Launching Heart Cells into Orbit: A Mission to Transform Patient Care

Chunhui Xu was present at Cape Canaveral during the launch of the SpaceX Crew-8 mission to the International Space Station in March 2024. Her enthusiasm, however, was more centered on the unique payload of functional heart cells than on the rocket technology.

Xu, a pediatric professor at Emory University School of Medicine, posits that understanding how heart muscle cells operate in the microgravity conditions of space could provide insights for aiding heart disease patients. The cells were integral to her study aimed at discovering more effective methods for utilizing similar cells to mend damaged hearts on our planet.

“The fundamental concept behind cell therapy is muscle regeneration,” Xu states. “However, cell survival remains a significant challenge. Specifically for heart muscle, when it is injured, it does not have the capability to regenerate. Once new cells are administered into the damaged area, many tend to perish.”

Building on previous studies indicating that cancer cells exhibit accelerated growth in space, Xu’s team initially attempted to simulate microgravity by utilizing a random positioning machine that continuously repositioned heart cells, preventing them from adapting to a persistent directional orientation. The enhanced survival rates of these cells prompted them to explore if the unique conditions of space could induce molecular transformations in heart cells that would increase their survival potential when injected into patients on Earth. “In a space setting, the cells are capable of perceiving their new surroundings and adjusting accordingly,” Xu explains.

Diving into the research

Xu’s findings, published in Biomaterials, employed specialized heart muscle cells that contract rhythmically, collectively enabling the cells to beat akin to a natural heart. These cells originated from generic human stem cells capable of differentiating into various types. Prior experiments had demonstrated that similar cell groups could avert heart failure in preclinical settings. Consequently, numerous researchers concluded that if methods to enhance cell longevity in heart therapy could be discovered, a limitless supply of new cells for heart repair could be achieved. The main obstacle remained to identify approaches that would bolster the survival rates of the transferred cells.

In their investigation, Xu’s team constructed bundles of heart muscle cells into microscopic three-dimensional spheroids that replicated the architecture and functionality of the human heart. The scientists preserved the cells through freezing for the journey to the International Space Station and thawed them just prior to launch. Control samples of heart cell aggregates were maintained on Earth for comparison purposes. Astronauts aboard the space station utilized microscopes to observe the development of the orbiting heart cells and disseminated videos showcasing the cells’ growth. They subsequently returned live cell cultures to Earth after the cells had spent eight days in space. Upon completion of the spaceflight, both the cells on Earth and those in space were analyzed to investigate the unique molecular changes experienced by the cells subjected to microgravity. The outcomes were intricate but indicated an increased synthesis of proteins related to cell survival.

A deeper understanding of how the microgravity environment influences the molecular behavior of heart cells to enhance their survivability could represent a significant advancement in employing these cells for the effective repair of damaged hearts. This necessitates a comprehensive understanding of all mechanisms governing the survival and growth of heart muscle cells under conditions of stress. Insights gained may lead to strategies for developing heart cells on Earth with improved longevity.

“Instead of transporting cells to space,” Xu remarks, “we essentially need to devise new methods to comprehend the molecular alterations that enhance the cells’ survival, enabling us to manipulate these changes in the cells as we prepare them on Earth. Our goal is to establish a novel approach for generating superior cells for cell therapy.”

This research was conducted in partnership with BioServe Space Technologies and the Georgia Institute of Technology, receiving financial support from the National Science Foundation and the ISS National Laboratory.

Citation: Forghani, P., et al. (2025). Spaceflight modifies protein levels and gene expression linked to stress response and metabolic traits in human cardiac spheroids. Biomaterials, 123080.