October 17, 2022: If you are undergoing a liver transplant, will you choose a donor younger than you or older? The answer, primarily, is the former.
Researchers from the University of Texas (UT) Southwestern Medical Center, Dallas, and TransMedics, Andover, Massachusetts, think otherwise.
They studied livers to identify characteristics to determine why these organs are so resilient, paving the way for considering the potential use of older liver donors.
And they presented their findings during the Scientific Forum of the American College of Surgeons (ACS) Clinical Congress 2022.
The researchers used the United Network for Organ Sharing (UNOS) STARfile to identify livers with a cumulative age — total initial age at transplant plus post-transplant survival — of at least 100 years.
Of 253,406 livers transplanted from 1990 to 2022, about 25 livers met the criteria of being centurion livers — those with a cumulative age over 100 years.
“We looked at pre-transplant survival—essentially, the donor’s age—as well as how long the liver went on to survive in the recipient,” said lead study author Yash Kadakia, a medical student at UT Southwestern Medical School.
“We stratified out these remarkable livers with over 100-year survival and identified donor, recipient, and transplant factors involved in creating this unique combination where the liver could live to 100 years,” Kadakia said.
New surgical techniques and immunosuppression advances improve outcomes for patients receiving a liver from an older donor
Immunosupression is the partial or complete suppression of an individual’s immune response. It is induced to help the survival of an organ after a transplant operation.
According to the study, optimising donor and recipient factors allows for much greater longevity for certain livers.
For these centurion’s livers, the average donor age was significantly higher, 84.7 years, compared with 38.5 years for non-centurion liver transplants.
The researchers noted that for a liver to reach 100, they expected to find an older average donor age and healthier donors.
Also, the donors from the centurion group had a lower incidence of diabetes and fewer donor infections.
“We previously tended to shy away from using livers from older donors,” said study coauthor Christine S. Hwang, MD, FACS, associate professor of surgery, UT Southwestern Medical Center.
“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.”
Centurion liver donors had lower transaminases, enzymes that play a vital role in the liver.
Elevated transaminases can cause problems in liver transplantation. Additionally, the recipients of centurion’s livers had significantly lower MELD scores (17 for the centurion group, 22 for the non-centurion group).
Elevated transaminases, commonly alanine transaminase (ALT) and aspartate transaminase (AST), may indicate liver dysfunction.
A higher MELD score indicates that a patient is more urgently in need of a transplant. It ranges from six to 40 and takes on several lab tests.
The researchers found that no grafts in the centurion group were lost to primary nonfunction or vascular or biliary complications.
There was no significant difference in rejection rates at 12 months between the centurion group and the non-centurion group.
Outcomes for the centurion group had significantly better allograft and patient survival.
“The existence of allografts over 100 years old is revealing of the dramatic resilience of the liver to senescent events,” the study authors concluded.
“Livers are incredibly resilient organs,” said Kadakia.
“We’re using older donors, and we have better surgical techniques, advances in immunosuppression, and better matching of donor and recipient factors. All these things allow us to have better outcomes.”