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
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