Scientists Assemble Frog Stem Cells Into First ‘Living Machines’
by Katherine J. Wu, Smithsonianmag.com
In Michael Levin’s laboratory at Tufts University, cells can expect to find themselves in unusual company.
Here, the precursors of frog skin sidle up to cells that, in another life, might have helped an amphibian’s heartbeat. They’re perfect strangers: biological entities that, up until this point, had no business being together. And yet, Levin and his colleagues have found that skin cells and heart cells can be coaxed into coalescing. Placed side by side, they will self-organize into intricate, three-dimensional mosaics of frog cells that aren’t actually frogs.
Designed by a computer algorithm and surgically shaped by human hands, these skin-heart hybrids, each roughly the size of a grain of sand, don’t resemble anything found in nature. But the tasks they accomplish are eerily familiar: Without any external input, they can zoom around Petri dishes, push microscopic objects to and fro, and even stitch themselves back together after being cut.
Levin calls these clusters of cells a “new form of life”—one that’s not quite an organism and not quite a machine, but perhaps somewhere in between. Named “xenobots” in honor of the Xenopus laevis African clawed frogs from which their cells derive…