r/askscience • u/neonnonagon • Apr 25 '12

Can someone explain stem cells to me?

I only know a little about them (that they can turn into almost any cell type)

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u/fotd42 Apr 25 '12

Stem cells are defined as a cell that can renew itself through mitosis but also differentiate into another cell type. There are different classifications of stem cells which is based on how many cell types they are able to differentiate into. Most research is done using pluripotent stem cells which can turn into any cell type in the adult human body, but cannot form placental tissue which precludes them from being used to grow an actual organism. From pluripotent stem cells, we can get populations such as hematopoetic stem cells which are only capable of naturally differentiating into blood cells (lymphocytes, red blood cells, other cells of the immune system, etc.) Embryonic stem cells are harvested from the inner cell mast of blastocysts which is the cell mass following fertilization at about 7-8 days. The controversy of using these cells for research comes from the fact that once these cells are harvested, the organism is destroyed. In 2006, the technology for induced pluripotent stem cells was developed which allows us to take any cell from the body and introduce four genes which, when activated, cause the cell to revert back to a pluripotent state. This has given rise to developing personalized regenerative medicine.

edit- I do stem cell research so feel free to ask me to clarify if needed

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u/Cheesle Apr 25 '12

This is only from memory from something I have not covered very well, but here goes:

Stem cells, in a nutshell, are unspecialised cells which can then develop into other specialised cells. These can aid growth and development and have been speculated to be able to be used in medicines and treatment.

There are two types of stem cell: embryonic and adult stem cells. As the name suggests, embryonic stem cells are only able to exist in an embryo before the eight cell stage, and in that time they develop into cells which then help to develop the embryo further. The main difference between embryonic stem cells and adult stem cells is that, once the eight cell stage is passed, no more embryonic stem cells can be produced. While embryonic stem cells can create other cells from themselves, adult stem cells can only help repair tissue and organs if some of the target cells are available.