In this blog post, we will consider whether genetic engineering experiments on pigs for the treatment of dementia are ethical.

Introduction

With the development of genetic engineering and technologies that manipulate the characteristics of life, research on gene function and its applications is actively underway. In particular, there is still intense interest in genetic engineering of animals and plants and how it can improve human life.
Animal genetic engineering refers to the artificial manipulation of animal genes to regulate their functions. Traditionally, genetically modified animals have been used to increase animal productivity through the selection and breeding of superior breeds and improvements in feeding management techniques. However, with the advancement of technology, its scope is gradually expanding.

What is genetic engineering?

Genetic engineering is being carried out in various ways on animals such as mice, rabbits, and cows. However, in relation to this topic, we will limit our discussion to genetically engineered pigs, which require ethical consideration.
Genetically modified pigs are developed for various reasons in various fields. For example, they are genetically modified to increase muscle mass explosively, as in the movie Okja by Korean director Park Chan-wook, and pigs resistant to porcine epidemic diarrhea (PED) are also created through genetic modification. Muscle pigs are efficient because they require less time and money to develop new pig breeds, and PED-resistant pigs play an effective role in preventing PED infection and developing vaccines, demonstrating the great advantages of animal genetic engineering technology.
However, these are not the only types of pigs. As mentioned earlier, genetically modified pigs are developed for various purposes. Among them, there are pigs developed for human benefit and to improve the quality of life. The two examples of pigs mentioned in the previous paragraph may ultimately be ethically problematic because they seek efficiency as food for humans, but pigs developed as alternatives for treating human diseases and saving lives may be even more ethically problematic and require more social discussion. Therefore, this article will focus on genetically modified pigs, excluding the examples mentioned in the previous paragraph.

Disease model pigs

First, there are “disease model pigs” that suffer from diseases similar to those of humans. These genetically modified pigs, also known as “immunodeficient pigs,” are born from surrogate mothers through somatic cell nuclear transfer or developed by transplanting human tissue. The most commonly used method is human tissue transplantation, which has the advantage of being relatively easy to develop because the transplanted tissue does not cause an immune response in pigs. For example, transplanting tissue from a person with liver cancer into a pig creates a “liver cancer disease pig,” and transplanting skin from an atopic patient into a pig creates an “atopic disease pig.”
A specific example of such a disease is dementia. According to 2014 health insurance statistics, approximately 70,000 people suffer from dementia. However, treatments are limited to improving cognitive function. In clinical trials, which are an important step in the development of new drugs, the toxicity of drugs is tested on mice, but because of the genetic differences between mice and humans, results that are successful in mice often fail in clinical trials. An alternative to this is clinical trials using large animals, and pigs are the most commonly mentioned animal for this purpose.
In 2016, a team of professors from Seoul National University’s College of Veterinary Medicine unveiled “dementia pigs” that exhibited behaviors similar to those of dementia patients, such as being unable to find simple paths and forgetting the location of automatic waterers. These pigs are genetically modified animals created for the purpose of treating dementia in humans.

Chimera pigs

The second example is “chimera pigs” with human organs. According to statistics from the Organ Transplant Management Center, as of 2014, only 15% of organ transplant candidates receive organ transplants, and 220,000 patients die every day due to organ shortages. To solve this problem, research is being conducted on xenotransplantation, which involves transplanting pig organs into humans, and on “chimera pigs,” which involve growing human organs in pigs.
The term “chimera pig” may be unfamiliar to many, but “chimera” refers to the phenomenon in which tissues with different genetic properties coexist within a single organism. Chimera pigs are genetically modified animals created as an alternative solution to the problem of human organ transplants.
In 2016, a research team in the US conducted research by injecting human induced pluripotent stem cells (iPS) into pig embryos whose genes had been edited to prevent the growth of the pancreas, and then implanting them into the uterus of a surrogate pig. The iPS cells used in this experiment were developed by a team of professors at Kyoto University in Japan. These cells are pluripotent stem cells that can be differentiated into various tissues by dedifferentiating somatic cells. Therefore, although the pig embryos used by the research team did not have the genetic information to create a pancreas, they could “theoretically” differentiate into a pancreas through the injection of iPS cells.
However, even if the pancreas differentiates successfully, it cannot be immediately transplanted into humans. This is because although the pancreatic cells are human, the blood vessels connected to the pancreas are still those of a pig. This is why this research is still “theoretical.”
In addition, pigs have a unique sugar in their blood vessel endothelium that humans do not have. The exact name is alpha-1,3-galactose transferase. Primates, including humans, are born with natural antibodies to this sugar, so if an organ connected to a pig’s blood vessels is transplanted into a human, an immune response occurs and the transplanted organ is destroyed within a few minutes or, at most, a few hours.
Due to this problem, several professors have stated that the next step in research should be to inject human iPS cells into pig embryos whose genes for creating blood vessels have been edited, as in the case of pancreatic editing. If the final experiment is successful, pigs will have human blood vessels, which is expected to solve the immune problem to a certain extent.
Although research on chimera embryos and chimera pigs has opened up great possibilities for interspecies transplantation, it has also sparked heated ethical debates. In September last year, the US National Institutes of Health announced that it would stop funding research on injecting human stem cells into other vertebrate embryos during the blastocyst stage, which is the stage before the embryo differentiates into tissues and organs. The US research team mentioned above announced that, out of ethical concerns, they had only grown chimera pig-human embryos in a surrogate uterus for 28 days.

Advantages of genetically modified animals

Genetically modified animals are efficient for developing new breeds because they undergo a process of artificial gene editing and correction. This takes less time than the traditional method of waiting for natural mutations to occur and is also less expensive. Therefore, genetically modified animals can produce better and higher quality animals.
Take pigs, for example. Genetically modified pigs have tender meat and, even when fed the same amount as normal pigs, their muscles grow more than twice as large, which could bring about revolutionary changes in the pig farming and livestock industries. This is because they are highly productive.
In addition, genetically modified animals can serve as an effective catalyst for the development of treatments for human diseases. This is because it enables personalized medicine.
Like genetically modified plants, genetically modified animals have the potential to gradually solve the food shortage problem facing humanity.

Ethical issues surrounding genetically modified animals

However, the ethical issues associated with this technology cannot be easily overlooked. Specifically, in the case of the chimera pigs introduced earlier, it is impossible to completely rule out the possibility that iPS cells may differentiate into tissues other than the target organs. In an extreme case, if they differentiate into brain cells, it could affect the cognitive abilities of the animals, which would raise ethical issues from the perspective of animal rights and protection.
Safety issues are also important. Currently, there are no genetically modified pigs sold for human consumption, but if genetically modified pigs are commercialized as an alternative to food shortages or other problems in the future, safety verification procedures will be essential. Research is needed on the effects of consuming such animals on the human body and how they will affect future generations if accumulated over the long term.
In addition to ethical issues, legal aspects are also important. With the advancement of genetic engineering technology, various methods are being applied, ranging from the insertion of previously non-existent genes to the induction of minute mutations, and the risks vary accordingly. Although such research is essential for the advancement of life sciences, it is necessary to discuss the scope of regulation, standards, and risks of such research in conjunction with ethical issues.

Conclusion

From an ethical standpoint, I am opposed to genetically modified animals. I believe that it is wrong to violate animal rights and create animals that must live with unwanted artificial mutations.
Furthermore, taking organ transplants from animals as an example, as technology advances, it may become possible to transplant not only digestive organs such as the stomach and liver, but also the brain of a pig, which is responsible for cognitive functions, into humans. If I were to find myself in such a situation, I would be confused and struggle with my identity.
In addition to ethical issues, technological advances that go against the laws of nature frighten me. I think people need to be more aware of how these technological advances will affect us humans.
As life sciences advance and technology becomes more sophisticated, the benefits of genetically modified animals may become even greater than they are now. This will also increase their impact on humans. Furthermore, there is no way to stop technological advancement. Genetic animal research will continue. However, it is necessary to discuss the ethical issues that it raises and consider the risks in order to reach a social consensus and establish rules. Genetic engineering clearly has advantages, so I believe that we should make good use of it to promote the healthy coexistence of animals and humans.