Two gene-edited pig hearts successfully transplanted into brain-dead humans

Researchers follow new protocol to ensure there are no infectious viruses in the pigs

Surgeons in the US have successfully transplanted two genetically engineered pig hearts into brain-dead individuals, further advancing a technique to save dying humans using animal organs.

The surgeries, known as xenotransplants, were performed on 16 June and 6 July at New York University’s Langone’s Tisch Hospital.

In both the transplants, there were no signs of early rejection, according to researchers. They said the hearts functioned normally with standard post-transplant medications and without additional mechanical support.

“Our greater purpose is to address the organ shortage and provide another option for the more than 100,000 people nationwide waiting on that lifesaving gift,” Robert Montgomery, professor and chair of the Department of Surgery at NYU Grossman School of Medicine, said in a statement.

The hearts used in the procedure were procured from pigs that had 10 genetic modifications, including four porcine gene “knockouts” to prevent rejection and abnormal organ growth as well as six human genes inserted to promote the expression of proteins that regulate important biologic pathways that can be disrupted by incompatibilities between pigs and humans.

The latest surgeries follow the first-ever human heart transplant in January in which an American man received a gene-edited pig heart. But he died two months after the procedure.

David Bennett, the 57-year-old, died from no clear causes on 8 March at the University of Maryland Medical Centre. But in a report published in May, scientists suspected the pig from which the heart was procured may have been infected with a virus.

Researchers say the latest xenotransplants used a new infectious disease protocol and no presence of porcine cytomegalovirus (pCMV) was detected in either case.

One of the critical elements of success in advancing the field, according to scientists, is enhanced porcine virus monitoring, which was incorporated in these latest procedures.

They say “strict protocols” to prevent and monitor the potential transmission of porcine endogenous retrovirus were also carried out.

Other procurement, transport, transplant surgery, and immunosuppression protocols followed in the latest cases were also aligned with current clinical standards used in heart transplantation.

“Our goal is to integrate the practices used in a typical, everyday heart transplant, only with a nonhuman organ that will function normally without additional aid from untested devices or medicines,” Nader Moazami, surgical director of heart transplantation at the NYU Langone Transplant Institute, said.

“We seek to confirm that clinical trials can move ahead using this new supply of organs with the tried-and-true transplant practices we have perfected at the NYU Langone Transplant Institute,” Dr Moazami said.

Researchers say such xenotransplant studies with recently deceased donors are critical to gathering additional data needed to advance the field, which for decades had been tested only using nonhuman primates.

“More sensitive screening methods have been introduced to detect low-level traces of pCMV in the donor pigs. We have included that additional screening in this heart transplant protocol to give the organ the best chance at long-term survival,” Dr Montgomery added.