Livers from old-age donors can function for more than 100 years

A team of researchers examined livers that were transplanted between 1990 and 2022 and identified 25 extraordinary livers that have the potential to stay functional for over 100 years. The study also reveals that livers transplanted from old-age individuals are likely to last longer than those that come from young-age donors, New Scientist reported.

The researchers studied about 253,406 transplanted livers and noticed a special group comprised of livers that had lived for more than 100 years in total (age before transplantation + age after transplantation). Some of the livers in the group even managed to survive for 108 years, which means that the livers could be transplanted to another human being after the death of the first recipient.

What's more surprising is that the identified centurion (age equal to more than 100 years) livers were transplanted from donors with an average age of 84.7 years. Generally, it is believed that organs from young donors are likely to last longer, but the findings from the current study represent a totally different picture, especially in the case of liver transplants.

What makes old livers so special?

When a person's liver stops functioning due to an injury or a liver disease, doctors replace the organ with a healthy liver from another person. The liver donor could be either a dead or a living person. In the latter case, generally, a part of the donor's liver is taken away and placed inside the recipient's body.

Since the liver is a regenerative organ having the power to regrow itself, the small and remaining portions of the liver inside the donor and recipient's bodies grow into fully-functional healthy livers. However, not every liver transplant operation is successful because a recipient's body could reject the graft due to various factors. For instance, sometimes the genetic makeup of a donated liver is very different from the liver that is replaced, and this makes the immune system of the recipient's body attack and rejects the transplanted organ.

Another factor that leads to liver transplant failure or restricts the age of a transplanted liver is related to high levels of an enzyme called transaminases. This enzyme is important for normal liver functioning and for removing toxins from the human body. During their study, the researchers found that livers from old age donors have low levels of transaminases, making them more compatible and long-lasting as compared to the grafts from young age donors.

This could be the reason why the donors of the centurion were mostly individuals aged over 80 years. The researchers also reveal that the MELD (Model for End-Stage Liver Disease) score, which is used to determine the possibility of chronic liver disease, is also low for old livers. It was 17 in the case of centurion livers and 22 for livers that were donated by people with an average age of around 38 years.

Christine Hwang, one of the authors and associate professor at the University of Texas, told ANI, "We previously tended to shy away from using livers from older donors. If we can sort out what is special amongst these donors, we could potentially get more available livers to be transplanted and have good outcomes."

The future of liver transplantation seems bright

Liver diseases are responsible for over two million deaths occurring globally every year. What makes the situation worse is that the waiting period for patients seeking liver transplants sometimes could range from months to years in even developed countries like the US. Dr. Hwang and her team highlight that currently, there are 11,113 patients waiting for a liver transplant, but their research show a way to mitigate this supply and demand crisis.

The study hints that old age livers are more likely to last longer and less likely to get rejected. Therefore, liver grafts obtained from elderly individuals can improve the number of transplantable livers available to doctors.

The study is proposed by researchers at the University of Texas Southwestern Medical Center in Dallas and TransMedics in Andover, Massachusetts. Recently, the authors presented their findings at the American College of Surgeons (ACS) Clinical Congress 2022.