Scientists at Johns Hopkins Medicine, who arranged for 48 samples of bioengineered human heart tissue to spend 30 days on the International Space Station, reported evidence that the low-gravity conditions of space weakened the tissues and disrupted their normal beat rate, compared to samples from the same source on Earth.
The scientists said heart tissue “doesn’t do very well in space,” and over time, tissue aboard the space station beat at half the rate of tissue from the same source preserved on Earth.
The findings, they say, expand scientists’ knowledge of the potential effects of reduced gravity on the survival and health of astronauts during long-duration space missions and may serve as models for studying heart muscle aging and therapy on Earth.
A report on tissue analysis by scientists is published in Proceedings of the National Academy of Sciences.
Previous studies have shown that some astronauts return to Earth from space with aging-related conditions, including reduced heart muscle function and arrhythmias (irregular heartbeats), and that some — but not all — effects dissipate over time after their return.
“Scientists have been looking for ways to study such effects at the cellular and molecular level in an attempt to find ways to keep astronauts safe during long-duration spaceflight,” says Deok-Ho Kim, Ph.D., professor of biomedical engineering and medicine at Johns Hopkins University School of Medicine. Kim led the project to send heart tissue to the space station.
Heart tissue doesn’t do very well in space
To create the useful cardiac load, researcher Jonathan Tsui, Ph.D. persuaded human induced pluripotent stem cells (iPSCs) to transform into heart muscle cells (cardiomyocytes). Tsui, who was a doctoral student in Kim’s lab at the University of Washington, accompanied Kim as a postdoctoral researcher when Kim moved to Johns Hopkins University in 2019. They continued space biology research at Johns Hopkins.
Tsui then placed the tissues into a miniaturized bioengineered tissue chip, which strings the tissues between two posts to collect data on how the tissues contract. The 3D cell casing was designed to mimic the environment of an adult human heart in a chamber half the size of a mobile phone, writes Phys.org.
To get the tissues aboard SpaceX’s CRS-20 mission, which launched in March 2020 to the space station, Tsui says he had to hand-carry the tissue chambers on a plane to Florida and continue tending the tissues during for a month at the Kennedy Space Center. Tsui is now a scientist at Tenaya Therapeutics, a company focused on preventing and treating heart disease.
Once the tissues were on the space station, the scientists received real-time data for 10 seconds every 30 minutes on the strength of the cells’ contraction, known as contractile forces, and on any type of of irregular beats. Astronaut Jessica Meir changed the liquid nutrients surrounding the tissues once a week and preserved the tissues at specific intervals for later gene reading and imaging analysis.
A hallmark of human heart disease
The research team kept a set of heart tissues developed in the same way on Earth, housed in the same type of chamber, for comparison with tissues in space.
When the tissue chambers returned to Earth, Tsui continued to maintain and collect data from the tissues.
In addition to losing strength, the heart muscle tissues in space developed irregular beats (arrhythmias) – disturbances that can cause the human heart to fail. Normally, the time between one beat of heart tissue and the next is about one second. This measure, in tissues aboard the space station, ended up being nearly five times longer than those on Earth, although the time between beats returned to near normal when the tissues returned to Earth.
The scientists also found that in tissues that had been sent into space, sarcomeres—the protein bundles in muscle cells that help them contract—became shorter and more disordered, a hallmark of human heart disease.
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Source: www.descopera.ro
