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The creation of Dolly
represented a further step in the development of nuclear replacement
technology. It showed that a nucleus
taken from an adult animal could be reprogrammed to allow the
full range of gene expression needed to produce a complete animal,
so called gene totipotency. Although this research is still in
its early stages and has not been reproduced it is a significant
scientific breakthrough and offers a number of basic research
applications of human relevance.
Nuclear replacement
research can improve our knowledge about physiological processes
and the genotype. For example, it is hoped that this work will
offer a greater insight into the origins of cancer and other cellular
development processes such as ageing and cell commitment. It may
also offer the potential to produce better animal models for human
disease which would aid research into new or improved therapies.
Many of these important questions will be difficult to study unless
the procedure shown in livestock animals can be extended to mice,
for example. 
In humans,
the possibility of using nuclear replacement technology for reproductive
cloning has been raised. However, it could also be used as a means
to avoid the transmission of inherited diseases derived from the
mitochondria.
This possible application need not involve human reproductive
cloning. It could involve, for example, taking an enucleated egg
from a donor containing normal mitochondria, which would then
receive the nucleus from an unfertilised egg taken from the individual
with mitochondrial disease. The reconstructed egg could then be
fertilised.
This
type of therapy would not involve the production of a genetically
identical individual or fetus. It is important to make the distinction
between human embryo research, which may be permitted under licence
under the 1990 Act and reproductive cloning, where an embryo is
implanted into a woman's womb. The Warnock Committee concluded
in 1984 that, "the embryo of the human species ought to have a
special status", which should be enshrined in legislation. The
Committee stated that this special status should not afford the
human embryo the same status as a living child or an adult, but
did mean that human embryos should not be used frivolously or
unnecessarily. The Committee went on to conclude that the special
status of the embryo would permit some embryo research up to the
fourteenth day of development provided the research was strictly
controlled and monitored. The recommendations of the Warnock Committee
were included in the provisions of the Human Fertilisation and
Embryology Act 1990, which allows research to be carried out on
embryos up to 14 days development under licence from the HFEA
within certain restrictions. Would the use of nuclear replacement
techniques or embryo splitting to create embryos raise any new
issues in relation to the special status of the human embryo?
Research
which might generate in-vitro
stem cells and cause them to differentiate into specific cell
types could provide insights into how to induce regeneration of
damaged human tissue without risk of rejection reactions. For
example: neural tissue for sufferers of Parkinson's Disease; skin
tissue to treat patients suffering from burn injuries; and muscle
tissue to treat patients suffering from heart damage. Under the
HFE Act 1990, limited human embryo research may be licensed for
specific purposes as defined in the Act. However, the Secretary
of State does have the power to broaden the scope of this research,
which would permit the HFEA to consider proposals to conduct human
embryo research for some therapeutic purposes (see paragraph 5.3).
Would any of the potential applications of nuclear replacement,
some of which are exemplified above, that would not result in
cloned fetuses or babies raise any new ethical concerns?
Gina
Kolata
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