What diffrenciates totipotent, pluripotent, multipotent and unipotent stem cells?

[hitmankratos]

Hi,

 

I know that there are several stem cells that can become several types of cells. However, I was wondering what characterises these stem cells - meaning, what is the diffrence in their metabolisms that make them totipotent, pluripotent, multipotent or just unipotent (is it how they are made, or is it some enzymes...or what?)

 

thanks in advance,

[Mr Skeptic]

The more they're allowed to differentiate, the less different types of cells they can differentiate into. I don't know much about it, but I think they need special chemicals to keep them from differentiating. Recently, we've been able to run that process in reverse, so that we get stem cells from skin cells.

[CharonY]

There are a lot of factors, not all of which are understood. The core is of course, regulation on various levels. This includes for instance the production of certain growth factors. The above mentioned reversal is based on the overexpression of certain growth factors in skin cells thus resulting in cells that are similar, but not identical to stem cells. There are of course much regulatory elements involved, but it is such a complex field that a short post could not do it any justice (not to mention outside of my specialty). If interested I would consider checking out books about developmental biology.

Edited September 7, 2010 by CharonY