Geron is a company with extensive history in several leading-edge medical technologies, including human embryonic stem cells.

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Some stem cells, including those for the heart, lung and kidney, cannot be found in adults.

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Since that time, more advanced cloning technologies have evolved, including the iPS system of induced pluripotent stem cells, which can be grown from nearly any skin cell.

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The gold standard embryonic stem cells still came from embryos themselves, including ones that were made through nuclear transfer.

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With the help of certain "growth" chemicals, they were able to transform the stem cells into "various cell lines and tissues, including beating human heart cells, " said Shoukhrat Mitalipov, a developmental biologist at Oregon Health and Science University in Portland, Ore.

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Induced pluripotent stem cells can come from any cell in the human body, including skin cells, so they don't have the moral quandaries surrounding them.

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Outside the U.S., adult stem cells have been used to treat patients with Type 2 diabetes in Argentina, heart disease in countries including Germany, Thailand and India, and babies with malformed hearts in Japan.

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