Once again the media are trumpeting the call among many in Congress, pushed by millions in Big Biotech lobbying money, for President Bush to reverse his decision to limit federal funding of embryonic-stem-cell research (ESCR) to those lines already in existence on August 9, 2001. Fronted this time by the grief-stricken Nancy Reagan, and boosted by Hollywood celebrities such as Christopher Reeve, Michael J. Fox, and Mary Tyler Moore, we are warned darkly, as a recent New York Times editorial put it, that the existing federal-funding restrictions “are so potentially damaging to medicine” that the administration is encountering opposition to its policy even among its “own conservative supporters.”
We have heard this mantra many times before but repetition does not make it true. A great deal has been learned about the potential of regenerative medicine since President Bush reached his “compromise” decision ending the stem-cell debate of 2001. And indeed, perhaps the time has come for us to revisit this issue, albeit from a different angle than suggested by ESCR boosters. Perhaps the problem with the Bush plan isn’t that it provides too little federal money for ESCR, but too much–at least if our national goal is to find cures to diseases such as Alzheimer’s, diabetes, and Parkinson’s in the shortest period of time.
The media is so excited about the supposed potential of embryonic stem cells that it gives far too little attention to the many and serious problems associated with this potential source of regenerative medicine. Listening to the hype, one might think that ESCR is on the verge of tremendous success. But the hard truth is that it does not appear likely that embryonic stem cells will soon become the panacea that fervid supporters of the research often claim. For example:
In animal studies, embryonic-stem-cell treatments have been found to cause tumors. In one mouse study involving an attempt to treat Parkinson’s-type symptoms, more than 20 percent of the mice died from brain tumors–this despite researchers reducing the number of cells administered from the usual 100,000 to 1,000.
Tissue rejection is another major hurdle to the use of embryonic stem cells in medical treatments. This is why ESCR is known as the gateway to human cloning, since one proposed way out of this potential dilemma is to create cloned embryos of patients being treated as a source of stem cells, a process known as “therapeutic cloning.” Not coincidentally, many of the same proponents who are now urging increased funding for ESCR also advocate that we legalize and publicly fund therapeutic-cloning research, which many find immoral because it creates cloned human life for the sole purpose of experimentation and destruction.
Besides being immoral, therapeutic cloning also looks to be wildly impractical. For example, a recent report published by the National Academy of Sciences warned that it could cost in the neighborhood of $200,000 just to pay for the human eggs to derive one cloned human embryonic-stem-cell line.
The hope that embryonic-stem-cell lines are immortal, thereby allowing them to supply unlimited cells for use in regenerative medical treatments, appears to be fading fast. Several studies, including one published in the March 25, 2004, New England Journal of Medicine, have now shown that over time embryonic-stem-cell lines develop severe chromosomal anomalies, including a form of cell change found in some types of cancer.
These and other significant scientific obstacles facing embryonic-stem-cell researchers mean that treatments from this source of stem cells are unlikely to become a part of medicine’s armamentarium at the clinical level for more than a decade–if ever. Indeed, as reported in Washington Fax in 2002, the noted stem-cell-research pioneer John Gearhart has suggested that embryonic stem cells, in the end, will probably not be “used in therapies.” Rather, he said, “patients’ own cells,” e.g. adult stem cells, are “where I see the future now.” (Gearhart does support ESCR, believing that it will provide useful information permitting patient’s own cells to be used in regenerative medicine.)
Fortunately, embryonic stem cells are not the only potential source for regenerative medical treatments. There are also adult stem cells, umbilical-cord-blood stem cells, and other cellular-based treatments that do not use embryos at all. Here we see a completely different picture emerging. Under-reported by the ESCR-besotted mainstream media, many of the diseases that embryonic cells are supposed to treat may be ameliorated with adult-stem-cell and related therapies far more quickly. These include:
Heart Disease: The FDA has allowed a human trial to proceed that will use bone-marrow stem cells to treat severe heart disease. The experiment will be conducted at Texas Heart Institute in Houston. This approach has already safely improved heart function in 14 patients in Brazil, as reported in the medical journal Circulation. Indeed, the researchers found “significant improvements in exercise capacity,” improving oxygen capacity “from 17 percent to 24 percent in treated patients.” A similar result has already been reported in the U.S. using a patient’s own blood stem cells, as have other human experiments in France and Hong Kong. (On a sour note, while not disproving the benefit of adult cells in treating heart disease, researchers in two mouse experiments failed to replicate earlier studies that seemed to show adult stem cells could be transformed directly into new heart muscle. Meanwhile, further studies still need to determine whether the treatment could cause dangerous arrhythmias.)
Diabetes: As reported in the November 14, 2003, issue of the distinguished journal Science, Type 1 (juvenile-onset) diabetes has been cured in mice using human spleen cells. The cells migrated to the mice pancreases, “prompting the damaged organs to regenerate into healthy, insulin-making organs” and thus curing their diabetes. The authors noted that “because the cell donors and hosts are adults, this system would preclude ethical issues associated with the use of embryonic stem cells, as well as concerns that [cell] transdifferentiation of embryonic stem cells may be incomplete.”
Neurological Conditions:HealthDay recently reported that “Cells found in a patient’s own bone marrow might someday be a safe, ethical source for replacing brain cells lost to Alzheimer’s, Parkinson’s and other neurological conditions.” German researchers cultured human bone-marrow stem cells and were able, within a few weeks, to morph them into mature neural or glial cells. We learned just this month that cells derived from dental pulp can be transformed into neural cells and may someday be a readily available source of treatment for conditions such as Parkinson’s.
Along these lines, human patients have already benefited substantially from the alleviating of symptoms of Parkinson’s with adult stem cells and related therapies. For example, Dennis Turner of southern California was the first human patient known to have been treated by his own brain stem cells for Parkinson’s. It is now a few years post treatment and his Parkinson’s–which by now was expected to have substantially disabled him–has instead gone into substantial remission. Turner has been able to reduce his medications and rarely experiences significant symptoms of his disease. Meanwhile, the May 2003 edition of Nature Medicine reported that five Parkinson’s disease patients, who received injections of a natural body chemical known as glial-cell-line-derived neurotrophic factor (GDNF), experienced significant improvement in their conditions. Three of the patients even regained their sense of taste and smell.
I could write pages about such successes. Adult-stem-cell and related therapeutic approaches are in current clinical trials or use for the treatment of cancers, autoimmune diseases, anemias, bone and cartilage deformities, corneal scarring, stroke, and skin grafts. Researchers have successfully restored some eye functions by extracting stem cells from human eyes, growing them in culture, and transplanting them into mice. Human trials are showing similar successes. Optimistic researchers hope that the technique could provide a cure for blindness within five years. Cells from human fat have proven to be true adult stem cells that look to be useful in regenerative medicine. Indeed, it appears that 62 percent of human fat cells “could be reprogrammed into turning into at least two other different cell types,” according to Duke University researchers.
The thrust of the research now seems indisputable: While certainly not yet a sure thing, and noting that much work remains to be done in animal and controlled human studies, barring unforeseen problems adult-stem-cell and related therapies may be potent sources of new and efficacious medical treatments in the years to come. Just as significantly, these therapies are likely to be available far sooner than embryonic-stem-cell treatments, since adult and related therapies do not appear to cause tumors, would not be rejected, and do not have to be maintained indefinitely in vitro, because they would come from patients’ own bodies.
As Colorado stem-cell activist Jim Kelly–a paraplegic who believes his best hope of walking again after an auto accident lies in adult-stem-cell treatments–told me, “We have to use our limited resources efficiently. Money spent on embryonic-stem-cell research and human cloning is money that cannot be spent on [investigating] adult stem cells.” If Kelly is right, increasing funding for embryonic-stem-cell research, especially if it comes at the expense of adult experiments, could actually delay the cures that so many suffering patients hope desperately to receive from developing cellular therapies.