Research cloning uses somatic cell nuclear transfer to produce
a clonal embryo. Sometimes called "embryo cloning" or "therapeutic
cloning," it would begin with the same procedure that would be
used for reproductive cloning: the nucleus from a body cell is put
into an egg from which the nucleus has been removed. The resulting
entity is triggered by chemicals or electricity to begin developing
into an embryo.
Instead of being implanted in a womb and brought to term as a cloned
child, the embryo would be used for research purposes—for example,
to generate embryonic stem cells.
Most scientists agree that research cloning for medical research
is not needed as a source of embryonic stem cells—these
can be obtained from embryos generated by in vitro fertilization.
Rather, researchers have proposed that research cloning may
turn out to be useful for producing "customized" embryonic
stem cells that could generate compatible replacement tissues
for individual patients. Replacement tissues generated in this
way would presumably not be rejected by a patient's immune system,
since their genetic make-up would be the same as that of the
Another proposal is for research to use research cloning to
create stem cells with genetic conditions that cause diseases
in order to study the diseases.
(Images courtesy of the Association of Reproductive Health Professionals)
Page last modified June 30, 2006