London, Oct 4 : A "Bank" of donated organs ready for use is on the anvil, for scientists have successfully froze, thawed and transplanted a pig's liver-paving the way for similar transplantation in humans.
It is believed that if human livers, which are about the same size, will be able to survive this process, the new method could actually prove to be a boon to the many people who are in dire need of transplants.
Many of the donated livers, when kept for a longer time, deteriorate rapidly without a blood supply within 12 to 24 hours. Thus it gets difficult to bring them to recipients on time.
According to study leader, Amir Arav, at the Israeli Agricultural Research Organization in Bet-Dagan, the key to limiting cell damage during freezing is to cool the liver very slowly, as this prevents the formation of jagged ice crystals.
In fact, there exist some frog species, which employ a similar technique when they allow parts of their bodies to freeze during hibernation.
"We didn't invent this process, nature did. Some frog species employ a similar technique when they allow parts of their bodies to freeze during hibernation," New scientist quoted Arav, as saying.
For their study, the researchers flushed the blood from the pig's liver, cooled it, and finally encased it in a pair of hollow brass cooling blocks attached to a supply of liquid nitrogen.
Developed by Core Dynamics, a company Arav co-founded in Ness Ziona, Israel, the device cooled the liver at a rate of 0.3 °C per minute bringing it to a temperature of -20 °C in about an hour and a half.
Them the researchers immediately let the liver thaw for 20 minutes before transplanting it into another pig, testing it in as a second liver.
To their surprise, the lover rapidly recovered its red colour, an indication of blood flowing through it, and began producing bile - both signs of health and normal function.
However, the pig was then killed after about 2 hours and the auxiliary liver analysed, which revealed that the cells were alive.
Many liver researchers have said that the study would have been more convincing if Arav's team had left the liver in the pig for longer and disconnected the existing organ, forcing the auxiliary to take over.
But, Arav said that he was not allowed to do more than a temporary piggyback transplant because of restrictions imposed by animal welfare regulators, but he is now expecting that positive results from this limited experiment will allow the restrictions to be eased.
"We hope to repeat it and do those other tests next time," he said.
Now he plans to evaluate how long livers can be stored, as well as the optimal storage temperature.