One of the biggest dangers of organ transplants is rejection: the body regards the transplanted organ as an infection and the immune system destroys it, leaving the recipient without a functioning organ as well the immune response itself giving rise to symptoms. The usual solution to this problem is to use a drug regimen to suppress the immune system, but these drugs are nonspecific, and suppress the immune system across the board, leaving the patient vulnerable to opportunistic infections. In addition, the drug regimen has to be used for the patient’s entire life. Stem cell techniques are beginning to be used to prevent rejection by mimicking the transplant recipient’s own organs, but this isn’t always feasible.
Now a new technique has been successful in animal studies and is being investigated for suitability in human transplants. Called dendritic cell therapy, it approaches the problem from the other side: instead of persuading the immune system that the organ is the body’s own, dendritic cell treatments use donor immune cells to sort of spread the word about the new arrival, preparing the immune system to receive the transplanted organ by getting the recipient’s body to recognize it as friendly. Dendritic cells are the cells responsible for bringing possible infectious agents to the attention of the T-cells that are responsible for determining whether an immune response is needed. By using dendritic cells already acclimated to the donated organ—a kidney, in the studies—researchers hope to prevent a response to the kidney without suppressing it overall.
In the study, conducted at the University of Pittsburgh, researchers were able to achieve successful results in rhesus macaques with only a single dendritic cell treatment. Not only were the transplanted kidneys not rejected, the animals proved to be healthier overall. The researchers say that if the technique proves to be workable in human beings, it will initially only be likely to be used for planned kidney donations from living relatives, though there is some possibility of it being modified for use for transplants from people who have passed on but arranged for their organs to be donated posthumously.