Meet the xenobots: the very first 'living' robots

The creatures can revolutionise regenerative medicine, assist climate change handling

One of the xenobot designs, created by frog stem cells

In another lifetime, if they had been allowed to follow their natural development, the stem cells taken from embryonic frogs would have turned into skin and heart tissue within living, breathing animals. Instead, in configurations designed by algorithms and constructed by humans, those cells have been assembled into something new and immensely revolutionary: the first-ever robots constructed entirely out of living cells.

Named xenobots after the African clawed frog (Xenopus laevis) from which they take their stem cells, these tiny, submillimetre-sized blobs were created using an evolutionary algorithm, which mimics natural selection by generating potential solutions and then repeatedly picking and mutating the most promising ones. The supercomputer algorithm conjured thousands of random configurations of between 500 and 1,000 skin and heart cells and each one was tested in a virtual environment. Many were useless lumps. But those that showed potential - such as being able to move -were tweaked and used to seed the next generation. After running this process 100 times, the researchers built the best designs out of living cells. For instance one can propel itself through water using two stumpy limbs, while another has a kind of pouch that it could use to carry a small load.

As a result of this work, we can now officially state we are witnessing a completely novel living machines, which Joshua Bongard, co-leader of the project and robotics expert at the University of Vermont, rightfully said that are "neither a traditional robot nor a known species of animal. It's a new class of artifact: a living, programmable organism."

The even more fascinating aspect is that the xenobots have already proven their ability to move about an aqueous environment for up to a week without the need for additional nutrients, powered by their own 'pre-loaded' energy stores in the form of lipids and proteins. They have also self-heal capabilities and can work together in group. Moreover, when the cells run out of nutrients, the xenobots simply become a small clump of dead cells, which means they are also biodegradable, which gives them another advantage over metal and plastic robots.

At the same time they can achieve things typical robots of steel and plastic cannot. As the authours of the study claim, the xenobots could potentially be used toward a host of tasks such as cleaning up radioactive waste, collecting microplastics in the oceans, carrying medicine inside human bodies, or even travelling into our arteries to scrape out plaque. The xenobots's ability to survive in aqueous environments without additional nutrients for days or weeks makes them suitable for internal drug delivery, as well.

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.

"If we could make 3D biological form on demand, we could repair birth defects, reprogram tumors into normal tissue, regenerate after traumatic injury or degenerative disease, and defeat aging," the researchers' said, adding this could have "a massive impact on regenerative medicine."

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