What is a Stem Cell?

Every organ and tissue in our body grew out of a cluster of stem cells early in development. A stem cell differs from every other cell in the body in its ability to renew itself. It can divide into many more just like it.

Stem cells can repair and replace tissue in the human body. In other words, stem cells have the power to heal.

Think of our skin. The tissue in our skin needs constant renewal that could not take place without stem cells. Or muscle — stem cells in our muscles are what repair damaged tissue when we are injured.

Early in life, stem cells have the extraordinary potential to develop into any type of cell in the human body.

They start in the embryo as unprogrammed cells, then become specialized to create bone, muscle, skin, the heart, the brain, and over 250 other types of specialized cells. These are called pluripotent stem cells.

Using Stem Cells to Save People

Researchers have found that stem cells can be used to treat disease and injury. They stimulate the body to repair itself.

For example, bone marrow transplants have been taking place for more than 40 years.

These procedures rely on transplanting stem cells derived from bone marrow and have dramatically altered the treatment of blood disorders and certain cancers such as leukemia.

In the past 20 years, significant new discoveries have emerged — breakthroughs that the original discoverers of stem cells never dreamed about. Researchers are finding new ways to use stem cells to rebuild tissue in many parts of the body where it has been damaged, such as the eye, the pancreas and the brain. Some revolutionary treatments for blindness, MS, stroke and spinal cord injury are already in early stage clinical trials.

Sources of Stem Cells

Much of the public discussion about stem cells has focused on where stem cells come from. Adult stem cells can be found in specific tissues in our bodies. As mature cells, they are already specialized to perform certain functions and are somewhat more limited in their application for therapeutic purposes. Generally, they can make only the kind of cells found in the tissue where they reside.

On the other hand, embryonic stem cells — derived from five-day old blastocysts that are precursors to embryos — are pluripotent in nature. They can generate any kind of cell in the body, any kind of tissue. This is why they are of such value to scientists doing both basic research in the lab and medical research in the clinic. They have the potential to regenerate tissue and cells that have been lost because of disease or injury.

An Unexpected Breakthrough

One of the most unexpected breakthroughs of the past decade was the discovery of induced pluripotent stem cells or iPS cells. These are adult stem cells that have been treated — or induced — to revert back to an embryonic-like, or pluripotent, state. By creating pluripotent cells from a patient’s own adult stem cells, there is even greater possibility to treat catastrophic and degenerative diseases, eliminating problems with tissue rejection after implantation.

The Future

Stem cells represent a revolution in health care, but we’re still in the early days. Bone marrow stem cell transplantation has been curing some kinds of cancer for decades, but in other potential areas we’ve barely begun scratching the surface.

Much work lies ahead. First, the tireless research that leads to breakthroughs in understanding. Then, the translation of those breakthroughs into practical clinical trials that may change the status of incurable diseases and conditions.