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Few areas of medical research are generating as much interest as stem cells. There are several reasons why they are receiving so much scientific attention. They are able to divide into copies of themselves. They're unspecialized. And they can produce other cell types.

Unlike other cell types, stem cells can divide into identical copies of themselves, and can do so for the life of the organism. Other specialized cell types are unable to do this. When they are damaged they cannot create replacement cells of the same type.

Stem cells are unspecialized. They don't have tissue-specific functions or properties like red blood cells or nerve cells. They can't oxygenate the body or make parts of it move or carry nerve impulses. They can however through a process called differentiation, divide and produce or give rise to other specialized cell types (blood cells, heart muscle cells, etc.)

Of great interest to scientists is the ability of stem cells to replicate many times over (proliferate), and remain unspecialized until called upon to differentiate into a specific cell type for repair of the body. Understanding this process is key to controlling the differentiation process and growing specific cells for, among other things, cell-based therapies.

A large part of the research effort is on the ability of stem cells to replace damaged cells in the body. As stem cells can, under the right conditions, be induced to become other cell types, they may be used to replace cells damaged or lost to injury or disease. It's thought that there is the potential to produce, through continued research, cures for diseases such as Parkinson's and diabetes, or to repair devastating injuries to the spinal cord.

Stem cells come in two varieties. The type that can differentiate into any adult cell type (pluripotent), or those that are limited in the types they can become (multipotent). Pluripotent stem cells are found in very early development organisms and multipotent stem cells among differentiated cells of the body.

The pluripotent cells used in research are derived from mammalian embryos in the very early stages of development (4-6 days old). Human embryos for stem cell research are those that are the result of in-vitro fertilization and donated, they are not from intra-uterine fertilization. These embryonic stem cells can potentially become each (more than 200) of the bodies cell types.

This ability to produce other cell types makes them a source for regenerative medicine and tissue replacement therapies. Though no treatments have been derived from embryonic stem cells yet, this is not unusual for any early research field so it's still very promising.

Multipotent stem cells are found throughout the various tissue types of the body including cord blood. Though unspecialized, they can only produce cells of they type in which they are found. They repair and maintain those types of cells. Blood forming adult stem cells in the bone marrow repair and replace blood cell types like red blood cells and white blood cells and platelets. Retinal stem cells only replace and repair the retina. While it was generally believed that multipotent cells can only produce a limited number of different cells, recent research seems to indicate that they may not be as limited as previously thought.

Because stem cells can repair and replace damaged tissues, they are considered to be important to regenerative medicine (growing and replacing damaged tissue, or making natural healing work faster). Understandably there is a great deal of work being done in this area.

Stem cell research has given hope to many suffering from untreatable or incurable diseases and injuries that an answer to their health issues may be on the horizon. While these new therapies may be years away, science is making steady progress in understanding the process that make stem cells so promising. One can only be encouraged by the progress made so far and hopeful that all of the optimistic projections are realized.