Recent published reports on the isolation and successful culturing of the first human pluripotent stem cell lines have generated great excitement and have brought biomedical research to the edge of a new frontier. The development of these human pluripotent stem cell lines deserves close scientific examination, evaluation of the promise for new therapies, and prevention strategies, and open discussion of the ethical issues. Over the next few weeks we will look at cloning, transgenics and the people who have brought us to these new frontiers of medicine. Let us first look at stem cells and the scientific case presently before the British Government looking for a change in the law governing the use of human embryos for research. Any changes in the law will involve allowing scientists taking stem cells at an even earlier stage of development - from an embryo a few days old - and using them directly to restore the function not only of defective bone marrow, but other diseased tissues.
Why do we need stem cells at all?
It is generally accepted that the earlier in human development stem cells are taken, the greater the chance of them being able to develop into a wider set of tissues. A stem cell taken from the umbilical cord blood of a newborn can easily be made to generate specialised blood cells, but not brain or heart tissue. Yet a stem cell taken from an early embryo just a few days old could theoretically develop into any of the 200 to 300 specialised cells and tissues of the human body. The potential for using embryonic stem cells to treat previously incurable conditions is vast. Harold Varmus, the former director of America' s National Institutes of Health, recently told the US Congress: "There is almost no realm of medicine that might not be touched by this innovation."
If it were possible to create an unlimited source of embryonic stem cells, many of the problems associated with the shortage of organs for transplants may be overcome. Britain's Royal Society, our de facto national academy of sciences, has told the Government's inquiry into the issue: "Organs damaged by trauma or disease do not always need replacing, and repair often would be possible if a suitable source of cells was available. Stem cells are a potential source. Patients suffering from certain degenerative diseases of the brain, liver (hepatitis), pancreas (diabetes), blood (leukaemias), joints (rheumatoid arthritis), heart and kidneys are likely to benefit from stem cell therapy. Other diseases which might be alleviated thus include muscular dystrophy and cystic fibrosis."
As the law stands, scientists can only work with stem cells taken from an embryo less than 14 days old if the research is geared towards understanding fertility, reproduction or congenital disorders. Austin Smith, the only scientist in Britain with such a licence, says that the law should be relaxed to allow people like him to use them for treating other medical disorders. "They are a wonderful natural resource as they can develop into almost any kind of human cell, such as brain, bone or heart. They offer a unique opportunity to replace tissues damaged by disease," Dr Smith says.
How does technology harvest stem cells at the moment?
At present, human pluripotent cell lines have been developed from two sources with methods previously developed in work with animal models:
(1) In the work done by Dr. Thomson, pluripotent stem cells were isolated directly from the inner cell mass of human embryos at the blastocyst stage. Dr. Thomson received embryos from IVF (In Vitro Fertilisation) clinics-these embryos were in excess of the clinical need for infertility treatment. The embryos were made for purposes of reproduction, not research. Informed consent was obtained from the donor couples. Dr. Thomson isolated the inner cell mass and cultured these cells producing a pluripotent stem cell line.
(2) In contrast, Dr. Gearhart isolated pluripotent stem cells from fetal tissue obtained from terminated pregnancies. Informed consent was obtained from the donors after they had independently made the decision to terminate their pregnancy. Dr. Gearhart took cells from the region of the fetus that was destined to develop into the testes or the ovaries. Although the cells developed in Dr. Gearhart's lab and Dr. Thomson's lab were derived from different sources, they appear to be very similar
So what's the problem?
Why doesn't the Government change the law to allow scientists to exploit the obvious benefits of embryonic stem cells? The answer of course is that some religious groups perceive even the earliest embryo as a potential human being that cannot be treated as an expendable resource. But there is another ethical issue mixed up with the Government's deliberations. This concerns whether permission should be given to scientists to attempt a form of human cloning for therapeutic, as opposed to reproductive, purposes.
What exactly is cloning?
The word 'clone' comes from the Greek 'klwn', meaning twig, and refers to one or more offspring derived from a single ancestor, whose genetic composition is identical to that of the ancestor. For example, every chrysanthemum plant you buy at a Garden Centre is a clone of some distant and probably long dead chrysanthemum. Whenever one divides an overgrown shrub or successfully cultivates a houseplant cutting you are cloning. In each case you are deliberately propagating a copy of the parent and producing a multitude of plants (clones) all genetically identical to the prized parent.
No sex is involved in the production of clones, and since sex is the normal means by which new genetic material is introduced during procreation, clones have no choice but to have the same genes as their single parent. In the same way, a clone of cells refers simply to the descendants of a single parental cell. Many tumours are clones, as are the offspring of organisms, which reproduce asexually, like corals. Thousands of years before anyone understood the physical nature of heredity, specific genetic constitutions were preserved through cloning because they bestowed on the plant desirable qualities such as disease-resistance, high yield and predictable growth. Cloning is as important to the production of fine wine, the supply of rubber and the fruit harvest as it is to the variety of an English country garden.
Furthermore, natural cloning is not confined to plants: microbes and some insects frequently propagate themselves by producing genetically identical offspring without recourse to sex. The toothless mammal, the armadillo, gives birth not to identical twins but to genetically identical octuplets, every litter a batch of eight clones. There is nothing a priori unnatural about cloning. In theory cloning provides an alluring short cut to amplifying the the number of animals with an apparently desirable genetic constitution
Dr. Patrick Treacy is Medical Director of Ailesbury Clinics Ltd and the Cosmetic Medical Group. He is also Medical Director of OnboardSpa Ltd. He is Chairman of the Irish Association of Cosmetic Doctors and is Irish Regional Representative of the British Association of Cosmetic Doctors. He is European Medical Advisor to Network Lipolysis and the UK's largest cosmetic website Consulting Rooms. He practices cosmetic medicine in his clinics in Dublin, Cork, London and the Middle East. He was amongst the first doctors worldwide to use the permanent facial endoprosthesis BioAlcamid for HIV Lipodystrophy patients. He was also the first person to introduce many techniques such as Radiofrequency assisted lasers, Fibroblast transplant and Contour Threads to Irish patients.
Dr. Treacy is an advanced aesthetic trainer and has trained over 300 doctors and nurses from around the world. He is also a renowned international guest speaker and features regularly on national television and radio programmes. He was invited to speak about stem cells and cosmetic medicine at the World Aesthetic Conference in Moscow this year.
The Irish College of Cosmetic Doctors
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Dr. Treacy is the European Representative for the NetWork-Lipolysis where he is on the Medical Advisory Board and the Scientific Advisory Board.
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