Discoveries
Space Doctors and Stem Cell Production in Microgravity
Have we entered a second Space Age?
In 2027, NASA plans to land astronauts on the moon and hopes to establish permanent bases there to help launch humans to Mars. Public and private space travel to low-Earth orbit and the International Space Station are at an all-time high.
In this new era of space travel, we also know more about the risks spaceflight pose to human health. As more professionals and civilians launch into the cosmos, the need for specialized, expert medical care will increase accordingly.
“When astronauts spend time in space, their bones and muscles degrade, their hearts weaken and they are exposed to radiation,” said Cedars-Sinai cell biologist Arun Sharma, PhD, research scientist and associate professor of Biomedical Sciences at the Board of Governors Regenerative Medicine Institute. “We need to better understand these effects on the human body and how to mitigate them.”
Conversely, microgravity may benefit biomanufacturing—namely unique ways to grow human stem cells and organoids to model disease and aid drug discovery.
Cedars-Sinai is exploring both the promise and peril of the growing space industry by:
- Investigating effects of microgravity and space radiation on the human body
- Growing stem cells and creating human tissues in microgravity on the space station
- Training medical professionals and researchers in space-related research
What Happens to the Body in Microgravity?
Studies have shown that astronauts’ bones can degrade after mere weeks in low gravity. To combat these effects, astronauts on the International Space Station exercise for two or more hours a day on specialized weightlifting, treadmill and stationary cycling equipment. But Sharma says these efforts are not sufficient to completely mitigate microgravity’s deleterious impact, and more research is needed to better understand the biological processes at work.
“What happens to people in space is very similar to what happens with age-related diseases experienced here on the ground, such as sarcopenia (the loss of muscle mass and function), osteoporosis or coronary disease,” said Sharma. “But in space, this decline happens much faster.”
When astronauts spend time in space, their bones and muscles degrade, their hearts weaken and they are exposed to radiation.”
— Arun Sharma, PhD
According to Sharma, this harm can be mimicked at the cellular level. For 10 years, he has studied the impact of microgravity on human cells, beginning with the launch of heart cells derived from stem cells to the space station in 2016.
That experiment showed genetic changes in the cells as well as a reduction in function. The heart cells worked, or contracted, less robustly in microgravity when compared to their normal function on Earth.
“Our results suggest that as the heart, muscles and bones suffer expedited decline in space, they also weaken at the cellular level,” said Sharma. “Of course, this is a simplified model looking at cells in a dish, but this could help explain what’s happening to the astronauts’ organs as a whole.”
Can Microgravity Benefit the Manufacture of Stem Cells?
While the human body suffers in microgravity, stem cells may thrive in it.
“On Earth, the force of gravity pushes the cells down onto a two-dimensional dish,” said Clive Svendsen, PhD, the executive director of the Regenerative Medicine Institute and the Kerry and Simone Vickar Family Foundation Distinguished Chair in Regenerative Medicine at Cedars-Sinai. “But what we’ve found is that in zero g-force, they float and arrange themselves in three-dimensional spheres, which may provide unique benefits for their production.”
The institute’s most recent stem cell experiment on the International Space Station, launched last year, was the first to successfully demonstrate the creation of new induced pluripotent stem cells (iPSCs) in space.
“There’s actually a tissue culture hood on the space station, and you talk to the astronauts while they do the experiments for you,” said Svendsen. “It’s an amazing thing to watch and be a part of.”
The institute is a leader in stem cell research and manufacturing iPSCs. These human skin or blood cells have been reprogrammed back into an embryonic-like pluripotent state, which enables them to be turned into any cell type in the human body.
The next step for space manufacturing, says Sharma, could be organoids, which are three-dimensional tissues derived from iPSCs that provide vehicles for disease research, such as Alzheimer’s disease and heart disease, on functioning tissue. In August, Regenerative Medicine Institute researchers will work with astronauts on the space station, attempting to produce stem cell-derived heart organoids and brain organoids in space for the first time.
“We anticipate that organoids may form better in space, since we’ve been able to show that stem cells in microgravity can just float around and come together naturally into three-dimensional shapes,” Sharma said.
Space may provide a more efficient environment for the Cedars-Sinai Biomanufacturing Center to initiate manufacturing these cells, maximizing their promise for new approaches in medical care, said Svendsen. However, once tissues are formed and left in microgravity, they may show accelerated aging. There are areas of research in which accelerated aging in stem cell models is beneficial—for example in mimicking diseases such as Alzheimer’s and heart disease and for testing drugs to treat these diseases.
While low-Earth orbit is more accessible than ever before, the costs are still significant. But Dhruv Sareen, PhD, chief biomanufacturing officer at the center, says that if Cedars-Sinai discovers biomedical products that can only be made in space, or can be made more efficiently there, larger-scale in-space biomanufacturing could become financially feasible.
“Down the road, we might be looking at automated manufacturing satellites, devoid of friction and contamination challenges, that could only be used for manufacturing biomedical or other products,” Sareen said. “Once created, these unique made-in-space materials could be returned to Earth for research or clinical applications.”
Educating a New Generation of Space Physicians and Researchers
With an eye to the future needs of the space industry, Cedars-Sinai plans to develop an educational program in space medicine and research.
A seminar series on space research and medicine has featured visiting astronaut Rayyanah Barnawi, who performed the experiments in the Regenerative Medicine Institute’s 2023 mission on the International Space Station, and will host biologist and astronaut Kate Rubins, who conducted the 2016 experiments on heart cell functionality in space.
“Young physicians, researchers and postdoctoral scholars are excited about this. We all are,” said Svendsen. “There’s that tingle when you talk about going to space.”
