President Bushs
recently appointed Council on Bioethics has begun to deliberate
about human reproductive cloning and embryo stem cell research
just as the US National Academy of Sciences has released
its panel of experts report on these subjects. The
Academys panel opposes reproductive cloning, that
is, the production of babies who would be genetic copies
of other people, and recommends that it be outlawed. It,
however, endorses cloning embryos as tools for research
into treating disease (therapeutic cloning). Judging from
the composition of the Presidents Bioethics Council
and its initial public statements, that body is likely to
end up opposing both types of cloning. I would guess that
it is also likely to endorse President Bushs decision
of August 9, 2001 to forbid the further production of embryos
for research and to thus limit the number of useable lines
of embryo stem cells to those in existence on that date.
Meanwhile, Congress is resuming its own debate on legislation
regarding these matters, on hold since September.
Lost in most of these discussions, which tend to focus on
matters of human dignity and the status of the embryo, is
the fact that to produce human embryos outside a womans
body requires not just human sperm, which apparently has
been readily accessible since biblical times and, no doubt,
long before. Producing embryos also requires human eggs,
and getting at those is much more difficult. Granted, in
vitro fertilization (IVF), which requires eggs, has become
a standard part of reproductive medicine, but it requires
relatively few eggs. Furthermore, these eggs are usually
extracted from women willing to take risks to produce their
own biological children. Even so, questions have been raised
about possible negative consequences of IVF for womens
health.
Manipulating a womans physiology to make her produce
large numbers of eggs for research, while encouraging her
to do so by paying for them, raises questions of medical
and scientific exploitation and ethics that have hardly
been discussed. To stimulate a womans ovaries to release
more than the usual single monthly egg she must receive
hormones, first to suppress ovulation entirely and then
to hyperstimulate it. The ripened eggs are then extracted
surgically from the ovaries while inspecting them by ultrasound.
None of this is fun and there is, as yet, no way to know
about its safety. To date, we know that hyperstimulation
can shut down a womans ovaries so that she experiences
premature menopause with incumbent increased risks of osteoporosis
and other symptoms of early aging. Some observations also
suggest that the hormones may increase the incidence of
ovarian and, perhaps, breast cancer, but there are not enough
data to be sure.
Meanwhile, it is by no means clear that the therapeutic
opportunities to be derived from embryo stem cells are superior
to those of using stem cells isolated from the tissues of
adults or from umbilical cord blood. As we go to press,
a University of Minnesota scientist announced that she has
discovered a new, versatile class of adult stem cells she
calls multipotent adult progenitor cells that
can grow into several types of body tissue. The rush to
explore the potential of embryo stem cells appears to be
based on the pursuit of patents and near-term profits. There
are more acceptable alternatives likely to yield therapies
and cures.
Ruth Hubbard is a CRG Board Member and a Professor Emerita
at Harvard University.