Crack open the door of the incubator at Novoheart’s Hong Kong headquarters and you’ll find about a dozen pea-shaped, pulsating blobs submerged in a warm, salty-sweet broth. They’re 3-D human heart organoids—a simplified, shrunk-down version of the real thing—the first ever to contain a hollow chamber, like one of the four that’s beating inside your chest right now. And they’re the future of drug testing.

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