Genetically modified pig hearts transplanted into two more patients

The team of researchers who transplanted a genetically modified pig's heart into a living human earlier this year have completed two more pig heart transplant surgeries, setting the protocol for such operations.

In January this year, 57-year-old David Bennett became the first man on the planet to receive a heart from a genetically modified pig. Before this, researchers transplanted kidneys from similarly modified pigs into patients that were brain dead. 

The organs are sourced from a company called Revivicor which uses genetic engineering to remove specific genes in the pigs to help in reducing transplant rejection while adding some that make the organs more compatible with the human immune system. 

Setting the protocol for such transplants

Researchers at NYU Langone carried out two more surgeries, one in June and another in July to develop a clinical protocol for such transplants. The procurement, transport, transplant, and immune suppression were carried out aligned with current clinical standards for a heart transplant.

"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," said Nader Moazami, who led the investigational procedures. 

Both surgeries were performed on brain-dead patients, and the newly transplanted hearts were maintained on ventilator support for 72 hours, during which no signs of rejection were observed. 

In the case of Bennett, who died two months after the surgery, the transplanted organ was found to have been infected with a pig virus. Robert Montgomery, the director of the Transplant Insitute at NYU Langone, said that transplant studies with deceased donors were critical to gathering additional data to advance the field. 

"Under normal circumstances, one donor can save up to eight lives. But in these special cases, donor heroes have the potential to save countless lives by participating in groundbreaking research," Leonard Achan, chief executive officer at LiveOnNY, an organization engaged in organ and tissue donation, said in the press release. 

Enhancing the screening for infectious diseases

"Studies have shown that porcine cytomegalovirus (pCMV) may be a factor in the success of xenotransplanted organs," said Montgomery in the press release. For this round of surgeries, the research team added a new infectious disease protocol to detect the presence of porcine cytomegalovirus (pCMV).

Additional protocols were also introduced to check and monitor the transmission of porcine endogenous retrovirus (PERV). The operation theater, where the surgery was carried out, has also been taken offline and will only be used for xenotransplantation research in the future.

"This is the first step in developing a deep understanding of the mechanical, molecular, and immunologic aspects of xenoheart transplantation and the feasibility of utilizing standard clinical practice and tools to do so," said Alex Reyentovich, director of NYU's advanced heart failure program.