Scientists have successfully grown an embryo-like structure using stem cells, creating an early human embryo model without the use of sperm, eggs, or a womb. The researchers from the Weizmann Institute achieved a remarkable milestone by creating a structure resembling a 14-day-old human embryo.
This breakthrough offers an ethical method to study the critical early stages of human development. The initial weeks following fertilization are a period of rapid and poorly understood change, often leading to miscarriages and birth defects.
Instead of using conventional sperm and egg, the scientists began with naive stem cells and reprogrammed them to have the potential to become any type of tissue in the body. These stem cells were then manipulated using chemicals to develop into four types of cells found in the earliest human embryos.
The resulting embryo model included epiblast cells (which become the embryo proper), trophoblast cells (which become the placenta), hypoblast cells (which become the yolk sac), and extraembryonic mesoderm cells. A precise mixture of 120 of these cells was used, and around 1% of them self-assembled into a structure resembling a human embryo.
This research aims to provide valuable insights into how different types of cells emerge, the earliest stages of organ development, and inherited or genetic diseases. It could potentially lead to improved in vitro fertilization (IVF) success rates by identifying why some embryos fail or testing the safety of medicines during pregnancy.
The study has raised ethical questions about the development of embryo models beyond the 14-day stage, as well as how closely these models should be regulated compared to normal human embryos.
