Human–animal chimeras: ethical issues about farming chimeric animals bearing human organs

Abstract

Recent advances in stem cells and gene engineering have paved the way for the generation of interspecies chimeras, such as animals bearing an organ from another species. The production of a rat pancreas by a mouse has demonstrated the feasibility of this approach. The next step will be the generation of larger chimeric animals, such as pigs bearing human organs. Because of the dramatic organ shortage for transplantation, the medical needs for such a transgressive practice are indisputable. However, there are serious technical barriers and complex ethical issues that must be discussed and solved before producing human organs in animals. The main ethical issues are the risks of consciousness and of human features in the chimeric animal due to a too high contribution of human cells to the brain, in the first case, or for instance to limbs, in the second. Another critical point concerns the production of human gametes by such chimeric animals. These worst-case scenarios are obviously unacceptable and must be strictly monitored by careful risk assessment, and, if necessary, technically prevented. The public must be associated with this ethical debate. Scientists and physicians have a critical role in explaining the medical needs, the advantages and limits of this potential medical procedure, and the ethical boundaries that must not be trespassed. If these prerequisites are met, acceptance of such a new, borderline medical procedure may prevail, as happened before for in-vitro fertilization or preimplantation genetic diagnosis.

Human‐Animal Chimeras: The Moral Insignificance of Uniquely Human Capacities

“…The main concern is that the human stem cells could theoretically contribute to the chimeric animals’ brains and thereby cause them to develop cognitive capacities that regular pigs or monkeys lack . Accordingly, many commentators recommend developing safeguards to prevent the human stem cells from forming neural tissues . Of course, insofar as the aim of such research is to create human neurons or humanlike brains—whether for drug testing, research purposes, or human neuron transplantation—it will be impossible to circumvent the relevant ethical concerns in this way.…”

Newspaper coverage of human‐pig chimera research: A qualitative study on select media coverage of scientific breakthrough

“…Additionally, the body of knowledge currently known about pig cell administration in humans from xenotransplantation trials is likely to help identify the infectious, immunological, and technical risks and barriers to overcome. 5 The article published in Cell Magazine by Jun Wu, Juan Carlos Belmonte, and their group at the Salk institute on January 26, 2017, is thus an important breakthrough for the field of genetics and its research application in humans. The article first established a working chimeric rodent model using rat pluripotent stem cell injected into mouse blastocysts which gave rise to rat-mouse chimeras that developed into adulthood.…”

In Vitro Production of Embryos: Principles, Techniques and Applications

“…However, there are serious technical barriers and complex ethical issues that must be discussed and solved before producing human organs in animals. The main ethical issues are the risks of consciousness and of human features in the chimeric animal due to a too high contribution of human cells to the brain or to the limbs [24]. Another critical point concerns the production of human gametes by such chimeric animals [25].…”