CNN – A research team from the United States and England says they have created the world’s first synthetic human embryo-like structures from stem cells, bypassing the need for eggs and sperm. These embryo-like structures are in the earliest stages of human development: for example, they don’t have a beating heart or brain. But scientists say they may one day help understand the causes of genetic diseases or miscarriages.

The research raises important legal and ethical issues, and many countries, including the US, do not have laws governing the creation or processing of synthetic embryos. The pace of discoveries in the field and the increasing complexity of these models worry bioethicists as life approaches the edge.

Unlike human embryos obtained through in vitro fertilization (IVF), where there is an established legal framework, there are currently no clear rules governing human embryo models derived from stem cells. There is an urgent need for regulations that will provide a framework for the creation and use of stem cell-derived human embryo models, James Briscoe, research director at the Francis Crick Institute, said in a statement.

Dr. Magdalena Zernichka-Goetz described the work Wednesday at the International Society for Stem Cell Research’s annual meeting in Boston. Zernichka-Goetz, a professor of biology and biological engineering at Caltech and Cambridge University, said the study was accepted into a highly respected scientific journal but not published. The study was first reported by The Guardian.

Zernichka-Goetz and his team, together with a rival team in Israel, had previously described the creation of model embryo-like structures from mouse stem cells. These “embryos” showed the onset of a brain, heart, and intestinal tract after about eight days of development.

Zernichka-Goetz said the embryo-like structures his lab created were grown from individual human embryonic stem cells that were forced to develop into three different tissue layers. It normally contains the yolk sac, the placenta, and the cells that develop the embryo itself. He told CNN that the embryo-like structures created by his lab were also the first to contain germ cells that would develop into eggs and sperm.

“I just want to emphasize that they are not human embryos,” said Zernichka-Goetz. Said. “These are models of embryos, but they’re very exciting because they look so much like human embryos, and that’s a very important way of figuring out why so many pregnancies fail, because most pregnancies fail at the time of development when we are building these embryos.”

He said that as far as I know, this is the first time a human model embryo has been created consisting of three layers of tissue. But he stressed that while it mimics some features of a natural embryo, it doesn’t have all of them.

The researchers hope these model embryos will shed light on the “black box” of human development, the period from 14 days after fertilization, the agreed limit for scientists to grow and study embryos in the lab. Currently, artificial models of human embryos are limited to test tubes. It would be illegal to implant the cells in the womb, and animal studies with stem cells in mice and monkeys have shown that they don’t survive even when scientists try to implant them—probably because researchers don’t understand how to do it. completely recreate the conditions of pregnancy.

Zernichka-Goetz said the goal of her research is not to create life, but to prevent its loss, to understand why embryos sometimes fail to develop after fertilization and implantation.

“We know very little about this step in human development, but this is a time when many pregnancies are lost, especially in the IVF setting,” said Roger Sturmey, senior research fellow in the Department of Maternal and Fetal Health at the University of Manchester. England, in a statement.

“For now, we can say that these ‘synthetic embryos’ share a number of features with blastocysts, but it is important to recognize that the way synthetic embryos form is different from how a normal embryo forms a blastocyst,” he said. . “A lot of work is needed to determine the similarities and differences between embryos formed by combining egg and sperm and synthetic embryos.” Source