Chinese scientists have achieved a groundbreaking feat by successfully growing kidneys that contain human cells in pig embryos. This landmark achievement has the potential to address the critical shortage of organs for transplantation. However, this development raises significant ethical concerns, particularly since some human cells were found in the brains of the pigs involved in the experiment. The study describing this accomplishment was published in the journal Cell Stem Cell.
Scientists from the Guangzhou Institutes of Biomedicine and Health focused on kidneys due to their vital role as one of the earliest developing organs and commonly transplanted organs in human medicine. Previous attempts to grow human organs in pigs had failed, making this accomplishment truly exceptional. The research team, led by senior author Liangxue Lai, aimed to improve the integration of human cells into recipient tissues and enable the successful growth of human organs in pigs.
The Chinese research team used CRISPR gene editing to delete two essential genes responsible for kidney formation inside pig embryos. This genetic modification created a “niche” within the pig embryos. They then introduced specially prepared human pluripotent stem cells, known for their ability to develop into any cell type, into these niches. Before implanting the embryos into surrogate mothers, they nurtured them in test tubes with substances that supported the growth of both human and pig cells.
Out of the 1,820 embryos transferred into 13 surrogate mother pigs, the pregnancies were terminated at 25 and 28 days to evaluate the success of the experiment. Five selected embryos exhibited functionally normal kidneys for their stage of development, with growing ureters that would eventually connect to the bladder. These kidneys contained between 50 and 60 percent human cells. However, there were still concerns about the presence of human cells in the pig brains, which need to be addressed to avoid the creation of uncontrolled human-pig hybrids.
While this breakthrough represents a significant milestone in growing whole organs containing human cells in pigs, the proportion of human cells in the kidneys is still not sufficiently high. Darius Widera, a professor of stem cell biology at the University of Reading, highlighted concerns about the presence of human cells in pig brains. The invasion of human cells into reproductive tissue could have serious ethical ramifications. Furthermore, the kidney’s pig-derived vascular cells present a potential rejection risk if transplanted into humans.
The Way Forward
The Chinese research team acknowledges that their technology is not yet ready for human transplantation due to several limitations. To overcome these challenges, they plan to optimize their methodology and extend the duration of kidney development. Additionally, they are working on growing other human organs, such as the heart and pancreas, within pigs. Despite the promising progress made, there are still significant hurdles to overcome before this bioengineering approach becomes a viable solution for organ transplantation.
Chinese scientists have made an unprecedented breakthrough by successfully growing human-cell kidneys in pig embryos. This achievement has the potential to revolutionize organ transplantation by addressing the critical shortage of organs. However, the presence of human cells in the pigs’ brains raises ethical concerns, highlighting the need for careful consideration of the implications. While there are challenges to overcome, the research team remains committed to refining their technology and exploring the growth of other human organs in pigs. As science progresses, further ethical, legal, and social discussions will be necessary to navigate the complex landscape of organ bioengineering.
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