SATURDAY, Oct. 9, 2004 (HealthDayNews) -- Scientists are concerned the American public is losing sight of the basic research that still needs to be done before some stem cells can be used to treat the diseases and disorders for which they are presently being touted.
"Stem cell research has come a long way, but it is not there yet," said Daniel Collins, chief scientific officer at BioE, a biotechnology firm in St. Paul, Minn., working to isolate such cells from umbilical cord samples.
Stem cells have the potential to assume any cell type. Every cell in the body "stems" from these original cells, which gave rise to their name.
All humans begin life as a fertilized egg -- a single totipotent stem cell capable of becoming any type of human cell. In the first few hours after fertilization, this cell divides several times to replicate itself. Any one of these totipotent cells can develop into any and all cells that comprise a human infant.
As an embryo develops into a fetus, stem cells continue to specialize into multipotent stem cells, with specific functions. For instance, multipotent skin stem cells can generate any of the different skin cells, but not blood or brain cells. Multipotent cells are often referred to as "adult stem cells" -- the term "adult" referring to the maturity of the cells, not the age of the individual.
The medical use of adult stem cells is neither new nor controversial. They have been employed for over 20 years to treat blood disorders and autoimmune conditions, as well as to replace bone and cartilage.
Dr. Richard Burt, chief of the Division of Immunotherapy and Autoimmune Disease at Northwestern University, performed the first stem cell transplants to treat systemic lupus seven years ago. According to Burt, this work, which had a 70 percent success rate among individuals with the relatively common autoimmune disorder, "does move the frontier of death, disease and suffering further away."
Other researchers point out that successes like Burt's may not be representative or easy to duplicate.
"These are a handful of isolated cases," said Dr. Robert Goldstein, chief scientific officer for the Juvenile Diabetes Research Foundation, in New York City. "Everything about stem cell progress has unfortunately been over-hyped."
According to Goldstein, the greatest limitation of adult stem cells is that they can't regenerate all types of cells because they are specialized for definite cellular functions.
Furthermore, it is impossible to extract certain adult stem cells, such as those that could regenerate brain tissue, without killing the donor.
For this reason, the focus has shifted to embryonic stem cell breakthroughs, putting pressure on researchers whose access to these cells is currently limited by the Bush administration.
Only a few weeks before former President Ronald Reagan's death earlier this year, former First Lady Nancy Reagan broke ranks with the Bush administration during a speech at a fund-raiser in California for juvenile diabetes research. "Science has presented us with a hope" for a cure to Alzheimer's disease, through stem cell research, she said.
Such cells are primarily available from embryos banked at fertilization clinics that are destroyed if not used by sperm and egg donors or for scientific research. According to Goldstein, many opposed to embryonic stem cell research don't realize the cells in question are already slated for destruction.
Many researchers remain optimistic that embryonic cells can do what adult cells can't: Specialize to become any tissue in the human body and replace deteriorated cells. There is hope they can one day be transplanted into the brain to treat Alzheimer's, for example.
What is seldom discussed, however, is that embryonic cell transplantation remains experimental, with glimmers of hope but few benefits to current medical care. There have been no human clinical trials using embryonic stem cells. Even successful animal experiments continue to report tumor growth, host-source incompatibility or rejection and perplexing anomalies. Furthermore, while mice stem cells are relatively easy to work with in laboratories, human stem cells are not, experts say.
Despite these complications, Burt believes the future for embryonic stem cell treatment is bright. "Every answer comes with problems," he said. "The discovery of the mechanics of stem cell regeneration is already as important a benchmark in medicine as the development of pharmaceuticals, surgery and radiation treatments."
Laurie Zoloth, a professor of medical ethics and humanities at Northwestern University's Feinberg School of Medicine, is also enthusiastic about the potential of embryonic stem cells.
"Medicine's use of pluripotent stem cells will be exciting," she said. "Not only are they likely to provide us with new treatments, but I believe they will teach us more than we ever dreamed about human development, birth defects and repairing damaged tissues."
More information
For more information about stem cell research, visit the National Institutes of Health.
