April 1, 2022 | LIFE | By Gabriella Casagrande

When an organ fails, a transplant may be needed to recover the function the organ performed and keep the recipient alive. Severe trauma to the body, widespread illness such as cancer, and extreme inflammatory response to infection can cause organ failure. Organ transplants are not 100% successful, as the efficacy is dependent on multiple factors on both the donor and recipient sides. However, medical advances have made the procedure relatively routine and transplants have become the treatment of choice for patients experiencing late-stage organ failure.

Although organ rejection is a risk with transplantation, preventative medications are becoming more effective. Rejection occurs when the body sees the new organ as a foreign organism like a virus and attacks it as such.

To mitigate this risk pre-transplant, donors and acceptors are matched as closely as possible by blood type and genetic testing. Post-transplant, lab results must be monitored frequently and patients must be vigilant about taking anti-rejection medication, which weaken the immune system’s ability to recognize foreign bodies. Recipients must also stay healthy to avoid outside infection the immune system may not be able to handle.

According to the Organ Procurement and Transplantation Network, since the beginning of 2022, 4,305 donors have been recorded as of March 21, while 15,580 new patients have been added to the waitlist as of March 25. According to the U.S. Department of Health and Human Services, a single donor can save eight lives and improve many more. If you want to sign up as an organ donor (with no effect on or detriment to your current medical care!) or learn more about post-mortem donation, visit donatelife.net.

Given the discrepancy between waitlisted patients and available donors, xenotransplantation – the transplantation of non-human animal organs or tissues into humans – is an exciting possibility currently being explored by members of the medical world. This new procedure could lower patient and physician reliance on human organ donations, allowing for the treatment of more patients on the waitlist.

Prior xenotransplantations have used non-gene edited non-human animal organs or have been transplantations into brain-dead humans –– neither have been successful in the long-term. However, strides in gene editing have proven useful in lowering the immune system response, and thus decrease the chance of organ rejection.

A patient at the University of Maryland Medical Center underwent the first heart xenotransplantation in a living human in Jan. 2022, receiving a 10-gene genetically modified pig heart. This highly experimental surgery was allowed by the Food and Drug Administration given the patient’s lack of options –– he was not eligible for a human to human transplant, could not receive a mechanical heart pump, and had been on a ventilator for two months. The modifications aimed to lower rejection, prevent blood vessel damage, prevent the pig heart from outgrowing the human chest, and more.

The patient survived on this pig heart for two months –– a huge success for the xenotransplantation field. Not many details have been released concerning the death; several possibilities exist.

First, pig hearts in general may not be anatomically strong enough; human hearts must work harder to pump blood against gravity than pig hearts. It could also be that the deterioration of this specific patients’ heart was too far gone, and the pig heart could have helped if the transplantation had occurred sooner. It is also possible that canonical organ rejection occurred.

Regardless of the exact cause of death, this is a huge milestone that will no doubt reignite xenotransplantation interest and usher in more research on the possibilities of future treatments.

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