By exploiting the body's natural ability to heal itself with stem cells, scientists are hoping to find therapies or cures for a long list of ailments including spinal cord paralysis, heart failure and Alzheimer's.
"Humans have a mechanism that sort of dampens down that ability. Infusions of stem cells are basically overcoming the damping-down mechanism," said Dr. Brian Butcher, associate director of the Tulane Center for Gene Therapy in New Orleans, the only institution sponsored by the National Institutes of Health to distribute adult stem cells to other academic researchers.
"Stem cells have the potential to completely change medicine and public health," adds Dr. Paul Whelton, senior vice president for health sciences at Tulane University.
And that has already begun...at least in the laboratory.
Breakthroughs in stem cell research include using stem cells to reverse damage from heart attacks, spur the growth of new brain cells and help children with a brittle bone condition.
Ethical Issues
Recently, the National Academy of Sciences proposed guidelines to govern human embryonic stem cell research. Among other things, the guidelines called for…
- Establishing Embryonic Stem Cell Research Oversight (ESCRO) committees, to review research.
- Requiring the consent of anonymous sperm donors when embryos from in-vitro fertilization (IVF) clinics are used.
- Restricting the creation of chimeras, which result when human cells are mixed with animal cells.
- Prohibiting the breeding of any animals that contain human embryonic stem cells.
- Restricting any payments to donors beyond reimbursement of direct expenses.
"Our hope is that this will provide an ethical foundation in which stem cell research can continue," says Dr. Bruce Albert, president of the National Academy of Sciences.
"There are no federal regulations governing stem cell research and no system for oversight," says Richard O. Hynes, co-chairman of the committee that prepared the guidelines. "This has led to a great deal of uncertainty in the public...and concern on the part of scientists, who would like to do research appropriately. These guidelines aim to encourage responsible practices in embryonic stem cell research, regardless of the source of funding, the derivation or the use."
Tulane researchers have circumvented many of the ethical issues by dealing only in adult stem cells.
They acquire the adult stem cells from bone marrow donations. A person can donate once every two months and be compensated $220 for giving marrow from both hips, a procedure that takes approximately 15 minutes. One teaspoon of bone marrow can yield about 300 million stem cells.
In addition, when working with actual patients, scientists at Tulane only use stem cells that originally came from that person, thereby reducing the likelihood of rejection.
Scientific Issues
But, while many uncertainties are of an ethical nature, at least as many involve a scientific component.
Some researchers at Tulane acquire adult stem cells from bone marrow; while others believe that adult stem cells drawn from fat are a better choice.
The different Tulane factions, at least, agree that adult stem cells are superior to embryonic stem cells because they do not increase the risk of cancer later in life.
On the other hand, it is widely acknowledged that embryonic stem cells have a greater capacity to differentiate into more tissue than adult stem cells.
There's also the issue of placental versus cord blood stem cells—which stem cells are best for lung repair? Which are best for heart repair? "There's not one snake oil for all," says Dr. Darwin Prockop, director of the Tulane Center for Gene Therapy.
There are also questions about whether all bone marrow stem cells are the same. There may be as many as 10 different types of stem cells that are in the bone marrow, Prockop explains. "We may be using different cells without knowing it."
In addition, researchers do not know how stem cells find tissues that are damaged.
"This research is still somewhere between science and art," says Prockop.
What Are Stem Cells?
Stem cells are precursor cells that may be transformed into any of the body's 220 cell types, including skin, blood, muscle, heart and nerve cells.
Stem cells can be directed to repair or replace cells damaged by diseases, such as multiple sclerosis, cancer and heart disease.
