Space travel has been found to deplete astronauts’ red blood cells but a new study of 14 astronauts suggests that their bodies can eventually replenish them after they’ve returned to Earth, thanks to fat stored in the bone marrow. The study, published in Nature Communications, may lead to important conclusions for health in space and on Earth.
1. MARROW experiment
This research is part of MARROW, a made-in-Ottawa experiment looking at bone marrow health and blood production in space, with funding from the Canadian Space Agency, Dr. Scott Smith and the NASA Biochemical Profile Protocol.
“We found that astronauts had significantly less fat in their bone marrow about a month after returning to Earth,” said senior study author Dr. Guy Trudel, a rehabilitation physician and researcher at The Ottawa Hospital and Professor in the Faculty of Medicine.
We think the body is using this fat to help replace red blood cells and rebuild bone that has been lost during space travel.Dr. Guy Trudel, senior study author
2. ”Space anemia”
The new study builds on Trudel’s earlier work, which found that astronauts’ bodies destroyed 54% more red blood cells during space travel than they normally would on Earth —known as “space anemia.”
“Thankfully, anemia isn’t a problem in space when your body is weightless, but when landing on Earth and potentially on other planets or moons with gravity, anemia would affect energy, endurance, and strength and could threaten mission objectives,” said Dr. Trudel of the Department of Biochemistry, Microbiology and Immunology. “If we can find out exactly what’s controlling this anemia, we might be able to improve prevention and treatment.”
For the latest study, 14 astronauts did MRI scans in their bone marrow at multiple time points before and after a six-month mission at the International Space Station. The researchers found a 4.2% decrease in bone marrow fat about a month after returning to Earth. This gradually returned to normal levels and was closely associated with increased production of red blood cells and restoration of bone.
“Since red blood cells are made in the bone marrow and bone cells surround the bone marrow, it makes sense that the body would use up the local bone marrow fat as a source of energy to fuel red blood cell and bone production,” Trudel said.
We look forward to investigating this further in various clinical conditions on Earth.Dr. Guy Trudel, senior study author
3. Recovering mobility on Earth
Trudel is a rehabilitation physician and most of his patients are anemic. They have lost muscle and bone mass after a long illness and limited mobility. Anemia makes it more difficult for them to exercise and recover muscle and bone mass. “I’m hopeful that this research will help people recover from immobility on Earth as well as in space,” Trudel said. “Our research could also shed light on diseases such as osteoporosis, metabolic syndrome, aging and cancer, which are associated with increases in bone marrow fat.”