ISS Study Connects Astronaut Bone Loss to Stem Cell Changes in Microgravity

An international team of researchers, led by Mayo Clinic physician and scientist Dr. Abba Zubair, has uncovered new insights into how space travel impacts human physiology, specifically focusing on bone density loss in astronauts. His research leverages the unique environment of the International Space Station (ISS) to study how microgravity influences stem cell behavior, revealing crucial connections between space conditions and cellular functions.

Dr. Zubair's work primarily investigates mesenchymal stem cells—adult stem cells vital for regenerative medicine and bone health. Since 2017, he has sent multiple research projects to the ISS to observe how these cells grow and differentiate in space. The absence of gravity appears to significantly alter stem cell division and growth rates, with some evidence suggesting that cells grown in microgravity may grow faster or behave differently than those developed under Earth's gravity.

One key area of focus is understanding the role of mesenchymal stem cells in bone formation and osteoporosis. Despite rigorous exercise protocols, astronauts often experience bone density reduction, raising questions about the cellular mechanisms at play. The research aims to identify how microgravity affects the ability of these precursors to produce new bone tissue, possibly informing future interventions for osteoporosis.

Furthermore, Dr. Zubair is exploring the impact of space radiation on leukemia stem cells, which could provide insights into radiation-induced cancers and ways to mitigate these risks during long-term missions—to planets like Mars—and on Earth, especially in nuclear accident scenarios.

An exciting prospect from this research is the potential for space-induced cellular changes to enhance cancer treatments. For example, if microgravity prompts cancer cells to enter an active growth phase, chemotherapy could become more effective in space, or theoretically, on Earth, by simulating similar conditions. Although replicating microgravity environments on Earth presents challenges, scientists utilize water buoyancy systems and microgravity simulators to mimic these effects for research.

Dr. Zubair's fascination with space stems from childhood, inspired by his observations of the night sky in Nigeria. His early dream of becoming an astronaut transitioned into a focus on medical science, where he now explores space's influence on human health. Future missions include studies on stem cell expansion from umbilical cord blood and compounds that could prevent space-related bone loss.

His groundbreaking work has earned him recognition, including NASA’s Exceptional Scientific Achievement Medal. As he continues to investigate the complex interplay between space environment factors and cellular responses, Dr. Zubair remains committed to unlocking therapies that benefit both astronauts and patients on Earth.

Source: https://medicalxpress.com/news/2025-07-iss-links-bone-loss-astronauts.html