Scientists Achieve Stem-Cell Milestone

Led by Kevin Eggan at the Harvard Stem Cell Institute and Christopher Henderson at Columbia University, the 13-person team reported online today in Science Express that they had generated motor neurons from the skin cells of two elderly patients with a rare form of ALS, or Lou Gehrig's disease, a progressive neurodegenerative condition. The new study marks an important first step on the road toward real stem-cell-based therapies, and also answers several plaguing questions about the pioneering stem-cell technique known as induced pluripotent stem cell, or iPS, generation.

IPS was first described by Japanese biologist Shinya Yamanaka, who, in 2007, showed that the introduction of four genes into an adult human skin cell could reprogram it back to an embryonic state (Yamanaka had reported the same achievement in mice the previous year). Like embryonic stem cells, these reprogrammed adult cells could be coaxed into becoming any other type of cell — from skin to nerve to muscle. But researchers questioned whether the new stem cells would behave as predictably or as safely as embryonic stem cells, or whether iPS would consistently yield usable cells. "Our work shows that the original method developed by Yamanaka works great," says Eggan.

Researchers also questioned whether iPS would work with delicate cells from older people or with cells taken from patients with disease (Yamanaka used skin cells from healthy middle-aged people in his study). Eggan and Henderson tackled both issues at once, by working with cells from two siblings, ages 82 and 89, who both had ALS. It turned out that generating iPS cells from older patients proved no more difficult than growing them from younger ones, says Eggan. "This study puts those issues definitively to rest," he says. "It opens the door to being able to make patient-specific stem-cell lines [to treat] diseases that affect people very late in life, like Parkinson's or Alzheimer's disease."

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