Pittsburgh Scientists Successfully Wean Liver Transplant Patients Off Immunosuppressants Using Donor Derived "Immune Priming" Cells

University of Pittsburgh researchers successfully used donor-derived cells to wean liver transplant patients off anti-rejection drugs for over three years.

By: AXL Media

Published: Apr 17, 2026, 8:06 AM EDT

Source: Information for this report was sourced from Nature Communications and the University of Pittsburgh.

Achieving the "Holy Grail" of Transplantation

For decades, organ transplant recipients have faced a difficult trade-off: a life-saving new organ in exchange for a lifetime of immunosuppressant drugs. While these medications prevent the body from attacking the donor organ, they often lead to severe side effects, including kidney damage, diabetes, and an increased risk of cancer. Now, a phase I/IIa trial published in Nature Communications has reached a major milestone in "transplant tolerance." Researchers have successfully trained the immune systems of multiple liver transplant patients to accept a donor organ as "friendly," allowing them to stop taking all anti-rejection medications entirely.

The Science of Immune Priming

The process, led by Dr. Angus Thomson and Dr. Abhinav Humar, centers on "regulatory dendritic cells" (DCregs). These specialized white blood cells act as teachers for the immune system, instructing it on which cells to attack and which to leave alone. In the trial, monocytes were filtered from the donor's blood weeks before the scheduled living-donor liver transplant (LDLT). These cells were then induced in a lab to become DCregs and infused into the recipient seven days before surgery. This "priming" phase was designed to educate the recipient's immune system to recognize the donor’s tissue before the organ was even implanted.

Clinical Results and Long-Term Success

The trial followed 13 patients who underwent living-donor liver transplants. One year after surgery, the team evaluated the participants to see if their immune systems showed signs of tolerance. Of the eight patients eligible for drug withdrawal, four successfully transitioned off immunosuppressants. Strikingly, three of those patients have remained completely off the medication for more than three years with no signs of rejection. This 37.5% success rate among eligible trial participants is nearly triple the 13% rate typically seen in non-trial patients who attempt to stop medication early.