Research on Human ES Cells, Cloning
When President Bush announced his plan for permitting federally funded human embryonic stem (ES) cell research last August, he insisted that those studies be restricted to a limited number of already established human ES lines. In hearing of those limits, scientists eager to move forward with such research instantly began raising questions about inevitable difficulties in dealing with the immune system that can be expected when basic ES cell findings become ready for testing and use in clinical settings.
Notwithstanding those concerns, the go-ahead for human ES cell research will enable researchers to better address many nagging questions over several autoimmune diseases, with longer-term implications for research on gene therapy and even infectious diseases. In much the same vein, the rising tide in Congress against any studies that could involve the cloning of human cells could impede efforts to study such diseases using materials obtained directly from those afflicted with them.
In terms of federal policy, the issues of human ES cell and cloning research became entangled during the extensive public debate over them last July and August. Politicians and much of the scientific establishment, for example, joined in deploring the disclosed plans of several doctors and a biotechnology company to attempt to clone individual humans as a means for aiding them to reproduce.
During a day-long meeting in August convened by the National Academy of Sciences (NAS) in Washington, D.C., scientists, clinicians, and bioethicists evaluated results from recent animal cloning experiments as well as those partly disclosed human cloning plans. Even as most participants deplored those clinical efforts as dangerously premature, some of them also worried that an out-and-out ban on all other research in this field could prove detrimental.
For instance, it might very well be helpful to use cloned cells from individuals with specific diseases as a safe and efficient way of studying those diseases at the cellular level in vitro, according to Irving Weissman of Stanford University in Stanford, Calif., who chairs the NAS cloning review panel. Moreover, many kinds of future therapeutic applications that come from ES cell research will likely depend on producing cells through cloning procedures that carry the precise immunologic signature of the individuals in whom they will be used.
However, President Bush all but precluded any early immunologic fine-tuning when he limited funding through the National Institutes of Health (NIH) for human ES cell research to only those "existing stem cell lines, where the life-and-death decision has already been made." Although the numbers remain uncertain, NIH officials say that some 60 or so "genetically diverse" stem cell lines that were developed in the United States and several other countries will meet Bush's criteria of acceptability for use in federally funded research projects. His restrictions do not apply to human ES cell research, including the derivation of new ES cell lines, conducted in the private sector.
"We're pleased with the President's decision to allow the use of federal funds for important basic research on human embryonic stem cells," says NIH Acting Director Ruth Kirschstein. "Using the more than 60 existing cell lines from around the world, many more researchers will now be able to explore the potential of human embryonic stem cells, in addition to the extensive work already sponsored by NIH using human adult stem cells."
The signal to move forward on such stem cell research is "a very positive thing," adds Anthony Fauci, director of the NIH National Institute of Allergy and Infectious Diseases. Such ES cells offer new ways to look at questions of "immunocompatability," have the "potentialfor reconstituting the immune system," and could be of particular importance in combatting HIV/AIDS, he points out. "We have so little experience with embryonic-derived stem cellswhich is the reason why we need to do fundamental research."
In a report on stem cell research prepared by NIH for President Bush and Secretary of Health and Human Services Tommy Thompson, officials point to autoimmune diseases as a particularly important area in which stem cells may contribute. For example, the report points to lupus, citing studies in mice in which hematopoietic stem cells are equipped with a "decoy" receptor for gamma-interferon to slow progress of this disease. Similarly, introducing other modified cytokine genes into ES cells that would differentiate into pancreatic beta cells might provide a means for blocking the autoimmune process that is believed to destroy such cells, leading to diabetes.
Jeffrey L. Fox
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