In a groundbreaking scientific endeavor, an international team of researchers from the United States and the United Kingdom has achieved a remarkable feat by creating synthetic human embryo-like structures using stem cells. This revolutionary approach bypasses the conventional requirement of eggs and sperm, opening up new possibilities for advancing our understanding of genetic diseases and the causes of miscarriages.
These embryo-like structures represent the earliest stages of human development and do not possess a beating heart or a functioning brain. Nonetheless, scientists believe they hold immense potential for unraveling the mysteries of human biology. By studying these structures, researchers aspire to gain invaluable insights into the complexities of genetic disorders and the factors contributing to pregnancy losses.
However, this cutting-edge research also raises profound legal and ethical questions. Unlike in vitro fertilization (IVF) embryos, which are subject to established regulations, synthetic embryos currently lack clear governance frameworks in many countries, including the United States. The rapid progress in this field and the growing sophistication of these models have prompted concerns among bioethics experts as they navigate the boundaries of life.
James Briscoe, associate research director at the Francis Crick Institute, emphasized the urgency of implementing regulations specific to stem cell-derived models of human embryos. “There is an urgent need for regulations to provide a framework for the creation and use of stem cell-derived models of human embryos,” he stated.
Dr. Magdalena Zernicka-Goetz, a distinguished professor of biology and biological engineering at CalTech and the University of Cambridge, unveiled this groundbreaking research during a presentation at the International Society for Stem Cell Research’s annual meeting in Boston. Although the study has been accepted by a reputable scientific journal, it has yet to be published. The Guardian first reported on this remarkable development.
Zernicka-Goetz and her team, alongside a rival research group in Israel, had previously made significant strides in creating model embryo-like structures using mouse stem cells. These “embryoids” demonstrated the emergence of rudimentary organs such as the brain, heart, and intestinal tract after approximately eight days of development.
In their latest breakthrough, Zernicka-Goetz’s lab cultivated embryo-like structures from individual human embryonic stem cells, coaxing them to differentiate into three distinct tissue layers. These layers encompass cells that would typically give rise to the yolk sac, placenta, and the embryo itself.
Importantly, these embryo-like structures also contained germ cells capable of maturing into eggs and sperm—a notable achievement. Zernicka-Goetz emphasized that these structures should not be mistaken for human embryos; rather, they are highly promising models that closely resemble human embryos, providing a crucial pathway towards understanding the underlying causes of pregnancy failures.
While it represents a significant milestone in scientific research, Zernicka-Goetz clarified that the synthetic model embryos do not fully replicate all the features of a natural embryo. Nevertheless, researchers anticipate that these models will shed light on the enigmatic “black box” of human development, the period following 14 days after fertilization. This timeframe serves as the agreed limit for scientists to study and grow embryos in laboratory settings.
Currently, the synthetic model human embryos remain confined to test tubes, as it is illegal to implant them into a womb. Previous animal research involving stem cells from mice and monkeys revealed that implantation attempts proved unsuccessful, likely due to the incomplete replication of the conditions necessary for pregnancy.
Zernicka-Goetz emphasized that the objective of this research is not to create life but to prevent its loss, aiming to comprehend why embryos sometimes fail to progress after fertilization and implantation.
“We know remarkably little about this critical step in human development, yet it is a period during which numerous pregnancies are lost, particularly in an IVF context,” stated Roger Sturmey, a senior research fellow in maternal and fetal health at the University of Manchester in the UK.
He further added, “Currently, we can say that these ‘synthetic embryos’ share several characteristics with blastocysts, but it is important to recognize that the formation process of synthetic embryos differs from the natural formation of a blastocyst. There is much work to be done to determine the similarities and differences between synthetic embryos and embryos formed through the union of an egg and a sperm.”
As researchers embark on further exploration and investigation, this extraordinary achievement opens up new vistas of knowledge, underscoring the critical importance of robust legal and ethical frameworks to guide the future of stem cell-derived models of human embryos. The implications of this research extend far beyond the confines of laboratories, holding profound implications for our understanding of life itself.
