Dr. Reemstma was a pioneer in organ transplantation. From 1963 to 1964, while a professor at Tulane, Dr. Reemstma transplanted primate kidneys to a series of human recipients. His controversial operations proved for the first time that primate organs could be transplanted to humans and continue to function for a significant amount of time.

Dr. Reemtsma is credited with being the first to show that nonhuman organs could be transplanted into humans and function for a significant period. He achieved that by giving six humans chimpanzee kidneys in the first chimpanzee-to-human organ transplants in 1963 and 1964. 

In addition to performing cross-species transplants, known as xenotransplantation, Dr. Reemtsma was an expert in all kinds of human transplants. He helped create a leading heart transplant center at Columbia Presbyterian Medical Center 

Dr. Reemtsma is credited with being the first to show that nonhuman organs could be transplanted into humans and function for a significant period. ...
 
After serving in the Korean war, Dr. Reemtsma became the chief resident at Columbia. He received a doctorate in medical science from Columbia in 1958 as he was leaving for Tulane (1958-1966). - New York Times / L.K. Altman (June 28, 2000)