Labeling human cloning for purposes of destructive experiments as "therapeutic cloning" is a stroke of marketing genius by cloning supporters. But it has little or no basis in fact.
The "therapeutic" need for human cloning has always been highly speculative; it now seems more doubtful than ever in light of recent advances in adult stem cell research and other noncontroversial alternatives. In the stem cell research debate, as one recent news report observes, "There is one thing everyone agrees on: Adult stem cells are proving to be far more versatile than originally thought."1 Adult stem cells have shown they can be "pluripotent" – producing a wide array of different cells and tissues.2 They can also be multiplied in culture to produce an ample supply of tissue for transplantation.3 Best of all, using a patient's own cells solves all problems of tissue rejection, the chief advantage cited until now for use of cloning.4
In 1997 the National Bioethics Advisory Commission reviewed the idea of cloning human embryos to create "customized stem cell lines" but described this as "a rather expensive and far-fetched scenario" – and added that a moral assessment is necessary as well:
Because of ethical and moral concerns raised by the use of embryos for research purposes it would be far more desirable to explore the direct use of human cells of adult origin to produce specialized cells or tissues for transplantation into patients.5Now PPL Therapeutics, the Scottish firm involved in creating "Dolly" the sheep, says it has indeed found a way to reprogram ordinary adult cells to become stem cells capable of being directed to form almost any kind of cell or tissue – without creating or destroying any embryos.6
Even in the field of embryonic stem cell research, new developments have called into question the need for cloning. The problem of tissue rejection may not be as serious as once thought when cells from early human development are used, and there are other ways of solving the problem – for example, by genetically modifying cells to become a closer match to a patient.7
For all these reasons, a recent overview of the field concludes that human "therapeutic cloning" is "falling from favour," that "many experts do not now expect therapeutic cloning to have a large clinical impact." Even James Thomson of the University of Wisconsin, a leading practitioner and advocate of embryonic stem cell research generally, calls this approach "astronomically expensive"; in light of the enormous wastefulness of the cloning process and the damage it does to gene expression, "many researchers have come to doubt whether therapeutic cloning will ever be efficient enough to be commercially viable" even if one could set aside the grave moral issues involved.8
In short, the "therapeutic" case for human cloning is as medically questionable as it is morally abhorrent.
- A. Zitner, "Diabetes Study Fuels Stem Cell Funding War," Los Angeles Times, April 27, 2001 (www.latimes.com/news/nation/updates2/lat_stemwar010427.htm).
- Citing eleven other studies, a study funded by the National Institutes of Health (NIH) and the Christopher Reeve Paralysis Foundation states: "Pluripotent stem cells have been detected in multiple tissues in the adult, participating in normal replacement and repair, while undergoing self-renewal." D. Woodbury et al., "Adult Rat and Human Bone Marrow Stromal Cells Differentiate Into Neurons," 61 Journal of Neuroscience Research 364-370 (August 15, 2000) at 364.
- See: D. Colter et al., "Rapid expansion of recycling stem cells in cultures of plastic-adherent cells from human bone marrow," 97 Proc. Natl. Acad. Sci. USA 3213-8 (March 28, 2000)(adult stem cells amplified a billion-fold in six weeks, retaining their multipotentiality for differentiation); E. Rosler et al., "Cocultivation of umbilical cord blood cells with endothelial cells leads to extensive amplification of competent CD34+CD38- cells," 28 Exp. Hematol. 841-52 (July 2000).
- A recent report on use of adult stem cells to form new muscles, nerves, liver cells and blood vessels observes: "None of these approaches use embryonic stem cells, which some oppose on ethical grounds. Another advantage is that they use tissue taken from the patient's own body, so there is no risk of rejection or need for drugs to suppress immune system defenses." See "Approach may renew worn hearts," Associated Press, November 12, 2000.
- Cloning Human Beings: Report and Recommendations of the National Bioethics Advisory Commission (Rockville, MD: June 1997) at 30-31. The Commission outlined three alternative avenues of stem cell research, two of which seemed not to involve creating human embryos at all.
- "PPL follows Dolly with cell breakthrough," Financial Times, February 23, 2001.
- P. Aldhous, "Can they rebuild us?", 410 Nature 622-5 (5 April 2001) at 623.
- Id. at 622.