Human Heart Cells Alter in Spaceflight but Return to Normal Quickly on Earth

A Stanford University study sheds light on the cellular phenomenon.
Fabienne Lang

With tourist space travel becoming more and more of a realistic notion, finding out how our human cells and bodies react while in space is fundamental. Currently, this is an important study for those already heading up to space: astronauts.

Researchers from Stanford University have delved into how our heart cells change when we're in space, and what happens to them when we return to Earth. 

The study was published on Thursday in Stem Cell Reports


The study 

The study quickly deduced that human heart cells alter when in spaceflight. However, they return back to normal relatively quickly once back on Earth. 

The point of the study was to find out how the cells change, and what could be done in the future to prevent these changes from happening. 

Previous studies pointed out that heart rate and blood pressure drop when in spaceflight, increasing the amount of blood pumped from our hearts. But these studies never explained how this happened. 

So Alexa Wnorowski of Stanford University and her colleagues decided to focus on the matter. 

"Our study is novel because it is the first to use human induced pluripotent stem cells to study the effects of spaceflight on human heart function," said senior study author Joseph C. Wu of Stanford University School of Medicine.

"Microgravity is an environment that is not very well understood, in terms of its overall effect on the human body, and studies like this could help shed light on how the cells of the body behave in space, especially as the world embarks on more and longer space missions such as going to the moon and Mars," Wu remarked.

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How did the team discover their findings?

To begin with, the team took blood from three volunteers who had no heart disease history. Some of the blood cells were reprogrammed and were made to form heart muscle cells.

Half of these cells were sent to the International Space Station (ISS), and the other half of the sample was kept on Earth. 

After 4.5 weeks, the ISS cells were brought back down to Earth and were examined for the effects of microgravity.

What did the team discover?

Upon returning to Earth, the team discovered differences in the way 3,000 genes were expressed in these cells. The genes responsible for metabolism and the functioning of mitochondria were the ones that underwent the greatest changes. 

Keeping a close eye on them, it was found that around 1,000 of these genes remained different after ten days back on Earth. The rest, however, did return to normal sooner. 

What the study did not discover, or focus on, was what effects these cell changes may have had on astronauts, or indeed future space travelers. 

So the team is continuing its research and is planning to send 3D tissue structures with a number of different cell types back up to the ISS to observe how they change. 

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