The False Promise of "Therapeutic" Cloning
Moral considerations aside, human cloning is not going to lead to useful medical treatments.
Mar 11, 2002, Vol. 7, No. 25 • By WESLEY J. SMITH
The simple answer is: We aren't going to get them. Assuming that therapeutic cloning researchers could overcome the genetic defects problem, and assuming that they could also control the growth of the new cells so as to prevent tumors, and even assuming perfect clinical conditions, there is no way around the fact that at least one human egg would be required for each patient. Now, consider the number of patients in this country alone with medical conditions for which embryonic stem cell therapies are being promoted as promising--people with Parkinson's disease, stroke, Lou Gehrig's disease, multiple sclerosis, spinal cord injuries, Huntington's disease, and more. According to a National Academy of Sciences estimate, there are more than 100 million such patients in the United States alone, meaning that even in a perfect cloning world, we would need at least 100 million human eggs to treat them. The only possible way out would be to use cow eggs. But few researchers speak publicly of wanting to go there.
And that isn't the half of it. As daunting as that number is, for the foreseeable future it will take many eggs to successfully create just one clone embryo. This means that the actual number of eggs that would be necessary for clinical application of therapeutic cell cloning is some unknown multiple of the figure above--an utterly staggering number.
David Prentice, an expert in stem cell research at Indiana State University and an opponent of human cloning, has done the math for just one patient group: diabetics. The results are devastating to the prospect of ever seeing therapeutic cloning take pride of place in medicine's armamentarium. There are some 16 million diabetics in the United States. Prentice assumed that 20 percent of cloning attempts would succeed in reaching the blastocyst stage of development. This number is based on published reports on successful production of blastocysts from animal cloning. The number is more than fair since cloning a genetically sound human embryo would be more difficult than cloning an embryonic mouse, sheep, or cat.
He next assumed that stem cells would be successfully derived from 10 percent of these clone embryos. This figure is also fair. It took 36 embryos for James Thomson of the University of Wisconsin to create 5 human embryonic stem cell lines, a 13.8 percent success rate. The Jones Institute used 110 embryos to get only three stem cell lines, a 2.7 percent success rate. And these embryos were created through fertilization, which does not pose the genetic defect problem found in clone embryos.
Using these figures, Prentice computed that it would take 800 million eggs just to treat the 16 million American diabetics with a therapy involving cloned embryonic stem cells.
Obtaining human eggs for this purpose would involve stimulating the ovaries to hyper-ovulate, which generally produces 7-10 eggs. Assuming a liberal 10 eggs harvested from each procedure, 80 million women of childbearing age would be needed as donors.
Considering the number of people in the United States with other diseases who have been promised they will benefit from therapeutic cloning, the actual number of women that would be required to donate eggs just to treat patients in this country can hardly be imagined.
Now, consider the difficulties involved with hyper-ovulation. The procedure is not exactly a walk in the park. After the ovaries are stimulated to release multiple eggs, the eggs are surgically extracted. A partial list of potential side effects from the procedure include rupture of the ovaries, severe pelvic pain, accumulation of fluid in the abdomen as well as around the heart and lungs, bleeding into the abdominal cavity, acute respiratory distress, and pulmonary embolism. That being so, how many American women are going to be willing to provide eggs for use in cloning?
Of course there are billions of women in the developing world who could provide eggs. But that would require creating a market in human ova in which poor women would submit to hyper-ovulation for pay without any personal therapeutic benefit. And even assuming a thriving market in eggs, the number that could realistically be obtained would not even scratch the surface of the actual therapeutic need.
The "egg dearth" is a mathematical certainty. This means that if clone embryonic stem cell therapy were ever successfully developed, it would have to be either severely rationed or available only to the very rich. But therapeutic cloning is being held out as a panacea for the many, not as a rare procedure available to the very few. That's a false hope. The real "promise" of therapeutic cloning is this: millions of Third World women being paid to submit to operations for the benefit of rich Americans.
Researchers already realize that therapeutic cloning will not be a generally available medical treatment, although they don't speak about it too loudly for fear of aiding the anti-cloning effort. Still, some cloning advocates rise to the level of public candor. For example, a year ago biotech researchers Jon S. Odorico, Dan S. Kaufman, and James A. Thomson admitted the following in the research journal Stem Cells:
"The poor availability of human ococytes [eggs], the low efficiency of the nuclear cell procedure, and the long population-doubling time of human ES cells make it difficult to envision this [therapeutic cloning to obtain stem cells] becoming a routine clinical procedure even if ethical considerations were not a significant point of contention."
Other researchers have made the same point privately. Peter Aldhous, Nature's chief news and features editor and a man with a reputation for giving the straight story, reported in the December 20/27, 2001, edition of Nature, "the idea of 'therapeutic cloning' seems to be on the wane. By creating cloned human blastocysts, some experts have argued that it should be possible to derive ES cells perfectly matched to individual patients. But most now believe this will be too expensive and cumbersome for regular clinical use." Or to put it another way, there just aren't enough human eggs.
Be that as it may, some readers might be thinking, why not go forward with research into human cloning anyway? The answer to that question brings us back to the issue of utility. If our goal as a society is to fund research into cellular technologies with the best hope of providing viable medical therapies in the shortest period of time, human cloning is the last thing we want to fund. After all, medical research dollars are a finite resource, and research into human cloning is very expensive. (It took $3.7 million just to clone one cat.) Thus, money poured into human cloning is money that will not be available for other areas of medical research.
Moreover, when it comes to the issue of stem cell therapies, the evidence is becoming overwhelming that our limited resources are most wisely spent pursuing research into adult stem cells as our best and quickest hope for developing efficacious new medical treatments. Adult cells don't appear to lead to tumors. And since the patient's own cells are used, tissue rejection is not an issue. Moreover, adult stem cells are already used to treat human ailments such as heart disease and auto immune deficiencies--which even the most optimistic proponents of therapeutic cloning admit are many years away using embryonic stem cells. In this regard, it is worth noting that the American Red Cross recently refused a National Institutes of Health grant to work on embryonic stem cells in order to focus more intensely on research involving stem cells found in umbilical cord blood. Why concentrate on umbilical cord blood and exclude work on embryos? The Red Cross representative could not have been clearer: "We really need to focus our resources, our attention, on those areas where we could most likely provide, in the shortest period of time, some therapies for our patients."
To pour money into human cloning embryonic stem cell research is to risk drilling one dry hole after another. The moral policy thus also turns out to be the pragmatic one. The United States Senate should vote to ban all human cloning now.
Wesley J. Smith, a frequent contributor to The Weekly Standard, is the author of "Culture of Death: The Assault on Medical Ethics in America."