A team of stem cell researchers in Israel have created artificial mouse embryos without using sperm or eggs; then they grew them in an artificial womb for eight days, a development that opens a window into a realm of fascinating science that could one day be used to create replacement organs for human beings.
The discovery of stem cells and their ability to take the form of any type of cell in the body has opened many doors in the field of medicine. From curing baldness to curing HIV, stem cells can be used everywhere. Studies have shown that stem cells are also present in small numbers in organs such as the skin, which constantly renews itself throughout our lives. The process requires cells of different types, and this is where the multiple potency of stem cells comes in handy.
The goal, the scientists involved in the research said, is not to create mice or babies outside the womb, but to advance understanding of how organs develop in embryos and use that knowledge to develop new ways to heal people.
medical milestone
“The embryo is the best machine for making organs and the best 3D bioprinter ; we try to emulate what it does,” explains Jacob Hanna of Weizmann’s Department of Molecular Genetics, who led the research team. Hanna explains that scientists already know how to restore “stemness” to mature cells. In fact, the pioneers of this cellular reprogramming won a Nobel Prize in 2012. However, going in the opposite direction, that is, making stem cells differentiate into specialized body cells, not to mention forming whole organs, has been very successful. more complicated.
“Until now, in most studies, specialized cells were often difficult to produce or aberrant, and tended to form a mixture rather than well-structured tissue suitable for transplantation. We were able to overcome these obstacles by unlocking the self-organizing potential encoded in stem cells.”
Embryos from stem cells
The researchers used stem cells that had been grown for years in a petri dish in the laboratory. Before being placed in a special incubator, these cells were divided into three groups. While one was not treated to become embryonic stem cells, the other two were pretreated over a 48-hour period to express genes that were master regulators of the placenta or yolk sac. Cells were mixed once more in the incubator and allowed to grow. While most did not develop properly, 0.5 percent, or 50 of 10,000 cells, developed into spheres, which then took the elongated shape of embryos.
These synthetic models developed normally until day 8.5 (nearly half of the mouse’s 20-day gestation), by which time all of the early organ progenitors had formed, including a beating heart, circulating stem cells blood vessels, a brain with well-formed folds, a nerve tube, and an intestinal tract. The synthetic models showed 95 percent similarity in both the shape of the internal structures and the gene expression patterns of different cell types.
“Our next challenge is to understand how stem cells know what to do, how they self-assemble into organs and find their way to their assigned places within an embryo. And because our system, unlike a uterus, is transparent, it can be useful for modeling birth defects and implantation of human embryos”, comment the experts, in their study published in the journal Cell.
In addition to helping reduce the use of animals in research, synthetic embryo models could become a reliable source of cells, tissues and organs for transplantation in the future.
Reference: Reference: “Post-Gastrulation Synthetic Embryos Generated Ex Utero from Mouse Naïve ESCs” by Shadi Tarazi, Alejandro Aguilera-Castrejon, Carine Joubran, Nadir Ghanem, Shahd Ashouokhi, Francesco Roncato, Emilie Wildschutz, Montaser Haddad, Bernardo Oldak, Elidet Gomez -Cesar, Nir Livnat, Sergey Viukov, Dmitry Lukshtanov, Segev Naveh-Tassa, Max Rose, Suhair Hanna, Calanit Raanan, Ori Brenner, Merav Kedmi, Hadas Keren-Shaul, Tsvee Lapidot, Itay Maza, Noa Novershtern and Jacob H. Hanna , 1 August 2022, Cell.
DOI: 10.1016/j.cell.2022.07.028
