Dopamine primes kidneys for a new host

Giving dopamine infusions to brain-dead organ donors while they still have a heartbeat seems to fortify their kidneys against the rigors of transplant, a new study shows. Patients receiving a kidney from such donors are less likely to require multiple sessions of blood-cleansing dialysis immediately after the transplant operation, researchers report in the Sept. 9 Journal of the American Medical Association.

What’s more, treating a donor with dopamine seems to prevent some of the damage to kidneys that happens while the organs wait to be transplanted, the scientists find.

Brain-dead donors supply the majority of kidneys for transplant. Such donors often have suffered trauma or brain hemorrhage and have no chance of regaining brain function.

Although dopamine is best known as a neurotransmitter that guides brain signaling, the chemical has been used in intensive care units to stabilize blood pressure in patients, says study coauthor Benito Yard, an immunologist at the University Clinic of Mannheim in Germany. Dopamine can also quell inflammation and preserve blood vessel cells, both of which might benefit a kidney headed for transplant.

In the new study, 122 brain-dead organ donors received infusions of dopamine while 137 similar donors did not. All donors had a heartbeat when they received the dopamine, but they had no brain function as measured by electroencephalography and they needed a ventilator to breathe.

After each organ transplant, the scientists monitored the health of the kidney recipient. Of recipients getting dopamine-exposed kidneys, 25 percent needed multiple kidney dialysis sessions during the week after transplant. Of those getting a kidney not exposed to dopamine, 35 percent needed the multiple sessions.

“This is a big deal for the recipient,” Yard says. A need for dialysis indicates that a donor kidney hasn’t started to filter blood yet. “The sooner it starts to function, the better it will be,” for the patients’ long-term prospects, he says.

In this study, recipients who needed multiple dialysis sessions in the week after surgery were more than three times as likely to have their new kidney fail within three years as were people who got no dialysis.

Dopamine may be particularly protective in kidneys that face delays before transplant. It usually takes several hours or even a day to get a kidney from donor to recipient, during which time the organ must be kept cold to slow tissue damage. In patients receiving a kidney that had been in storage for more than 17 hours — which was one-fourth of the kidneys in this study — 91 percent of dopamine-exposed kidneys were still functioning three years later compared with only 74 percent of kidneys whose donors didn’t get dopamine. In addition to preserving blood vessel health, Yard says, dopamine exposure before transplant seems to mitigate inflammation in the kidney that can attract the attention of the recipient’s immune system and raise rejection risk.

“I think this study is very elegant, especially since dopamine is routinely used in intensive care medicine,” says Duska Dragun, a transplant nephrologist at Charité Hospital in Berlin. “At least in Europe, it is very difficult to estimate how long a kidney will be in cold storage,” she says. Dragun argues that the new trial is good enough to warrant use of dopamine for kidney transplants.