How did organ transplants originate?

In 1967, South African surgeon Christian Barnard performed the first successful heart transplant. Since then, as medicine and medical devices have become more advanced, medical doctors have gradually solved problems such as infections in transplanted organs, leading to successful transplants of limbs, livers, skin, retinas and even testicles. The medical community believes that the next frontier in organ transplantation is brain cell transplants, which could cure medical problems such as Alzheimer's and Parkinson's disease.