Feeling a bit nippy? For now you'll have to stick to your hat and scarf to warm up, but one day some antifreeze proteins from a fish or a tick might do the trick.
In a preliminary study published Wednesday in PLOS ONE, researchers report using specially bred mice -- ones spliced with the genes that give ticks antifreeze cells -- to show that mammals can benefit from the proteins that other species use to keep from icing over.
Ticks aren't the only species with so-called antifreeze proteins, which help keep creatures that don't moderate their own body temperatures from ending up with frozen cells (or, in some cases, just keep that freezing from having harmful effects) by preventing the formation of ice crystals inside tissue. But lead study author Erol Fikrig, a professor of medicine at Yale and an investigator for the Howard Hughes Medical Institute, focuses on the ticks and their antifreeze properties in particular in his lab.
Ticks have a protein called IAFGP that kicks in during winter. Fikrig and his colleagues wondered if it could be harnessed by mammals.
"The most typical thing that happens to us in the cold is frostbite," he said. So after breeding genetically modified mice to produce IAFGP, the lab tested their tolerance to cold.
In both skin sample tests (where they stored skin cell samples in just above freezing temperatures for several days) and tests on living mice (where tails were placed in a cooling solution for seven days), the mice that produced IAFGP showed less frostbite. Sixty percent of the treated mice had no frostbite at all on their tails at the end of the trial, as compared to 11 percent of the normal mice.
Of course, the potential human applications are a long way off.
"Our study doesn't address the question of how we'd deliver the protein," Fikrig explained. "We're using transgenic mice, and we're obviously not going to put this gene into people."
In future experiments, he said, they'll see if injecting the purified protein itself has any effect. If it does, the IAFGP therapy could have applications in treating human illnesses that cause cold sensitivity -- but it would be even more immediately helpful when it came to organ donation and transplants.
Once a donor organ is removed, transplant teams only have about 24 hours to put it into a recipient before the tissues are too damaged by the cold being used to preserve them.
"If there was a way to enhance organ transplantation storage with this," Fekrig said, "That would undoubtedly be a great thing."