Year in Review: Caffeine triggers cloning advance

Human embryonic stem cells copied successfully

CELL MAKER  Using a tiny needle and guided by a laser, researchers extract the DNA from a human egg. It’s the first step in a cloning procedure developed to create human embryonic stem cells.

Courtesy of M. Tachibana


With a tweak to the technique that cloned a sheep in 1996, scientists have generated stem cells in the lab that genetically match those found in human embryos.

The feat pumps life into a sputtering field. Until now, researchers had to harvest the cells from embryos left over from in vitro fertilization, or tinker with ways to turn adult cells into embryonic ones, a task riddled with technical challenges.

Embryonic stem cells are so prized because they can transform into any type of cell in the body. This boundless potential carries the promise of personalized medicine: Doctors could one day dose patients with new, healthy cells made from patients’ own bodies. Though scientists had previously cloned cells from frogs, sheep and even monkeys, no one had figured out how to perfect the procedure in human cells.

The cloning procedure, called somatic cell nuclear transfer, requires scientists to remove the DNA-containing nucleus from an egg and replace it with one taken from an adult cell. Under the right conditions, the egg reprograms its new nucleus and develops into an embryonic stem cell. Because each animal’s cells have their own quirks, scientists have to tailor the procedure for different creatures.

To successfully clone human cells, eggs must be dunked in caffeine, study leader Shoukhrat Mitalipov of the Oregon National Primate Research Center in Beaverton and colleagues found (SN: 6/15/13, p. 5). This and other technical changes give researchers a new recipe for creating embryonic stem cells in the lab. And because the recipe doesn’t rely on leftover embryos, it may sidestep some of the ethical issues surrounding stem cell research.

See all top science stories of 2013 

Meghan Rosen is a staff writer who reports on the life sciences for Science News. She earned a Ph.D. in biochemistry and molecular biology with an emphasis in biotechnology from the University of California, Davis, and later graduated from the science communication program at UC Santa Cruz.

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