Actionbioscience | Stem Cells for Cell-Based Therapies

December 2012

We know the human body comprises many cell types (e.g., blood cells, skin cells, cervical cells), but we often forget to appreciate that all of these different cell types arose from a single cellthe fertilized egg. A host of sequential, awe-inspiring events occur between the fertilization of an egg and the formation of a new individual:

Embryonic stem (ES) cells are also called totipotent cells.

Stem cells also exist in adults and have varying abilities to self-renew.

In addition to embryonic stem cells, stem cells also exist in adults (adult stem cells) that allow specific tissues to regenerate throughout an individuals life. They also have the ability to self-renew and can give rise to a subset of differentiated cells depending upon the nature of the adult stem cell. Such adult stem cells and lineage-specific progenitor cells (with limited self-renewal ability) have long been known to exist in organs that continually regenerate, such as skin and blood. Some adult stem cells are active all the time (e.g., blood), and some only respond to injury (e.g., hair follicle stem cells) or physiological clues such as hormones (e.g., mammary stem cells).

More recently, however, stem cells have been identified in organs previously thought not to have regenerative capability, including reproductive organs. Female infants were previously thought to be born with a finite number of eggs, but a recent report identified egg stem cells in human ovarian tissue that can form egg cells, called oocytes, in the laboratory.1 Many tissues in the adult body (e.g., neural, muscle, and fat tissues) now appear to contain stem/progenitor cells.

The main use of stem cells in medicine is as a source of donor cells to be used as therapy to replace damaged or missing cells and organs. Stem cells are also useful for creating models of human disease and for drug discovery.

Stem cells can be obtained from several sources:

Scientists can obtain stem cells from multiple sources, including embryos, amniotic fluid, adult tissue, and even cadavers.

Adult stem cells and induced pluripotent stem cells are generally viewed as posing less of an ethical dilemma.

Originally posted here:
Actionbioscience | Stem Cells for Cell-Based Therapies