Dr. Muhammad Mohiuddin, a Pakistani American Muslim, led a team of U.S. surgeons that implanted a genetically modified pig heart into a human being.
It was a medical first that could help solve the chronic shortage of organ donations.
About 110,000 Americans are waiting for an organ transplant, and more than 6,000 patients die each year before getting one, official data show.
Mohiuddin is at the center of xenotransplantation research, which involves grafting animal organs into dying patients.
He is the director of the Cardiac Xenotransplantation Programme at the University of Maryland School of Medicine.
Mohiuddin has spent 30 years trying to help increase the chances of survival for terminal patients who need heart transplants.