We've all seen it or read about it in sci-fi: a human is induced into hibernation, often in a vat or a pod, to preserve them during deep space travel or keep them in a suspended state to protect them after an injury.
Could this actually be possible in real life? A study published on Thursday builds on a growing field of research that some experts say is "revolutionizing" our understanding of the brain's ability to regulate body heat.
Learning from nature
Hibernation is, of course, observable in the natural world. Mammals hibernate by lowering their body temperature and, in doing so, dramatically slow their metabolisms and conserve energy in winter months when food is scarce.
Though the precise mechanisms are unclear, previous research into the process of hibernation indicates that the central nervous system is involved thermoregulation by increasing temperature in the form of infection-fighting fevers.
A recent study, published in Nature, details how researchers from the University of Tsukuba were able to identify neurons in the brains of rodents — both mice and rats — that can be artificially activated to send the animals into a state that greatly resembles hibernation.
The findings are notable because, much like humans, rats and mice do not hibernate, though mice do often go into a similar short-term state called torpor.
The authors of the study have said that further research could enable a way to induce hibernation in humans, something that “would be beneficial for many medical applications, as well as being of relevance to the possibility of long-distance space exploration in the future,” they told the Japan Times.
Medical applications could include therapeutic hypothermia, which would reduce tissue damage following strokes or heart attacks, as well as organ preservation for transplants, the researchers said.
As part of their laboratory experiments, the researchers genetically modified mice so they could activate a set of neurons, called Q neurons, in the hypothalamus using chemicals or light.
The body temperature of the mice with the activated neurons fell 10 degrees or more to below 30 degrees Celsius, their pulse slowed considerably, their breathing became shallow, and their metabolic rate was reduced.
The mice remained in this state for approximately 48 hours, after which they woke up showing no signs of ill health or physical harm.
The same technique was recreated in rats. This was especially surprising as rats are "a species that neither hibernates nor has daily torpor," first author Tohru Takahashi said in a press release.
Team lead Takeshi Sakurai said that the findings mean that "in the future, we may put humans in a hibernation-like state for missions to Mars and beyond."
Commenting on another recent study into the neurons within the hypothalamus that regulate torpor in mice, Clifford Saper and Natalia Machado of Harvard Medical School said that recent research in the field was “revolutionizing our understanding of the preoptic neurons at the heart of thermoregulation.”
NASA is already banking on further advances in this field and is working on habitats for inducing this hibernation-like torpor to humans in space. The space organization has contracted private organization Spaceworks to help in their mission to create travel deep space travel hibernation habitats.