Frog Skin Cells can turn Into “Living Machines”

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. That surprising development is a great example of life reusing what’s at hand.

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). Scientists have grown them for over four months in the lab. It is noted that they do really interesting things if you grow them, including forming strange balloon-like shapes.

This xenobot is about 500 micrometers across and is made of frog cells, even though it looks and acts nothing like an actual frog.

It’s not yet clear what sorts of jobs these xenobots might do, if any. Cleaning up waterways, arteries or other small spaces comes to mind, the researchers say. More broadly, these organisms may hold lessons about how bodies are built.

Citations:

D. Blackiston et al. A cellular platform for the development of synthetic living machines. Science Robotics. Published online March 31, 2021. doi: 10.1126/scirobotics.abf1571.