Human-like kidneys are being grown in pigs by scientists

Chinese researchers have created human-cell-containing kidneys in pig embryos, a global first that may one day assist to alleviate the scarcity of organ donors. However, the result, which was reported in a paper published on Thursday in the journal Cell Stem Cell, poses ethical questions, particularly because some human cells were also discovered in the pigs’ brains, according to experts.

Because kidneys are one of the earliest organs to grow and the most often transplanted in human medicine, the Guangzhou Institutes of Biomedicine and Health researchers concentrated on kidney development.

However, prior efforts to grow human organs in pigs have failed, according to lead 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 previous high-profile American successes, where genetically altered pig kidneys and even a heart have been implanted inside people, this method is less risky.

It “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 very 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 kind 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.

Five embryos were chosen for examination, and it was discovered that their kidneys were functionally normal for their developmental stage and had started to create the ureters that would later join them to the bladder.

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.”

Because there is a chance of the uncontrolled formation of human-pig hybrids, it is thought to be essential to prevent the invasion of human cells into reproductive tissue.

But Darius Widera, a professor of stem cell biology at the University of Reading, stated that the existence of any human cells in the pig brains still raises questions.

“Although this approach is clearly a milestone and the first successful attempt to grow whole organs containing human cells in pigs, the proportion of human cells in the generated kidneys is still not high enough,” the researcher said.

Although they acknowledge it isn’t currently ready, the team eventually hopes to refine its method for use in human transplants.

The kidneys’ vascular cells, which might result in rejection if transplanted into a person, was a significant drawback.

However, the researchers want to continue and give the kidneys more time to mature. Other human organs, such the heart and pancreas, are being grown in pigs as well.