Scientists at Harvard University have “built” a school of robotic fish that can swim on their own. But what powers them aren’t batteries or solar energy; it’s cells from a human heart. The objective behind this creation, called “biohybrid fish,” wasn’t to inspire authors of dystopian sci-fi — but to push the boundaries of medical innovation.
The team built the fish using paper, plastic, gelatin, and two strips of living heart muscle cells, the contractions of which pulled the fish’s tail from side to side and allowed it to swim.
The exploration group distributed its discoveries in the diary Science last week, and a video delivered by Harvard School of Designing and Applied Sciences (Oceans) on Twitter shows a little mechanical fish fluttering its tail and moving about for around 20 seconds.
The review denotes a confident advance in the headway of heart medicines like pacemakers. “The advantage of this fish project is that we are as yet attempting to dominate the art of involving live cells as a designing substrate,” Pack Parker, one of the creators of the review, told on Monday.
The heart is very complex and it’s not to the point of imitating the anatomy,” added Parker, an Oceans teacher. “One should reproduce the biophysics to have the powerful conduct expected of building designed hearts for Youngs brought into the world with distorted hearts.”
When the muscle cells on one side contract, the tail moves in that direction, propelling the fish through the water.
The movement also causes the strip of muscle cells on the opposite side to stretch. This stretching, in turn, produces a signal that causes the cells to contract, which perpetuates the swimming motion.
“Once that cycle starts, these things just start motoring,” Parker says.
The fish are equipped with a special cluster of cells that initiate the cycle of stretching and contracting, Parker says.
The robotic fish were assembled by a team of scientists including Keel Yong Lee of Harvard and Sung-Jin Park of Emory University and Georgia Tech.
The team tested some early samples by artificially activating the muscle cells, Park says. Then they put the leftover fish in an incubator and forgot about them for a couple of weeks.
When they finally opened the incubator, “all the fish were swimming by themselves,” Park says.
The fish kept swimming for more than three months, sustained by nutrients added to the fluid around them.
From synthetic fish to healing hearts
Showing that it’s possible to produce human heart tissue that beats on its own is important because the body can’t replace heart cells lost to disease or inflammation.
The team chose to test its lab-grown heart cells in robotic fish because of the similarities between swimming and the pumping action of a heart, Parker says.
In some ways, a fish is a pump, he says. But instead of pumping blood through the body, it pumps itself through the water.
In 2016, Parker’s lab built a stingray powered by rodent heart cells. They used light to control the cells in a way that caused the robot’s fins to undulate, propelling it through the water.
This time, his team used stem cell technology to transform human skin cells into cardiac muscle.
Heart cells stay healthy by constantly rebuilding themselves, a process that takes about 20 days, he says. Because the fish swam for more than 100 days, he says, “each cell has rebuilt itself in there about five times.”
The muscle cells also became stronger with exercise the way cells in a human heart do. This suggests the cells could eventually be used to repair a failing heart.
What lies ahead for biohybrid bots
For now, though, this sort of research should help scientists understand how the heart works and test drugs for problems like heart failure, says Ritu Raman, a mechanical engineer at MIT.
Robots powered by living cells have raised questions about whether scientists are blurring the lines between machines and living creatures.
But as biohybrids become more sophisticated, Raman says, they may merit the same ethical consideration given to animals.
But Parkers remains unfazed. “I think that other methods will be faster than us… But in the long run, creating tissue that relies on the patient’s cells could offer unexpected benefits over pig organs or synthetic alternatives,” he noted.
The experiment’s success has proved that Parker’s end goal of building artificial hearts may be a possibility; it may be a distant one, but the scientists are, at least, a few steps closer and much more optimistic.