Known effects of weightlessness include muscle atrophy, reduced bone density, and fluid distribution changes. Recent research on mice and other organisms has identified additional changes. In this study, blood samples were collected from six astronauts during and after their 120-day mission on the ISS to investigate these changes. Extracellular DNA and RNA in the blood samples were analyzed using a method called "liquid biopsies."

Previous studies indicated that mitochondria are released from cells into the bloodstream during space missions. This study confirmed that mitochondria are involved in responses to the space environment and can be isolated using CD36 as a marker. This technique allows the condition of extracellular mitochondria to be assessed and the cell type they originate from to be identified.

This process has revealed previously unknown systemic responses to the space environment, including changes in the brain, eyes, heart, vascular system, lungs, and skin. A similar analysis of mouse samples showed that mice experience changes similar to those seen in humans and that mitochondrial changes are induced in response to gravity changes.

Research Report:Release of CD36-associated cell-free mitochondrial DNA and RNA as a hallmark of space environment response

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University of Tsukuba
Space Medicine Technology and Systems