Download THERAPEUTIC CLONING 1) What is therapeutic cloning

THERAPEUTIC CLONING
1) What is therapeutic cloning ?
Therapeutic cloning involves taking someone’s DNA extracted from say, a skin cell, and
inserting it into a human egg from which the DNA has been removed.
2) What are stem cells ?
Stem cells are a class of undifferentiated cells that are able to differentiate into specialized
cell types. Commonly, stem cells come from two main sources:
- embryos formed during the blastocyst phase of embryological development (embryonic
stem cells)
- adult tissue (adult stem cells).
3) What is the difference between human adult stem cells and embryonic stem cells ?
Most adult stem cells in the body have a particular purpose which cannot be changed. For
instance, a liver cell is developed to perform specific functions, and cannot be transformed to
suddenly take on the role of a heart cell.
Embryonic stem cells are different. They are still at an early stage of development, and retain
the potential to turn into many different types of cell and therefore organs.
Scientists believe the most useful stem cells come from the tissue of embryos because they
are pluripotent : they have the ability to become virtually any type of cell within the body. It
is thought the potential of adult stem cells to become other types of cell is more limited (than
that of embryonic stem cells).
4) Why is therapeutic cloning so promising ?
Scientists believe stem cells can provide us with a ready supply of replacement tissue. These
cells can be implanted into a patient’s body to repair the damage caused by degenerative
illnesses like heart or liver condition.
Currently when patients suffer from acute heart failure and their medications are no longer
working, the only option is a heart transplant. However many hurdles have to be overcome
before the potential recipient is transplanted.
What are they ?
- there is a serious shortage of organs : organs are only removed for transplantation after a
person has died. One of the problems is that only a very small number of people die in
circumstances where they are able to donate their organs. The organs transplanted have to be
in very good condition and should match blood group and tissue type.
Therapeutic cloning would allow the creation of a perfect match tissue. At the moment , if
you have a transplant your body will try to reject the donated organ because it sees it as
foreign. Doctors dampen this immune response by prescribing powerful drugs that patients
must take for life, not to mentien the numerous side-effects engendered by a transplant.
5) Why is the use of embryonic stem cells controversial ?
There are several ethical issues that are raised while working with stem cells.
The largest controversy with stem cell research is the use of an embryo. Therapeutic cloning
does result in the destruction of an embryo after stem cells are extracted and this destruction
has stirred controversy over the morality of the procedure. Some argue that the pros outweigh
the cons with regards to treating disease while others have likened the destruction to an
abortion. Still others state that this doesn't change the fact the embryo could potentially be a
human being and so destruction of the embryo is no different than destruction of a human life.
Because reproductive cloning does utilise SCNT (Somatic cell nuclear transfer) as the
primary step, there is also still fear that given our knowledge base to perform reproductive
cloning, a scientist may attempt to move beyond therapeutic cloning to creation of a human
being.
To this date, no human being has been successfully cloned but the possibility of this occurring
is a frightening one not only for the general public and policy makers, but also for most of the
ethical scientific field. The majority of scientists are adamantly opposed to reproductive
cloning and instead, support therapeutic cloning for treating disease. With policies and careful
monitoring in place to ensure that therapeutic cloning is used responsibly, we can all benefit
from the potential of this procedure to eventually treat, or perhaps one day cure, many
diseases.
Another problem with therapeutic cloning is that many attempts are often required to create a
viable egg. The stability of the egg with the infused somatic nucleus is poor and it can require
hundreds of attempts before success is attained.
VOCABULARY
Somatic cell : a somatic cell is any cell of the body except sperm and egg cells.
Totipotent : the ability to differentiate into all possible cell types. Examples are the zygote
formed at egg fertilization and the first few cells that result from the division of the zygote.
Pluripotent : the ability to differentiate into almost all cell types. Examples include embryonic
stem cells and cells that are derived from the mesoderm, endoderm, and ectoderm germ layers
that are formed in the beginning stages of embryonic stem cell differentiation.