Researchers have discovered that space travel can suppress the genes responsible for hair growth in astronauts, which raises further questions about possible health effects of future space exploration.
A team of Japanese scientists used hair follicle samples from astronauts who had spent six months at the International Space Station.
“We detected a change in gene expression in hair follicles during spaceflight,” lead author Masahiro Terada, from the Jikei University School of Medicine in Tokyo, Japan, told SBS Science. The study has been published in the open-access journal PLOS One.
Space travel ain’t easy
The effects of space travel are increasingly well documented and include a loss of bone density, reduced muscle mass in legs, and changes to the heart muscle – it becomes rounder and weaker. All of these changes are attributed to the body not working as hard as it would on Earth.
Terada says that both space radiation and entry into microgravity, which causes a shift of body fluids toward the upper half of the body in the early ‘days’ of spaceflight, could have an impact on the body at a cellular and molecular level.
“I think the sense of balance is diminished in microgravity and changes in the cell cycle occur,” he says.
However, Terada acknowledges several limitations of the study that make it hard to draw a definitive link between space travel and hair growth (or lack thereof).
“We analysed only [the] gene expression level and we did not measure the length of growing hair shaft,” says Terada. “Therefore, we don’t know whether these detected changes of gene prevent the actual hair growth or not.”
A hairy problem
Associate Professor Catherine Suter, an epigenetics expert from the University of New South Wales, does not think they will be due to the changes only being observed in the hair follicles.
“What you observe in the hair follicles is obviously not going to necessarily be transmitted to the germ cells of that individual,” Suter told SBS Science.
“Hair is constantly growing, so the cells are constantly dividing and new hair is constantly being produced,” she said. “You’re most likely to observe [gene expression changes] in something that’s rapidly dividing during the exposure.”
Suter was sceptical of the findings due to the low sample size - only 10 astronauts were part of the study – as well as a lack of metabolic data.
“I don’t think it’s telling us anything that we didn’t already know. I’m not surprised that this is in PLOS One, it’s really not showing anything novel.”
Still, Terada is hopeful that future experiments will provide a greater understanding of the gene activity changes occurred. He also believes that the hair follicle analysis technique can be further developed as a diagnostic tool.
“Our final purpose is to establish diagnostic methods to evaluate astronauts’ health conditions by analysing the samples that we can easily get during spaceflight, such as hair follicles or shafts,” he said.