Stem Cell Concepts: intro & What is Stem Cell?

Here's is another series of posts I am starting about random concepts about Stem Cells.
I will be writing about different kinds of Stem Cells, and about the concepts behind some of the conventional procedures like PCRs and molecular tagging and such.

I found it appropriate that I should start this series by clarifying what Stem Cell really is. :D

What is Stem Cell?
There are some misconception among popular culture that stem cells are type of cells that can give rise to all the cells in human body. Most of them often believe also that there is just one kind of stem cells. This is not entirely wrong, as there is one type of stem cell that give rise to all kinds of cells in human (well not necessarily just humans) body, the fertilized egg :D

There are two main ways in which the stem cells are categorized. They are categorized by their origin, (What I mean by the 'origin' is simply where the cells are found. For example, Bone Marrow Mesenchymal Stem Cells (BMMSC), are extracted from one's bone marrow.)
or their potency.
Potency specifies the differentiation potential (the potential to differentiate into different cell types) of the stem cell.[1] Which means that different stem cells can only differentiate into certain kinds or number of daughter cells. There are a lot of research done on the matter of cells' potency, so it is not absolute, but I think this definition will suffice here.

Here is the list of different types of Stem Cell potency:
Totipotent: Totipotent cells are fertilized eggs are cells within couple divisions since the fertilization. They can differentiate into both embryonic and extraembryonic cell types. This is what is different between totipotent and pluripotent stem cells. Embroyonic cell types are the ones that differentiate into one's body and extraembryonic cell types are the ones that differentiate into cells that support the bady in the womb.

Pluripotent: Pluripotent cells are decendents of totipotent cells and can differentiate into nearly all cell types, such as Embrynoic Stem Cells (ES cells) which can differentiate into all embryonic cell types. I will write more in depth about ES cells in the future

Multipotent: Multipotent stem cells can differentiate into few different cell types, but only those of a closely related family of cells. Much of the Adult stem cells are multipotent. Example of mulipotent cellss are BMMSC and WJ cells.

Oligopotent: stem cells can differentiate into only a few cells, such as lymphoid or myeloid stem cells. (from wikipedia)

Unipotent: cells can produce only one cell type, their own, but have the property of self-renewal which distinguishes them from non-stem cells (e.g. muscle stem cells). (from wikipedia)

Didn't learn about Oligopotent or Unipotent cells at my internship yet, so I paid wikipedia a visit ;)

If you didn't know already, Stem Cell research is one of the hottest field in Bio-medial research because it has a great number of possible usage and potential. It has been proven, though, that it is not easy to control stem cells as we want to, but number of stemcell treatments already exist and with time, stem cell will change the medical field greatly, as invention of medical imaging once did.




[1] - Hans R. Schöler (2007). "The Potential of Stem Cells: An Inventory". in Nikolaus Knoepffler, Dagmar Schipanski, and Stefan Lorenz Sorgner. Humanbiotechnology as Social Challenge. Ashgate Publishing, Ltd. pp. 28. ISBN 0754657558.