Human embryonic stem cells (hESCs) have many remarkable properties, not the least of which is their ability to turn into every other kind of cell in our body. But there are limits to what researchers can do with embryonic stem cells. One issue is that there aren’t always hESCs available – they come from eggs donated by couples who have undergone in vitro fertilization. Another is that researchers can only develop these cells in the laboratory for 14 days (though that rule may be changing).

Now researchers at Caltech have developed a kind of hESC-in-a-dish that could help make it easier to answer questions about human development without the need to wait for a new line of hESCs.

The team, led by Magdalena Zernicka-Goetz, used a line of expanded pluripotent cells (EPSCs), originally derived from a human embryo, to create a kind of 3D model that mimics some of the activities of an embryo.

The cool thing about these cells is that, because they were originally derived from an embryo, they retain some “memory” of how they are supposed to work. In a news release Zernicka-Goetz says this enables them to display elements of both polarization and cavitation, early crucial phases in the development of a human embryo.

“The ability to assemble the basic structure of the embryo seems to be a built-in property of these earliest embryonic cells that they are simply unable to ‘forget.’ Nevertheless, either their memory is not absolutely precise or we don’t yet have the best method of helping the cells recover their memories. We still have further work to do before we can get human stem cells to achieve the developmental accuracy that is possible with their equivalent mouse stem cell counterparts.”

Being able to create these embryo-like elements means researchers can generate cells in large numbers and won’t be so dependent on donated embryos.

In the study, published in the journal Nature Communications, the researchers say this could help them develop a deeper understanding of embryonic development.

“Understanding human development is of fundamental biological and clinical importance. Despite its significance, mechanisms behind human embryogenesis remain largely unknown…. this stem cell platform provides insights into the design of stem cell models of embryogenesis.