Muscling the Negative Effects of Human Spaceflight

Muscling the Negative Effects of Human Spaceflight

by Steven J. Madore, PhD, ICBR Associate Director of Science

(Summarized from Parafati et al., in Stem Cell Reports 8 July 2025)

The quest for human space exploration entails living and working in a very hostile environment. The musculoskeletal system is particularly vulnerable to the effects of spaceflight, with prolonged muscle disuse and the absence of gravity-induced mechanical loading resulting in rapid muscle atrophy. To understand the biological mechanism of this process, Dr. Siobhan Malany, Professor in the Department of Cellular and Systems Pharmacology in the UF College of Pharmacy, has developed a unique and innovative way to model the effects of microgravity on human muscle tissue.  In a paper published in the journal Stem Cell Reports, lead author Maddalena Parafati and Dr. Malany present the findings from their research using a muscle “lab-on-chip model” exposed to microgravity on the International Space Station (ISS). This model system utilizes 3D-bioengineered human muscle tissue (myobundles) derived from young and older adult donors exposed to microgravity. Myobundles treated identically but kept in special incubators here on earth served as controls for this study. To simulate muscle movement, the myobundles were stimulated with electric current to induce contraction. Dr. Malany and her colleagues found that intermittent contraction of the myobundles reduced contraction magnitude in microgravity and decreased protein levels of myosin heavy chain 7, the main protein isoform in human slow-twitch muscle fibers. Examining RNA levels to assess gene activity was performed from RNA isolated from the myobundles in the ICBR Gene Expression & Genotyping and Next Generation DNA Sequencing Shared Resources. This analysis revealed that while myogenesis (the differentiation of progenitor cells called myoblasts into mature, multinucleated muscle fibers) occurred in both ground control and spaceflight samples, younger electrically stimulated myobundles displayed enhanced mitochondrial-related gene expression in microgravity, while older and non-electrically stimulated myobundles were less responsive. Comparative analysis between young and older derived myobundles identified 86 muscle-specific age-associated genes altered in microgravity, linked to inflammation, mitochondrial dysfunction, and cellular stress.

These exciting results from research carried out in Dr. Malany’s laboratory highlight a unique age-related molecular response in muscle tissue exposed to microgravity and suggest that perhaps electrical stimulation of human muscle may act to counter the negative effects associated with time spent in space.