American surgeons have successfully transplanted a genetically modified pig kidney into a living patient for the first time, a U.S. hospital announced on Thursday, marking a significant step toward addressing the chronic shortage of organ donors. The Massachusetts General Hospital in Boston stated in a release that the 62-year-old patient is "doing well" after the procedure, which took place less than a week ago. Previously, kidney transplants from genetically modified pigs had been performed on brain-dead individuals. Likewise, living patients have undergone heart transplants from genetically modified pigs, but they later passed away. The pigs are genetically modified to reduce the risk of the recipient's immune system rejecting the transplanted foreign organ. The man was suffering from end-stage kidney disease. The surgery was performed on March 16 and lasted four hours.