In microgravity conditions, in this case meaning in space, the human body goes through a lot of changes. One of the major reasons Scott Kelly spent 340 consecutive days in space was to study the long term effects on the human body, especially in comparison to his twin brother and fellow astronaut Mark Kelly. What we know right now is that microgravity definitely has negative impacts on the body, which we’ll get to in a moment. The question after this conclusion is how well can other organic cells thrive in microgravity.
This is where scientists have turned to stem cells. Whether we’re using them to try replenishing the body after being in microgravity or simply looking for a better place to farm them, stem cells have been sent to space to see if they can do better. Actually, stem cells have gone to space several times while astronauts study their effects and uses. For the most part, testing on this subject has grown to encompass more questions with every experiment that finishes.
Before we dive into the studies specifically, we should know what scientists are trying to solve.
Effects on the Human Body in Microgravity
One may think that smaller amounts of gravity weighing down a person would actually be better for our health. In practice, this isn’t the case at all. Microgravity means staying in free fall which means less exercise to keep up bone density and muscle strength. Bone loss and muscle wasting are common problems after spending long amounts of time in space.
Anemia and immune depression are also common problems faced in microgravity. This is caused by blood redistributing due to weightlessness. Since the cardiovascular system is used to pumping blood through our bodies in Earth’s 1g, there are negative effects when we’re suddenly dropped into microgravity. As predicted, this also creates problems with the heart.
Another serious issue are the eyes. Thanks to the muscle wasting problem, the eyeball itself, the muscles connected to the eye, and the retina all face negative effects that could impact sight. What’s more, we haven’t even touched on the radiation risk of being in space. The ion exposure is another reason eyesight could be lost, not to mention act as a huge contributor to the other health risks listed so far.
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With all these bad things mounting up, it may seem crazy that scientists want to try out stem cells in space, too. However, the idea was that microgravity would help growth. The stem cells wouldn’t be limited to growing across a plate but would rather spread in a 3D manner thanks to to the microgravity environment. The logic, at least, held merit.
The Study in Space
These experiments date back to the Space Shuttle program, having been conducted on Space Shuttle Discovery. Dr. Elizabeth Blader along with colleagues from NASA Ames Research Center and University of South Wales originally reported and documented their findings on the effects of microgravity on stem cells.
Fast forward a few years and the International Space Station or ISS have conducted a few experiments of their own in 2010 and 2011. Both experiments were headed by Dr. Eduardo Almeida of NASA Ames Research Center to build on the previous conclusions made aboard the Space Shuttle Discovery. Experiments continue to be on-going thanks to the extensive research already conducted, so we’re not even close to the end of understanding the subject matter. However, we do already have some results to share.
Results of Microgravity and Stem Cells
So there was some good news and bad news to come out of the studies. Unfortunately, not everything turned out to be sunshine and rainbows but that’s okay. There would be no reason to run a test if we always knew the outcome. In this case, even the bad news was extremely valuable.
Failed to Induce Stem Cells in Space
The long and short of it was that stem cells need gravity to grow properly. The results from one of the ISS missions read “many genes required for stem cell self-renewal and immortality were over-expressed in microgravity, suggesting that gravity is required for inducing the transition between stem cell progenitors and differentiated cells involved in tissue regenerative health.” The stem cells actually grew too well and couldn’t make the transition from a stem cell to something we can actually use.
See, stem cells are like cellular building blocks. They have the ability to turn into other cells and replicate from there, which is the transformative aspect that makes stem cells so unique and useful. Without the transformation part, they aren’t useful. All this said, these scientists are very smart and have found some silver lining to this conclusion.
Succeeded to Have Better Results Once Back in Earth’s Gravity
So while the transition didn’t really work while the stem cells replicated in space, it actually worked a lot better once they were back on Earth compared to non-space-faring stem cells. Scientists described them as having more “stemness” as in a greater ability to self-replicate, self-renew, and transition to another type of cell.
The results went on to say that the microgravity preserved the “stemness” of the stem cells while they grew and concluded that the results “possibly provide a cellular mechanistic explanation for decreased tissue regeneration in space and in disuse conditions on Earth.” Their results show that the stem cells still hold the potential for change but only grow. They can’t transform because no stress – ie, gravity – is being exhibited on them. This could link back to why tissues in microgravity break down in the first place, as well as the breaking down of tissues as a result of disuse on Earth.
The Next Step
The testing on stem cells in space doesn’t end here. NASA now wants to figure out exactly why they only grow instead of transform in space and why they transform better once back on Earth. Tests to follow include understanding how the stem cells can detect gravity and if we can simulate that detection. If we can add some stress to the cells while allowing them to grow freely, the transformation process could be kickstarted.
What We Know Now
The positive takeaway from this whole experiment is that stem cells are better cultivated in microgravity environments. Farming stem cells in space and then bringing them back to Earth for use may not sound like an inexpensive option right now but it’s certainly possible. Cutting down on growth time can be a huge step forward for treatments and stem cell research in general.
Plus, these experiments help to understand physiology and space’s effects on the body. With more exploration being talked about every day, space agencies like NASA are eager to learn more about how people can survive in microgravity long-term. So, all-in-all, we have great conditions to learn more about a subject that’s already so wealthy in knowledge and potential. The rest will come in time so long as people stay passionate.
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