeloma," he said.
In space, because of zero gravity conditions, astronauts experience very rapid bone loss.
Working with NASA, the researchers measured calcium isotope ratios in urine from 30 shuttle astronauts, before, during, and after the flights. This allowed them to confirm that the test worked at high sensitivity. "We were able to confirm that Ca isotopes of the shuttle shifted as expected, meaning that they we could see in more or less real time the ongoing bone loss. We did this using a simple urine sample, taken at various points during their flights," said Anbar.
The researchers have also looked at a group of 71 patients who either had multiple myeloma (bone cancer), or were at risk of multiple myeloma.
"What we saw with cancer patients was interesting. Those patients who tended to lose the lighter 42Ca isotope seemed to be the ones where the cancer was the most active. "This means that the tests could theoretically feed into decisions on whether or not to treat a patient, for example if a cancer was dormant or growing very slowly, and to assess the effectiveness of treatments," Anbar added.
