Voting no by using his veto pen for only the third time in his presidency will also be President Bush, who has said he will not sign any legislation ending the ban he imposed on the use of federal funds to create new stem cell lines in August of 2001. The House vote fell well shy of a veto-proof majority, leaving certain that the President’s ban will remain in place for at least another year.  

Few branches of science have ever grown as rapidly and generated as much promise for improving the human condition as the field of biomedicine. Over just the past decade, biomedicine has produced such extraordinary scientific breakthroughs as the mapping of the human genome, and the successful isolation and cultivation of human stem cells.   

And yet no other branch of science is so deeply fraught with ethical concern and debate within and outside of government.  

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 tens of thousands of 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 no oasis nation for such research.  

But we must not ban SCNT, as some in Congress have in recent years wanted. SCNT is potentially useful for 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 there 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 place 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.   

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