The kidney of a pig was transplanted into a brain-dead man who had donated his body to science. The pig had been genetically modified so that the organ would not be immediately rejected by the human body. Such animal organ transplants on humans, called xenotransplants, could offer a solution to the chronic shortage of kidney donations. More than 100,000 Americans are currently on the waiting list for kidney transplants, including nearly 88,000 waiting for a kidney. The experiment lasted a record 61 days, NYU Langone's statement said.