Once outside of the body, human organs have a very short shelf life, ranging from roughly five to just over thirty-five hours. Of course, this puts a major dent in the number of organs available for transplant. The development of new technologies might allow doctors to keep organs alive for significantly longer periods of time.
A Multi-Step Solution
One possible answer to this problem comes from researchers at Massachusetts General Hospital (MGH). During a recent study, this group developed a new method for preserving the livers of laboratory rats. Their approach centered around a multi-step process, and involved a special machine designed to prolong the lives of these organs.
The process begins when the donor livers are attached to the device, referred to as a machine perfusion system. In addition to being infused with oxygen, the livers also receive a cocktail of preservatives. Included in this concoction is both a nontoxic sugar compound and polyethylene glycol.
Since the liver cells are unable to dissolve the compound into smaller pieces, this substance instead accumulates within the cells. As a result, the cells acquire an insulation against cold temperatures. The other half of the equation, polyethylene glycol, works to prevent the membranes of the liver cells from freezing.
After the solution has been injected into the liver, the temperature of the organ is then cooled to 21° Fahrenheit (6° Celsius). As intended, the preservative mixture prevented the rat livers from freezing, allowing them to remain in what the MGH team called a “supercooled” state.
A Four Day Window?
Once the organ temperatures had been reduced they were placed in cold storage. Some were kept on ice for 72 hours, while others were stored for a period lasting four full days. The organs were then rewarmed, a task carried out with the same machine used to cool them.
This new preservation technique yielded some impressive results, though a liver’s performance largely hinged on the amount of time it was stored. The livers cooled for three days were transplanted into a dozen rats; after three months, all of these rodents were still alive. In comparison, cooling a liver for an extra day nearly halved the effectiveness of this technique. Only 58 percent of rats given a liver cooled for four days were still living after the same timeframe.
It should be noted that all of the “supercooled” organs outperformed livers stored using traditional methods. During the study’s observation period, 100 percent of rats with conventionally-stored livers died, succumbing to liver failure in under an hour. Based on the study’s findings, the authors believe that their machine can keep rat livers alive for approximately four days. After this point, the organ’s chances for success sharply declines, and the liver quickly becomes unusable.
The Next Step
It is too early to say if this new preservation technique can be applied to human organs, which are much more complex than those found in rodents. Despite this obstacle, the MGH team plans to further test the capabilities of their new device. Their next goal is to replicate to the results of this experiment with both larger animals and different organs.