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The following is not to be taken as medical fact, but is only the personal opinion of the writer, Dr James F Slattery, PhD Soc Sc ---------------------------------------------------------------------------------------------------- STEM CELL and CLONING RESEARCH Much of the dispute about stem cells and cloning arises from a misunderstanding of the terms used, between their specific and unique meaning to scientists, and their common meaning to the general public. EMBRYONIC STEM CELLS Take, for instance, the word "embryo". The scientist defines the term as a human organism from the first cell cleavage to 8 weeks. However, in the view of most non-scientific-minded people, "embryo" is synonymous with "foetus", and therefore presents as a tiny, developing human being. However, the organism from which stem cells are derived for research is typically four or five days old. It comes from eggs that have been fertilized "in vitro", i.e., in a glass dish usually at a fertilisation clinic. They are NOT derived from eggs that have been fertilized in a woman's body. At this stage, the organism is called a blastocyst. The embryonic stem cells are isolated by transferring the inner cell mass of the blastocyst into a culture medium in a dish. The cells can then be cloned (replicated) many times. However, this process is somewhat inefficient, as stem cell lines are not produced each time that cells are extracted and transferred to a culture dish. If a person has a view that "life" begins at conception (as soon as the sperm enters the ovum) and that doing anything the fertilized ovum is wrong, other than implanting it in a womb in order to produce a human child, then nothing one can say to the contrary will change their mind. Any attempt to remove cellular material from such an organism, even though the material is going to be replicated, and not implanted in a womb, would be considered as "abortion" by such a person, and the disposal of the unwanted tissue from the blastocyst would be classed as "murder". However, if people have a mistaken view about the methodology of extracting "embryonic" stem cells, and have the facts lain before them, that ESCs are produced from an ovum, from the tiny mass of the blastocyst, and NOT from an already developing foetus, then we may have a chance at convincing them of the value and ethicality of ESC research. ADULT STEM CELLS Adult stem cells are undifferentiated cells, found throughout the body after embryonic development, that multiply by cell division to replenish dying cells and regenerate damaged tissues. Also known as somatic stem cells (meaning "of the body"), they can be found in juveniles as well as in adults. The term "adult" as used here implies post-foetal. Scientific interest in adult stem cells centres on their ability to divide (self-renew) indefinitely, and to generate all the cell types of the bodily organ from which they originated, potentially regenerating the entire organ from a few cells; thus, they are more properly called "progenitor cells". Unlike embryonic stem cells, the use of adult stem cells in research and therapy is not considered to be controversial, as they are derived from adult donor tissue samples rather than embryonic tissue. Progenitor cells have the capacity to differentiate into a specific type of cell. In contrast to stem cells, however, they are already far more specific, and can be "pushed" to differentiate into their "target" cell. The most important difference between embryonic stem cells and progenitor cells is that stem cells can replicate indefinitely, whereas progenitor cells can only divide a limited number of times. Using adult stem cells is considered by the non-scientific community to be more "ethical" than using ESCs. THERAPEUTIC CLONING In genetics and developmental biology, SCNT (somatic cell nuclear transfer) is a laboratory technique for creating a cloned embryo, using an ovum (female egg). The process can be used in embryonic stem cell research, or potentially, in regenerative medicine where it is referred to as "therapeutic cloning". In SCNT, the nucleus of a somatic cell (a body cell other than a sperm or egg cell) containing that organism's DNA, is removed and saved, and the remainder of the cell is discarded. At the same time, the nucleus of an ovum (egg cell) is removed from the ovum, to be replaced by the nucleus of the somatic cell. After being inserted into the egg, the somatic cell nucleus is "reprogrammed" by the host cell. The ovum, now containing the nucleus of a somatic cell, is stimulated with a shock, and begins to divide. After many mitotic divisions (cell division in which the nucleus divides into nuclei containing the same number of chromosomes) in a culture dish, this single ovum forms a blastocyst (an early stage embryo with about 100 cells), with almost identical DNA to the original somatic cell. The aim of carrying out this procedure, rather than the embryonic stem cell method, is to obtain stem cells that are genetically matched to the donor somatic cell. Some people still call this process "abortion", although no embryo is formed and destroyed. They consider the "enucleated" ovum obtained in the therapeutic cloning to be the equivalent of the ovum in the embryonic method, although the enucleated ovum is not capable of being planted in a womb. They refer to the material discarded from the ovum as "murder". This despite the fact that millions of women throughout the world "destroy" at least one complete ovum every month, in the process of menstruation. My personal opinion is in favour of adult stem cell therapy, and I hope I live long enough to benefit from it. ---------------------------------------------------------------------- To sign-off Parkinsn send a message to: mailto:[log in to unmask] In the body of the message put: signoff parkinsn