Open Letter from the Foundation Director
Should the U.S. government support the creation of new lines of embryonic stem cells?
The answer to that question is not simple. The rancorous US debate about embryonic stem cells bespeaks a healthy society with genuine concern about each and every member, the tiniest and the sickest. Everyone, on both sides of the debate, wants to do what’s right.
But what is “right?”
Should frozen embryos “left-over” in fertility clinics be “sacrificed” to create stem cells to treat heart failure, autoimmune diseases, diabetes, osteoporosis, cancer, Alzheimer’s disease, Parkinson’s disease, spinal cord injuries, and birth defects?
The answer is not necessarily.
Embryonic stem cells from “left-over” frozen embryos are just one example of pluripotent stem cells (pluripotent: the potential to develop into all body tissues). Embryonic stem cells have been important model systems for research, but they will have the same tissue compatibility problems as other transplanted organs.
The most therapeutically useful stem cells will be pluripotent stem cells that contain the genes of the patient. At present, there are two ways to accomplish that, both of which require the assistance of an unfertilized human egg.
Genetic transplantation (“Somatic Cell Nuclear Transplants”)
Human eggs are huge cells with the capacity to “remodel” genetic information transplanted into them, just like they “remodel” sperm at fertilization. This powerful capacity is not fully understood. It can erase the memory in the genes of an adult cell, such as a skin cell, and convert those genes back in time, back to functioning like a pluripotent stem cell. The egg does this after its own chromosomes have been removed. Then, when activated artificially by chemicals or an electrical pulse, the egg uses the transplanted genetic information to develop into a line of stem cells genetically identical to the skin cell donor.
This technology has not been fully developed for human eggs. The first line of human stem cells derived by such transplant technology was reported by a Korean research team in March, 2004, but the efficiency was very low, more than 200 human eggs were transplanted with genes. Moreover, because this same basic technology led to cloning Dolly the sheep in 1997, there is fear it could lead to cloning a human. Such fears could obviously be set aside by legislation to outlaw cloning a human, but allow gene transplantation technology to go forward.
Another avenue for creating pluripotent human stem cells is artificial egg activation, termed “parthenogenesis.” It has been known for many years that human eggs spontaneously activate, sometimes inside the ovary, leading to dermoid cysts, and sometimes outside the ovary, leading to benign tumors called teratomas. Teratomas contain different types of cells, such as hair and teeth, and support the concept that activated, unfertilized human eggs could be a valuable source of pluripotent stem cells without destroying human embryos.
The first attempt to activate unfertilized human eggs appeared in 2001, but no stem cell lines were derived (see FAQs, this site). A parthenote cell line from an unfertilzed monkey egg (Cyno-1), has been developed, however, and has demonstrated promise in monkey models of several human diseases.
But would technology requiring human eggs exploit women? A woman is born with about one million eggs; by the time she is 55 years old, they are all gone. Thus, approximately 2000 eggs naturally die each month; only one or two are released during her monthly cycle. If the technology could be perfected, some of the eggs that would otherwise be wasted could be used for stem cells. More research may reveal methods to remodel genes without needing eggs. Unfortunately, the U.S. congress included all forms of activated human eggs, including eggs not fertilized by sperm, in its moratorium on federal funding in 1996. President Bush extended the moratorium in 2001.
Therefore, the research can go on only in privately funded laboratories in the U.S, which has generated legitimate concerns about ethical oversight. Conducting the research in public charities with strong, active ethical oversight is an obvious answer. The Bedford Stem Cell Research Foundation, a Massachusetts public charity, is conducting such research with unfertilized human eggs. The eggs are donated by woman under rigorous guidelines developed specifically for stem cell research by an ethics advisory board chaired by Professor Ron Green, Dartmouth College.
Private funding is essential to continue the work in the U.S. The National Institutes of Health grants about 18 billion dollars a year to U.S. scientists. Without cutting funds to other meritorious programs, the NIH will not be able to dedicate substantial funds to pluripotent stem cell research for several years. Thus, in the short term, with or without government approval, the funds must come from the private sector.