そうね。
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In the year since the papers’ retraction, he and Kojima had tweaked the procedure, making small adjustments to the media and returning to the original chemical stimulus, ATP, which also fuelled the cells, instead of the hydrochloric acid indicated in the publications. For months, they had tried to make a teratoma, the first major step to indicating pluripotency.
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Now we walked over to Vacanti’s lab to see the results. He wasn’t optimistic. Before my arrival, he told me, he had called an emergency phone meeting with Kojima and his brother Martin. “I said, ‘We have to have something to demonstrate that this is indeed real or we’re going to look really stupid.’ ” As it happened, he said, just a few days before, he had seen the best-looking spheres in many months. They had tested positive for the embryonic-stem-cell markers Oct4 and Nanog, calculated by a machine that is not subject to the vagaries of auto-fluorescence. He had broken the spheres apart and placed the cells in a medium that encouraged the growth of neurons. The new plan was to test them for a protein called nestin, which, he said, would show that a mature skin cell had been transformed into a neural stem cell—taken back down to the root and up another branch.
