Two months after doctors replaced an ailing human heart with a pig heart, the patient has died.

57-year-old David Bennett died on Tuesday at the University of Maryland Medical Center.

While doctors did not state Bennett’s exact cause of death, they did say that his condition had begun deteriorating several days before.

Doctors at the Baltimore hospital replaced Bennett’s failing heart with a pig heart on Jan. 7th. The operation was a FDA approved experiment in an attempt to save Bennett’s life.

Authorities say Bennett was a candidate for the experimental procedure only because he otherwise faced certain death which made him ineligible for a human heart transplant.

“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, who performed the surgery at the Baltimore hospital, said in a statement.

Other attempts at conducting animal to human transplants have failed largely because the patients’ bodies immediately rejected the animal organ. Scientist, however, modified specific animal genes inside the transplant in an effort to allow the human body to accept it.

While the Bennett has passed away, officials say they have gained insight that would allow them to further their research:

“We have gained invaluable insights learning that the genetically modified pig heart can function well within the human body while the immune system is adequately suppressed,” said Dr. Muhammad Mohiuddin, scientific director of the Maryland university’s animal-to-human transplant program.