To infinity and beyond. Maybe all the way to Mars. The attraction for the unknown and the desire to explore the universe – which the character Buzz Lightyear from the animated film ‘Toy Story’ expressed with his famous slogan – is pushing man to delve further and further into deep space . And among the long-term objectives declared by the agencies in the sector, but not set far in time, there is also that of send man to the red planet. But what could be the impact on health? A study just published in ‘Nature Communications’ tries to provide some answers, adding a new page to the new branch of space medicine, warning about the kidney health of astronauts. From stone formation to cosmic radiation-induced kidney failure, there could be various repercussions of a long space journey.
The work, whose first author is Keith Siew, University College London, also involved Viola D’Ambrosio, a PhD student at the Department of Experimental and Translational Medicine at the Università Cattolica del Sacro Cuore, Rome campus, who conducted the study at the London Tubular Centre, Department of Nephrology, University College London. So what happens to astronauts’ kidneys? Since humanity will be embarking on a series of commercial spaceflight trips and deep space exploration in the coming years, with Mars as the first stop, experts are trying to understand whether the body is ready to face these journeys that could last many years.
As for kidney health, the researchers examined data from 5 humans and 11 mice who actually lived in space and, alongside these, they studied the consequences of simulated microgravity in a rat and those of galactic cosmic radiation. simulated on 4 rats. The study has shown that space travel could increase the risk of kidney stone formation (and ‘space’ renal colic would certainly not be a pleasant experience, experts point out), due to an alteration in the functioning of some kidney enzymes and, in part, for the mobilization of calcium from the bones (astronaut osteoporosis) which then, filtered by the kidneys, ends up in the urine. Astronauts, according to the evidence collected, in the first year after a space mission run a risk of developing kidney stones 2-7 times greater than before the flight. And during a prolonged space mission, the risk could be even double that.
In space, the scientists then observe, the renal excretion of oxalates, another common ‘ingredient’ of stones, also increases; and this could be due to the alterations that the intestinal microbiome undergoes in space, such as an increase in Oxalabacter, bacteria responsible for oxalate metabolism, and Bacteroides, increased stone-forming bacteria. To protect astronauts from the danger of the formation of kidney stones – a few years ago we were one step away from interrupting a Soviet space mission due to the renal colic of a poor astronaut who then managed to spontaneously eliminate the stone – it would therefore be appropriate to put preventive measures are in place such as drinking a lot, taking potassium citrate by mouth, administering bisphosphonates to ‘neutralize’ astronauts’ osteoporosis and the mobilization of calcium from the bones, or thiazide diuretics which reduce renal excretion of calcium. And there are also those who think of instructing the crew to deal with the emergency of renal colic, placing a urethral stent or carrying out lithotripsy (an operation to crush stones).
Even the shape of the nephrons, the functional units of the kidney, changes in space since the kidney is a ‘plastic’ organ, capable of remodeling its architecture, in response to variations in blood pressure and potassium content in the diet, already within a few days. And this could have an impact on functionality. The authors of the study also simulated the consequences for the kidneys of exposure to a quantity of cosmic radiation equal to that to which an astronaut would be exposed on a return trip to Mars; these could cause a malfunction, leading to terminal renal failure and astronauts requiring dialysis. In fact, the kidney – experts observe – is a very sensitive organ both to radiation and to the redistribution of blood perfusion (the blood in the space ‘migrates’ to the upper half of the body), which occurs in microgravity conditions. Furthermore, 6 months in space are enough to age the arteries by about 20 years and this also opens the door to kidney failure.
Living for months or many years in weightlessness and bombarded with cosmic radiation it will therefore have consequences for human health and the kidneys are among the various organs in the crosshairs, even if they have been the least studied so far in space. However, a series of consequences affecting the eyes, the cardiovascular, musculoskeletal and nervous system have been known for some time and can occur even during the first weeks of a space mission. “The study published in Nature Communications – concludes Giuseppe Grandaliano, professor of nephrology at the Catholic University of the Sacred Heart and director of the Nephrology Uoc of the Gemelli Irccs Foundation – fills many of the knowledge gaps relating to kidney health, suggesting instructions for use to keep them in good health during a long journey into deep space and marks the birth of a new specialty, space nephrology.”
#mission #Mars #Kidneys #risk #astronauts