New study sheds light on role of bone marrow in space travel

A study on astronauts discovered that space flight might reduce red blood cells and bones. It further postulated that the human body could ultimately restore them once back on Earth using fat stored in the bone marrow. 

“We found that astronauts had significantly less fat in their bone marrow about a month after returning to Earth. We think the body is using this fat to help replace red blood cells and rebuild bone that has been lost during space travel,” said Dr. Guy Trudel, a rehabilitation physician, and researcher at The Ottawa Hospital, in an official release. 

Examination of 14 ISS astronauts

For this study, the researchers used MRI scans of the 14 astronauts' bone marrow at various periods before and after a six-month stint aboard the space station. 

A month after returning to Earth, the team noticed a 4.2 percent drop in bone marrow fat. This gradually reverted to normal levels and was linked to improved red blood cell production and bone regeneration.

“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,” explained Dr. Trudel. “We look forward to investigating this further in various clinical conditions on Earth.”

Furthermore, the study suggests that younger astronauts’ bodies may possess a greater capacity to harness the energy from bone marrow fat, while female astronauts' bone marrow fat increased more than predicted after a year.

The findings have crucial implications for both space and terrestrial health.

“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,” added Dr. Trudel.

The study is published in the journal Nature Communications.

Study abstract:

Space travel requires metabolic adaptations from multiple systems. While vital to bone and blood production, human bone marrow adipose (BMA) tissue modulation in space is unknown. Here we show significant downregulation of the lumbar vertebrae BMA in 14 astronauts, 41 days after landing from six months’ missions on the International Space Station. Spectral analyses indicated depletion of marrow adipose reserves. We then demonstrate enhanced erythropoiesis temporally related to low BMA. Next, we demonstrated systemic and then local lumbar vertebrae bone anabolism temporally related to low BMA. These support the hypothesis that BMA is a preferential local energy source supplying the hypermetabolic bone marrow postflight, leading to its downregulation. A late postflight upregulation abolished the lower BMA of female astronauts and BMA modulation amplitude was higher in younger astronauts. The study design in the extreme environment of space can limit these conclusions. BMA modulation in astronauts can help explain observations on Earth.