Brain Organoids in Space: Insights into Microgravity’s Impact on Brain Development

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Brain Organoids in Space: Insights into Microgravity’s Impact on Brain Development

Asked by terryaster at 6:48am on Dec 26 2024

Microgravity is known to affect muscles, bones, the immune system, and cognition, but its direct effects on the brain remain unclear. To investigate, scientists at Scripps Research, in collaboration with the New York Stem Cell Foundation, sent tiny clusters of stem-cell-derived brain cells, called organoids, to the International Space Station (ISS).

After a month in orbit, the organoids returned to Earth healthy and intact. However, they exhibited accelerated maturation compared to identical organoids grown on Earth. These space-exposed cells were closer to becoming adult neurons and showed early signs of specialization. The findings, which may reveal potential neurological effects of space travel, were published on October 23, 2024, in Stem Cells Translational Medicine.

"The fact that these cells survived in space was a big surprise," said co-senior author Jeanne Loring, PhD, professor emeritus at Scripps Research. "This opens the door for future space experiments involving other brain regions affected by neurodegenerative diseases."

Creating Brain-Like Structures for Space Study

On Earth, the team used stem cells to produce organoids containing cortical or dopaminergic neurons, the cell types affected in multiple sclerosis and Parkinson’s disease—both areas of Loring’s long-standing research. Some organoids also included microglia, the brain's resident immune cells, to study how microgravity influences inflammation.

Organoids typically grow in a nutrient-rich liquid medium that requires regular maintenance to supply nutrients and remove waste. To simplify this process for spaceflight, the researchers developed a novel method of growing smaller organoids in cryovials—airtight containers initially designed for deep freezing.

Prepared at the Kennedy Space Station, the organoids traveled to the ISS in a compact incubator. After a month in microgravity, they were retrieved and analyzed.

Accelerated Development and Reduced Inflammation

To understand microgravity’s effects on cellular functions, the team compared RNA expression—a marker of gene activity—in space-grown organoids to Earth-bound controls. They discovered that cells exposed to microgravity showed higher expression of genes related to maturity and lower levels of genes associated with proliferation, indicating faster development and reduced replication.

"We found that the gene expression profiles in both types of organoids resembled those of later developmental stages compared to the ground controls," Loring explained. "While they developed faster, they weren’t adult neurons, so this doesn't provide insights into aging."

Contrary to expectations, the organoids grown in microgravity exhibited less inflammation and lower expression of stress-related genes. The reasons for this unexpected result remain unclear and warrant further study.

A Brain-Like Environment in Microgravity

Loring suggests that microgravity conditions may more closely mimic the natural environment within the brain compared to traditional lab conditions on Earth.

"In microgravity, there's no convection—materials don’t move as they do in gravity," she said. "In space, these organoids are more like the brain itself, forming a tiny, independent system resembling a 'brainlet' or a microcosm of the brain."

Future Space Missions

This research marked the team’s inaugural space mission, but they have since sent four additional missions to the ISS, replicating the initial conditions and expanding the scope of their experiments. These continued efforts aim to deepen our understanding of how microgravity shapes brain development and to explore its potential relevance to neurodegenerative diseases.

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