In the absence of effective countermeasures, prolonged spaceflight can result in many of the same physiological changes associated with aging—bone loss, muscle deterioration, and altered immune system function—only at a much quicker rate. This makes the microgravity environment of the International Space Station (ISS) a valuable platform for research on conditions associated with the aging process.

Two investigations launching on SpaceX’s 25th Commercial Resupply Services (CRS) mission will use tissue chips in space to study age-related conditions to benefit people back on the ground. Researchers from the University of Florida will examine muscle loss, and a research team from the University of California, San Francisco (UCSF) will study immune system aging.

Both projects are funded by the National Institute of Health’s National Center for Advancing Translational Sciences (NCATS) through the Tissue Chips in Space initiative in collaboration with the ISS National Laboratory. Tissue chips are small devices designed and engineered to model the function of human tissue. By taking tissue chips to space, researchers can observe microgravity-induced changes in human physiology relevant to disease, which could lead to novel therapies for patients on Earth.

Muscle Bundles in Space

Adults lose muscle mass as they age; without countermeasures, astronauts in space lose it even faster. Siobhan Malany, an associate professor in the College of Pharmacy at the University of Florida, is sending tissue chips with human muscle cells to space to better understand muscle wasting. “Our experiment should provide new insight into muscle cell biology by leveraging the unique environment of microgravity,” she said.

Microgravity speeds up changes to muscle physiology, making it possible to study what is happening inside muscle cells over a shorter period than is possible on Earth. The team is launching 16 tissue chips that contain three-dimensional muscle bundles developed from donated sets of skeletal muscle cells obtained through a partnership with healthcare company Advent Health. The cells come from two specific age groups: people who are under age 40 and those who are over age 60.

The tissue chips will be housed in a CubeLab from ISS National Lab Commercial Service Provider Space Tango. The CubeLab is outfitted with a camera and microscope system to record muscle movement. Half of the cells from each group will receive electronic stimulation, which prompts muscle contraction, allowing Malany and her team to visually examine how the muscles function in space. Additionally, the team will study genetic changes in the tissue chips once they return to Earth.

“We’re going to look at the actual muscle function of these bundles while they’re in this unique anlood stress-induced environment,” Malany said. “By comparing these two different age groups, we can validate cellular processes associated with muscle wasting in space, which could lead to the development of new treatments for patients on Earth with muscle loss.”

According to Malany, sarcopenia—a condition associated with muscle loss and mobility issues—commonly affects people over age 65, and there are no known treatments for it aside from exercise. She hopes data from this investigation could help unlock new treatments for sarcopenia and other muscle-related diseases here on Earth.

Reversing Immune Aging

The tissue chip investigation from UCSF will examine the relationship between immune aging and healing outcomes in space. Led by Sonja Schrepfer, professor of surgery at UCSF, the experiment will investigate the effects of microgravity on the body’s immune system and how those effects play into the aging of immune cells.

“Sending these immune chips into space will enable us to simulate the aging process of the immune system and understand how it affects our body’s ability to repair itself as we grow older,” Schrepfer said.

By observing immune function in microgravity and during cell recovery back on Earth, the research team hopes to better understand not only how the immune cells change but also how the immune aging process could be reversed. According to Schrepfer, previous space-based research shows that immune cells start aging within three days of being in microgravity.

“When we have a viral infection where the virus stays in the body for a long period of time, the immune system is constantly activated,” Schrepfer said. “This eventually exhausts the immune system, leading to what we call an ‘aged immune system.’”

Schrepfer said that this can happen at any age, not just in older adults. “When we have this aging immune system, it’s just not protecting the body as effectively and is not defending the body against infection,” she said.

To examine immune aging processes in microgravity, some of the team’s tissue chips will contain healthy tissue and some will have tissue from patients with an aged immune system. The experiment, which is supported by Commercial Service Provider BioServe Space Technologies, will run on the ISS for about a month. The tissue samples will be returned alive so the research team can observe how well the immune cells can repair themselves back on the ground.

This investigation could lead to more effective treatments for patients on Earth, which would be a game-changer in terms of patient care, Schrepfer said. “Now, instead of just preventing immune system aging, we hope to learn how to reverse it.”

SpaceX CRS-25 is targeted for launch from Kennedy Space Center no earlier than July 14 at 8:44 p.m. EDT. This mission will include more than 15 ISS National Lab-sponsored payloads. To learn more about all ISS National Lab-sponsored research on SpaceX CRS-25, please visit our mission overview page.