() — A team of researchers from the US and UK claim to have created the world’s first synthetic structures similar to human embryos from stem cells, bypassing the need for eggs and sperm.
These embryonic structures are in the earliest stages of human development: for example, they do not have a heart or brain. But scientists say they could one day help to better understand genetic diseases or the causes of miscarriages.
The research raises vital legal and ethical questions, and many countries, including the United States, lack laws regulating the creation or processing of synthetic embryos.
The pace of discoveries in this field and the increasing sophistication of these models have alarmed bioethicists as they move ever closer to the limit of life.
“Unlike human embryos from in vitro fertilization (IVF), where there is an established legal framework, there is currently no clear regulation that regulates human embryo models derived from stem cells. There is an urgent need for regulations that establish a framework for the creation and use of stem cell-derived models of human embryos,” said James Briscoe, associate director of research at the Francis Crick Institute.
Dr. Magdalena Zernicka-Goetz described the work in a presentation Wednesday at the annual meeting of the International Society for Stem Cell Research in Boston. Zernicka-Goetz, Professor of Biology and Biological Engineering at CalTech and the University of Cambridge, explained that the research has been accepted in a prestigious scientific journal, but has not yet been published. The investigation was first published by The Guardian.
Zernicka-Goetz and her team, along with another from Israel, previously described creating embryo-like structures from mouse stem cells. Those “embryos” showed the beginnings of a brain, a heart and an intestinal tract after about eight days of development.
The embryonic structures that Zernicka-Goetz says his lab has created were grown from individual human embryonic stem cells that were forced to develop into three distinct tissue layers. They include cells that would normally develop a yolk sac, a placenta, and the embryo itself.
Zernicka-Goetz explained to that the embryonic structures created by her lab are the first to have germ cells that will develop into eggs and sperm.
“I just want to stress that these are not human embryos,” Zernicka-Goetz said. “They are models of embryos, but they are very exciting because they look so much like human embryos and they are a very important path towards discovering why so many pregnancies fail, since most pregnancies fail around the time of development when we built these embryo-like structures.”
She said that, to her knowledge, it was the first time that a human model embryo had been created with three layers of tissue. But she stressed that while it mimics some of the characteristics of a natural embryo, it doesn’t have all of them.
The researchers hope that these embryo models will shed light on the “black box” of human development, the period after infants. 14 days after fertilizationwhich is the agreed limit for scientists to grow and study embryos in a laboratory.
Right now, synthetic human embryo models are confined to test tubes. It would be illegal to implant one in a uterus, and animal research with stem cells from mice and monkeys has shown that even when scientists have tried to implant them, they don’t survive, likely because researchers haven’t figured out how to fully replicate the conditions of pregnancy.
Zernicka-Goetz explained that the objective of her research was not to create life, but to prevent its loss, understanding why embryos sometimes do not develop after fertilization and implantation.
“We know very little about this stage of human development, but it is a time when many pregnancies are lost, particularly to IVF,” says Roger Sturmey, Senior Research Fellow in Maternal and Fetal Health at the University of Manchester, UK. ).
“Today, we can say that these ‘synthetic embryos’ share a number of characteristics with blastocysts, but it’s important to recognize that the way synthetic embryos form is different from what happens when a normal embryo forms a blastocyst,” he said. . “Much work remains to be done to determine the similarities and differences between synthetic embryos and embryos that form from the union of an egg and sperm.”
