Human brain organoid transplantation: ethical implications of enhancing specific cerebral functions in small-animal models

Abstract

Brain organoids are self-organizing, three-dimensional tissues derived from pluripotent stem cells that recapitulate many aspects of the cellular diversity and architectural features of the developing brain. Recently, there has been growing interest in using human brain organoid transplantation in animal models as a means of addressing the limitations of in vitro culture, such as the lack of vascularization, and to explore the potential of organoids for neural repair. While there has been substantial debate on the ethical implications of brain organoid research, particularly the potential for organoids to exhibit higher-order brain functions such as consciousness, the impact of human organoid grafts on animal hosts has been less extensively discussed. Enhancement of host animal brain function may not be technically feasible at this time, but it is imperative to carefully consider the moral significance of these potential outcomes. Here, we discuss the ethical implications of enhancing somatosensation, motor processes, memory, and basic socialization in small-animal models. We consider the moral implications of such outcomes and if safeguards are needed to accommodate any increased moral status of animals transplanted with human brain organoids.