Big hopes for transplant patients are raised, scientists developed human-like kidneys in pigs, Chinese researchers have developed kidneys in pig embryos that contain human cells, a world first that could one day help to reduce the global shortage of organ donors.
However, the discovery, which was reported in a paper published on Thursday in the journal Cell Stem Cell, poses ethical questions, particularly given that some human cells were also discovered in the pigs’ brains, according to experts.
As the first organs to develop and the most often transplanted in human medicine, the Guangzhou Institutes of Biomedicine and Health researchers concentrated on kidneys.
However, prior attempts to grow human organs in pigs have failed, according to senior author Liangxue Lai. “Rat organs have been produced in mice and rat organs have been produced in rats,” she said in a statement.
The ability to develop human organs in pigs is made possible by our method, which enhances the incorporation of human cells into recipient tissues.
In contrast to recent high-profile American successes, where genetically altered pig kidneys and even a heart have been implanted inside humans, this method is less risky.
The new study “describes pioneering steps in a new approach to organ bioengineering using pigs as incubators for growing and cultivating human organs,” according to Dusko Ilic, a professor of stem cell sciences at King’s College London who was not involved in the study.
Developing the experiment into a workable solution would be difficult, Ilic said, but “nevertheless, this captivating strategy warrants further exploration.”
Editing genes
Because pig cells are more competitive than human cells, generating such hybrids has proved extremely difficult.
To get around the problems, the scientists utilized CRISPR gene editing to remove two genes required for kidney development from a pig embryo, so establishing a “niche.”
The niche was then filled with specially produced human pluripotent stem cells, which have the capacity to differentiate into any type of cell.
They developed the embryos in test tubes with nutrients that fed both the human and pig cells before implanting them in sows.
They used 13 surrogate women to get 1,820 embryos in total. To evaluate how well the experiment had gone, the fetuses were aborted at 25 and 28 days.
For their stage of development, the kidneys in the five embryos that were chosen for study were found to be functionally normal. Between 50% and 60% of them were made of human cells.
According to co-author Zhen Dai, “We discovered that if you create a niche in the pig embryo, then the human cells naturally go into these spaces.”
“We found no human cells in the genital ridge and only a very small number of human neural cells in the brain and spinal cord.”
However, Darius Widera, a professor of stem cell biology at the University of Reading, expressed concern about the possibility of human cells present in the pig brains.
“The proportion of human cells in the generated kidneys is still not high enough, despite the approach being a clear milestone and the first successful attempt to grow whole organs containing human cells in pigs,” he continued.
The team acknowledges that their technology isn’t quite ready but eventually hopes to optimize it for use in human transplants.
The kidneys’ vascular cells, which could result in rejection if transplanted into a human, was a significant drawback.
However, the team is already engaged in research to produce other human organs including the heart and pancreas in pigs.
