What’s the Deal With Xenotransplantation?

Volume 21, Issue 1

Solid-organ transplantation is the gold standard treatment modality for patients with end-stage organ failure. Unfortunately, organ scarcity continues to plague the United States and other places around the world. As such, many sick patients die each year waiting for a life-saving transplant.

Various efforts to alleviate organ scarcity have been implemented recently. One example is the use of hepatitis C positive donors, which was impossible before the discovery of direct-acting antiviral therapy for hepatitis C. With these new drug therapies, we are able to safely transplant organs from donors with hepatitis C, which has modestly increased the donor pool.

Unfortunately, limiting the donor pool to humans is unlikely to ever fully alleviate the issue of organ scarcity. This is especially true in light of the ever-rising number of patients with end-stage organ failure every year. One possible solution is to turn to xenotransplantation.

Xenotransplantation is the use of nonhuman donors. Recently, the first successful transplant of a pig heart into a human donor was completed at the University of Maryland. Unfortunately, this patient only survived about 60 days post-transplant, but that is long enough to prove this approach is feasible and worthy of additional study.

The pig that was used in this case was genetically modified so the proteins on the surface of the animal’s cells would be less immunogenic for a human donor. In this way, the human immune system is less likely to recognize that the new organ is nonhuman and launch a full-blown assault on the animal tissues.

Xenotransplantation is still in its infancy, and there are certainly drawbacks. Patients who are transplanted with pig hearts are susceptible to infection with porcine viruses, which happened to this first recipient. And the optimal strategy for suppressing the immune system in a patient undergoing xenotransplantation remains to be elucidated. Nevertheless, this novel strategy of using nonhuman donors most certainly warrants additional study, as it carries the potential to alleviate the issue of organ scarcity if the technique can be further refined.