Unlocking the Secrets of Human Development: Stem Cell-Derived Synthetic Embryos Offer Revolutionary Insights and Applications


In a groundbreaking achievement, a research team led by Prof. Jacob Hanna at the Weizmann Institute of Science has successfully generated complete models of human embryos from stem cells cultured in the laboratory.

These synthetic embryo models, grown outside the womb up to day 14, exhibit all the intricate structures and compartments characteristic of this stage of development, including the placenta, yolk sac, chorionic sac, and other external tissues.

This significant advancement holds immense potential for various fields of research, such as infertility studies, drug testing, tissue transplantation, and gaining insights into the early stages of embryonic development.

The Challenge of Studying Early Embryonic Development

The early stages of embryonic development have long been shrouded in mystery due to ethical and technical constraints. Studying this crucial period has proven to be challenging, primarily because it is difficult to access and observe these early events within the womb. However, these initial weeks are paramount in determining the future growth and development of a human being.

As Prof. Hanna explains, “The drama is in the first month, the remaining eight months of pregnancy are mainly lots of growth.” Despite its significance, this first month remains largely uncharted territory in our understanding of embryonic development.

Until now, the scientific community lacked an ethical and accessible means of examining this crucial phase.

Creating Synthetic Human Embryos

Prof. Hanna’s team drew from their previous success in generating synthetic stem cell-based models of mouse embryos. In this pioneering research, the scientists did not rely on fertilized eggs or a natural womb. Instead, they started with pluripotent stem cells sourced from different origins, including adult skin cells and cultured human stem cell lines.

These pluripotent stem cells, capable of differentiating into various cell types, were then reprogrammed to a “naïve state,” analogous to day 7 of natural human embryonic development when implantation occurs.

The researchers divided the cells into three groups, each treated with specific chemicals to activate genes associated with the development of essential tissues required to sustain the embryo: placenta, yolk sac, or extraembryonic mesoderm (which creates the chorionic sac). Under carefully controlled conditions, these cells formed clumps, and approximately 1 percent self-organized into complete embryo-like structures.

Unleashing the Internally Encoded Potential

One of the most remarkable aspects of this research is that the synthetic embryo-like structures, termed SEMs, developed autonomously outside the womb for eight days, reaching a developmental stage equivalent to day 14 in human embryonic development.

This stage marks the acquisition of internal structures necessary for further development into body organs.

Remarkable Structural Resemblance

When the researchers compared the inner organization of their stem cell-derived embryo models with classical embryology atlases from the 1960s, they made an astonishing discovery. The models exhibited an uncanny structural resemblance to natural human embryos at the corresponding stage. Every compartment and supporting structure was not only present but also in the correct size, shape, and location. Even cells responsible for producing pregnancy hormones were active, as confirmed by a positive result in a commercial pregnancy test.

Unlocking New Research Avenues

These synthetic human embryo models offer a revolutionary means of studying early embryonic development. The research has the potential to open numerous pathways in various domains:

  • Understanding Birth Defects and Infertility: The models can be used to investigate the causes of birth defects and types of infertility that often originate in the first few weeks of pregnancy, providing insights into early pregnancy failure.
  • Drug Testing: Researchers can utilize these models to study the effects of exposure to drugs or other substances on fetal development, eliminating the need for experiments on live embryos.
  • Transplant Tissues and Organs: The technology may lead to the development of new techniques for growing transplant tissues and organs, addressing the shortage of donor organs.


The creation of complete human embryo models from stem cells marks a significant milestone in scientific research. These models, cultured in a lab and grown up to day 14, closely mimic the development of natural human embryos. Their authenticity and accessibility provide an ethical way to explore the critical early stages of embryonic development, shedding light on hitherto elusive processes.

This breakthrough promises to advance our understanding of human development, offering innovative solutions for infertility, drug testing, and the growth of tissues for transplantation while upholding ethical research standards.

reference link : https://wis-wander.weizmann.ac.il/life-sciences/human-embryo-models-grown-stem-cells


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