Frog skin cells turned themselves into living machines

Amazing stuff!

"Using blobs of skin cells from frog embryos, scientists have grown creatures unlike anything else on Earth, a new study reports. These microscopic “living machines” can swim, sweep up debris and heal themselves after a gash. ...

In a way, the bots were self-made. Scientists removed small clumps of skin stem cells from frog embryos, to see what these cells would do on their own. Separated from their usual spots in a growing frog embryo, the cells organized themselves into balls and grew. About three days later, the clusters, called xenobots, began to swim.

Normally, hairlike structures called cilia on frog skin repel pathogens and spread mucus around. But on the xenobots, cilia allowed them to motor around. ...

Xenobots have no nerve cells and no brains. Yet xenobots — each about half a millimeter wide — can swim through very thin tubes and traverse curvy mazes. When put into an arena littered with small particles of iron oxide, the xenobots can sweep the debris into piles. Xenobots can even heal themselves; after being cut, the bots zipper themselves back into their spherical shapes.

Scientists are still working out the basics of xenobot life. The creatures can live for about 10 days without food. When fed sugar, xenobots can live longer (though they don’t keep growing). “We’ve grown them for over four months in the lab,” ... “They do really interesting things if you grow them,” including forming strange balloon-like shapes. ..."

From the abstract:

"Robot swarms have, to date, been constructed from artificial materials. Motile biological constructs have been created from muscle cells grown on precisely shaped scaffolds. However, the exploitation of emergent self-organization and functional plasticity into a self-directed living machine has remained a major challenge. We report here a method for generation of in vitro biological robots from frog (Xenopus laevis) cells. These xenobots exhibit coordinated locomotion via cilia present on their surface. These cilia arise through normal tissue patterning and do not require complicated construction methods or genomic editing, making production amenable to high-throughput projects. The biological robots arise by cellular self-organization and do not require scaffolds or microprinting; the amphibian cells are highly amenable to surgical, genetic, chemical, and optical stimulation during the self-assembly process. We show that the xenobots can navigate aqueous environments in diverse ways, heal after damage, and show emergent group behaviors. We constructed a computational model to predict useful collective behaviors that can be elicited from a xenobot swarm. In addition, we provide proof of principle for a writable molecular memory using a photoconvertible protein that can record exposure to a specific wavelength of light. Together, these results introduce a platform that can be used to study many aspects of self-assembly, swarm behavior, and synthetic bioengineering, as well as provide versatile, soft-body living machines for numerous practical applications in biomedicine and the environment."

Frog skin cells turned themselves into living machines | Science News Newly created ‘xenobots’ swim and move particles around in their environment

A cellular platform for the development of synthetic living machines (open access)

Small clusters of skin cells taken from frog embryos grow into larger spheres, called xenobots (pictured), that can swim, move particles and heal themselves.