Space flight changes human heart cells

Previous studies have found that space flight lowers an astronaut's heart rate and blood pressure and increases the amount of blood pumped out of the heart, but the research is done in animals or entire human tissues or organsTo further clarify the situation, Alexa Vonojousky of Stanford University in California and colleagues conducted experiments using human heart cellsfirst, the team took blood samples from three people with no history of heart disease, then recombined some blood cells into stem cells and induced them to form myocardial cellsHalf of the resulting cardiomyocytes were sent to the International Space Station by a nasax from Space Exploration Technologies, and the other half remained on Earth as a referencefive and a half weeks later, the cells sent to the International Space Station returned to Earth, where the researchers examined the effects of microgravityfound that 3,000 of these cells were expressed differently, most notably genes responsible for metabolism and mitochondria (the cell's energy source) function, and that 10 days after returning to Earth, 1,000 genes were still expressed differently, about 4 to 5 percent of all known human genesBut most genes responsible for changes in cell mitochondria and metabolism are back to normalresearchers say it is unclear what impact the change could have on astronautsPrevious twin studies have also shown that one person has been in space for a year and the other is left on Earth, and that the genes in the body of the person who has been in space have changed in their cells' mitochondria and metabolismVonojowski said new research suggests that space flight may be "equal" to many cells, including the heart and blood cells, but there is not enough data to support this conclusion.