2023-09-07 18:21:16
In this study, the results of which were published Thursday in the scientific journal Cell Stem Cellresearchers from the Canton Institute of Biomedical and Health Sciences focused on the kidneys, as they are both among the earliest organs to develop and the most commonly transplanted in 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 trying to grow a pig embryo into a pig embryo. kidney as close as possible to that of a human.
“Rat organs had previously been grown in mice, mouse organs in rats, but past attempts to grow human organs in pigs had failed,” 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, stem cell specialist at King’s College London, this study “describes the founding steps of a new approach in the bioengineering of organs using pigs as incubators for the growth of human organs”.
In addition to ethical issues, there are still many challenges for this experiment to be a viable solution to the shortage of organ donations, “but it is nonetheless a fascinating strategy that deserves to be explored. 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 compete with human ones. To overcome this hurdle, 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 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 to say 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. However, five of the embryos chosen for analysis had functioning kidneys for this stage of development and were beginning to develop a urethra which 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 were found in the genitals of the pigs, their presence outside the kidneys, and especially in the brain, raises ethical questions regarding the 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 successful first attempt to grow organs containing human cells in pigs, the proportion of human cells in the generated kidneys still does not remain very high,” he said. -he adds.
For the time being, 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 produced in this way retain a system of vascular cells inherited from the pig, which risks causing rejection in the event of transplantation of these organs into a human.
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