A couple of days ago, Rob told you about scientists who had built a "jellyfish" in the lab, using rat cells. Which is awesome. Naturally, it's not quite as awesome as it sounds, though.
The scientists haven't created life. Instead, they've built a little construct of cells and silicone. This construct—the medusoid—is interesting, in that, when you spark it with electricity, it moves in ways that are very similar to a juvenile jellyfish. But it's not actually an animal. It doesn't eat. It can't make more of itself. It needs that outside zap to move at all.
But despite all that it is not, the medusoid is a very cool first step towards doing some amazing things. At Scientific American, journalist Ferris Jabr looked at what the scientists have done, how living jellyfish work, and what it would take to build a for-real-real artificial jellyfish.
Whereas a real jellyfish generates electrical impulses to stimulate its muscle cells, a medusoid is entirely dependent on voltage generated by electrodes in its tank. Moon jellies have eight pacemaker cells scattered around the middle of their bodies (just about every jellyfish body part comes in multiples of four). Pacemaker cells keep the jellies' muscles pulsating rhythmically. We have pacemaker cells in our hearts that do the same thing. So do rats. Janna Nawroth thinks it's possible to weave pacemaker cells from a rat's heart into the heart muscle tissue that makes up a medusoid, which might allow the artificial jellyfish to bob on its own, sans electrodes.
The upgrade would rely on a technique known as "co-culturing," in which different types of cells are grown together. It's often difficult enough to get one cell type to live happily in the lab, let alone a mixture of different kinds of cells. Think of them as high-maintenance houseplants that are fussy about their neighbors, withering if they do not like their circumstances. Although scientists have not yet mastered co-culturing, they have made impressive advances, cultivating little gardens of gut tissue and bacteria, for example, as well as epithelial cells and immune system cells.