Rick Slayman, 62, was discharged from Massachusetts General Hospital today. Slayman is the third person to receive a genetically modified pig organ.

The previous two received the heart and died shortly after their transplants. The transplantation of organs from genetically modified animals opens an era of possibilities and risks in medicine. More than 100,000 people in the United States are waiting for an organ and 17 people die every day. The kidney is the most often needed and rates of end-stage renal disease are estimated to increase by 29% to 68% by 2030.