According to researchers at the University of Texas (UT) Southwestern Medical Center, Dallas, and TransMedics, Andover, Massachusetts, there is a small but growing subset of livers that have been transplanted and have a cumulative age of over 100 years old. They studied these livers to identify characteristics to determine why these organs are so resilient, paving the way for examining the potential expanded use of older liver donors. The research team presented their findings at the American College of Surgeons (ACS) Clinical Congress 2022 Scientific Forum.
The researchers used the United Network for Organ Sharing (UNOS) STAR file to identify livers that had a cumulative age (total initial age at transplant plus post-transplant survival) of at least 100 years. Of 253,406 livers transplanted between 1990 and 2022, 25 livers met the criteria of being livers of centurions – those whose cumulative age was over 100 years.
“We looked at pre-transplant survival — basically the age of the donor — as well as how long the liver survived in the recipient,” said study lead author Yash Kadakia, a medical student at the UT Southwestern Medical School. “We stratified these remarkable livers with a survival of over 100 years and identified the donor factors, recipient factors and transplant factors involved in creating this unique combination where the liver was able to live for up to 100 years. »
Centurion livers came from older donors
For these centurion livers, the mean donor age was significantly higher, 84.7 years versus 38.5 years for the non-centurion liver transplants. The researchers noted that for a liver to reach 100 years old, they expected to find a higher average donor age as well as healthier donors. Notably, donors in the centurion group had a lower incidence of diabetes and fewer donor infections.
“We previously tended to avoid using livers from older donors,” said study co-author Christine S. Hwang, MD, FACS, associate professor of surgery, UT Southwestern Medical Center. “If we can sort out what’s special among these donors, we could potentially get more livers available to transplant and have good results.” »
As of September 22, 2022, 11,113 patients were on the waiting list for a liver transplant. As Dr. Hwang noted, more frequent use of older liver donors could potentially expand the pool of liver donors.
More details on the study
Centurion liver donors had lower transaminases, which are enzymes that play a key role in the liver. Elevated transaminases can cause problems during liver transplantation. Additionally, recipients of centurion livers had significantly lower MELD scores (17 for the centurion group, 22 for the non-centurion group). A higher MELD score indicates that a patient has a more urgent need for a transplant.
“Donors have been optimized, recipients have been optimized, and it takes this unique intersection of factors to come up with a really good outcome,” Kadakia said.
The researchers found that no grafts from the centurion group were lost due to primary nonfunction or vascular or biliary complications. In particular, there was no significant difference in rejection rates at 12 months between the centurion and non-centurion groups. Additionally, the results for the centurion group had significantly better allograft and patient survival.
“The existence of allografts over 100 years old is indicative of the liver’s dramatic resilience to senescence events,” the study authors conclude.
“Livers are incredibly resilient organs,” Kadakia said. “We are using older donors, we have better surgical techniques, we have advances in immunosuppression and we have a better match of donor and recipient factors. All of these things allow us to have better results. »