The human stem cell has become a common denominator of hope for millions suffering from such diseases as diabetes, muscular dystrophy, cystic fibrosis, Alzheimer 's and Parkinson 's, and from injuries to the spinal cord and other organs. There remains a lengthy distance science must travel before such diseases are cured or even prevented. But the potential is enormous, as must be the investment.
A central element in the political drama over stem cells since 2001 has been the widespread public and political confusion over the different scientific terms involved in this particular science. One such term is "cloning ". In the 1990s, Scottish scientists announced the birth of Dolly, a sheep produced by injecting the nucleus of a skin cell from one sheep into a non-fertilized egg from another, an egg from which the nucleus had been removed. After four to five days, the egg was implanted into a third sheep, and some months later Dolly, an exact copy of the sheep from which the skin cell was removed, was born.
News of successful animal cloning, known more accurately as "reproductive cloning " and accomplished by a technique known as somatic cell nuclear transfer (SCNT), led some to fear that reproductive cloning of humans was in our future. But such fears are unfounded; no one is proposing cloning humans to replace loved ones, or for spare parts.
Ninety-nine percent of the twenty-thousand attempts at cloning five different mammalian species have resulted in the death of the clone, either in the womb or soon after birth. Of the few clones that do survive, many are less than healthy, and have shortened life spans. Because there are numerous serious biological problems associated with reproductive cloning, many of which may never be fully understood or overcome, any attempt to use SCNT to create a human clone would amount to the worst form of human experimentation.
There is universal ethical and political agreement on prohibiting human cloning. Every national and international scientific body vociferously condemns the idea of reproductive cloning for humans. Human cloning would be immoral, and should be deemed illegal by all governments. There must be allowed no oasis nation for such research.
But we must not ban SCNT, as some in Congress have wanted. SCNT is potentially useful in research, not for reproductive cloning, but for what is known as "therapeutic cloning ", which does not involve creating animal clones.
"Therapeutic cloning " does come with its own host of ethical concerns for some, mainly the deeply religious, for it involves extracting stem cells from a four- to five-day-old human embryo. But these embryonic stem cells (ESCs) are incredibly potent, able to form and replace damaged cells of whatever organ in which they reside. Their promise lies in their ability to heal defective tissue, which, for certain diseases, might actually be their cure.
ESCs are extracted from a blastocyst, the four- to five-day-old pre-implantation embryo. Frozen fertilized human embryos are obtained - without monetary transaction - from in vitro fertilization (IVF) clinics with the consent of donor parents. They are then grown on a culture dish until they reach the 100-cell blastocyst phase of development. Inside the blastocyst is the Inner Cell Mass (ICM), made up of embryonic stem cells. The ICM is removed and placed into another culture dish, where, if provided the right environment, the stem cells divide and replicate indefinitely to form what is known as a "stem cell line ".
These are embryos that would otherwise never develop into humans. They are leftover from successful IVF procedures. No longer needed, their parents are making the decision to donate their fertilized eggs to science.
Most proponents of stem cell research hold that it is morally permissible, even morally required, to use these extra and otherwise unwanted embryos for potentially life-saving biomedical research. Opponents, however, object, saying that the destruction of any embryo is the moral equivalent of killing a human life. President Bush agreed, in August 2001, when he imposed a ban on using federal funds to create new stem cell lines, a ban still in place now nearly five years on.
While private research has continued since 2001, private investment cannot match the resources government can provide. Powerful political support has developed in favor of permitting public investment. In early summer 2005, both Republican-controlled houses of Congress actually passed bills ending the Bush ban, but the House bill fell forty-seven votes shy of the two-thirds majority needed to override a threatened presidential veto. In the meantime, two states, California and New Jersey, have passed their own laws permitting public funding of stem cell research.
The United States is quickly ceding its biomedical leadership to others. Beyond our shores, human embryonic stem cell research is proceeding apace, supported by government in places as diverse as Sweden, England, Singapore and South Korea. As a result we may someday soon find ourselves paying a premium price for the therapies derived from stem cell research overseas.
No one is suggesting we be careless with embryos. They must always be treated with special consideration and respect. Selling embryos on the open market is unequivocally wrong. Experimenting with them to create human clones must be made severely punishable. But the promise of human benefit from responsible embryo research is enormous, and such research must neither be curtailed nor criminalized.
Stem cells offer an enormous potential to improve life and relieve suffering. Human stem cell research is already leading to new ways of diagnosing disease, and could potentially lead to the discovery of safer drugs for treatment, in addition to the potential use of stem cells in replenishing or replacing mature cells and tissues destroyed by disease.
The resolution of the ethical and religious considerations to stem cell research will doubtless take some time. After all, there is genuine morality and passion on both sides of this debate. But the decision we face is whether an unwanted blastocyst, a mass of one hundred cells fully eleven weeks away from any neural function, has moral rights equivalent to the moral obligation we have to act for the benefit of the sick among us. Two forms of human life are at stake: human embryos and living persons. The question is which is due more respect.