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Biomedical Research

Brain Transplants: Aye or Nay?

What are some of the controversies behind brain transplants? How do the possible benefits measure up to the difficulties of the procedure and their ethical implication?

By Melle Hsing

Published 7:40 PM EST, Mon July 26, 2021

Introduction

The idea that an entire brain could be transplanted into another person remains a very controversial topic in the medical sciences. Although there has historically been no record of an entire brain transplant (also known as a head transplant) into a living human unlike what is depicted in some films, there has already been an allegedly successful human brain transplant between two human corpses in 2017. A team of surgeons have even claimed to perform an estimated 1,000 head transplants on mice! Hence, human brain transplants may just be possible, although still highly unlikely in the near future. In what situations would they be considered, and what is the controversy behind transplanting a human brain? These are some of the questions which I will explore, through three considerations: the difficulties of the procedure, the possible benefits, and of course, the ethical implications.

The Difficulties and Risks of a Brain Transplant

First of all, it should be established that a brain transplant would be extremely difficult to perform. The reason for this is that transplanting an organ from one donor to a patient should be done only when both parties are immunologically compatible with each other. This concept of “immune compatibility” is an essential consideration when transplanting a heart, liver, or kidney to another patient. As long as there isn’t an immune response in light of a foreign organ in the patient’s body, the patient should be fine. Doctors identify immune compatibility based on the similarity of genes of the human leukocyte antigens and major histocompatibility complex, which are both involved in triggering an immune response. After, immune-suppressors are injected to ensure that an immune response really won’t occur during and after the transplant. However, scientists are not very familiar with antigens located on neurons and other glial cells which poses a huge risk on patients that want to get a brain transplant.

Another factor to consider is that the brain is highly sensitive to changes in the environment, and neurons can readily die because of lack of oxygen during the transplant. In order for a brain transplant to successfully occur, the surgical room environment must be highly controlled, specifically accommodating the needs of a living brain exposed to the open air. Furthermore, the surgeons performing the transplant would need to be very careful when reconnecting the blood vessels between the implanted brain and the patient’s peripheral nervous system. They would also need to be wary of connecting the spinal cord to the brain.

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Figure 1: Surgical Operation, sourced from Verywell Mind

Why Carry Out a Brain Transplant?

According to Dr. Sergio Canavero, an Italian neuroscientist, head transplants would be used on untreatable neurological disorders that cause significant harm to the patient (e.g. muscle-wasting). On the other hand, head transplants may also be used when a patient has an unhealthy body that is beyond repair or management (essentially inhabitable) but an otherwise perfectly functional brain, in order to give them another chance at life. There are many problems with this though, and one of them is the fact that a healthy and uninhabited body is needed in preparation for the operation (which, as one could imagine, entails several ethical considerations in itself). Furthermore, there is the question of whether a person’s soul can be preserved once a transplant has been done – as in their personality and memories.

Therefore, with the large area of uncertainty towards the effectiveness of a brain transplant, brain transplants seem like a possibility that shouldn’t be taken just yet. 

Ethical Implications of Brain Transplants

There are lots of ethical considerations made for brain transplants. Firstly, there is the ethical consideration of consent, which may entail asking questions such as “who is going to donate a healthy body for a terminally ill patient with an otherwise healthy brain?” or “how does the patient feel about getting a brain transplant?”. These questions are key to answer before a brain transplant can even be performed, however they are also difficult both on the doctor’s and patient’s part to answer. The patient would have to be aware of all possible risks in going through with the operation (which could be a myriad of things), and would have to really consider what life would be like given a successful brain transplant.

The possibility of life after a brain transplant may be a scary thought, especially given that there is no telling whether the patient’s “soul” would still exist in a new body. After all, are an individual’s personality, opinions, memories, and essentially every characterization about themselves localized in the mind, or does one’s body also pose a significant influence on one’s “soul”? The interconnectivity of human bodily systems and the fact that scientists may not completely understand the complexity of interactions underlying behaviour (not just in the brain but in the entire body itself) makes this a very mind-bending (if at all philosophical) question to consider. Given that research has found links between one’s mood and emotional behaviour to other bodily systems (take the gut-brain axis as an example), how much of that behaviour would be altered as a result of such a risky operation? If other bodily systems do influence behaviour, then that would imply that the patient would exhibit different behaviours than before surgery due to being in a foreign body of differing chemical composition and stature. Hence, doctors may have to consider more than just immune compatibility when planning a brain transplant. The amount of research needed to clarify the uncertainties present in doing a brain transplant is therefore profound, such that there is very little chance for a brain transplant to actually happen in the near future. 

Conclusion

The brain, while known to be the most complex object we’ve ever known in the observable universe, is also a very fragile organ which must be dealt with utmost care. The prospect of brain transplants leaves for very interesting philosophical discussions about soul preservation and human behaviour, while it also uncovers how much humans don’t yet know about the human body and behaviour. However, it is precisely because there is so much that society doesn’t know about the human body yet and what could happen after an operation that this operation seems highly unlikely to be carried out soon.

Melle Hsing, Youth Medical Journal 2021

References

Appleton J. (2018). The gut-brain axis: Influence of microbiota on mood and mental health. Integrative medicine (Encinitas, Calif.), 17(4), 28–32.

BBC News. (2021, May 29). The brain is the ‘most complex thing in the universe’. BBC News. https://www.bbc.com/news/uk-scotland-18233409

Earth, R. (n.d.). [A surgical operation]. Verywell Mind. https://www.verywellhealth.com/head-transplant-4801452

Kirkey, S. (2017, November 17). World’s first human head transplant successfully performed on a corpse, scientists say. National Post. https://nationalpost.com/health/worlds-first-human-head-transplant-successfully-performed-on-a-corpse-scientists-say

Tay, A. (2017, July 11). Brain transplants – are they possible? NeuWrite West. http://www.neuwritewest.org/blog/brain-transplants-are-they-possibleWhiteman, H. (2015, October 15). The first human head transplant: ‘It will be a success’. Medical News Today. https://www.medicalnewstoday.com/articles/301073

By Melle Hsing

Melle Hsing is a student at Chinese International School in Hong Kong. She is interested in the fields of medicine, biology, and neuroscience.

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