For the first time in history, a team of scientists from the University of Vermont and Tufts (USA) has presented “reprogrammable organisms”, halfway between a robot and a living being: they are the first living robots.
These first living machines were created by assembling cells of African frogs (specifically of the Xenopus laevis species) into small robots that move by themselves.
Neither robots nor animals: a living and programmable organism
The researchers adapted stem cells taken from the embryo of the African frog Xenopus Laevis and created tiny ‘living robots’ called Xenobots. They are only 1mm wide and can be programmed to perform a wide variety of tasks , including delivering drugs directly to a point in the body, killing cancer cells, or removing microplastics from the oceans.
According to experts, these new ‘artificial cells’ can be molded in any necessary way, are ‘indestructible’ and capable of repairing themselves.
These first robots built entirely from living cells are tiny sub-millimeter-sized droplets containing between 500 and 1,000 cells that have been able to move around a Petri dish, self-organize and even carry tiny payloads. They are certainly different from any living organism or organ that we have found or created to date because they are not traditional robots or animals and their possibilities are fascinating.
“They are novel living machines,” said computer scientist Joshua Bongard, a co-author of the work in the journal PNAS.
Evolutionary algorithm
The design of the xenobots required the use of a supercomputer ( Deep Green) and an algorithm that could virtually gather a few hundred heart and frog skin cells in different configurations (like LEGO bricks) and simulate the results.
Based on the blueprints, a team of biologists from Tufts University, Massachusetts, assembled the cells into live bots, just one millimeter wide. Assembled in ways never seen in nature, the cells began to work together. The skin cells formed a “body” and the contractions of the heart muscle cells were reused to create forward motion, allowing these incredible robots to move on their own. The xenobots were able to explore their watery environment for days or weeks, powered solely by reservoirs of embryonic energy. Some crawled in a straight line, while others circled or joined others as they moved.
“As we have shown, these frog cells can be induced to create interesting life forms that are completely different from what their default anatomy would be,” said Michael Levin, a co-author of the study. “These xenobots are very small, but ultimately the plan is to scale them .” They could be built with blood vessels, nervous systems, and sensory cells, to form rudimentary eyes. By building them from mammalian cells, they could live on dry land.
Ethical issues
The authors acknowledge that the work raises ethical issues, particularly as future variants could have nervous systems and be selected for their cognitive ability. “The important thing to me is that this is public, so we can have a discussion as a society and policy makers can decide which is the best path,” said Sam Kriegman of the University of Vermont. In fact, the source code used is freely available through the Github platform.
Although the team calls them “alive,” this naming may depend on how we define living creatures. These xenobots cannot evolve on their own, there are no reproductive organs, and they cannot multiply, so when cells run out of nutrients, they turn into dead cells (so they would also be biodegradable).
Could they become biological weapons? Some wonder. For the moment, they are far from posing a threat to humanity.
Referencia: A scalable pipeline for designing reconfigurable organisms. Sam Kriegman, Douglas Blackiston, Michael Levin, and Josh Bongard. PNAS first published January 13, 2020 https://doi.org/10.1073/pnas.1910837117
