Scientists have discovered that the gray mouse lemur has the ability to hibernate.
Hanane Hadj-Moussa, Carleton University; Aline Ingelson-Filpula, Carleton University, and Kenneth B. Storey, Carleton University
Science fiction becomes reality. With humanity’s plans to return to the Moon this decade and further ambitions to travel to Mars in the next decade, we need to figure out how to keep astronauts healthy for these year-long missions. One solution that science fiction has long advocated is to pause animation or put people in hibernation for the duration of the travel time.
We can turn to nature for guidance and a possible solution to this challenge.
Primates have been used in space exploration for decades. Space pioneer Miss Baker, a squirrel monkey, rode a Jupiter IRBM into space in 1959 and returned safely. (NASA / Marshall Space Flight Center)
It’s cold and dark out there
Space is unforgiving. In this freezing void of darkness there is no oxygen, no gravity and no protection against the constant shower of cosmic rays. Man has evolved under constant attraction. So when you take people into space, strange and dangerous things happen to their bodies.
However, scientists and engineers working with astronauts on the International Space Station have innovated and continue to grapple with these issues. For example, we know that space travel results in a loss of muscle and bone density because our bones and muscles don’t have to work against gravity to move us.
However, we still don’t know how to address other space-related medical problems, including changes in the immune system, impaired vision, and exposure to dangerous cosmic rays.
These physiological challenges go hand in hand with the technological difficulties of sending multiple people on those long missions where they face logistical complications in packing and allocating adequate supplies and supplies, as well as social issues in dealing with extreme isolation in space.
Let the body pause
Paused animation and biostasis can evoke science fiction images of people in cryosleeping pods. If we could put humans in a state of suspended animation by greatly slowing down or even completely stopping metabolic activity, we could alleviate problems related to space travel: time, health concerns, size of the spacecraft, and the allocation of supply.
WIRED takes a look at the science behind suspended animation.
But how can we safely hibernate people and then bring them back at the right time without risking muscle and bone loss, to name a few challenges? These are questions that the US Department of Defense and other space agencies are actively investigating.
Animals that spend the winter in a state of suspended animation – hibernation – do not experience significant muscle and bone loss. Their existence, and their ability to reversibly shut down biological processes that appear to be necessary for life, could be key to creating the conditions for human hibernation strategy that could pave our way to surviving long interstellar journeys to distant stars.
In fact, the use of biostasis has already been proposed to transport large numbers of travelers to Mars, where crew members are provided with specially formulated total nutritional fluids while they are “sleeping”.
How do we translate hibernation in animals into hibernation in humans? Recent work has discovered such a capability in animals that are evolutionarily similar to humans: primates in hibernation. What is special about these primates is that they can go into hibernation when resources are scarce and temperatures get cold without their body temperature dropping seriously.
One of the driving forces behind this extreme ability are microRNAs – short pieces of RNA that act as molecular gene silencers. MicroRNAs can regulate gene expression without changing the genetic code itself. By studying the microRNA strategy of these animals, we can use this genetic on / off switch to make rapid, reversible changes that could aid hibernation in humans.
Our work on gray mouse lemurs (Microcebus murinus) shows how microRNAs control which biological processes remain switched on to protect the animal and which are switched off to save energy. Some of these microRNAs have been found to combat muscle wasting during hibernation. Other tasks seem to be preventing cell death, slowing down or stopping unnecessary cell growth, and switching fuel stores from quickly depleted sugar to more slowly burned fats.
While microRNAs are a promising avenue of research, they are only part of the puzzle. Our laboratory also studies other aspects of primate hibernation, such as: For example, how these lemurs protect their cells from stress, control global gene values and how they store enough energy to survive hibernation.
Mouse lemurs are more closely related to humans than mice, which are typically used for research purposes.
Our lab also studies how microRNAs help animals survive other extreme environmental stresses such as freezing, lack of oxygen, and hot, dry climates. There is no more extreme stress than the vacuum of space, and we hope that our research will contribute to the new RNA-based interventions that will grab attention and emerge as viable human therapeutics.
Space is within our reach, and if we examine what is already on Earth, we can get there.
Hanane Hadj-Moussa, PhD student in molecular biology, Carleton University; Aline Ingelson-Filpula, M.Sc. Candidate in Biochemistry and Molecular Biology at Carleton University and Kenneth B. Storey, Professor of Biochemistry at Carleton University
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