Chinese scientists have succeeded in developing kidneys containing human cells in pig embryos, a first in the world that raises ethical questions and could provide new ways to address the shortage of organ donors.
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 kidneys because they are among the first organs to grow and are often transplanted into humans.
If researchers in the United States recently succeeded in transplanting genetically modified pig kidneys, or even a heart, into humans, scientists in China have chosen another approach by trying to transplant a pig embryo into a pig embryo. That human.
“Mut organs have already been transplanted into mice, and mouse organs into mice, but previous attempts to transplant human organs into pigs have ended in failure,” said Liangxu Lai, one of the study’s lead authors.
“Our approach has improved the incorporation of human cells into recipient tissues and allows us to grow human organs in pigs,” he adds.
For Dusko Ilić, a stem cell specialist at King’s College London, this study “describes the foundational stages of a new approach to organ bioengineering using pigs as an incubator for human organ growth.”
In addition to the ethical issues, there are still many challenges facing this experiment to constitute an effective solution to address the shortage of organ donors, “but it is nonetheless a wonderful strategy that deserves to be delved into,” adds this specialist who did not participate in this experiment. Chinese study.
– Hereditary ‘status’ –
One of the major challenges in creating such hybrids is that pig cells compete with human cells. To overcome this obstacle, the Canton Institute team used a new genome-editing tool called CRISPR, which allowed them to cut DNA at a specific location.
Specifically, they cut out two genes associated with kidney development in the pig fetus to create what they call a “niche.” Then they added human pluripotent stem cells, that is, capable of turning into any type of cell.
In total, the researchers implanted 1,820 embryos into 13 surrogate mothers and terminated their pregnancies after 25 to 28 days to see if the experiment was successful.
But five of the fetuses selected for analysis had functioning kidneys by this stage of development, and were beginning to develop the urethra that would eventually connect the kidneys to the bladder.
The researchers concluded that it was composed of between 50% and 60% of human cells.
“We discovered that by creating a suitable niche in the pig embryo, this allows human cells to take their place naturally,” said Chen Dai, co-author of the study, adding that human cells have been found in the spinal cord and brains of pigs. Pigs.
Although no human cells have been found in pig reproductive organs, their presence outside the kidneys, especially in the brain, raises ethical questions about the hybrid creatures, notes Darius Videra, professor of molecular biology at the University of Reading.
“If this applies to a fresh room in the bathroom and a pre-existing tent on the surface of the organs that contain human cells in the porcs, the proportion of human cells in the reins that do not remain in the upper reaches,” he adds. .
At the moment, the Chinese team admits that it is not ready to transplant one of these kidneys into a human, but hopes to get there one day by improving its technology.
One major problem is that kidneys produced in this way retain a system of vascular cells inherited from pigs, which could cause rejection if these organs were transplanted into humans.
In addition to the kidneys, the Canton Institute team is already working on transplanting other human organs into pigs, such as the pancreas or heart.
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