Rat cells used in creation of artifical swimming jellyfish

Their method for building the tissue-engineered jellyfish, dubbed Medusoid, has significance for building new hearts in the future.

“A big goal of our study was to advance tissue engineering,” says Janna Nawroth, a doctoral student in biology at Caltech and lead author of the study.

“In many ways, it is still a very qualitative art, with people trying to copy a tissue or organ just based on what they think is important or what they see as the major components.”

Jellyfish are believed to be the oldest multi-organ animals in the world, possibly existing on Earth for the past 500 million years.

Because they use a muscle to pump their way through the water, their function – on a very basic level – is similar to that of a human heart.

“It occurred to me in 2007 that we might have failed to understand the fundamental laws of muscular pumps,” says Kevin Kit Parker, Tarr Family Professor of Bioengineering and Applied Physics at Harvard and a coauthor of the study.

“I started looking at marine organisms that pump to survive. Then I saw a jellyfish at the New England Aquarium, and I immediately noted both similarities and differences between how the jellyfish pumps and the human heart. The similarities help reveal what you need to do to design a bio-inspired pump.”

Parker contacted John Dabiri, professor of aeronautics and bioengineering at Caltech – and Nawroth’s advisor – and a partnership was born.

Nawroth and colleagues looked at several materials from which to fashion the body of their beast, eventually settling on an elastic material that is relatively similar to the “jelly” found in a real jellyfish.

The team at Harvard fashioned the silicone polymer that makes up the body of the Medusoid into a thin membrane that resembles a small jellyfish, with eight arm-like appendages.

Next, they printed a pattern made of protein onto the membrane that resembled the muscle architecture in the real animal.

When the researchers set their creation free in an electrically conducting container of fluid and oscillated the voltage from zero volts to five, they shocked the Medusoid into swimming with synchronised contractions that mimic those of real jellyfish.

In fact, the muscle cells started to contract a bit on their own even before the electrical current was applied.

“I was surprised that with relatively few components – a silicone base and cells that we arranged – we were able to reproduce some pretty complex swimming and feeding behaviors that you see in biological jellyfish,” says Dabiri, with fluid-dynamics measurements that match up to those of the real animal. “

This advance in bio-inspired engineering, the team says, demonstrates that it is inadequate to simply mimic nature: the focus must be on function. Their design strategy, they say, will be broadly applicable to the reverse engineering of muscular organs in humans.

In addition, Dabiri and colleagues say, their new process of harvesting heart-muscle cells from one organism and reorganising them in an artificial system will be useful in building an engineered system using biological materials.

“We’re reimagining how much we can do in terms of synthetic biology,” says Dabiri. “A lot of work these days is done to engineer molecules, but there is much less effort to engineer organisms. I think this is a good glimpse into the future of re-engineering entire organisms for the purposes of advancing biomedical technology.”