2023-09-10 16:15:42
Chinese scientists have succeeded in developing kidneys containing human cells in pig embryos, a world first which raises ethical questions and might offer new avenues in the face of the shortage of organ donations.
In this study, the results of which were published Thursday in the scientific journal Cell Stem Cell, researchers from the Guangzhou Institute of Biomedical and Health Sciences focused on the kidneys because they are among the first organs to grow and most often transplanted into humans.
If researchers in the United States have recently succeeded in transplanting genetically modified pig kidneys, or even a heart, into humans, scientists in China have opted for another approach by attempting to grow a pig embryo in a pig embryo. kidney as close as possible to that of a human.
“Rat organs had already been grown in mice, mouse organs in rats, but past attempts to grow human organs in pigs ended in failure,” Liangxue Lai said in a statement. one of the main authors of the study.
“Our approach has improved the integration of human cells into recipient tissues and allows us to grow human organs in pigs,” he adds.
For Dusko Ilic, a stem cell specialist at King’s College London, this study “describes the founding stages of a new approach in the bioengineering of organs using pigs as an incubator for the growth of human organs”.
Besides ethical issues, there are still many challenges for this experiment to constitute a viable solution to deal with the shortage of organ donations, “but it is nevertheless a fascinating strategy that deserves to be dug”, adds this specialist who did not participate in this Chinese study.
– A genetic “niche” –
One of the main challenges in creating such hybrids is that pig cells will compete with human ones. To overcome this obstacle, the Canton Institute team used a new genome editing tool called CRISPR that allowed them to cut DNA at a specific location.
Specifically, they cut out two genes related to kidney growth in the pig embryo to create what they call a “niche.” Then they added pluripotent human stem cells, that is, capable of transforming into any type of cell.
In total, the researchers transplanted 1,820 embryos into 13 surrogate mothers and terminated their pregnancies between 25 and 28 days later to see if the experiment was successful or not.
But five of the embryos chosen for analysis had functioning kidneys for this stage of development and were beginning to develop a urethra that would eventually connect the kidneys to the bladder.
And they were composed of between 50% and 60% human cells, the researchers concluded.
“We discovered that by creating a niche in the pig embryo, this allows human cells to naturally take their place,” said Zhen Dai, co-author of the study, adding that human cells had however been found in the spinal cord and brains of pigs.
Although no human cells have been found in the genitals of pigs, their presence outside the kidneys, and particularly in the brain, raises ethical questions regarding hybrid creatures, notes Darius Widera, professor of molecular biology at the University of Reading.
“Although this approach is a new milestone in research and a first successful attempt to grow organs containing human cells in pigs, the proportion of human cells in the kidneys generated still does not remain very high,” he said. -he adds.
For the moment, the Chinese team admits that it is not ready to transplant one of these kidneys into a human, but it hopes to get there one day by refining its technique.
And one of the main problems is that the kidneys thus produced retain a system of vascular cells inherited from pigs, which risks causing rejection if these organs are transplanted into a human.
In addition to kidneys, the Canton Institute team is already working on growing other human organs in pigs, such as a pancreas or a heart.
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