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Stem Cells FAQ

Your Stem Cell Questions Answered

Q: What are embryonic stem cells? continued...

While embryonic stem cells can become any kind of cell in the body, it's unlikely they would be used directly as treatments. Because they have the ability to divide over and over again, they can become rapidly growing tumors. And because they are in such an early stage of development, they take a long time to become functional adult cells.

However, researchers are learning to coax embryonic stem cells to become more mature stem cells. One clinical trial, for example, matures embryonic stem cells into nerve stem cells. These nerve stem cells are being explored as a treatment for Lou Gehrig's disease.

Q: Why not just study adult stem cells?

A: Adult stem cells have some advantages. When they come from your own body, your immune system will probably not try to reject them. And adult stem cells aren't controversial.

But there are several main disadvantages to using adult stem cells:

  • Adult stem cells aren't able to form all types of cells, so their use may be limited.
  • They are relatively rare among the body's billions of cells, so they're hard to find.
  • They take a long time to grow.
  • Adult stem cells donated by one person may be rejected by another person's immune system.
  • Adult stem cells can't reveal to researchers the secrets of early human development.

Q: Why all the excitement about stem cells?

A: A relatively small number of stem cells taken from the body can be grown in the laboratory until they have created millions and millions of new stem cells. This makes it possible for researchers to explore cell-based therapies.

Cell-based therapies, collectively known as regenerative medicine, hold the promise of repairing or even replacing damaged or diseased organs.

Depending on which tissues they come from, stem cells have very different properties. Those from umbilical cord blood are quite different from those from fat, for example.

Q: Are there current stem cell treatments?

A: Yes. Stem cells from bone marrow have long been used to treat certain types of leukemia.

The bone marrow is a rich source of blood stem cells. These cells replace the white blood cells crucial to the immune system.

When used for leukemia, the goal is to to wipe out all of a person's white blood cells with radiation and/or chemotherapy -- and then to replace them with a bone marrow transplant from a matched donor. Stem cells from the donor marrow replace the diseased blood cells with healthy blood cells.

A stem cell product designed to avoid the need for a matched donor recently received limited approval in Canada. The product, Prochymal, appears to rescue bone marrow transplant patients who are rejecting their transplant.

In the U.S., the FDA has approved a product called Hemacord, which contains blood stem cells derived from cord blood. The product is approved for patients with diseases that affect their ability to make new blood cells, such as certain blood cancers and immune disorders.

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