Do No Harm
March 10, 2003
Several prominent scientists who support human cloning to create embryos for embryonic stem cell research (dubbed "therapeutic" cloning by supporters) have recently asserted in news media that numerous scientific studies prove the ability of cloning to produce medical benefits.
Their assertions came in a UPI article, "Analysis: Research results
support cloning" (Steve Mitchell, 3/3/03). There they harshly
criticize Rep. Dave Weldon (R-FL, a physician and the prime sponsor of
the human cloning ban recently passed in the House) for his statement
during floor debate that there are no published studies demonstrating
the supposed therapeutic benefits of "therapeutic" cloning. One
scientist is even quoted as calling Dr. Weldon's remarks "asinine,"
while another tries to question the validity of his medical degree.
It is clear in the UPI story that the question is whether there are studies demonstrating the validity of therapeutic cloning to produce cures, that the scientists quoted understand that this is what they are being asked about, and that their answers are unambiguously affirmative.
The sources quoted refer vaguely to studies published in such prestigious journals as Science, Nature, Nature Medicine and the Journal of Clinical Investigation. More specifically, Dr Paul Berg of Stanford University refers to three studies he claims show the validity of therapeutic cloning (although no sources for these studies are given), and reference is made to a paper co-authored by Robert Lanza of Advanced Cell Technology and published in Nature Biotechnology.
Remarkably, for a report billed as an "analysis," UPI "analyst" Steve Mitchell apparently made no effort to check his sources' assertions by reviewing the studies they referred to. Had he done so, here is what he would have found:
• Neither Science, nor Nature, nor Nature Medicine, nor the Journal of Clinical Investigation have published studies demonstrating the success of "therapeutic" cloning.
In fact, Nature has published an article by its own chief News and Features editor reporting that "many researchers have come to doubt whether therapeutic cloning will ever be efficient enough to be commercially viable." The article cites one British scientist who says "it is too early to give up on therapeutic cloning," but the author observes that "his has become a minority view" (P. Aldhous, in Nature, 410, 622-625; April 5, 2001).
• The study referred to and co-authored by Robert Lanza (Lanza et al., "Generation of histocompatible tissue using nuclear transplantation," Nature Biotechnoology 20, 689-696; July 2002; published online June 3, 2002), in fact explicitly states it is not an example of therapeutic cloning.
While the UPI story claims this study used therapeutic cloning to generate functioning kidneys, the actual study reveals that Lanza et al. gestated cloned cow embryos in a cow's womb to the FETAL stage, then aborted them for their kidney tissue. Lanza and his team write: "Because cloned cells were derived from early-stage fetuses, this approach is not an example of therapeutic cloning and would not be undertaken in humans." Lanza confirmed this on another occasion, saying: "We said it in the paper: This study is not therapeutic cloning and should not be undertaken in humans" (K. Philipkoski, "The Next ACT in Clone Controversy," Wired News, 6/11/02, www.wired.com/news/medtech/0,1286,53104,00.html). The story misrepresents Lanza's own research, while Lanza criticizes Rep. Weldon for accurately quoting that very same research.
• None of the three studies cited by Paul Berg had anything to do with cloning.
According to UPI, Berg cites a study at NIH in which "brain cells derived from embryonic stem cells were transplanted into the brains of mice with a genetic defect that simulates Parkinson's disease," allegedly alleviating the symptoms. There have been a number of studies trying to show progress on this front, but NONE of them involved cloning. In fact, because several of them involved transplanting cells from one species into another (e.g., human embryonic stem cells into mice, or mouse embryonic stem cells into rats), they could not possibly have involved cloning. Incidentally, even as examples of success using (non-cloned) embryonic stem cells these studies are problematic. A co-author of the NIH research said in a recent overview: "These ES-derived neurons may function to restore behavior in animal models of PD, but there could be a major problem with teratoma-induced lethality" (i.e. growth of fatal tumors). (Tsai, Kittappa and McKay, in Developmental Cell 2, 707-712 at 711, emphasis added).
By contrast, adult stem cells are already successfully treating human patients with Parkinson's Disease. Dr. Michel Levesque, at the Cedars-Sinai Medical Center in Los Angeles, reports an almost complete reversal of symptoms in the first Parkinson's patient treated. The patient is still without symptoms three years after the adult neural stem cells were removed from his brain, coaxed into becoming dopamine-producing cells, and then reimplanted (Results presented April 8th, 2002, at the meeting of the American Association of Neurological Surgeons).
Berg next cites research done at the Christopher Reeve Center at the University of California in Irvine, involving the injection of neurons derived from embryonic stem cells into paralyzed rats. But again, this research (conducted by Dr. Hans Kierstead) did not use cloning to avoid tissue rejection – in fact, it involved injecting HUMAN embryonic stem cells (obtained from "excess" embryos at fertility clinics) into rats. Dr. Kierstead has also declared in a news interview that even application of his work to humans will not require cloning, because the problem of immune rejection in neural tissues is not serious and can be addressed with readily available immunosuppressant drugs. (In the same article, none other than Robert Lanza was quoted as agreeing with Kierstead that cloning is not the only way to avoid tissue rejection.) (T. Abate, "Drugs posited as stand-in for stem cell cloning," San Francisco Chronicle, March 18, 2002).
Finally, Berg cites a Stanford study supposedly showing that "insulin-producing cells could be implanted into diabetic mice, enabling them to make insulin and maintain nearly normal blood sugar levels." But yet again, this study had nothing to do with cloning. And even as an embryonic stem cell study it produced only modest results (Y. Hori et al.; "Growth inhibitors promote differentiation of insulin producing tissue from embryonic stem cells"; Proceedings of the National Academy of Sciences USA 99, 16105-16110; December 10, 2002, published online November, 2002). A recent critique of insulin secretion by embryonic stem cells by Douglas Melton and others at Harvard suggests that the new cells may not have produced new insulin at all, but only absorbed it from the surrounding tissues and then re-released it (Rajagopal et al., in Science 299, 363; Jan. 17, 2003).
By contrast, a team of scientists from the University of Florida has reported far more impressive results, reporting full reversal of diabetes in mice, using adult stem cells from either pancreas or liver. (L. Yang et al.; "In vitro trans-differentiation of adult hepatic stem cells into pancreatic endocrine hormone-producing cells"; Proceedings of the National Academy of Sciences USA 99, 8078-8083; June 11, 2002, published online June 4, 2002; V.K. Ramiya et al.; "Reversal of insulin-dependent diabetes using islets generated in vitro from pancreatic stem cells," Nature Medicine 6, 278-282, March 2000).
• Oddly, none of the scientists quoted in the UPI "analysis" mentioned the only published study where "therapeutic" cloning was actually attempted.
The study, done in mice, was published in the journal Cell in 2002 (Rideout et al., in Cell, 109, 17-27; April 5, 2002). The experiment failed to show success with therapeutic cloning.
Rather, supposedly genetically identical cells from cloned embryos were rejected by the mouse's immune system and no therapeutic benefit was achieved. Success was achieved only after a mouse produced by cloning and genetic engineering was brought to the NEWBORN stage and then had ADULT stem cells harvested for transfer into the original mouse. For fuller analysis of this study, please see:
Given the disproved claims about numerous published studies demonstrating the benefits of therapeutic cloning, coupled with the UPI reporter's apparent failure to review the original sources, one is left wondering whether this whole enterprise is the result of ignorance or an effort to mislead.
Dr. Lawrence Goldstein of the University of California, San Diego, is quoted in the UPI story as saying: "Stack up Congressman Weldon's statements about the science and compare them to the statements of those who see great opportunities here…Why would we value (Weldon's) opinion about this …rather than these (scientists)?"
One answer is: Because Rep. Weldon is demonstrably telling the truth and others are not.