April 2010
Written by Erica Brown and Stacey Herzer

Tags: basics, stem cells, science and society

Stem cells are full of potential. They can become blood cells, heart cells, skin cells, brain cells and bone cells—in fact they can develop into many or all of the over 200 different types of specialized cells that make up our body (1, 4).

• Stem cells have two important characteristics that set them apart from our other body cells (2): They are able to divide and produce more stem cells (self-renew) over long periods of time or indefinitely (an immortal cell line).
• Receiving the right signals, stem cells can be stimulated to become specialized cells (this process is called ‘differentiation’).

Why Do We Have Stem Cells?
Each cell type has a specific job in our body: for example, some brain cells (neurons) make sure that information is processed and transmitted properly so that we are able to learn, reason, and speak. Our red blood cells (erythrocytes) help carry oxygen throughout our body.
Because stem cells can differentiate into any mature cell type, they can replace worn out, damaged or diseased cells and promote the growth of our tissues, maintaining them in a healthy state throughout our lives.

Are There Different Types of Stem Cells?
To date, scientists have discovered at least four types of stem cells, and there may be even more in the future.  The four current types of stem cells are categorized and named after their source: Embryonic Stem Cells (ESCs), Adult Stem Cells, Umbillical Cord Stem Cells, and Induced Pluripotent Stem Cells (IPSCs).

Can Stem Cells be Used as a Therapy?
Ultimately, it is hoped that stem cells may be used to replace cells or regenerate organs that are diseased or failing in our body, such as replacing destroyed heart tissue in people with heart disease, or regenerating brain cells that are lost due to old age, substance abuse, or neurodegenerative diseases.  With a better understanding of how to coax stem cells into becoming the desired type of differentiated cell, and then increasing the survival of these cells after they are transplanted, successful therapies for treating disease will emerge.

To learn more about these cell types, see the following articles:

• Embryonic Stem Cells
• Adult Stem Cells
• Umbilical Cord Stem Cells
• Induced Pluripotent Stem Cells

References:

1. National Institute of Health Stem Cell Information http://stemcells.nih.gov/
2. Nussbaum RL et al. Thompson and Thompson Genetics in Medicine. 6th ed. 2004. Saunders.
3. Gibbs, N. Stem Cells: The hope and the hype. Time. Jul 30, 2006.
4. Lanza R, Rosenthal N. The Stem Cell Challenge. Scientific American 290(6). Jun2004.
5. Canadian Institute of Health Research (CIHR). Updated Guidelines for Human Pluripotenet Stem Cell Research. June 28 2006.
6. Wagner JE, Laughlin M, Petz L. Seventh annual international umbilical cord blood transplantation symposium, Los Angeles, California, June 5-6, 2009. Biol Blood Marrow Transplant. 2009