SHAFAQNA – The Grand Ayatollah Sobhani answered a question about organ transplant.
Question: Is it allowed for organ transplantation of brain dead patients and also organ transplant from inherently and ritually unclean (Najisul-Ain) animal to the human being?
The Grand Ayatollah Sobhani: Death of the brain is not a permission to take body parts, death of the heart must also occur, and the person must be dead totally; and with the permission of the guardian if it is necessary, the heart, the kidneys, and the liver which the life of another person depend on them can be taken, and there is no problem in this case. And anytime the transplanted organ of the inherently and ritually unclean (animal) is fused into the body of the human being; it is ruled as the body of the human being.
Source: PERSIAN SHAFAQNA