Tuesday, October 19

Scientists form clusters of human cells that act like early-stage embryos | Mother cells

Scientists have created clumps of human tissue that behave like early-stage embryos, a feat that promises to transform research into the first tentative steps of human development.

The clusters of cells, called blastoids, are less than a millimeter in diameter and resemble structures called blastocysts, which form within days of fertilization of an egg. Normally, blastocysts contain about 100 cells, which make up all the tissues in the body.

Two teams of researchers discovered that they could produce tiny blastoids from stem cells or reprogrammed skin cells by culturing them in 3D wells filled with a broth that contained the chemicals necessary for normal blastocyst formation.

In pull apart documents Published in Nature, the scientists describe how the cells self-assembled into ball-shaped blastoids after six to eight days in culture. The tests revealed that they contained all the cells seen in natural blastocysts. Some were attached to plastic culture dishes, mimicking the implantation process in the uterus.

By studying blastoids, scientists hope to learn how newly formed embryos develop in the run-up to implantation and to understand why so many miscarriages occur at this delicate stage of human pregnancy.

Additional work will use cells to understand how particular birth defects can arise and investigate the impact of environmental toxins, medications, and even viral infections on healthy embryonic development.

“We believe that the ability to work at scale will revolutionize our understanding of these early stages of human development,” said Professor José Polo, who led one of the teams at Monash University in Australia.

Until now, research on the early stages of human development has relied heavily on couples donating surplus IVF embryos to science. The practice has raised ethical objections and limited donations have severely restricted the progress of scientists. By law, researchers can only study human embryos until they are 14 days old.

The creation of blastoids should overcome these problems by allowing scientists to create hundreds of embryo-like structures in the laboratory at one time.

“We are very excited,” said Jun Wu, assistant professor at the University of Texas Southwestern Medical Center in Dallas, Texas, and leader of a separate team. “Studying human development is really difficult, especially at this stage of development. It’s essentially a black box. ”Wu said the blastoids were cultured until about day 10 for a human embryo.

Matrix of stained blastoids.  Scientists say their cell research could help understand the causes of early miscarriage and infertility
Matrix of stained blastoids. Scientists say their cell research could help understand the causes of early miscarriage and infertility. Photograph: Monash University / PA

Naomi Moris, from the Francis Crick Institute in London, who uses stem cells to model human embryo development, described the work as important and highlighted the rapid advances that are being made in this field. “The thrill of these models is that hopefully we can use them to begin to understand how normal human development progresses and what processes may be at play when things go wrong – in miscarriage or birth defects, for example,” he said. .

Polo and Wu said that while the blastoids were similar to early-stage embryos, they were not identical and could only mimic the first week of human development. The approach will not be used to produce embryos for implantation, said Amander Clark of the University of California, Los Angeles, who worked with Polo.

But in an accompanying article in Nature, scientists at the University of Michigan suggested that progress in science would lead to blastoids that more closely mimic human blastocysts.

The scientists, Yi Zheng and Jianping Fu, wrote: “This will inevitably lead to bioethical questions. What should be the ethical status of human blastoids and how should they be regulated? Should the 14 day rule apply? These questions will need to be answered before research on human blastoids can proceed with due caution. “


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