Now, the findings are in. A study published on July 25 in Stem Cell Reports reveals that space-exposed muscle cells exhibit metabolic changes indicating impaired muscle regeneration and gene activities linked to age-related muscle loss, known as sarcopenia. Drug treatments were found to partially prevent the adverse effects of microgravity.
"Space is a really unique environment that accelerates qualities associated with aging and also impairs many healthy processes," said Huang (@NganHuang), an associate professor at Stanford University. "Astronauts come back with muscle atrophy, or a reduction of muscle function, because the muscle isn't being actively used in the absence of gravity. As space travel becomes more common and available to civilians, it's important to understand what happens to our muscle in microgravity."
To study microgravity's effects on muscles, the researchers launched muscle chips-bioengineered packages of oriented muscle cells on patterned biomaterials that mimic the structure of real muscles-into space, where they grew for seven days under astronauts' care.
Comparing muscle cells grown in microgravity to those grown on Earth, the researchers found impaired muscle fiber formation and differences in gene activity and protein profiles. Genes related to mitochondrial function, essential for muscle energy, were compromised, while genes associated with fat formation were enhanced. These findings suggest that microgravity can disrupt muscle regeneration.
Space-exposed muscles also showed gene activities similar to those in sarcopenia, which commonly affects people aged 60 and older.
"We think our research on muscle chips in microgravity may have broader implications on sarcopenia," Huang explained. "Sarcopenia usually takes decades to develop on Earth, and we think that microgravity may have some ability to accelerate the disease process in orders of days."
In a proof-of-concept experiment, astronauts tested the muscle chips for drug screening by treating them with drugs aimed at combating sarcopenia or enhancing muscle regeneration. The treatment partially mitigated some negative effects of microgravity on the muscles, preventing a metabolic shift towards fat formation. Examining gene activity patterns, the drug-treated muscle in microgravity more closely resembled Earth-grown samples than untreated samples in microgravity.
Due to the labor and resource-intensive nature of space research, the current study was a one-time experiment with a limited number of samples. The scientists are now using equipment that simulates microgravity to overcome some limitations and aid their research. Huang's muscle chips are set for another space mission in 2025 to continue identifying drugs for treating microgravity-induced muscle impairment.
"This concept of engineered tissue chip platform in microgravity is a potentially transformative tool that could allow us to study a variety of diseases and do drug screening without animal or human subjects," added Huang.
Research Report:Skeletal Muscle-On-A-Chip in Microgravity As a Platform for Regeneration Modeling and Drug Screening
Related Links
Cell Press
Space Medicine Technology and Systems
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