First Pig to Human Transplant Could Have Major Implications for Organ Shortage

Image provided by University of Maryland School of Medicine

• A heart from a pig was transplanted to a human for the first time.
• This type of surgery known as xenotransplantation was possible due to gene-editing tools and anti-rejection medication.
• Currently, 106,632 people are waiting for a lifesaving organ transplant. Of those people, more than 62,000 are active waiting list candidates. 

A 57-year-old man with terminal heart disease successfully received a transplant of a genetically-modified pig heart. 

The surgery, a first of its kind, shows that this type of procedure — known as xenotransplantation — is feasible with the help of anti-rejection medications and gene-editing tools. 

Doctors are continuing to monitor the patient to determine whether the animal heart will provide lifesaving benefits in the months and years ahead. 

Though there were a record number of organ transplants conducted in 2021, there continues to be a significant organ shortage in which many people have to wait months, sometimes years, for an organ to become available. 

Scientists are still exploring the risks and benefits of xenotransplantation, but this type of organ transplant could potentially redefine the future of organ transplants. 

“This was a breakthrough surgery and brings us one step closer to solving the organ shortage crisis. There are simply not enough donor human hearts available to meet the long list of potential recipients,” Dr. Bartley P. Griffith, the University of Maryland School of Medicine physician who surgically transplanted the pig heart into the patient, said in a press release.

How the procedure worked

Xenotransplantation has the potential to save thousands of lives, but the procedure comes with serious risks as some patients’ bodies could reject the organ, which can be life threatening. 

The pig had been genetically-modified to avoid serious rejection reactions. Three genes that cause the human body to reject pig organs were removed, and six genes that help the human body accept the pig heart were inserted into the pig genome. Another gene that can cause excessive growth of the pig heart was removed. 

The physicians also used a new type of drug to help the body accept the foreign organ.

“We don’t know how long this organ will function. This patient would otherwise not have been a human heart transplant candidate, and he won’t be a bridge to a human heart later. But it will be a great save for him and a momentous feat for xenotransplantation,” says Dr. David Mulligan, a transplant surgeon and the chief of transplantation at Yale Medicine.

Physicians will continue to monitor the patient to evaluate if and how the pig heart functions in the long term.

“The goal is for this muscular organ to continue to function and respond to changing physiologic demands for years to come,” Mulligan said.

If successful, this procedure could pave the way for xenotransplantation and open up new avenues for organ transplants. 

“As we consider other more complex organs that have additional metabolic demands and blood filtration systems like livers and kidneys, we will need to assess how porcine organs compare to human ones when it comes to making our vital proteins and metabolizing our nutrients and synthesizing our hormones,” Mulligan said. 

The current state of organ transplants 

Currently, 106,632 people are waiting for a lifesaving organ transplant. Of those people, more than 62,000 are active waiting list candidates. 

Approximately 17 people die each day are waiting for an organ transplant, and every 9 minutes, a new person is added to the waiting list. 

In 2021, there were 41,354 transplants conducted with the help of 20,398 donors. 

While the number of organ transplantations has grown in recent years, striking a record in 2021, there is still a significant shortage of organs made available for transplants each year.

Waiting times for organs vary — critically ill patients may only wait days while healthier patients could wait months or years.

“The implications are that we can use genetically-modified organs from high volume supplies to supplement the scarcity of organs for lifesaving transplants, either with long-term outcomes or as a bridge to a human organ later,” Mulligan said. 

The bottom line

A 57-year-old man with terminal heart disease successfully received a transplant of a genetically-modified pig heart. 

The surgery, a first of its kind, shows that this type of procedure — known as xenotransplantation — is feasible with the help of anti-rejection medications and gene-editing tools. Scientists are still exploring the risks and benefits of xenotransplantation, but this type of organ transplant could potentially redefine the future of organ transplants.