Using stem cells, they made synthetic mice

According to the Associated Press, scientists have successfully manufactured artificial mouse embryos using stem cells, which means that the embryos did not need sperm, eggs, or a uterus.

Up until the eighth day following conception, mouse embryos generated in the lab are indistinguishable from those conceived naturally. The same structures, including one that looks like a heart in motion, are present in both.

Short-term goals for using these embryos include reducing the number of laboratory animals used for research on early stages of development and disease processes. Moreover, they could open the path for future studies including the use of human embryos.

Magdalena Zernicka-Goetz of Caltech and her colleagues reported their study’s findings in Nature. This is another another piece detailing the creation of synthetic mouse embryos.

This month, Jacob Hanna and coworkers from Israel’s Weizmann Institute of Science published a similar research in the journal Cell. Also contributing to the Nature publication is Hanna.

According to stem cell biologist Zernicka-Goetz, studying embryonic development is important since up to 70% of in vitro fertilization embryos do not implant and develop, and the majority of human pregnancies are lost in the early stages. She notes that the scarcity of human embryos given for research is one of the obstacles to studying natural development. In addition, there are moral restraints.

The development of embryo models provides an alternate strategy for investigating these concerns.

Scientists mixed embryonic stem cells with two other kinds of stem cells, all from mice, to generate the synthetic embryos, or embryoids, detailed in the Nature publication. To facilitate the merging of the three cell types, they developed a unique dish. Zernicka-Goetz claims that the best of the embryos they made were “indistinguishable” from normal mouse embryos, despite the fact that the embryos they created weren’t flawless. They create structures resembling both hearts and heads.

She claims that this is the first model that permits the study of brain development alongside the development of the complete mouse embryo.

Zernicka-Goetz and Hanna have both said that their respective organizations have been doing this study for quite some time. Zernicka-Goetz said that her team’s findings were published in Nature last November.

The researchers stated the next step was to attempt to coax the synthetic mouse embryos to continue developing through day eight, with the ultimate objective of carrying them to term (which in a mouse is 20 days).

Gianluca Amadei, a researcher at the University of Cambridge and co-author of the study published in Nature, said that it is “impossible to pass” the eight-and-a-half-day barrier at this point.

After around 11 days of development, scientists believe the embryo will die without a placenta, but they hope to one day discover a technique to construct a synthetic placenta as well.

The scientists added that they do not plan to develop human versions of these synthetic embryos in the near future, but they do think it is possible.

Human stem cells have been utilized before to make a “blastoid,” a pre-embryonic tissue that may stand in for a genuine embryo in scientific experiments.

Inherently unethical labor conditions are common in this field. The “14-day rule” has been used as a standard by scientists to determine how long human embryos should be grown in the lab for. The International Society for Stem Cell Research last year proposed allowing exceptions to the norm in certain cases.

The creation of a human being from a synthetic embryo is not feasible, and scientists insist on this point.

Luis Montoliu of Spain’s National Center for Biotechnology, who was not involved in the study, stated, “Without a doubt, we are experiencing a new technological revolution that is currently highly inefficient but has huge promise.”

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