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Miracle Cell

Susan J. Fisher, Ph.D.

My father has had several difficult and serious heart surgeries. Why have I never heard about stem cells for repairing his damaged heart (as was done for the teenager shot in the heart with the nail gun)? He is in his mid-60's ... not elderly. Is the cost of stem cell treatment prohibitive or are there only a few facilities providing this treatment?

The teenager who was shot in the heart with a nail gun evidently was treated with his own adult stem cells, from his bloodstream, in an experimental procedure that the FDA has since said cannot be carried out again without further study. It appears that when the blood stem cells were transplanted into the teenager's heart they specialized into heart cells and have helped to improve his heart function. However, scientists are still not certain whether blood and bone marrow stem cells actually specialize into certain cell types when they are transplanted into tissue or whether they, instead, fuse with existing cells in the tissue. If they fuse, there could be unknown health risks. The issue of how these cells behave when transplanted is under intense scrutiny now.

Who are some leading stem cell researchers in the United States?

The groundbreaking ("proof of concept") studies in mice were done by Dr. Gail Martin (University of California, San Francisco, or "UCSF") and Dr. Martin Evans (Cambridge University). (Dr. Martin of UCSF is also credited with coining the term embryonic stem cell.) The first investigator to make a line of human embryonic stem cells was Dr. James Thomson (University of Wisconsin). Dr. Doug Melton (Harvard) recently announced the generation of 17 new human embryonic stem cell lines. Dr. Irving Weissman (Stanford University) has done important work on hematopoietic stem cells.

Are adult stem cell transplants currently available within the United States?

Bone marrow transplants have been available for many years. They are carried out to restore stem cells in the bone marrow that have been destroyed by high dose chemotherapy or radiation. These adult stem cells can divide to form more stem cells, or they can mature into white blood cells, red blood cells, or platelets.

As for developing other forms of adult stem cell therapy, it is always very difficult to determine when basic research will be translated into clinical practice. Usually progress occurs in "fits and starts."

Since stem cells are more effective when harvested from young people, does that mean that people at large should be looking into freezing a supply of their stem cells so they can be more effectively used when they are getting older?

Much of the work on the regenerative ability of adult stem cells is being re-evaluated, as many investigators think that some of the early results were due to cell fusion rather than to stem cell regeneration.

I understand the Federal Funding issues revolving around research grants, but what are the legal limitations to privately funded research on either type of stem cell (adult or embryonic)?

Private funds may be used to generate and study new human embryonic stem cell lines that are not registered with the National Institutes of Health and, at least in some states, including California, state funds are also used. However, this work cannot be conducted in so-called "federal space," i.e., laboratory space supported by the overhead dollars that federal grants generate. There are no federal restrictions on adult stem cell research.

Where and when were these laws (if any) enacted?

On August 9, 2001, President George Bush approved the use of federal funds for research on existing human embryonic stem cell lines, and created the NIH Stem Cell Registry, which lists the approved lines. Limiting research to existing human embryonic stem cell lines that were submitted to the NIH registry is seen by many investigators as a significant hindrance. For example, less than a quarter of the original lines can be propagated, or undergo division (self-renewal), a fundamental characteristics of all stem cells.

Have any of the laws been tested in court?

I am unaware of any pending legal actions, but I am not a legal expert.

How long after a spinal cord injury could a stem cell transplant potentially help someone? I have been in a chair for 19 years and want to walk again. Could stem cells help me?
The answer to both questions depends on the outcome of a great deal of basic research that still needs to be done. Additionally, it will take time to learn whether the findings, usually obtained by using animal models, are applicable to humans.

What are some conditions that stem cells have been used to treat so far?

Bone marrow transplants, which involve the transplant of adult bone marrow stem cells or adult peripheral blood stem cells into the blood stream, are the most common. Both lead to the production of new blood cells -- white blood cells, for fighting infection; red blood cells, which carry oxygen to, and remove waste products from, organs; and platelets, which enable the blood to clot.

In the future, what conditions may potentially be treatable with stem cells?

The reason that scientists and physicians are so excited about regenerative medical techniques that involve stem cells is that these approaches hold the promise of curing many types of diseases. The common examples are diabetes and Parkinson's Disease. In theory, any organ could be repaired by replacing diseased or defective tissue with stem cells that could reconstitute normal function. However, it will take many years of study before it is clear if, and in which circumstances, stem cells will prove effective in treating disease. Patients with other conditions may benefit as well. For example, some cancers may arise due to the uncontrolled proliferation of a stem cell population. In this case, our knowledge of factors that control stem cell growth and survival could be used to eradicate tumors.

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