Researchers have created robots made of living cells that can not only complete tasks, but also reproduce – and they reproduce in a way that no other living creature does.
These Xenobots, named after the African clawed frog (Xenopus laevis), are synthetic lifeforms first announced in 2020. They are made from a mixture of skin cells and heart muscle cells from the very early stages of frog embryos. However, despite their genome, they are not frogs.
A computer-designed blueprint organized those cells in a configuration that can do tasks like moving, pushing, or carrying objects. As reported in the Proceedings of the National Academy of Science, with the right design, Xenobots can also reproduce.
They do so by kinematic replication. This has been seen at a molecular level, but never at this scale. The work shows that living cells possess more possible behaviors than what we have uncovered by studying the natural world.
“People have thought for quite a long time that we've worked out all the ways that life can reproduce or replicate. But this is something that's never been observed before,” coauthor Dr Douglas Blackiston, the senior scientist at Tufts University who assembled the Xenobot “parents”, said in a press statement seen by IFLScience.
“These are frog cells replicating in a way that is very different from how frogs do it. No animal or plant known to science replicates in this way,” added lead author Dr Sam Kriegman, from the Tuft’s Allen Center and Harvard University’s Wyss Institute for Biologically Inspired Engineering.
The version of the replicating Xenobot would quickly die after having reproduced once. So the team went back to the Artificial Intelligence they are using to design these living machines, tasking the AI to produce a version that would not just die. The AI performed billions of simulations to arrive at the configuration that eventually worked.
“We asked the supercomputer at UVM [University of Vermont] to figure out how to adjust the shape of the initial parents, and the AI came up with some strange designs after months of chugging away, including one that resembled Pac-Man,” says Kriegman. “It’s very non-intuitive. It looks very simple, but it’s not something a human engineer would come up with. Why one tiny mouth? Why not five? We sent the results to Doug and he built these Pac-Man-shaped parent Xenobots. Then those parents built children, who built grandchildren, who built great-grandchildren, who built great-great-grandchildren.”
While some might have concerns about self-replicating biotechnology, the team stresses that the Xenobots are contained in a lab, easily extinguished, and vetted by federal, state, and institutional ethics experts. The team is more concerned about the other challenges in society and how our technology is not fast enough to adapt.
“We need to create technological solutions that grow at the same rate as the challenges we face,” co-author Dr Joshua Bongard added. Their potential to be fast and adaptable might make Xenobots the answers to various challenges from collecting microplastic to medical applications.
“If we knew how to tell collections of cells to do what we wanted them to do, ultimately, that's regenerative medicine—that's the solution to traumatic injury, birth defects, cancer, and aging,” co-author Professor Michael Levin explained. “All of these different problems are here because we don't know how to predict and control what groups of cells are going to build. Xenobots are a new platform for teaching us.”