Chinese scientists have made a remarkable breakthrough in organ bioengineering by successfully growing kidneys containing human cells in pig embryos, providing a solution to the global organ donation shortage. This groundbreaking achievement, described in a study published in the journal Cell Stem Cell, holds immense promise for future medical advancements. However, the development raises ethical concerns as the presence of human cells was also detected in the pigs’ brains.
The researchers from the Guangzhou Institutes of Biomedicine and Health focused their efforts on kidneys, as they are among the first organs to develop and the most commonly transplanted in human medicine. Previous attempts to grow human organs in pigs had failed, making this accomplishment even more significant. The team’s approach involved improving the integration of human cells into recipient tissues, ultimately enabling the growth of human organs in pigs.
In contrast to recent high-profile breakthroughs in the United States, where genetically modified pig kidneys and even a heart have been transplanted into humans, the Chinese researchers adopted a different strategy. They used CRISPR gene editing to delete two genes crucial for the formation of kidneys in pig embryos, which created a “niche.” Specially prepared human pluripotent stem cells, capable of developing into any cell type, were then added to fill this niche. The embryos were grown in test tubes containing nourishing substances for both human and pig cells before being implanted into surrogate mothers.
Out of the 1,820 embryos transferred into 13 surrogate mothers, five were selected for analysis. These embryos exhibited functionally normal kidneys for their stage of development, with the beginnings of ureters that would eventually connect to the bladder. Remarkably, they contained between 50% and 60% human cells. While the breakthrough is significant, there are still challenges to overcome.
While preventing the invasion of human cells into reproductive tissue is crucial to avoid the uncontrolled creation of human-pig hybrids, the discovery of human cells in the pig brains raises concerns. The presence of any human cells in the animals’ brains demands careful ethical scrutiny. Darius Widera, a professor of stem cell biology at the University of Reading, commented that although this achievement is a milestone, the proportion of human cells in the produced kidneys is not yet high enough.
The long-term goal of the researchers is to optimize their technology for use in human transplantation. However, there are limitations that need to be addressed. The kidneys developed in the pig embryos had pig-derived vascular cells, which could potentially lead to rejection if transplanted into a human recipient. Despite this, the scientists remain determined and plan to continue allowing the kidneys to develop for a longer duration. Additionally, they are also working on growing other human organs in pigs, such as the heart and pancreas.
The Chinese scientists’ achievement in growing kidneys containing human cells in pig embryos represents a significant breakthrough in the field of organ bioengineering. While ethical concerns exist surrounding the presence of human cells in pig brains, this accomplishment opens doors to potential solutions for organ shortages in the future. Further exploration and research are warranted to optimize the integration of human cells, improve the proportion of human cells in the generated organs, and address the limitations of vascular cell rejection. By pushing boundaries and constantly innovating, scientists may eventually overcome these challenges and revolutionize the field of transplantation, offering hope to countless individuals waiting for life-saving organ transplants.