Recently, scientists have come to the conclusion that the main obstacle to long-term space travel may not be the lack of necessary technologies, but the human body, which is not adapted to long-term stays in space. Scientists have discovered that in zero gravity, DNA mutates, blood is destroyed, bone mass decreases, kidney failure develops, etc. It would take a long time to list all the negative changes that occur in the body in microgravity conditions. In a recent study, scientists discovered that people will also have heart problems in space.
Cosmonauts in zero gravity quickly develop heart problems. Photo source: fonstola.ru
What happens to the heart in space
It has long been known that prolonged exposure to zero gravity leads to muscle atrophy. Even physical exercise is not fully able to counteract this process. With this in mind, in a recent study, Johns Hopkins University researchers with the support of NASA's Johnson Space Center decided to find out how the heart muscle reacts to microgravity. For the experiment, they sent 48 samples of bioengineered human heart tissue to the ISS.
As a result, the study showed that being in space for 30 days weakened the heart tissue and its ability to maintain rhythmic beats. In addition, age-related heart disease developed in the muscle tissue and the time between heartbeats increased. However, after returning to Earth, almost all indicators returned to normal.
Arrhythmia and other heart problems develop in space. Photo source: labquest.ru
It must be said that these results did not come as a surprise to scientists. As is known, astronauts sometimes have to stay on the ISS for much longer than 30 days. Upon returning to Earth, they often suffer from various health problems. Including a decrease in the function of the heart muscle and heart rhythm disturbances. However, over time, most of these symptoms disappear.
Why space has a negative effect on the heart
Although the negative impact of space on the heart has long been known, until recently scientists did not know what was happening to the tissues at the cellular and molecular level. To find out, the researchers used a “heart on a chip,” that is, artificial heart tissues obtained from stem cells. Previously, we talked in detail about what “tissue on a chip” technology is.
The chips in which the heart tissues were placed collected data on how rhythmically the contractions occurred. One such set of chips was sent to the ISS, and the second remained on Earth as a control group. Data on the tissues in space was sent to Earth in real time, which made it possible to track the changes that were occurring in them.
Capsule with cardiac tissue. Photo source: sciencealert.com
The observation showed that the protein bundles in the tissue cells that help them contract (sarcomeres) became shorter and more disordered than in the control group. This is another symptom of heart disease. The study at the cellular level also showed that the mitochondria in the tissue cells became larger and rounder. Due to the loss of folds, they produced and used energy worse.
Reading the genetic data showed increased production of genes in the tissues associated with inflammation and an imbalance of free radicals and antioxidants, which leads to oxidative stress. These changes are characteristic of age-related heart disease. That is, in microgravity conditions, the human heart ages quickly. The authors of the study report this in the publication PNAS.
According to the researchers, the information obtained expands the scientific knowledge of scientists about the potential impact of microgravity on health. Perhaps in the future it will be possible to create drugs that will help protect the heart in space. Moreover, such drugs are currently being tested on the ISS. For this, the same “heart on a chip” is used. In addition, the results of the study may help improve the effectiveness of therapy for age-related heart disease on Earth.
New research may help treat age-related heart disease. Photo source: altailife.ru
But perhaps the changes that scientists have discovered are not only related to microgravity. It is worth remembering that tissues in space are exposed to cosmic radiation. Therefore, researchers are currently improving the “tissue-on-a-chip” system and studying the effects of cosmic radiation on heart muscles.
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These tests will assess the threat that solar and cosmic rays pose to the health of the cardiovascular system beyond low Earth orbit. After all, if astronauts fly to Mars or even the Moon, they will remain for a long time without the protection of the Earth's magnetic field.