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VARIOUS TEXTS: What Is Stem Cell Research?

What is stem cell research?

To answer this question, we must first define the term stem cell. The name for this type of cell may be traced to the stem of a plant. The different branches, leaves, and flowers on a plant all originate from the stem. Therefore, a "stem cell" is a type of cell from which other cells have their origin. In a human embryo, stem cells play an important role in the initial formation of many different kinds of tissues1. In more mature human beings, stem cells give rise to new cells in order to replace old cells that have died or that no longer function properly.

Some stem cells (those found in early embryos) are naturally capable of generating the more than two hundred types of tissue in the human body. Other stem cells (such as "mesenchymal" stem cells) have long been known for their ability to produce several kinds of tissue (such as bone, cartilage, or fat). Still other types of stem cells have been thought to have the capacity to give rise to cells of only a single kind (e.g., a liver cell that can produce only more liver cells and not cells with other functions).

Given the startling2 advances in animal cloning, it's tempting to think that just about any cell can be stimulated to give rise to all human tissue types. To the extent that human cloning can be carried out successfully, such thinking is justified. Cloning involves placing the nuclear genetic material of an adult cell into an egg cell that has been stripped of its nucleus3. The egg is then "tricked" into acting as if it had been fertilized, with the result that a new embryo-containing stem cell capable of generating all types of human tissue during its development - is created.

The current debate over stem cell research has been raging since two teams of U.S. scientists announced in November of 1998 that they had successfully isolated and cultured human embryonic stem cells in the laboratory. This feat4 was a scientific first and set off high hopes in patients and researchers alike that these stem cells held the key to treating - and even curing - many of the most devastating human afflictions5. The basis of this belief rests with the nature of an embryo's stem cells: since they are capable of generating all types of human tissue, having access to them in the lab would potentially provide scientists with the means to produce new heart tissue, liver tissue, brain tissue, lung tissue, or any other type of tissue that a patient might need.

The stem cell batches6 that sparked the ongoing ethical debate did so because they were derived from "surplus" human embryos (obtained from fertility clinics) who were destroyed in the process, as well as from fetal7 tissue obtained from electively aborted8 babies. Availability of these types of stem cells (referred to as embryonic or fetal stem cells) is primarily dependent upon decisions to intentionally end the life of very young human beings. Proponents9 of research on such cells say that the research should proceed because of its allegedly great promise for medical benefit, while opponents deem it unethical - regardless of what benefits might emerge.

A second type of stem cell is that which is not derived from a human embryo or fetus. This type of stem cell is commonly referred to as an 'adult stem cell ' even though such cells are also found in children and teenagers and may even be collected from the umbilical cord10 of a newborn infant. These cells do not carry the same ethical concerns as do embryonic stem cells, since the individuals from whom the cells are obtained are not harmed in any way. Of great interest to scientists, patients, and much of the general public is the emergence of unexpected evidence that adult stem cells also have a great capacity to develop into many (and perhaps all) types of human tissue. Such cells may prove equivalent - or even superior - to embryonic stem cells in terms of their therapeutic value. This is very good news, since the destruction of human embryos required to obtain embryonic stem cells is unethical.
701 words

Source: Basic Questions on Genetics, Stem Cell Research, and Cloning ; Kregel Publications, 2004, Grand Rapids, MI, pp. 81-83

Annotations:
1. tissue - Gewebe
2. startling - alamierend, aufsehenerregend
3. nucleus - Zellkern
4. feat - große Leistung
5. afflictions - Leiden, Krankheiten
6. batch - Charge, Menge
7. fetal (from 'fetus' = Fötus, Leibesfrucht)
8. aborted (from 'abortion' = Abtreibung)
9. proponents - Befürworter
10. umbilical cord - Nabelschnur


Assignments:
1. What is a stem cell and its main function?
2. How does cloning basically work?
3. Why is culturing human embryonic stem cells in a lab such a breakthrough?
4. Why has culturing embryonic or fetal stem cells sparked off an ethical debate?
5. Why has research on adilt stem cells not been criticized so much as research on embryonic stem cells?
6. What is your opinion about research on 'surplus' human embryos obtained from fertility clinics?


Also listen on a BBC programme on stem cells here:
Stem Cells



amazon.de Basic Questions on Genetics, Stem Cell Research, and Cloning
by
Gary P. Stewart
amazon.de




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