Chemotherapy and radiation therapy—treatment methods used to target and destroy cancer cells—often have severe side effects that impact healthy cells in the body, leading to hair loss, a weakened immune system, bladder and kidney problems, and a myriad of other side effects.¹ In an effort to combat these harmful repercussions, scientists have discovered the potential of a creature of microscopic origin with macroscopic capabilities: the tardigrade. These creatures can withstand radiation, survive freezing conditions, and even endure outer space! Tardigrades can transform the field of oncology and other medical treatments, and scientists have been exploring these creatures’ unique abilities. To ascertain their properties and utility in radiation-based treatments, scientists have investigated the biological mechanisms by which these creatures protect themselves against harsh conditions. 

Tardigrades, also known as water bears or moss piglets, are a part of the phylum Tardigrada, which is split into two classes: Eutardigrada and Heterotardigrada. These creatures have eight legs and four to eight claws, and are less than a millimeter in length. They are mostly found in fresh and saltwater systems, and the tardigrades’ lifespans range from three months to two and a half years. They have needle-like structures in their mouths that allow them to intake fluids from plants, algae, and fungi. These special creatures were first discovered in 1773 by German zoologist Johann August Ephraim Goeze, and over 1,300 species of this phylum have since been uncovered.²

The species’ special characteristics to survive extreme conditions come from the tardigrade’s biological processes. When faced with harsh, life-threatening circumstances, their bodies undergo cryptobiosis, a mechanism in which the tardigrades may stop their metabolism by releasing a set of unique proteins. These proteins—Dsup, CAHS, SAHS, MAHS, and late embryogenesis-abundant proteins—form a tough cocoon around each cell, protecting it from damage.³ Tardigrades squeeze out more than 95% of the water from their body to achieve the ametabolic state.⁴ In this death-like state, the body of the tardigrades turns into a dried-out little ball, called a tun, by fully retracting their head and legs.⁵

Many tardigrade experiments have been conducted to test the extent of the unparalleled properties of these creatures.⁶ In 2007, a European team of researchers sent 3,000 tardigrades to orbit the Earth on the outside of a spacecraft for 12 days. By the end of this experiment, 68% of the creatures survived, proving that a majority of the tardigrades were capable of withstanding extreme dehydration and cosmic radiation. In 2016, Japan’s National Institute of Polar Research examined tardigrades from a frozen moss sample collected in Antarctica, which was frozen for more than 30 years. After thawing, the researchers determined that the water bears successfully resume normal biological functions, such as reproduction, after decades in frigid conditions. Another experiment scientists conducted was to test if these creatures could survive the cosmic impact of space. In a 2021 study, researchers launched tardigrades in hibernation at a sand target. The animals were able to survive at speeds up to 2000 mph. A fascinating discovery in 2020 ascertained that long-term exposure to high temperatures can kill tardigrades, even though these creatures are found in scorching environments like hot springs and mud volcanoes. Tardigrades were put in boiling water, where half of them died, leading researchers to believe they found the creature’s “Achilles Heel”.

Even though tardigrades have not yet been used in medical treatments, they have shown capabilities in alleviating oxidative stress, reducing DNA damage, and increasing radio tolerance in transfected human cells. For instance, a recent study in 2023 led by Senior Research Scientist Silvia Sanchez-Martinez of the University of Wyoming Department of Molecular Biology explored the benefits of tardigrade proteins in cell-based therapies. “Amazingly, when we introduce these proteins into human cells, they gel and slow down metabolism, just like in tardigrades,” Sanchez-Martinez says. “Furthermore, just like tardigrades, when you put human cells that have these proteins into biostasis, they become more resistant to stresses, conferring some of the tardigrades’ abilities to the human cells.”⁷ Tardigrades show extreme promise in the medical field, as their proteins could help diminish cytotoxic injuries resulting from chemotherapy and other radiation therapy. These remarkable abilities demonstrate the potential of these powerful creatures, as they hold the key to groundbreaking advancements that can revolutionize the future of medicine!

References

1. Cleveland Clinic. (2022, November 3). Chemotherapy and Radiation Side Effects. Cleveland Clinic. https://my.clevelandclinic.org/health/articles/10257-chemotherapy-side-effects
2. Bradford, A. (2017, July 14). Facts About Tardigrades. Live Science. https://www.livescience.com/57985-tardigrade-facts.html
3. Smythers, A. L., Joseph, K. M., O’Dell, H. M., Clark, T. A., Crislip, J. R., Flinn, B., Daughtridge, M. H., Stair, E. R., Mubarek, S. N., Lewis, H. C., Salas, A., Hnilica, M. E., Derrick R.J. Kolling, & Hicks, L. M. (2024). Chemobiosis reveals tardigrade tun formation is dependent on reversible cysteine oxidation. PLOS ONE, 19(1), e0295062–e0295062. https://doi.org/10.1371/journal.pone.0295062
4. Kasianchuk, N., Rzymski, P., & Kaczmarek, Ł. (2023). The biomedical potential of tardigrade proteins: A review. Biomedicine & Pharmacotherapy, 158, 114063. https://www.sciencedirect.com/science/article/pii/S0753332222014524#:~:text=Their%20general%20characteristics%20and%20properties,apoptotic%20and%20anti%2Dosmotic%20agents.
5. Schnuer, J. (2024, February 5). Scientists now think they know why tardigrades are so indestructible. CNN. https://www.cnn.com/2024/02/05/world/tardigrade-water-bear-survival-mechanism-scn/index.html
6. Rosa-Aquino, P. (2022, December). 5 of the wildest experiments tardigrades have survived in the name of science. Business Insider. https://www.businessinsider.com/tardigrade-water-bears-wildest-experiments-survived-2022-12
7. University of Wyoming. (2024, March 26). Researchers show that introduced tardigrade proteins can slow metabolism in human cells. ScienceDaily. Retrieved October 22, 2024 from www.sciencedaily.com/releases/2024/03/240326170055.htm

Image reference

Eye of Science/Source of Science. (n.d.). Color-enhanced scanning electron micrograph (SEM) of a water bear (Paramacrobiotus craterlaki) in moss [Image]. Science Source. https://www.sciencesource.com/1486761-water-bear-or-tardigrade-stock-image-rights-managed.html