From: Randy Isaac <>
Date: Sun Apr 10 2005 - 08:50:46 EDT

Someone mentioned chimeras a while back. I forgot who and in what context but today's NYTimes has a rather lengthy article on the topic. It gets to the heart of the ethics of stem cell research.

To whet your appetite, here's an excerpt:

"Driving the surge in chimeric experimentation is the enormous but still
untested promise of human stem cells. In theory, stem cells isolated from an
early human embryo can transform themselves into virtually any kind of cell
in the body, kindling hope that one day they may be transplanted into human
patients to provide new tissue wherever it is needed -- heart muscle for
cardiac patients, insulin-producing cells for diabetics, nerve cells to
repair crushed spinal cords and so on. But there are serious hurdles to
overcome before this dream can be realized, including figuring out what
controls the differentiation of stem cells and combating their tendency to
form tumors. Clearly it is unethical to study the unknown actions of stem
cells in human subjects. One obvious solution is to insert the cells into
animals and watch how they develop. Depending on what kind of stem cells are
used and where they are put in the animal, it may also be possible to pluck
some particular human biological feature or disease trait out of its natural
context and recreate it in an animal model, where it can be examined and
manipulated at will.

While the objections to stem-cell research have largely revolved around the
ethics of using human embryos, there is another debate bubbling to the
surface: how ''human'' are chimeric creatures made from human stem cells?
Fueling the anxiety has been the lack of coherent regulations in the United
States governing the creation of chimeras. The President's Council on
Bioethics has twice taken up the issue in recent weeks, and Senator Sam
Brownback, the Kansas Republican and outspoken social conservative, has
introduced legislation to restrict chimeric experiments......."

I think we all recognize the concern. But would we support legistlative restrictions? If so, what would we
think is appropriate?

Received on Sun Apr 10 08:51:07 2005

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