This article is one in a series of 10 stories we're running this week covering today's most significant emerging technologies. It's part of our annual "10 Emerging Technologies" report, which appears in the March/April print issue of Technology Review.

In the break room near his lab in MIT's brand-new neuroscience building, research scientist Rutledge Ellis-Behnke provides impromptu narration for a video of himself performing surgery. In the video, Ellis-Behnke makes a deep cut in the liver of a rat, intentionally slicing through a main artery­. As the liver pulses from the pressure of the rat's beating heart, blood spills from the wound. Then Ellis­-­Behnke covers the wound with a clear liquid, and the bleeding stops almost at once. Untreated, the wound would have proved fatal, but the rat lived on.