By Dr. Mindy Aisen
The field of stem cell research offers enormous promise for the treatment of human disease. Stem cells are “undifferentiated” cells; they have the potential to develop into virtually any specialized type of cell in the body. So theoretically, stem cells might be used to regenerate human tissue or organs damaged by disease. There is hope that some day stem cells may provide effective restorative therapy for many human conditions, including those caused by damage the nervous system such as stroke, Parkinson’s Disease, spinal cord injury and cerebral palsy. At the present time, however, the field of stem cell research is in its infancy, and there are few effective uses of this type of therapy.
Stem cells can be derived in several ways. Embryonic stem cells (removed from early stage embryos) can be maintained in the laboratory and coaxed into differentiating into various cell types. Fetal cord blood contains human stem cells that can also be grown in the laboratory or frozen for later use. A recent technique for generating human stem cells involves obtaining cells from skin biopsies and “deprogramming” them into stem cells that can then be differentiated into various human cell types. The adult human brain contains viable neural stem cells; it may be possible to use medications to stimulate these natural stem cells into regenerating damaged brain tissue.
Stem cell scientists are currently working on the optimal conditions to maintain stem cells in the laboratory, the precise methods necessary to convert stem cells into the specific cells that might reconstitute damaged human tissues, and the techniques required to direct such cells to function effectively together. At the present time, much work remains to be done before the practical application of stem cells to the treatment of human disease becomes feasible.
In cerebral palsy, brain tissue is damaged at a very early stage of development: in utero, at or around the time of birth, or up until the age of 2 years. The brain is, of course, the most incredibly complex of all human organs. The brain consists of many different cell types interacting in a precisely organized fashion to produce the different aspects of thought and behavior in different brain regions. Before stem cells can be used to repair damaged brain tissue in cerebral palsy or any other brain disorder, scientists will have to discover how to turn stem cells into various specific types of brain cells, and induce them to form the precise connections and organization necessary for meaningful brain function. It is likely that stem cells converted into brain cells will have to be implanted in the precise areas that they are needed in order to provide effective treatment.
Specific Types of Approaches: Cord Blood Infusions
It is extremely unlikely that the administration of stem cells by peripheral infusion of cord blood can effectively treat cerebral palsy. Such cells have not been “taught” to form the necessary types of brain cells, and they will not be able to enter the brain, because there is an anatomic and physiological barrier which prevents certain medications and cells from reaching the brain, known as the blood brain barrier.
How can one explain the reports of improvements in the symptoms of cerebral palsy (CP) following cord blood infusions? Medicine is filled with such “anecdotal” reports of improvements when novel treatments are applied to chronic conditions. The symptoms of all chronic conditions fluctuate, and subjective factors, including the optimistic expectations that accompany novel therapies, often seem to alleviate disease manifestations. But in almost all cases, the underlying disease remains unchanged, and there is no meaningful long-term benefit. Indeed, in most cases, the risk of harm outweighs the chance of benefit when unproven novel therapies are used.
CPIRF strongly supports research into the use of stem cells to treat CP. But at present, CPIRF, in consultation with leading stem cell scientists, has reached the firm conclusion that use of cord blood or other forms of stem cell treatments for CP is inadvisable. Basic and applied research into various approaches to stem cell neural regeneration therapy must be vigorously pursued, and CPIRF will continue to fund such efforts. But at present, administration of cord blood to people with CP offers no meaningful chance of benefit.
Furthermore, the long term risks of cord blood infusions have not been studied, receiving infusions in other countries from donated cord blood may have significant risk and certainly present substantial financial strain for the families of those being treated.
We strongly endorse an organized scientifically rigorous initiative focused on rapidly identifying the most effective methods for using stem cell treatments to help repair the damaged brains of children and adults with developmental brain conditions.