The scientists have created world’s first living, self-healing robots using stem cells derived from frog embryos.
The creation is named as xenobots after the African clawed frog from which they take their stem cells. The team calls it a living robot, though it’s made entirely of organic material, it’s not so much grown as developed.
The tiny blobs measure only 0.04 inches (1 millimeter) wide and are made of living tissue that biologists assembled into bodies designed by computer models, according to the new study.
The researchers from the University of Vermont (UVM) and Tufts University said that xenobots has two stumpy legs that propel it along on its “chest”, another has a hole in the middle that the team of researchers turned into a pouch so it could shimmy around with miniature payloads.
“These are entirely new lifeforms. They have never before existed on Earth,” said Michael Levin, the director of the Allen Discovery Center at Tufts University in Medford. “They are living, programmable organisms.”
Xenobots are made using an artificial intelligence system that relies on, aptly enough, evolutionary algorithms.
“They’re neither a traditional robot nor a known species of animal,” study co-author Joshua Bongard, a computer scientist and robotics expert at the University of Vermont, said in a statement.
“It’s a new class of artifact: a living, programmable organism.”
In order to build xenobots, the researchers first craped living stem cells from frog embryos and left them to incubate. After that, the cells were cut and reshaped into specific “body forms” designed by an algorithm that form “never seen in nature,” according to a news release from the University of Vermont.
By the use of the evolutionary algorithm that runs on a supercomputer, the team determined the best design for this new life form. The program generates random 3D configurations of 500 to 1,000 skin & heart cells.
Each design is then tested in a virtual environment, to see, for example, when the heart cells are set beating. The best performers are used to spawn more designs, which themselves are then put through their paces.
The scientists waited for the computer to churn out 100 generations before picking a handful of designs to build in the lab. They used tweezers and cauterizing tools to sculpt early-stage skin and heart cells scraped from the embryos of African clawed frogs, Xenopus laevis.
Algorithms shaped the evolution of the xenobots. They grew from the skin and heart stem cells into tissue clumps of several hundred cells that moved in pulses generated by heart muscle tissue, said Sam Kriegman, a doctoral candidate at the University of Vermont’s Department of Computer Science, in Burlington.
Biologists fed computer constraints for the autonomous xenobots, such as the maximum muscle power of their tissues, and how they might move through a watery environment. Then, the algorithm produced generations of tiny organisms. The best-performing bots would “reproduce” inside the algorithm.
And the result was basically clumps of frog cells with a cluster of pumping cardiac cells on one end acting as the motor on a boat to propel the clump forward through the water.
They even spontaneously cooperated to move around in circles, pushing pellets into a central location.
As an evolution, the cells were working on their own, the skin cells bonded to form structure, while pulsing heart muscle cells allowed the robot to move on its own. Xenobots even have self-healing capabilities; when the scientists sliced into one robot, it healed by itself and kept moving.
The robots move pretty slowly, so to verify they were actually functioning as designed, the researchers flipped them over on their backs. This made them stop moving forward, just like a turtle flipped on back of its shell.
“We can imagine many useful applications of these living robots that other machines can’t do,” said co-leader Michael Levin, who directs the Center for Regenerative and Developmental Biology at Tufts.
“Like searching out nasty compounds or radioactive contamination, gathering microplastic in the oceans (or) traveling in arteries to scrape out plaque.”
The xenobots come preloaded with their own food source, which should run out in about a week unless they’re in a nutrient-rich environment.
The xenobots look more like a tiny blob of moving pink flesh. The researchers say this is deliberate this “biological machine” can achieve things typical robots of steel and plastic cannot.
“At the moment though it is difficult to see how an AI could create harmful organisms any easier than a talented biologist with bad intentions could,” said the researchers’ website.
“That fear is not unreasonable,” Levin said. “When we start to mess around with complex systems that we don’t understand, we’re going to get unintended consequences.”
Building on simple organic forms like the xenobots could also lead to beneficial discoveries, he added.
“If humanity is going to survive into the future, we need to better understand how complex properties, somehow, emerge from simple rules,” Levin said.
Xenobots could be used to clean up radioactive waste, collect microplastics in the oceans, carry medicine inside human bodies, or even travel into our arteries to scrape out plaque. The xenobots can survive in aqueous environments without additional nutrients for days or weeks — making them suitable for internal drug delivery.
Aside from these immediate practical tasks, the xenobots could also help researchers to learn more about cell biology — opening the doors to future advancement in human health and longevity.
A paper detailing the research was published Monday in the Proceedings of the National Academy of Sciences.
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