Man who started stem cell war may end it

The fact is, Thomson said, he had ethical concerns about embryonic research from the outset, even though he knew that such research offered insights into human development and the potential for powerful new treatments for disease. Thomson said, announcing that he had obtained human embryonic stem cells was “scary”.“It was not known how it would be received.”

But he knows what he wrought. Stem cells, universal cells that can turn into any of the body’s 220 cell types, normally emerge only fleetingly after a few days of embryo development. Thomson, 48, did not set out to throw bioethical bombs. All he wanted was to answer the most basic scientific questions about cellular development.

First there was a degree in biophysics from the University of Illinois. As a student, Thomson began working with mouse embryonic stem cells and then he extracted stem cells from monkey embryos. After earning two doctorates from the University of Pennsylvania, he continued research at the University of Wisconsin.

Eventually he realised, if he wanted to understand how human embryos develop and why their development sometimes goes awry, he needed human stem cells. But, he says, he hesitated.

In 1995, he began consulting with two ethicists at his university, Dr Norman Fost, a physician, and Ms Charo, a law professor. He wanted to anticipate what the ethical problems might be. “It is unusual for a scientist to think about the ethical implications of his work,” Fost said.

As Thomson was planning his effort to obtain human embryonic stem cells, another discovery changed his entire view of development. “Dolly changed the way I thought about developmental biology,” Thomson says. More work remains, but he is confident that the path ahead is clear.

“Isn’t it great to start a field and then to end it,” he said.