Technological advances offer more hope for liver transplant patients. Photo / File
COMMENT:
Each year in New Zealand around twice as many people are waiting for a liver transplant than there are livers available. With a lack of suitable donors and a storage time of only 12 hours the odds of finding a suitable liver and matching it to a patient and surgeon team who can be ready in time is small.
Now researchers have built a new machine that can keep a human liver alive outside of the body for a whole week and it could revolutionalise the world of transplant medicine.
There are many reasons why people need a new liver - in 2018, however, there were only 49 livers donated in New Zealand for a waitlist of over 70 patients.
One of the unique aspects of liver donation compared to other organs is that a failing liver can sometimes be replaced with part of a healthy liver, Although it is a high-risk operation. This means that a liver donor can choose to donate part of their liver to somebody that they might know personally while they are still alive. In New Zealand around half of the liver transplants carried out in children use a live donor for their replacement organ.
Currently, a donor liver is removed, flushed with a cold solution and stored on ice. This helps to slow down the metabolic activity of the liver enough that it can be stored for up to 12 hours. More advanced techniques using supercooling can store donated livers at -4°C which can extend the time of storage to up to 27 hours. Although more than double, this is still a relatively short time-frame when it comes to the logistics of pulling together everything needed in a liver transplant surgery.
Now, new research published in the journal Nature Biotechnology shows that a new machine can store a liver for up to a week outside the body. Rather than remove and chill the organ, the machine is engineered to keep the liver alive by providing a similar environment to the human body. Through a pump system it is able to pump blood into the organ and remove waste products from the blood while also regulating oxygen levels and blood pressure. To keep the liver healthy and active, the machine introduces nutrients and hormones such as insulin and through an artificial diaphragm physically moves the organ in a rhythmic way to reduce the damage that can be caused by the pressure of lying still.
Initial tests on pigs showed successful transplants for livers that had been stored for a week in the machine with no difference in the function of the tissue of the livers seen when compared to short-time ice stored donated livers.
When it came to testing human livers, rather than use healthy donated livers they used livers which had been deemed to be poor quality. Although they had been turned down for transplantation, after a week in the machine, 6 of the 10 low-quality livers showed so much improvement that they were deemed suitable for transplantation.
This finding of damaged livers being able to repair themselves in a short period of time within the new machine could revolutionise liver donation shortages by boosting the number of livers that could be used for transplant.
While these human livers have yet to be transplanted into a patient, the fact that they can repair themselves and recover to be healthy enough for transplantation is a huge advance in modern medicine. In addition to repairing livers that would otherwise have been discarded, this new machine could enable donated livers to be transported across long distances which will hopefully reduce the number of patients who end up dying while waiting for a liver transplant.