A recent study led by University College London (UCL) researchers reveals that space flight can significantly impact the structure and function of the kidneys, with galactic radiation causing permanent damage that would jeopardise any mission to Mars.
Published in Nature Communications, this groundbreaking study is the most extensive analysis of kidney health in space flight to date and includes crucial health data for commercial astronauts.
Since the 1970s, researchers have been aware of the negative health effects of space flight. These include bone mass reduction, weakened heart and eyesight, and kidney stone formation. It is believed that these issues are caused by exposure to space radiation, such as solar winds from the Sun and Galactic Cosmic Radiation (GCR) from deep space, from which the Earth’s magnetic field protects us.
Most manned space flights occur in Low Earth orbit (LEO), providing partial protection, while only the 24 individuals who have traveled to the moon have experienced unmitigated Galactic Cosmic Radiation (GCR), albeit for a brief period of time (6-12 days).
The impact of space travel on the human body, particularly on the kidneys and other vital organs, remains largely unexplored. In a groundbreaking study funded by Wellcome, St Peters Trust, and Kidney Research UK (KRUK), a team of researchers from over 40 institutions across five continents, led by UCL, conducted extensive experiments and analyses to examine the effects of space flight on the kidneys.
This comprehensive investigation encompassed biomolecular, physiological, and anatomical assessments using data and samples from 20 study cohorts. The study incorporated samples from more than 40 low Earth orbit space missions involving both humans and mice, with a majority of missions to the International Space Station, as well as 11 space simulations involving mice and rats.
The findings from seven simulations involving mice exposed to simulated galactic cosmic radiation (GCR) doses equivalent to 1.5-year and 2.5-year Mars missions are enlightening. These simulations, mimicking space flight beyond Earth’s magnetic field, revealed that both human and animal kidneys undergo ‘remodeling’ in space.
Specifically, kidney tubules responsible for fine-tuning calcium and salt balance exhibited signs of shrinkage after less than a month in space. Researchers suggest that microgravity, rather than GCR, is likely the cause of these structural changes. However, further research is needed to determine if the combination of microgravity and GCR can accelerate or exacerbate these alterations.
The development of kidney stones during space missions was previously attributed primarily to microgravity-induced bone loss leading to a build-up of calcium in the urine. However, the UCL team’s findings suggested that space flight fundamentally alters the way the kidneys process salts, likely constituting a primary factor in kidney stone formation.
One of the most concerning discoveries is that mice exposed to radiation simulating galactic cosmic rays for 2.5 years experienced permanent kidney damage and loss of function, raising serious concerns for astronauts embarking on extended missions, such as a three-year round trip to Mars.
“We know what has happened to astronauts on the relatively short space missions conducted so far, in terms of an increase in health issues such as kidney stones. What we don’t know is why these issues occur, nor what is going to happen to astronauts on longer flights such as the proposed mission to Mars,” said Dr. Keith Siew, first author of the study from the London Tubular Centre, based at the UCL Department of Renal Medicine.
“If we don’t develop new ways to protect the kidneys, I’d say that while an astronaut could make it to Mars, they might need dialysis on the way back. We know that the kidneys are late to show signs of radiation damage; by the time this becomes apparent, it’s probably too late to prevent failure, which would be catastrophic for the mission’s chances of success.”
The authors note that while the findings reveal significant challenges for a potential Mars mission, it is crucial to first identify these obstacles in order to develop appropriate solutions.
“Our study highlights the fact that if you’re planning a space mission, kidneys really matter. You can’t protect them from galactic radiation using shielding, but as we learn more about renal biology, it may be possible to develop technological or pharmaceutical measures to facilitate extended space travel,” said Professor Stephen B. Walsh, senior author of the study from the London Tubular Centre, UCL Department of Renal Medicine. “Any drugs developed for astronauts may also be beneficial here on Earth, for example, by enabling cancer patients’ kidneys to tolerate higher doses of radiotherapy, the kidneys being one of the limiting factors in this regard.”
Additionally, the study provides the most comprehensive data available on the effects on the kidneys for a period of up to two and a half years.
Journal reference:
- Keith Siew, Kevin A. Nestler, Charlotte Nelson, Viola D’Ambrosio, Chutong Zhong, Zhongwang Li, Alessandra Grillo, Elizabeth R. Wan, Vaksha Patel, Eliah Overbey, JangKeun Kim, Sanghee Yun, Michael B. Vaughan, Chris Cheshire, Laura Cubitt, Jessica Broni-Tabi, Maneera Yousef Al-Jaber, Valery Boyko, Cem Meydan, Peter Barker, Shehbeel Arif, Fatemeh Afsari, Noah Allen, Mohammed Al-Maadheed, …Stephen B. Walsh. Cosmic kidney disease: an integrated pan-omic, physiological and morphological study into spaceflight-induced renal dysfunction. Nature Communications, 2024; DOI: 10.1038/s41467-024-49212-1