Sea leech may hold key to deep-freezing humans alive

Han Solo should be thankful that Jabba the Hutt’s troops didn’t have samples of Ozobranchus jantseanus to study—otherwise, he probably would have spent a long time (in a galaxy far, far away) covered in leeches instead of carbonite.

 

 

A team of scientists from Japan have verified that O. jantseanus, a type of leech that parasitizes sea turtles, is capable of surviving in incredibly cold temperatures, and can even withstand being frozen in liquid nitrogen. Their findings were published on January 22 in the online research journal PLOS ONE.

 

Just chilling under the sea

 

O. jantseanus is known to latch on to sea turtles that stay for up to 11 days in waters as cold as -2 to -4°C. Upon closer examination, the researchers found that this cold-resistant sea leech is capable of surviving long-term storage at temperatures as low as −90°C for up to 2 years and 8 months. Furthermore, the leech also managed to stay alive even after being stored in liquid nitrogen (−196°C) for a full day. The scientists also discovered that the parasite can endure repeated cycles of freezing and thawing, going back and forth between 20°C and −100°C.

 

However, the scientists did not find any traces of trehalose or glycerol – compounds that serve as “cryoprotectants.” According to the researchers, it’s highly probable that the leech’s “cryotolerant ability has arisen in response to some as yet unclarified adaptation,” as the leeches were not allowed to enter a state of super-hydration (a technique usually employed to survive harshly cold temperatures) prior to the experiment.

 

“This finding is particularly interesting because the leach [sic] can survive these temperatures without any acclimation period or pretreatment,” wrote the team, led by Dai Suzuki, in their paper. “The results demonstrated that the novel cryotolerance mechanisms employed by O. jantseanus enable the leech to withstand a wider range of temperatures than those reported previously for cryobiotic organisms.”

 

“We propose that, compared to other cryobiotic organisms, O. jantseanus exhibits the most robust cryotolerance ability reported to date.”

 

A new hope for cryonics?

 

The researchers are optimistic about the implications of their findings on further developments in cryopreservation. “It is hoped that these findings will contribute to the development of new cryopreservation methods that do not require additives, and also to the resuscitation of organisms that have been frozen underground in permafrost areas, on Antarctica, and possibly on other planets,” said the scientists.

 

The idea of preserving humans in low-temperature environments remains a “hot” topic for discussion.  While the concept presents many fascinating possibilities for patients with illnesses that cannot be treated by current medical methods, the world is still unsure as to how it could be turned into a viable option, as cryopreservation is currently not reversible through contemporary means.

 

 

As theoretical physicist Dr Michio Kaku explained, the process is not as simple as it sounds.

 

“First of all, if you suddenly freeze the human body, the problem is that ice crystals begin to form inside the cells,” said Dr Kaku. “As the ice crystals expand, they rupture the cells.  So in other words, freezing the human body seems to work only superficially, but if you look at the human tissue in the microscope, you find massive tearing and disruption of cell walls.”

 

According to Dr Kaku, to effectively translate human cryopreservation into reality, a “natural kind of antifreeze” for the human body has to be developed first, much like how glucose serves the purpose of being an anti-freeze agent in fishes and frogs.

 

“[A]t the present time, the levels of glucose found in frogs and fish that enabled them to undergo suspended animation would kill a human being,” explained Dr Kaku. “So I'm not saying it's impossible, I'm just saying that those organizations that advertise that you can live forever this way may be misleading the public, because when the body is thawed out, what you have is dead tissue.”

 

Still, the limitations of current technology are not enough to discourage scientists from pursuing cryogenics and recognize it as a “legitimate science-based endeavor”, proving that the world’s best minds don’t get cold feet so easily. — TJD, GMA News