The human heart suffers age-related damage by going into space, scientists have shown in tests that saw heart tissue sent into space for study.
Bioengineered heart chambers
It is already known that astronauts returning from space display age-related heart conditions, such as weakened muscle function and irregular heartbeats. But to examine the effects of space on the heart at a cellular and molecular level, a team from Johns Hopkins Medicine created a batch of bioengineered heart tissue samples using stem cells and put them on the International Space Station (ISS) for 30 days.
The tissues were contained in small, bioengineered chips made to resemble an adult human heart chamber, that can gather data about how the tissues beat or the “twitch forces”. The delicate payload had to be hand carried on an aircraft to Florida’s Kennedy Space Center where they were nurtured for a month by team member Jonathan Tsui.
“An incredible amount of cutting-edge technology in the areas of stem cell and tissue engineering, biosensors and bioelectronics, and microfabrication went into ensuring the viability of these tissues in space,” says Deok-Ho Kim, team head.
Carried aboard SpaceX’s March 2020 CRS-20 mission, the samples then spent a month on the ISS where they were kept in liquid nutrients and readings were taken 10 seconds in every 30 minutes. The findings were compared to a batch of heart tissues kept in the same conditions but back on Earth.
Five seconds between heart beats
The tests showed that heart tissues in space develop several problems that are usually associated with age. The protein bundles or sarcomeres in their muscle cells lose length and order, mitochondria become enlarged and less energy efficient, and the tissues also showed signs of inflammation and oxidative damage.
These symptoms were typical for astronauts returning to Earth, astronaut Jessica Meir said, who went as far as saying they “are consistently demonstrated in post flight checks of astronauts.”
While the researchers used euphemistic language, saying heart tissues “really don’t fare well in space,” in raw terms this means that the time between heart beats can be as long as five seconds, five times as long as on Earth, and that over time, the Space Station tissues beat about half as strongly as their Earthbound counterparts.
The findings, published in the Proceedings of the National Academy of Sciences will contribute to the scientific community’s understanding of the effect of low gravity on astronauts’ health and survival during long space missions, as well as how human heart health and age-related conditions can be treated and prevented.
