Working toward human hibernation during long-term spaceflight

Editor’s note: As we begin to leave the planet on longer space missions, the issue of crew health, nutrition, life support and general safety will become a pressing issue. If you can do what sci-fi films often do and put the crew into some sort of hibernation or “suspended animation” you could potentially address these issues. They could also use this option to deal with serious injuries or illnesses during the mission that the crew is unable to handle. The idea of ​​sending humans to distant worlds is quickly becoming constrained by the reality of human lifespan and life support needs. Anything that serves to reduce life support needs and/or extend a human’s lifespan will serve to enable human exploration missions further afield than would otherwise be the case.

Hibernation is a widespread and highly efficient energy conservation mechanism in mammals. However, a major challenge during hibernation is maintaining blood circulation at low body temperatures, which depends heavily on the viscoelastic properties of red blood cells (RBCs).

Here we examined the thermomechanical properties of hundreds of thousands of individual erythrocytes from the hibernating noctule (Nyctalus noctula), the non-hibernating Egyptian flying fox (Rousettus aegyptiacus) and humans (Homo sapiens) over physiologically relevant time periods. We exposed erythrocytes to the temperatures encountered during normothermia and hibernation and found a significant increase in elasticity and viscosity as temperatures decreased.

Our data show that erythrocyte temperature adaptation depends mainly on membrane properties rather than the cytosol, while viscous dissipation in the membrane of both bat species exceeds that of humans by a factor of 15. Finally, our results show that erythrocytes from both bat species show a transition to a more viscous state as the temperature decreases.

This process on a tiny time scale has an effect size comparable to fluctuations in erythrocyte viscoelasticity throughout the year, meaning that environmental factors such as diet have less influence on the ability of erythrocytes to respond to different temperatures than generally physical ones Properties of the cell membrane.

In summary, our results suggest that membrane viscoelasticity is a promising target for identifying mechanisms that could be manipulated to ensure blood circulation at low body temperatures in humans, which could be a first step toward safe synthetic solidification in medicine and space travel could.

astrobiology, space medicine,