Human tumor cells have been transplanted into immunocompromised mice in pre-clinical oncology research. However, there are medical, legal and ethical issues when transplanting foreign cells, tissues or organs from nonhuman sources to humans. Although considered a potential treatment for end-stage organ failure, human xenotransplantation still raises a lot of concerns including life span and disease transmission.
Human xenotransplantation has been done before. In 1984, a female infant with hypoplastic left heart syndrome called Baby Fae received a a baboon heart. Twenty-one days after the procedure, Fae died due to a humoral-based graft rejection caused by an ABO blood type mismatch.
Pigs have been identified as the best candidates for organ donation and they are often used for xenotransplantation experiments. However, the idea of using nonhumans organs for human transplants still raises a lot of concerns. Here’s a look at the pros and cons:
List of Pros of Xenotransplantation
1. It increases the number of organ sources.
A human organ transplant takes time because the procedure would depend on available resources. Pigs are readily available and have been used widely in xenotransplantation experiments. Unlike primates who carry the risk of disease transmission (because they are closely related to humans), new infectious agents are less likely with pigs because humans have domesticated them for generations.
2. It can save a patient’s life.
The shortage of organs for transplantation results all around the world accounts for 20-35% of deaths of patients on the waiting list. There are certain procedures being investigated in early clinical trials that use cells or tissues from nonhuman species to treat diseases that are life threatening such as cancer, diabetes, liver failure and Parkinson’s Disease.
3. It is a valuable asset in developmental biology.
Developmental biology has been vital for human health and providing researchers with the tools they need will only help them make life better.
List of Cons of Xenotransplantation
1. There has been no successful xenotransplantation procedure yet.
There have been no successful xenotransplantation trials to date because of problems that arise from the response of the immune system of the patient. The responses are more extreme compared to human-to-human transplants and eventually leads to the rejection of the xenograft. As mentioned earlier, an attempted heart transplant on a young girl resulted in her death.
2. It risks introducing new infections to humans
One of the concerns over using primates as potential organ donors is their close relationship to us. Being closely related carries certain disadvantages, particularly that of disease transmission. Although animal to human infection is rare, it has happened before. Avian influenze is surely one example where the influenza A virus is transmitted from birds to humans.
3. There are ethical concerns.
Opposition to xenotransplantation has been widespread since the procedure was first attempted. Animal rights groups in particular have been vocal about the killing of animals to harvest their organs for use in humans. Jewish and Islamic communities prohibit the consumption of pig. Although there have been no major objections from major religions over the use of genetically modified pig organs for organ transplants, there have been objections from those with certain religious beliefs.