Researchers at the Weizmann Institute of Science in Israel have achieved a groundbreaking feat by growing human embryo-like structures in a lab, without the need for sperm, eggs, or a womb. These synthetic embryo models developed from stem cells and were nurtured outside the womb for up to 14 days.
The study, published in the journal Nature, demonstrated that these artificial embryos exhibited all the essential structures characteristic of this early stage, including the placenta, yolk sac, chorionic sac, and other external tissues crucial for dynamic growth.
Jacob Hanna, a professor at the Weizmann Institute of Science, described the stem cell-derived human embryo model as closely mimicking the development of a real human embryo.
The researchers did not rely on fertilized eggs or a womb. Instead, they began with pluripotent stem cells, which have the potential to differentiate into various cell types. Some stem cells were derived from reprogrammed adult skin cells, while others originated from long-cultured human stem cell lines.
To achieve the desired state, the scientists reprogrammed pluripotent stem cells to revert to an even earlier, more versatile state. This stage corresponds to day 7 of a natural human embryo’s development, around the time of implantation in the womb.
The cells were divided into three groups. The cells intended to form the embryo remained unchanged, while the other groups were treated with chemicals to activate specific genes, directing them towards becoming placenta, yolk sac, or extraembryonic mesoderm membrane cells.
Under carefully controlled conditions, these cells formed clumps, with around 1 percent self-organizing into complete embryo-like structures. These stem cell-based structures developed normally outside the womb for 8 days, equivalent to day 14 in human embryonic development, when internal structures necessary for further development are acquired.
These models accurately replicated the early embryo’s process of acquiring the necessary structures for its transformation into a fetus. This breakthrough offers insights into early-stage development, including potential causes of birth defects and infertility.
Additionally, this approach may pave the way for advancements in growing transplant tissues and organs, and enable research that was previously impossible on live embryos, such as studying the effects of drugs or substances on fetal development.