Their loved ones died after receiving pig organ transplants. The families have no regrets.

David Bennett Jr. knelt by his bedside, phone in hand, anxiously awaiting a call that no one had ever received: The hospital was due to update him on whether his father was still alive after getting a new heart — from a pig. 

It was the first time any living human had received a pig organ transplant.

“You never know what the news is, but my dad opened his eyes, and he was awake, and he was doing well. It was incredible,” Bennett Jr. said.

Bennett’s father, David Bennett Sr., had severe congestive heart failure and wasn’t a candidate for a human transplant. He knew he would likely die soon. There was nothing more to do — other than take a chance on a novel, cutting-edge surgery. Bennett Sr. and his son agreed it was worth the risk.  

The achievement made headlines around the world after the transplant surgery in January 2022. The results at first seemed promising, and some family members even began to entertain the idea that Bennett Sr. might eventually leave the hospital.

“There were definitely futuristic conversations, just about home setup and who was going to take care of him and how that would look,” Bennett Jr. said. “Everybody was very optimistic and hopeful.”

David Bennett Jr. with his family.Rosem Morton for NBC News

But two months later, Bennett Sr.’s body rejected the heart and he died at age 57. In a paper, his doctors at the University of Maryland Medical Center explained that his body had likely produced too many antibodies that fought off the new organ. A drug he’d been given may also have increased the odds of rejection, and a virus in the pig heart further complicated matters. 

Three other patients have followed in Bennett Sr.’s footsteps and received pig organs, most recently a pig kidney transplant in April. Together, they represent the pioneer patients of the burgeoning field of xenotransplantation. For their families, three of which spoke to NBC News about the experience, the journey came with a roller coaster of emotions, from uncertainty to blind hope — and, ultimately, admiration for their loved one’s decision. 

“I would love to still have my dad here, obviously, but I know that his sacrifice wasn’t for nothing,” Bennett Jr. said.

None of the patients survived more than three months. To the public, that might seem like failure. But to the families, the transplants accomplished their goals: to buy their loved ones more time and advance research that could potentially save lives one day.

“Larry approached it in this way: He was going to die. It was inevitable, and it was coming soon,” said Ann Faucette, whose husband of nearly 38 years, Lawrence Faucette, was the second person to receive a pig heart. “So why not offer up his body as a test subject for them to get as much data, do as much research as they could, so in the future there’s that other option for people who need those transplants?”

The promise of xenotransplants lies in the shortage of available human organs. An estimated 17 people die in the U.S. each day waiting for an organ transplant, according to the Health Resources and Services Administration. Because pig organs are more readily available, doctors envision a future in which these operations are as common as a hip replacement.