"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", Joseph C. Wu, senior study author from Stanford University School of Medicine, said in the statement.
"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 explained. But to date, most cardiovascular microgravity physiology studies have been conducted either in non-human models or at tissue, organ, or systemic levels. Wu's team included NASA astronaut Kate Rubins, who did graduate work at Stanford before tending to the cells in orbit. They generated hiPSC lines from three individuals by reprogramming blood cells, and then differentiated them into hiPSC-CMs.
"Working with the cells that launched to and returned from the International Space Station was an incredible opportunity", Wnorowski said. However, they did adapt by modifying their beating pattern and calcium recycling patterns. The cells spent 5.5 weeks on the space station, while a control group of cells were studied simultaneously on Earth. A comparison of the samples revealed that hiPSC-CMs adopt a unique gene expression pattern during spaceflight, which reverts to one that is similar to groundside controls upon return to normal gravity.
"We were surprised by how quickly human heart cells adapted to microgravity", Sharma said.
According to Wu, limitations of the study include its short duration and the use of 2D cell culture. The cells' ability to become almost any tissue in the body makes them an invaluable resource for physicians wishing to study the effect of drugs on specific, hard-to-obtain tissues or for researchers wanting to delve into the molecular missteps that lead to all manner of diseases. "We also plan to test different treatments on the human heart cells to determine if we can prevent some of the changes the heart cells undergo during spaceflight", Wu says.
Once stem cells grew into heart cells aboard the International Space Station, their exposure to microgravity changed the expression of thousands of genes.
During an interview hosted by Spaceflight Now on the grounds of the Washington DC's International Astronautical Congress Bridenstine stated that maintaining United States access to the space station is of utmost importance, as NASA is set to move from its reliance on Russian Soyuz spacecraft in the near future to using a balanced squadron of three human-rated vehicles, being the Russian Soyuz, Boeing Starliner, and the SpaceX Crew Dragon.