Stem cell research coming back strong?

Scientists at the Weizmann Institute have developed an embryo model closely resembling a 14-day-old human embryo, all without using traditional sperm, eggs, or a womb. This revolutionary model, created using stem cells, even produced hormones that triggered a positive pregnancy test in lab settings. The primary goal of these embryo models is to provide a more ethical means of comprehending the earliest stages of human life.

The initial weeks following fertilization are a time of profound transformation, yet remain poorly understood, and are often associated with miscarriages and birth defects. "It's a black box and that's not a cliche - our knowledge is very limited," explains Prof. Jacob Hanna from the Weizmann Institute of Science.

Embryo research is fraught with legal and ethical complexities, but a growing field seeks to replicate natural embryo development. The Weizmann Institute's research, published in Nature, marks the first creation of a "complete" embryo model, encompassing all key structures of early embryo development.

Instead of relying on sperm and egg, the researchers used naive stem cells, reprogrammed to possess the potential to form any type of bodily tissue. Chemical signals were then employed to coax these stem cells into four essential cell types seen in the early human embryo:

• Epiblast cells, which give rise to the embryo.

• Trophoblast cells, which develop into the placenta.

• Hypoblast cells, forming the yolk sac.

• Extraembryonic mesoderm cells.

By precisely mixing 120 of these cells, researchers observed around 1% spontaneously assembling into a structure resembling a human embryo. This breakthrough opens the door to understanding how various cell types emerge, the earliest stages of organ development, and the origins of inherited or genetic diseases.

However, there's room for improvement, given the 99% failure rate. The research also poses ethical questions as the models approach actual embryo likeness, sparking debates on regulation.

Nonetheless, Prof. Alfonso Martinez Arias of Pompeu Fabra University praises this research as "a most important piece of research," marking the first faithful construction of the complete structure of a human embryo from stem cells, facilitating studies on human body plan formation. The researchers emphasize that using these embryo models for actual pregnancies would be unethical, illegal, and biologically unfeasible beyond a certain point.

You can find out more about It here on the Weizmann Institue's YouTube channel

Dr. Noa Novershtern, Dr. Vladyslav Bondarenko, Prof. Jacob Hanna, Dr. Bernardo Oldak and Emilie Wildschutz