Patients in China and the US have Received Pig Organ Transplants

(CTN News) – The transplant of pig organs into human patients grabbed global headlines this week after two milestone breakthroughs in the field, but ethical concerns such as viral transmission may still prevent it from becoming a widespread practice.

The first feat entailed Chinese scientists transplanting a pig liver into a brain-dead patient.

The breakthrough surgery allowed the organ to function for 10 days until it was removed per the family’s wishes. In China, brain death is not regarded as a legal death.
In the United States, a pig kidney was transplanted into a patient with end-stage kidney failure, marking the second milestone transplant. The operation had previously been carried out on clinically dead people.

Recent procedures have shown that xenotransplantation, which involves transferring organs or tissues from one species to another, can save lives.

“One of the potential benefits of xenotransplantation is the limitless graft supply that would help a lot of patients with urgent need for transplant,” said Albert Chan Chi-yan, a clinical professor at the University of Hong Kong and director of Queen Mary Hospital’s Liver Transplant Centre.

The endless supply of organs could provide hope to hundreds of thousands of patients worldwide who are waiting for their names to be added to transplant lists amid global shortages.

However, ethical issues may be a stumbling block.

“[One concern is] the risk of disease transmission from animal species to human,” he stated.

Pigs used for human transplants are often raised in dedicated facilities to ensure their pathogen-free status. However, this hasn’t always worked.

In 2022, a milestone transplant in which the first pig heart was implanted into a patient with severe heart disease resulted in the patient’s death owing to an undiscovered virus.

Although the “potential benefits are considerable,” the risk of spreading infectious pathogens remains a serious issue, especially since some may not be recognized until transplant, according to the US Food and Drug Administration (FDA).

He said, “Tolerance to the new organ and the risk of acute rejection are other problems to overcome in this field.”

Animals used in xenotransplantation are usually genetically engineered to lessen the likelihood of organ rejection. Pigs can also be genetically modified to include human genes, ensuring the organ fits better.

According to Nature, the kidney utilized in last week’s US transplant came from a pig with a record 69 gene modifications.

Scientists in China have also attempted to humanize donor animals by injecting human stem cells into pig embryos, resulting in embryos with kidneys formed mainly of human cells.

In this study, the authors acknowledged the main ethical worry that human cells could get placed in the embryo’s brain or genital ridge, perhaps leading to differentiation into reproductive cells.

Chan also expressed concern about “the psychological impact to the organ recipient” following surgery.

According to FDA rules, the transplantation of animal organs into humans should be restricted to patients suffering from “serious or life-threatening diseases” for whom alternative therapy may be unavailable.

Despite the ethical difficulties, a report on a 2018 meeting in China that included the World Health Organization indicated that xenotransplantation “could bridge the gap between demand for, and supply of, human organs for transplantation”.

While xenotransplantation is still in its early stages in practice, Chan stated that more work remains.

“Future research should focus on how genetic editing could help to modify the animal organ to become entirely suitable and acceptable for human application,” he added.