Khaberni - Researchers have succeeded in discontinuing immunosuppressive drugs in several patients who have undergone liver transplantation, for more than three years, through a unique clinical trial that is the first of its kind to depend on "immunological priming".
The recent study, whose results were published in the journal Nature Communications, was conducted by the UPMC Medical Center and the University of Pittsburgh.
Researchers confirmed that it is possible and safe to administer injections of immune cells derived from the donor to liver transplant recipients one week before transplantation, and then, after a year, to start withdrawing the immunosuppressive drugs.
Despite their necessity to prevent the rejection of the new organ, the long-term use of immunosuppressive drugs causes serious side effects, including kidney damage, metabolic complications, making patients more prone to infections and some types of cancer, along with diabetes.
Principal author Angus Thomson, Professor of Surgery and Immunology at the University of Pittsburgh, states that relieving patients from these effects was a goal that researchers in Pittsburgh, under the supervision of the late Thomas Starzl, began pursuing three decades ago.
The liver has a unique ability to regenerate, allowing a healthy person to donate a part of their liver to someone with liver failure, after which both parts grow into full livers.
UPMC is a leader in this type of transplantation in America, having performed 89 operations in the year 2025. However, even with this excellence, transplant recipients needed lifelong immunosuppressive medications, because the immune system attacks the new organ as an intruder.
In 2017, researchers launched their trial on 13 patients. Weeks before the transplant, the team filtered white blood cells called "monocytes" from the donor's blood, then transformed them into "regulatory dendritic cells".
The function of these cells is to teach the recipient's immune system how to differentiate between harmful and friendly cells. These cells were then given to the recipient one week before surgery, to teach their immune system that the donor's liver is a friend and doesn't need to be attacked.
One year after the transplant, the participants underwent tests to determine if their immune systems were ready to stop taking the immunosuppressive drugs. It turned out that 8 out of 13 patients were eligible to start withdrawing the drugs. Among these, 4 succeeded in completely stopping the medications, and 3 of them remained without any medications for more than three years. This means that the tolerance rate of the transplanted organ among qualified patients reached 37.5%, compared to just about 13% in patients not included in the trial.
The researchers caution that, although promising, the results are still exploratory and not conclusive. The trial was small and not originally designed to prove definitive effectiveness.
The researchers are now planning to conduct larger future trials, where patients will be divided into two groups: one receiving the regulatory dendritic cells and the other receiving standard care, to perform a direct comparison.
The team also suggests testing different immunosuppressive drugs that might be more suitable for the function of these cells, giving the cells after the surgery instead of before it, and even considering obtaining these cells from deceased donors. Thomson confirms that they look forward to collaborating with other transplantation centers to accelerate and expand their research.
