Frequently Asked Questions About Stem Cell Research

The International Society for Stem Cell Research (ISSCR) is an independent, nonprofit organization formed in 2002 to foster the exchange of information on stem cell research. Here are some frequently asked questions about stem cell research, with the information that the Society has provided:

What are stem cells?
Where do stem cells come from?
What are the potential uses of human stem cells?

What are stem cells?

Stem cells are the foundation cells for every organ, tissue and cell in the body. They are like a blank microchip that can ultimately be programmed to perform any number of specialized tasks. Stem cells are undifferentiated, "blank" cells that do not yet have a specific function. Under proper conditions, stem cells begin to develop into specialized tissues and organs. Additionally, stem cells are self-sustaining and can replicate themselves for long periods of time.

These unique characteristics make stem cells very promising for supplying cells to treat debilitating diseases like Alzheimer's disease, cancer, Parkinson's disease, type-1 diabetes, spinal cord injury, stroke, burns, heart disease, osteoarthritis and rheumatoid arthritis. Today, donated organs and tissues are often used to replace those that are diseased or destroyed. Unfortunately, the number of people needing transplants far exceeds the number of organs available. Stem cells offer the potential for supplying cells and tissues, which can be used to treat these various diseases.

Where do stem cells come from?

All human beings start their lives from a single cell, called the zygote, which is formed after fertilization. The zygote divides and forms two cells; each of those cells divides again, and so on. Pretty soon, about five days after conception, there is hollow ball of about 150 cells called the blastocyst. The blastocyst is smaller than a grain of sand and contains two types of cells, the trophoblast and the inner cell mass. Embryonic stem cells are the cells that make up the inner cell mass. As embryonic stem cells can form all cell types in an adult, they are referred to as pluripotent stem cells.

Stem cells can also be found in very small numbers in various tissues in the adult body. For example, bone marrow stem cells are found in the marrow of the bone and they give rise to all specialized blood cell types. Adult stem cells are typically programmed to form different cell types of their own tissue; they are called multipotent stem cells. Adult stem cells have not yet been identified in all vital organs. In some tissues like the brain, although stem cells exist, they are not very active, and thus do not readily respond to cell injury or damage. Scientists are now also exploring ways in which they can induce the stem cells already present to grow and make the right cell types to replace the damaged ones.

Stem cells can also be obtained from sources like the umbilical cord of a newborn baby. This is an accessible source of stem cells, compared to adult tissues like the brain and bone marrow. Although scientists can grow these cells in culture dishes, they can do so only for a limited time. Recently, scientists have discovered the existence of stem cells in baby teeth and in amniotic fluid-the "water bath" that surrounds an unborn baby- and these cells may also have the potential to form multiple cell types. Research to characterize and study these cells is very promising but at a very early stage.

What are the potential uses of human stem cells?

Most of the body's specialized cells cannot be replaced by natural processes if they are seriously damaged or diseased. Stem cells can be used to generate healthy and functioning specialized cells, which can then replace diseased or dysfunctional cells.

Replacing diseased cells with healthy cells, called cell therapy, is similar to the process of organ transplantation only the treatment consists of transplanting cells instead of organs. Some conditions or injuries can be treated through transplantation of entire healthy organs, but there is an acute shortage of donors. Stem cells can serve as an alternate and renewable source for specialized cells. Currently, researchers are investigating the use of adult, fetal and embryonic stem cells as a resource for various, specialized cell types, such as nerve cells, muscle cells, blood cells and skin cells, that can be used to treat various diseases.

For example, in Parkinson's disease, stem cells may be used to form a special kind of nerve cell, a kind that secretes dopamine. These nerve cells can theoretically be transplanted into a patient where they will re-wire the brain and restore function, thus treating the patient.

For more frequently asked questions about stem cell research, please visit the ISSCR website at http://isscr.org/public/faq.htm