The Ethics of Stem Cell Research

If given a choice between funding alternative methods of deriving human embryonic stem cells (hESCs) or expanding the current federal policy in this area, a group of scientists testifying before a Senate Appropriations subcommittee agreed that biomedical research would be better served by the latter.

Led by Senators Arlen Specter (R-Pa.) and Tom Harkin (D-Iowa), chairman and ranking member, respectively, of the Labor, Health & Human Services, Education & Related Agencies Subcommittee, the hearing focused on a handful of potential alternative methods for deriving hESC lines that are being touted as more ethically palatable than current methods, which destroy embryos to harvest the cells.

The goal of the hearing, however, was to reinforce the need to loosen the federal restriction on hESC research that limits federal funding to studies involving just 22 approved lines that were derived before Aug. 9, 2001. Legislation to open the federal policy to include studies on lines derived from excess in vitro fertilization (IVF) embryos has already passed in the House (H.R. 810; C&EN, May 30, page 12). Specter and Harkin have cosponsored a similar bill (S. 471) in the Senate that is expected to be brought to the floor for a vote as early as this summer.

At the hearing, Specter and Harkin expressed their concern that the sudden popularity of the alternative methods for stem cell sources is a ploy by the White House and others to pull support away from passing S. 471. A bill targeted specifically at funding these alternative methods has already been introduced in the House (H.R. 3144) by Rep. G. Roscoe Bartlett (R-Md.), and one is expected to be introduced soon in the Senate.

THE METHODS at issue were highlighted in a white paper put out by the President's Council on Bioethics this past May. Each of the four outlined methods, however, are speculative, with little to no published evidence that they will be effective, pointed out James F. Battey Jr., chair of the National Institutes of Health Stem Cell Task Force, at the hearing.

One method currently being investigated involves the extraction (or biopsy) of a single blastomere cell from an eight-cell embryo--leaving the embryo unharmed. Removing a cell at this stage is already done by IVF clinics when performing a preimplantation genetic diagnosis, said Robert Lanza, medical director at Advanced Cell Technology. Lanza is part of the research group that has a publication pending showing the successful derivation of a stem cell line using this process with mice. But he acknowledged that it's too early to know how long it will take to demonstrate the process in humans.

Another method, known as altered nuclear transfer, is a derivation of somatic cell nuclear transfer--commonly referred to as cloning. In this process, the DNA of a somatic cell is altered prior to its transfer into an egg so that it develops into a blastocyst but doesn't continue its development into an embryo. According to William B. Hurlbut, consulting professor in the program in human biology at Stanford University and a member of the President’s Council on Bioethics, this method allows scientific advancement while protecting moral principles. Other witnesses, however, questioned the ethics of creating what they called a "disabled embryo."

Yet another method involves deriving hESC lines from embryos that fail to divide during the IVF process and are deemed "dead." There is no evidence for the successful generation of hESC lines from these embryos in mice, nonhuman primates, or primates, and there will be some question of the cells' genetic content, Battey noted. This method carries with it the ethical complication of determining when an embryo is dead as opposed to resting--something that Lanza noted he has observed.

The final method discussed is the most speculative, involving the reprogramming of somatic cells to return to a pluripotent or embryonic state. This method avoids the use of an embryo but is a long way from being a practical option, the witnesses agreed.

After hearing the testimony, the senators and witnesses unanimously agreed that funding these alternative methods as a substitute for expanding the federal policy will slow the progress of finding cures and treatments for diseases.

"These so-called alternatives are not true alternatives, as they currently represent only speculative proposals for research that might yield new stem cell lines and are fraught with their own ethical problems," said George Q. Daley, associate professor of pediatrics at Children's Hospital Boston and associate professor of biological chemistry and molecular pharmacology at Harvard Medical School. Although Daley supports continued research on the prospective methods, he pointed out that a bill that supports these alternative methods instead of an expanded federal policy is "a vote to delay biomedical research."