Scientists use human stem cells to model preembryos

Scientists are using human stem cells to create structures that can mimic the pre-embryo and serve as an alternative to real embryos.

They say these “blastoids” provide an efficient and ethical way to study human development and pursue biomedical discoveries in childbirth and contraception.

Latest efforts Explained in detail on Thursday Journal Nature. Although the structure is not an embryo, scientists still respected long-standing ethical guidelines and did not grow for more than two weeks.

Blastoid is a model of a blastocyst that is formed within a week after fertilization and is a sphere of cells about the width of a hair. Nicholas Liveron, a researcher at the Austrian Academy of Sciences and one of the authors of the Nature Paper, said the model is a “great alternative” to human embryos for research.

“It is very difficult to discover molecules, genes, and principles using such human embryos, which allows us to better understand development and make biomedical discoveries,” Rivron said. Says.

However, he said, laboratory-created substitutes could be created, modified, and researched in large numbers, complementing earlier research.

“This unleashes the potential for scientific and biomedical discoveries,” he said. For example, what researchers have learned in the study of blastoids can be used to develop hormone-free contraceptives.

Magdalena Zernika Getz, a stem cell biology expert at the University of Cambridge who wasn’t involved in the latest research, said this isn’t the first time scientists have created human precursor cells. But “every step is important,” she said, improving efficiency when researchers try to master the model.

To create the blastoid, Rivron and his colleagues used two different types of stem cells. Embryonic stem cells from previously established cell lines, or stem cells reprogrammed from adult cells such as skin cells. No new germ cell line was created for the study.

In the future, he said, stem cells reprogrammed from adult cells are likely to become the new standard of research, but now that established embryonic cell lines are “still the ultimate standard”. is necessary. He said that the blastocysts were cultured separately and compared side-by-side with the structures created in the laboratory.

This study showed that Blastoid reliably replicates important stages of early embryonic development. Upon contact with hormone-stimulated endometrial cells, about half of them began to attach and grow, similar to blastocysts.

According to Livron, the researchers stopped growing after 13 days and analyzed the cells. At that time, he said, the collection of cells did not reflect 13-day-old embryos. They weren’t growing enough and weren’t organized.

He said ethical concerns were also involved. For decades, the “14-day rule” for embryo growth in the laboratory has guided researchers. Earlier this year, the International Stem Cell Research Association recommended easing the rules under limited circumstances.

Livron, who is part of a working group that has updated the social guidelines, said that blastoids are not subject to the same rules, but that the guidelines should not be transferred to animals or humans.

“It’s very clear that blastoids aren’t embryos … and if not, why apply the 14-day rule to these structures?” He said. Nevertheless, they decided to quit “for transparency and to ensure that things are very well understood by the masses.”

Dr. Barbara Golder, Editor-in-Chief of The Linacre Quarterly, a journal of the Catholic Medical Association, said the development of blastoids shows “how science advances.” But she said it was problematic for embryonic cell lines to remain the standard of science.

“As long as there is a link to stem cells from an aborted fetal and a set of stem cell lines needs to be correlated with one from embryonic stem cells, there are ethical issues,” she said. .. ..

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