Each day in the United States, eighteen people die while waiting for a transplant organ to become available. While a shortage of donors is certainly a factor in that, there is also a tight 12 hour time limit on transplanting the organs to avoid tissue death. A new technique could extend the amount of time to a couple of days by supercooling the organ without freezing it. The research was led by Korkut Uygun, of Massachusetts General Hospital in Boston and the team’s paper was published in Nature Medicine.
The researchers took rat livers and treated them with oxygen and cooled chemicals that act as an anti-freeze, and slowly brought the livers down to 4 °C (39 °F) without completely freezing them. They were then stored at -6 °C (21.2 °F) for three days. The livers were slowly rewarmed and transplanted into recipient rats. The rats that received livers that had been supercooled were all alive three months after the transplant. A control group of rats were given livers that had been stored for three days using conventional methods, though none of those animals lived for three months after the surgery.
Though the technique was done with livers, the researchers believe this could eventually be done using any transplant organ. If this technique eliminates the strict 12 hour available window, there could be up to 5,000 additional organs available for transplant every year. Remember that figure earlier about 18 people dying each day due to a lack of organs? This could save 13 of them. As organs are matched on a variety of factors, including it could even allow for transport to different countries in order to create the best possible match and best chance of survival.
Of course, there are some logistics that need to be worked out first. Human livers are much larger than rats, which affects the rate at which the organ can be cooled down or warmed up. Temperature changes need to be done evenly across the organ, which gets harder when size is increased. Additionally, motion associated with transporting the organ could possibly disturb them enough to cause them to freeze, which would damage the tissue.
Testing is proceeding with larger animals in order to get the timing right with larger organs and will include other organs as well. The researchers hope that clinical testing in humans will be able to begin within the next 2-3 years. Most of the chemicals used in the process are already FDA-approved for use in humans, which will expedite some of the process.
[Hat tip: Sara Reardon, Nature]
Correction 6/3/2014: An earlier version of this article incorrectly stated that the livers were stored at 6 degrees C (39 degrees F). The livers were, in fact, stored at -6 degrees C (21.2 degrees F). Apologies for any confusion this may have caused.