Arthritis Treatment: What Are the Different Types of Stem Cells and What Is Their Function?

One of the most exciting areas in medicine now involves the potential use of stem cells to treat degenerative disease such as arthritis.

This article will discuss the various types of stem cells and what they are used for.

The stem cell (SC) that occurs in the earliest phase of life is called the embryonic SC. This type of SC is omnipotent or pluripotent, depending on how you want to look at it. Basically, at this stage, the SC can become any type of tissue. While attractive, embryonic SCs have proven to be an elusive research tool.

Ethical concerns have limited their use and there is also the risk of malignancy since these cells have unlimited differentiating potential.

As the organism matures, other types of SCs develop. These SCs do not have the ability to differentiate like embryonic SCs. These have what are called multipotent powers. They can be coaxed into becoming specific types of tissue or organ systems but cannot become any type of tissue. In other words, their potential is restricted to certain categories. They pretty much are limited to make cell types of the tissue that they come from.

An example might be an adult liver-derived SC. This could make more liver tissue but could not make a blood cell. A nerve derived SC could become a brain cell but probably not kidney tissue.

Current clinical applications of adult SCs are typically tissue specific. Examples would be blood-derived SCs for the treatment of blood disorders or following chemotherapy, skin SCs to help with skin grafting, and eye-derived SCs to treat diseases of the cornea.

Adult SCs are primarily responsible for tissue repair. They replace dead or dying cells and are attracted to areas of injury.

The bone marrow is a large repository of adult SCs. These cells are often referred to as "mesenchymal SCs." What is exciting about this reservoir of SCs is that are capable of becoming connective tissue. This property is valuable in the treatment of disorders such as tendon and ligament damage as well as with arthritis.

Another type of SC is the fetal SC. Since a fetus has matured well beyond the embryonic stage, the SCs from a fetus behave like an "adult" SC in that they are tissue specific.

SCs are found in abundance in the umbilical cord at birth. These umbilical cord blood SCs are often used to treat diseases of the blood and also are used to help patients regenerate blood cells destroyed by chemotherapy.

Japanese researchers reported a fantastic breakthrough in 2006. They were able to take adult mouse skin cells and by using four viruses to transport material from one nucleus to another, created a cell that worked like an embryonic SC. In other words, they took an adult cell and made it into a cell that behaved for all true purposes like an embryonic SC. This type of cell is called an induced pluripotential SC. Over the years, it's become evident that induced pluripotential SCs don't behave exactly like embryonic SCs.

However, they have proven useful for research purposes. Using these SCs, scientists will be able to study diseases and test new drugs more efficiently. They are not yet ready to be used in a human clinical setting.