Bone Loss Research Aboard the ISS

During long-duration missions, astronauts may experience a gradual reduction in bone density—typically around 1% to 2% per month—even with consistent exercise routines. While scientists understand how bones work on Earth, they aren’t sure exactly why bones weaken so quickly in microgravity.

Previous research aboard the space station revealed that microgravity changes how stem cells behave and what substances they release. Scientists now want to dig deeper into these cellular changes to better understand what causes bone loss in space and explore potential ways to prevent it.

The Microgravity Associated Bone Loss-B (MABL-B) investigation focuses on special stem cells called mesenchymal stem cells, or MSCs. As these cells mature, they build new bone tissue in the body.

Scientists suspect that a protein called IL-6 might be the culprit behind bone problems in space. Data from the earlier MABL-A mission suggests that microgravity promotes the type of IL-6 signaling that enhances bone degradation. The MABL-B experiment will investigate this by testing ways to block this IL-6 signaling pathway.

The experiment will grow mesenchymal stem cells alongside other bone cells in special containers designed for space research. Cells will be cultured for 19 days aboard the space station, with crew members periodically collecting samples for analysis back on Earth.

The research could lead to targeted treatments that protect astronauts from bone loss during long-duration missions to the Moon, Mars, and beyond. As crews venture farther from Earth, bone health becomes increasingly critical since medical evacuation or emergency return to Earth won't be possible during Mars missions.

The findings could provide new insights into age-related bone loss that affects millions of people on Earth. Understanding how the IL-6 protein affects bone health may lead to new treatments for osteoporosis and other bone conditions that come with aging.