Man who received 1st pig heart transplant has died

A man who received a groundbreaking transplant using a heart from a genetically modified pig has died, according to news reports.

The man, 57-year-old David Bennett Sr., died Tuesday (March 8), two months after his surgery, according to The New York Times. The exact cause of death is still unclear, and his doctors will conduct a thorough examination to determine the cause, the Times reported.

"We are devastated by the loss of Mr. Bennett. He proved to be a brave and noble patient who fought all the way to the end," Dr. Bartley Griffith, director of the Cardiac Transplant Program at University of Maryland Medical Center (UMMC) and the surgeon who performed the transplant, said in a statement from UMMC. "Mr. Bennett became known by millions of people around the world for his courage and steadfast will to live."

Bennett, who had severe heart disease, received the first-of-its-kind heart transplant on Jan. 7. The heart used in the transplant was from a pig that had been genetically modified to make its heart more acceptable to a human immune system. For example, scientists had removed three genes from the pig's genome that induce an immune response in humans — which could contribute to organ rejection — and deactivated a gene to prevent the heart from growing too large for a human, Live Science previously reported.

Animal-to-human organ transplants had been attempted before, but they failed because the person's body rapidly rejected the organ, Live Science previously reported. Over the past decade, scientists have been working to produce genetically modified pigs with organs that are safe to transplant into humans, the Times reported. If done successfully on a wider scale, such a feat could increase the supply of organs available for transplantation; currently, more than 100,000 Americans are on the waiting list for an organ transplant, and more than 6,000 die each year waiting for a transplant, according to the federal government's organdonor.gov website.

Bennett was a candidate for the experimental transplantation because he urgently needed a heart transplant but was considered ineligible for a human heart transplant by several medical centers, Live Science previously reported. 

Bennett's transplant still represents an advancement because the organ wasn't immediately rejected and worked for at least a month, which is an important milestone for transplant patients, the Times reported.

"As with any first-in-the-world transplant surgery, this one led to valuable insights that will hopefully inform transplant surgeons to improve outcomes and potentially provide lifesaving benefits to future patients," Griffith said in the statement.

Originally published on Live Science.