What is a Stem Cell?
Stem cells are found in various tissues throughout the body. Stem cells can remain inactive in host tissues for long periods of time. They are activated by disease, injury or demands on the body that stimulate the body to mobilize healing cells to an injured area of the body. Harvesting stem cells provides the basis for the development of stem cell therapy. Stem cells are found in higher concentrations in certain tissues such as:
- Embryonic tissue
- Bone marrow
- Adipose or fat tissue
Stem cells have unique characteristics. As defined by the U.S. National Institutes of Health (NIH), all stem cells have 3 general properties: (1) they are capable of dividing and renewing themselves for long periods, (2) they are unspecialized, and (3) they can give rise to specialized cell types. An example of a stem cell is an embryonic stem cell derived from an early human embryo. Currently, it is illegal for physicians in the U.S. to utilize embryonic stem cells to treat medical conditions. However, physicians in the U.S. can obtain cells from bone marrow or adipose tissue. These cell preparations are called “stem cells,” but this is truly a misnomer, as stem cells are the least abundant cell type in these cell preparations. For every 1 million cells obtained from bone or fat from an adult for example, there is anywhere from 1 to 1000 stem cells present. Thus, the majority of the cells contained in a cell preparation do not meet the definitions of a stem cells as outlined above. Furthermore, it is illegal for physicians in the US to manipulate these cells that are obtained beyond centrifuging them. We cannot isolate the stem cells and apply growth factors to them in an effort to stimulate them to differentiate into a certain cell type such as cartilage. We can only inject a minimally manipulated cell preparation containing a small number of stem cells into an injured area.
Dr. Cunningham is a shoulder and knee specialist at Vail Summit Orthopedics and Neurosurgery. When indicated, he utilizes stem cell therapy for patients suffering from various knee and shoulder injuries.