A pig kidney has been successfully transplanted into a living human for the first time, a US hospital announced on Thursday. Massachusetts General Hospital said the genetically-edited pig kidney was transplanted into a 62-year-old man living with end-stage kidney disease. Surgeons from the Mass General Transplant Center conducted the four-hour-long surgery on Saturday. The procedure marked a major milestone in the quest to provide more readily available organs to patients, the hospital said. Mass General Brigham chief executive Anne Klibanski said researchers and clinicians were pushing the bo…