The making of cells and organs in xenogeneic animal bioreactor

For patients with end-stage organ dysfunction, organ transplantation is the only viable treatment option. However, the most significant challenge at present is the severe shortage of donor organs, and no technology exists that allows for long-term, sustainable organ generation. The utilization of xenogeneic animals as in vivo bioreactors constitutes a viable method for the generation of functional and transplantable cells, tissues, and organs in vivo. The primary technology, blastocyst complementation, involves the injection of donor pluripotent stem cells into an organogenesis-disabled host embryo. This allows donor stem cells to compensate for organ defects and ultimately generate tissues or organs derived from the donor. Recent advancements in the field have demonstrated the successful generation of xenogeneic tissues and organs in rodents and large animals through the utilization of blastocyst complementation techniques. In addition, the replacement of nephron progenitor cells in the kidneys can be achieved through the application of the organogenic niche method. Furthermore, the expansion of xenogeneic hepatocytes and blood cells in immunodeficient animals is a viable approach. In this review, we introduce the history of blastocyst complementation and the impact of the pluripotent state of stem cells, one of its elements, on chimeric efficiency. Additionally, we provide a synopsis of the research progress concerning the utilization of rodents, pigs, and cattle as in vivo bioreactors to generate xenogeneic cells, tissues, and organs. Finally, the potential opportunities, challenges, and prospects for generating human blood cells in pigs are discussed.