Modifying humans for deep space journeys

This would allow for hibernation in humans in space flights, writes Joe Pinkstone

Hibernating rodents evolved cold-sensing neurons with diminished ability to detect temperatures below 20 °C. Experts found the key to resisting the cold is hidden in the brains of all mammals and they believe it could be activated in human cells. tolerance to human cells, with potential implications for medicine. Understanding the hibernation phenomenon in general will pave the way to inducing hibernation in humans, which seems necessary for long-term space flight.”

While humans and space flight is the long-term goal, the next step involves genetically altering rodents.

The authors continued: “At this moment we are working on generating a ‘squirrelised’ mouse. We are trying to make a non-hibernating species of mouse cold tolerant by substituting the mouse TRMP8 gene with the squirrel gene. We expect that such genetically modified mouse will develop tolerance to cold.”

The temperature at which TRMP8 gets triggered varies massively from species to species, the study found. All rodents have receptors on brain cells known as somatosensory neurons that sense cold.

But the chemicals in ground squirrels and Syrian hamster take a lot more to be activated compared to those in animals that do not hibernate. To compare the biology of the different types of rodents, the researchers performed tests on ground squirrels, hamsters and mice.

Scientists put the rodents on two temperature controlled plates, one warm at 30°C and another cooler one which they varied from 20°C down to 0°C. The animals had the choice to move between the two plates and the mice strongly preferred the warmer plate.

Mice always strongly preferred the warm plate. But the temperature change made no difference to the ground squirrels and hamsters until it reached a cool 5°C. Surprise! When the card is received, inside it includes a printed code, which plays the video on the screen of the receiver’s device when scanned with a smartphone or tablet.

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Dr Gracheva’s team connected this behaviour to a chemical pathway in neurons called TRPM8 which, when triggered, leads to the sensation of feeling cold. TRPM8 is a protein on the outside of specialist sensory cells in the brain which control the flow of charged sodium and calcium ions in and out.

This flow causes a charge to build up which then fires off an electrical impulse, continuing the signal. In ground squirrels and hamsters, TRPM8 is less sensitive to cold than the same chemical, or ion channel, in mice.

Dr Gracheva added: “This process is very complex, and TRPM8 is just one part of the mechanism.”

The full findings of the study were published in the journal

he says.

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