A Russian emigrant living in Paris by the name Serge Voronoff developed the concept of transplanting cells to a person deficient in the hormones that the cell carried or produced. Voronoff carried out experiments where he transplanted testicles from baboons or chimpanzees to male humans. He would slice up the animals’ testicles and insert them into the humans’ testicles. There were minimal reports of complications and instead positive results seemed to have come from his experiments. It is possible though that it was just a psychological effect. Nonetheless, it became quite a popular procedure throughout many parts of the world. In recent years we have been using this cell rejuvenation concept to transplant human pancreatic islets that produce insulin into patients with severe type 1 diabetes.
Xenotransplantation is a surgical procedure which involves the transplantation, implantation or infusion into a human patient from a nonhuman source. The thing being transplanted can be cells, tissues or organs. Xenotransplantation is largely driven by the fact that there are an exceedingly increasing amount of organs needed worldwide but not nearly enough available. I will be delving further into the history, the methodology and the ethics concerning animal to human xenotransplantation.
History
Blood; In the 17th century a Jean-Baptist Denis attempted blood transfusion from animals to humans. The experiment had many varying results causing France to ban xenotransfusion for multiple years to come.
Skin; In the 19th century skin graft transplantation became quite popular. Skin grafts are a surgical procedure which removes healthy skin from the donor and transplants it onto the recipient to the site in which they were wounded so as to cover it up. The interspecies skin graft transplantation was mostly done with sheep, rabbits, dogs, rats, chickens, pigeons and frogs which were sometimes skinned alive. There were varying results, sometimes the procedure did not work while other times it worked but it rarely stayed permanent.
Cornea; The 1st corneal xenotransplantation, from pig to human was performed in 1838, while the 1st human to human corneal transplantation did not occur until 65 years later in 1905. The interspecies transplantation was unsuccessful while the intraspecies one was successful.
Blood vessel anastomosis; This refers to the joining of 2 blood vessels. Alexis Carrel, a French surgeon, was awarded a Nobel prize in 1912 for developing surgical techniques for blood vessel anastomosis which then led to organ transplantation being carried out successfully for the 1st time.
Kidney; By the 1960s kidney transplantation had already been established, but the unavailability of donors made it extremely rare. Keith Reemtsma then came along and theorized that perhaps primate kidney transplantation to humans might be a solution to renal failure. He experimented on 13 patients in total, transplanting kidneys from a chimpanzee to a human. Most of them failed within 4 to 8 weeks. One of his patients lasted 9 months. She went back to her regular life, even went back to work seemingly healthy throughout, when one day she just collapsed and died. When the kidney was investigated it showed no damage, so it was then theorized that an acute electrolyte disturbance was the cause of her death. Other surgeons dabbled with interspecies kidney transplantation as well but all failed.
Heart; In 1964, James Hardy, inspired by Keith Reemtsma work, decided he wanted to try out heart xenotransplantation. He got chimpanzee hearts and a patient that would not have been accepted for this transplantation by today’s standards. The patient had a widespread atheromatous vascular disease throughout his body that had forced him to get both legs amputated. While the surgery for the transplantation was taking place the patient was in a semi-comatose state. Due to the condition that the patient was in a close relative was made to sign the agreement for the surgery, but Hardy failed to mention that a chimpanzee’s heart was the one to be used for this procedure. Ultimately the procedure failed and the patient died within a couple of hours of the surgery. Later in 1983 Leonard Bailey attempted a heart transplantation from a baboon to an infant called Baby Faye. The surgery itself went well, but the transplanted graft was rejected and the infant died 20 days later. At the time it was practically impossible to find a heart donor for infants with congenital heart disease, so this procedure shed some light on that issue. Later Leonard Bailey went on to establish a very successful allotransplantation, transplantation of tissue or organs from one person to another of the same species but different genotype, program for infants and children at Loma Linda University.(Erlbraum, C.)
Liver; In the 1960s Tom Starzl attempted liver xenotransplantation between nonhuman primates and humans. The results were not very successful, only a couple of days of survival. Later on in the 1990s when the immunosuppressive medications and techniques had improved Staryl once again attempted a liver xenotransplantation with a baboon this time. The patient ended up living for another 70 days after the surgery before dying. The trials on liver xenotransplantation stopped there because there weren’t enough successes to allow the continuity of these trials.
How it works
CRISPR-Cas9 or Clustered Regularly Interspaced Short Palindromic Repeats is a genome editing technology. This CRISPR is a specialized part in the DNA that has repeated nucleotides and spacers. Cas9 is a protein that acts like scissors that can cut through the DNA. Once the Cas9 binds itself onto the DNA and cuts it, the DNA will try to repair itself but the damage makes it shut off the particular gene that was cut.
Stem cells are unspecialized cells that have the ability to basically transform and clone themselves into any particular cell in the body. These stem cells have many medical uses including xenotransplantation. The stem cells from the human are taken and inserted into the porcine embryo, the offspring of a pig. That pig will then grow human organs, which can later be transplanted into a patient..
By using stem cell research and CRISPR technology, scientists are attempting to grow human organs in a variety of different species. The pig for example is taken and the HOX gene, that is used for coding the growth of certain organs, is cut out. The genes that code for porcine microorganisms in their genome are also cut out. Genetic engineers can remove certain genes that code for the development of certain organs in the pig and replace those genes with specialized human stem cells that will then grow human organs instead. Now the pig will be growing human organs inside of it instead of its own organs.
Recently, pigs and hogs have been the primary organisms experimented on for interspecies xenotransplantation as their organs are the most similar to humans in size, physiology, and anatomy. Additionally pigs can be bred in large amounts and they don’t take long to grow and mature. The cost of breeding pigs is also not an alarming number making them easily available for anyone. With pigs being bred in large amounts it allows for there to be plenty of organs to go around as needed, so we’ll never be at a shortage of organs. Human to human organ transplantation isn’t always reliable as it may take a long time to find a donor, which may then be too late for the patient or sometimes a donor isn’t found at all for the organ needed for the transplant. Many complications due to disease and transmittable infections can also be avoided with pig to human transplantation. The pigs that are grown for the transplantation will be bred in a closed and secure environment where they are regularly supervised, so the risk of infection is very low and when contracted can be easily controlled.
Ethics
If xenotransplantation becomes a successful clinical practice it will involve the breeding and killing of animals on a large scale for the benefit of human transplantation. If transgenic pigs are to be the way in which we practice xenotransplantation, there will also be the issue of the genetic modification of animals on the table. It is well known that animals like humans are very much vulnerable to pain and suffering. Many argue that it is morally wrong to see animal suffering as less than humans, just as it would be wrong to see one human suffering as less than another. These actions can only be acceptable when they increase the benefits or reduce harm to as many people as possible. When we want to weigh whether animals can be used for any medical related trial we must first assess whether the pain and suffering caused to the animals is justifiable by the benefits it may bring humans.
In a number of cases animal suffering is seen as more important than the results it may pose to humans. An example is the use of animals for the testing of cosmetic products. It is widely agreed that the benefits we might get from testing it on animals is minute compared to the suffering it inflicts upon them. For other cases it is mostly accepted that the pain caused upon the animals is worth it for the results it yields us, as long as the experimentation and pain to the animals is kept at a minimum.
Many others believe that animals like humans have a fundamental right to life. There are things that simply should not be done to the holders of these rights, whether they be human or animal, no matter the benefits. Animals have a greater value than just to be used for human gain, and to experiment on them would be crossing a moral and ethical line which no living being deserves to be inflicted upon them. It is argued that humans and animals alike should not be killed for the benefit of others no matter how painlessly that killing might be.
It is also argued that the use of animals for experimentation should be based on their level of self awareness and personhood. This is referring to the consciousness and awareness that a person has to their condition and experiences. Self awareness allows for an individual to make choices, form complex social relationships, ability to make judgements and to speak in a language that articulates their thoughts and emotions. Up until recently all these features that make an individual self aware have been attributed to only humans, but recent research has shown that a variety of species have these features to some degree. Primates especially have been shown to have a lot of these features in common with human beings to a very high degree. Additionally there are humans which may not have a lot of these features, it may be due to congenital diseases, accidents or other diseases. In that case some animals would be considered more self aware and have more personhood than some humans. To base the rights of individuals, humans and animals, based on their personhood and awareness would mean to have to dismiss the rights of certain human beings due to their lack of such features.
Conclusion
There are a great many arguments and issues that come with xenotransplantation. It is still largely at an experimental stage where we are not even sure if it will be successful or not. Even with the potential benefits of these clinical trials all the prior experiments haven’t caused a great deal of change or very minimal at that. It is important to continue to discuss whether the potential benefits are more important and will surely cause a plethora of changes that it is ethically sound to inflict pain and suffering to animals at large for it.
Animal experimentation is still a heavily debated and controversial topic that is being tackled to this day. Even with all these disagreements it is justifiable to say that there are a number of procedures and experiments that are downright unethical to inflict or continue to do so on any individual, human or animal. These procedures have minimal benefits and are endlessly painful and cruel to the subject being experimented on. With further research we can determine whether xenotransplantation is one of those experiments. Is it worth it or is it just a vicious and selfish way of using our power for a not even largely beneficial gain?
Bibliography
Cooper, D. K., Ekser, B., & Tector, A. J. (2016, November 1). A brief history of clinical xenotransplantation.
Matthewroop. (2025, February 24). What is xenotransplantation, and how far away is it?
Research, C. F. B. E. A. (2021, March 3). Xenotransplantation.
(2024, November 4). Animal-to-human transplants: the ethics of xenotransplantation.
Gilbert, S. (2022, January 19). Xenotransplantation: three areas of concern.
Erlbraum, C. (2018). Xenotransplantation:The Science, the Advantages, the Ethics.
