Question: At what stage are embryonic stem cells the most useful? and at what stage are they injected into organisms?

David Christensen answered on 12 Nov 2013:

This is a complicated and difficult question, so thanks!

Embryonic stem cells are cells that fit a specific definition. These cells can become any cell type of our bodies and they can self-renew (we can grow them in the lab, keeping them as embryonic stem cells for a long time). This means that there aren’t really exactly stages of embryonic stem cells. (To make this more complicated actually there sort of different stages – it seems for some reason that embryonic stem cells from mice are slightly more able to become all cell types than human embryonic stem cells are – but this isn’t really relevant to your question.)

To be useful to a patient, probably we need to make our embryonic stem cells that we grow in the lab change so that they become the type of cell the patient needs; for example nerve/brain cells for people with Alzheimer’s. Recently there have been tests where people with some eye diseases that cause blindness have had cells injected into their eyes and these cells were stem cells that had been forced to become particular types of cells found in the eye.

Finally, embryonic stem cells might be useful for research in ways other than in producing treatments for diseases, so different ways of using embryonic stem cells might be useful. In my work, I’m looking at embryonic stem cells and trying to stop them becoming other cell types, whereas other people are trying to force them to become other cell types. Depending on the question a scientist wants to ask, embryonic stem cells could be useful in a lot of different ways and I think research on all of these things is useful and important.