A subtle vibration was felt beneath the feet of a researcher named Ngan Huang as a rocket bearing her experiment—living human muscle cells cultivated on small chips—took off into the atmosphere, heading to the International Space Station National Laboratory. This research aims to enhance her understanding of muscle degeneration, a condition frequently observed in astronauts and the elderly, while also testing potential drug treatments.
A subtle vibration was felt beneath Ngan Huang’s feet as a rocket carrying her experiment—living human muscle cells cultivated on small chips—soared upwards and vanished into the sky towards the International Space Station National Laboratory. These chips would aid Huang in gaining insights into muscle degeneration, often found in astronauts and older individuals, while evaluating drugs to address this issue.
Now, the findings have arrived. In a study released on July 25 in Stem Cell Reports, Huang’s research group revealed that muscle cells exposed to space exhibited metabolic alterations indicating hindered muscle recovery and changes in gene activity linked to age-related muscle loss, known as sarcopenia. However, drug treatment was able to partially alleviate the negative impacts of microgravity.
“Space presents a truly unique environment that speeds up aging-related characteristics and disrupts many healthy functions,” Huang explains, an associate professor at Stanford University. “When astronauts return, they experience muscle atrophy or diminished muscle function because muscle isn’t being actively engaged without gravity. As space travel becomes increasingly accessible to the general public, it’s crucial to understand how our muscles respond in microgravity.”
To explore the consequences of microgravity on muscle health, researchers deployed muscle chips—engineered constructs containing aligned muscle cells on specially designed biomaterials designed to replicate real muscle structure—into space for a week under the supervision of astronauts.
Upon comparing the muscle cells that grew in microgravity with those developed on Earth, the researchers observed disruptions in muscle fiber development. Additionally, they identified alterations in gene expression and protein characteristics. Genes responsible for mitochondrial function, which provides energy for muscles, were affected, while genes associated with fat production were upregulated. These results imply that microgravity may cause issues in muscle recovery.
Muscles that traveled to space exhibited gene activity patterns similar to those found in individuals suffering from sarcopenia, which primarily affects those aged 60 and above.
“We believe that our investigations using muscle chips in microgravity could have wider relevance for sarcopenia,” Huang remarks. “Sarcopenia usually takes years to manifest on Earth, and we suspect that microgravity could accelerate this condition in just a few days.”
In a preliminary experiment aimed at testing the muscle chips for drug evaluation, astronauts introduced drugs intended to combat sarcopenia or boost muscle recovery into the chips. This treatment partially countered some of the adverse effects of microgravity on muscle tissue, helping to avoid a shift towards fat production. By analyzing gene expression patterns, the drug-treated muscles in microgravity displayed characteristics more akin to Earth samples than those untreated samples subjected to microgravity.
Due to the labor-intensive and resource-heavy nature of space research, this study is a singular experiment, and only a limited number of samples were transported aboard the rocket. The team is currently preparing equipment for Earth-based simulations of microgravity to alleviate some of these challenges and support their ongoing research in space. Huang’s muscle chips are set for another space mission in 2025, continuing the investigation into drugs that could mitigate muscle degeneration caused by microgravity.
“The concept of an engineered tissue chip platform in microgravity could serve as a groundbreaking tool for studying various diseases and conducting drug screenings without the need for animal or human testing,” says Huang.
