Bioengineers create a jellyfish from rat cells

Harvard and Caltech bioengineers used silicone and a rat’s heart cells to create an artificial jellyfish, which when placed in an electric field, pulses and swims just like a real one.

Named a medusoid, the artificial jellyfish is modeled after a moon jelly, which is shaped a bit like a flower with eight petals, made from “a single layer of muscle, with fibres that are tightly aligned around a central ring and along eight spokes,” reports Nature. When placed between two electrodes in water, the petals beat downwards, causing the medusoid to swim.

Built in a lab that works on creating artificial models of human organ tissues for regeneration and testing drugs, the medusoid was built to help the team understand the pumping function of a human heart.

Harvard biophysicist Kit Parker who lead the work and Caltech grad student Janna Nawroth, who performed much of the experiment, explained their process to Nature.

Nawroth created a structure with the same properties by growing a single layer of rat heart muscle on a patterned sheet of polydimethylsiloxane. When an electric field is applied across the structure, the muscle contracts rapidly, compressing the medusoid and mimicking a jellyfish’s power stroke. The elastic silicone then pulls the medusoid back to its original flat shape, ready for the next stroke.

When placed between two electrodes in water, the medusoid swam like the real thing. It even produced water currents similar to those that wash food particles into jellyfish’s mouths. “We thought if we’re really good at this, we’re going to recreate that vortex, and we did,” says Parker. “We took a rat apart and rebuilt it as a jellyfish.”

“Morphologically, we’ve built a jellyfish. Functionally, we’ve built a jellyfish. Genetically, this thing is a rat,” Parker told Nature, in one of the more sci-fi-sounding quotes we’ve heard all year.

Next the lab will make a medusoid out of human heart cells. “You’ve got a heart drug?,” Parker said. “You let me put it on my jellyfish, and I’ll tell you if it can improve the pumping.”