A group of scientists first developed pig embryos whose kidneys contain 50–60 percent human cells and that after 28 days of gestation in this animal they showed the normal structure for their phase of development.

So-called chimera embryos contain cells from two species, in this case human and pig, and are an area of ​​research for the still distant future. the possibility of creating human organs in other animals for transplants.

The Chinese researchers are publishing these results in the journal Cell Stem Cell, which notes that this is the first time a “humanized solid organ” has been cultured from another species, although similar methods have been used to create human tissues such as blood or skeletal muscle in pigs.

Team led by Guangzhou Institute of Biomedicine and Health Sciences (China) successfully created these chimeric embryos and transplanted them into sows.where the developing humanized kidneys had normal structure and tubule formation after 28 days.

Researchers Focused on Kidneys because they are among the first organs to develop and are also the most commonly transplanted in human medicine.

Until now, rat organs have been grown in mice and vice versa, but attempts to grow human organs in pigs have failed.

The Chinese team tested an approach that improves the integration of human cells, Liangxue La, the study’s coordinator, explained to the magazine.

The first step was create a “niche” inside the pig embryo so that human cells do not have to compete with pig cells.

To do this, they used the gene-editing tool CRISPR to create a one-cell pig embryo that was missing two genes necessary for kidney development.

After, developed human pluripotent stem cells (which can become any type of cell) to make them more susceptible to integration.

Before implanting the developing embryos into sows, the researchers grew the chimeras in conditions optimized to provide unique nutrients and signals to both human and pig cells, since they often have different needs.

results

The researchers transferred 1,820 embryos into 13 animals and, after 25–28 days, terminated the pregnancy and they extracted the embryos to evaluate whether the chimeras succeeded in creating humanized kidneys.

Five chimeric embryos were analyzed (two at 25 days postimplantation and three at 28 days), in which The humanized kidneys were “structurally normal.” at the stage of their development and consisted of 50-60% human cells,” the note adds.

The kidneys were at the mesonephros stage (the second stage of kidney development); They formed tubules and cell buds that eventually became the ureters connecting the kidney to the bladder.

The team also examined whether human cells were present in other embryonic tissues, which could have ethical implications, especially if numerous human cells were found in neural or germline tissues and the pigs were brought to term.

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However, human cells were located primarily in the kidneyswhile the rest of the embryo consisted of pig cells.

“If a niche is created in a pig embryo, human cells will naturally end up in these spaces,” explained lead author Zhen Dai from the Guangzhou Institute of Biomedicine and Public Health.

The researcher assured that they saw “very few” human neuronal cells in the brain and spinal cord and “none” in the genital ridge, indicating that “human pluripotent stem cells do not differentiate into germ cells.”

This work provides “important achievements in one of the areas that has attracted the greatest interest in recent yearsDevelop a model for producing organs suitable for transplantation by using pigs as a transport animal, according to Spanish nephrologist Rafael Matesans, who was not involved in the study.

The founder of the National Transplantation Organization, quoted by the Science Media Center (a platform that offers journalists scientific sources), recalled the pioneering research of the Spanish scientist Juan Carlos Izpisua, who demonstrated the possibility of hybridization between two species.

A team of Chinese researchers now wants allow humanized kidneys to develop over a longer period of time and they are working to create other human organs in pigs, such as the heart and pancreas.

While the long-term goal is to optimize this technology for human organ transplantation, the team acknowledges that the work will be complex and could take many years.

Growing a fully functional humanized organ in a pig will require some additional steps since organs are made up of multiple types of cells and tissues.

In this study, the scientists created a niche for only a portion of the cells, meaning that the kidneys have vascular cells derived from pigs, and this may lead to organ rejection when used in a transplant scenario, therefore, much more research is needed.

For now, the technology, says Miguel Esteban of the Guangzhou Institute of Biomedicine and Health, “opens a window into the study of human development” and developmental diseases.

(EFE)