Cellular Biology: Stem Winder

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But it was biology that beckoned the gifted Oak Park, Ill., teenager. Encouraged by Fred Meins, one of his professors at the University of Illinois, to try his hand at lab work, Thomson became intrigued by the mysteries of early development--the burst of biological activity when the fertilized egg implants itself in the womb, then starts dividing and forming the specialized cells that turn miraculously into various tissues in the body. Most researchers studying these events used mice, but Thomson, after earning a Ph.D. in molecular biology at the University of Pennsylvania, as well as a veterinary-medicine degree, turned to more humanlike rhesus monkeys. Even so, it took him nearly four years to isolate and cultivate their stem cells.

By 1995 Thomson was ready to try human cells, but first he asked himself searching questions that endocrinologist James Prihoda, his college roommate, sees as a sign of his deep "respect for life and strong feeling that there is a purpose to it." Is this research ethical? Is it moral? Thomson, a nonpracticing Congregationalist who is married to a fellow scientist and is the father of two young children, wasn't sure. He read every study he could get his hands on and consulted, among others, University of Wisconsin bioethicists R. Alta Charo and Norman Fost. Since the embryos he planned to use were doomed anyway--one of the arguments cited by Bush--he decided he was justified by the good that might come of the research. "I could not see that throwing them out was better," he says.

By contrast, two other groups chose a more provocative path. In July of this year, the Jones Institute for Reproductive Medicine in Norfolk, Va., made headlines by announcing that it had created embryos (from donated sperm and eggs) expressly to extract their stem cells. A few days later, a Massachusetts biotech firm, Advanced Cell Technology, disclosed that it was trying to create embryos using human-cloning techniques. The back-to-back developments surprised opponents and supporters alike, and brought new calls for a ban on all embryonic stem-cell research.

With no fanfare, Thomson set himself up six years ago in an off-campus lab under a nonprofit arrangement with the University of Wisconsin's alumni association. That way he freed himself from existing federal restrictions--and avoided jeopardizing the university's government-funded research. Geron Corp., the Menlo Park, Calif., biotech firm that was financing Gearhart's efforts, partly bankrolled Thomson's work in exchange for commercial rights. (Thomson, however, was free to distribute his stem cells to fellow academics.) Because he could afford only one part-time assistant, he ended up doing much of the work himself, getting up at 5 a.m. and trudging off to the lab, rain or shine, to tend his precious cells. "You have to watch them every day or they differentiate"--that is, start turning into specialized tissue. After six months of watching them divide and multiply without undergoing any change, he was sure he had mastered the art of growing his life-giving seeds and set about writing the scientific paper in Science that alerted the world to his coup.