The first early human eggs from stem cells

Why this matters

Making viable eggs from stem cells has already been accomplished in mice. In 2016, our collaborator Katsuhiko Hayashi demonstrated that mouse skin cells can be turned into âinduced pluripotent stem cellsâ (iPSCs, which are engineered cells capable of becoming any kind of cell in the body) and then turned into usable eggs. These eggs produced healthy pups that lived normal lifespans and reproduced naturally, having healthy pups of their own.

**Figure 2 **â Adult mice from eggs derived from pluripotent stem cells (Hikabe et al., 2016)

Figure 2â Adult mice from eggs derived from pluripotent stem cells (Hikabe et al., 2016)

This process, known as "in vitro gametogenesisâ (IVG), has been far easier to achieve in mice than in larger animals. Still, given how dramatically impactful this technology could be, it is well worth pursuing for human application.

**IVG has the potential to redefine reproduction worldwide. From a simple blood draw, one could make as many healthy eggs as a family needs. **

This capability could create freedom from biological and genetic limits. It could dramatically expand familiesâ options for having healthy children and enable women to have children at a much older ageâ all without the hormone injections or surgical retrieval currently required for IVF.

The technology is one of the most complex therapies ever to be developed. We are not making just a single cell type; we are building entire mini-ovaries in the lab derived from stem cells, as the whole organ is important for proper egg development. Weâre excited that weâve made hugely significant progress towards this goal, and we wanted to share a peek into our process.

Our Approach: Making mini-ovaries in the lab

**Figure 3 **â Conception's overall process for making egg cells from stem cells.

Figure 3â Conception's overall process for making egg cells from stem cells.

Conception's thesis is simple: there are no useful shortcuts. A cell that expresses a few egg markers is not enough. We need to rebuild, as closely as possible, the sequence that nature uses â and benchmark our cells against human development at every major step.

Our approach follows the major steps of egg development above in Figure 3. After taking a blood sample, we turn a subset of blood cells into iPSCs, and then guide the iPSCs toward becoming each of the kinds of cells found in a developing ovary: âprimordial germ cellsâ are the cells that will eventually become eggs, and