When Pigs Die

Professor Robert Winston wants to genetically engineer pigs so that they will produce a heart which is compatible with human beings.  Then, he wants to kill the pigs, harvest their hearts, and use the harvested organs for transplants into human beings.  He says he can have the pigs available in 2 years.  The transplants are about 10 years away.  The process is known as xenotransplantation (transplanting between species).  The question is just how ethical is this procedure?  Do we want to be genetically engineering species of living things?  May we rightly harvest organs from living animals to save dying humans?  The news article about this event is linked here.