A team of scientists from the American Universities of Vermont and Tufts have presented some re-programmable organisms, halfway between a robot and a living being, known as the first living robots.
These small robots that move by themselves have been created by assembling cells of African clawed frogs (Xenopus laevis).
The researchers adapted the stem cells taken from the African frog embryo and created small living robots called Xenobots. They are only 1 mm wide and can be programmed to perform a range of tasks. These tasks include transporting medicine directly to a specific point in the body, destroying cancer cells or removing microplastics from the oceans.
According to experts, these new artificial cells are indestructible and are even capable of repairing themselves.
These robots, built entirely from living cells, are small droplets of a sub-millimetre size that contain between 500 and 1,000 cells. They are able to move through a Petri dish, to self-organise and even transport tiny payloads.
They are different from any living organism or organ that people 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, co-author of the study published by PNAS magazine.
The design of the xenobots required the use of a supercomputer (Deep Green) and an algorithm that could virtually gather a few hundred hearts and frog skin cells in different configurations (as if it were LEGO bricks) and simulate the results.
A team of biologists from the University of Tufts assembled the cells into living bots, only one millimetre wide. When these cells were assembled in ways that have never been 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 a forward movement, which allowed these incredible robots to move by themselves.
The xenobots were able to explore their aqueous environment for days or weeks, driven only by embryonic energy deposits. Some crawled in a straight line, while others circled or joined others as they moved.
"As we've shown, these frog cells can be coaxed to make interesting living forms that are completely different from what their default anatomy would be,” noted Michael Levin, co-author of the study.
"These xenobots are very small, but ultimately, the plan is to make them scale.”
Xenobots could be constructed with blood vessels, nervous systems and sensory cells, to form rudimentary eyes and they could live on land, as there are built from mammalian cells.
The authors acknowledge that the work poses ethical problems, particularly because future variants could have nervous systems and could be chosen for their cognitive ability.
“The important thing for me is that this is public, so we can have a discussion as a society and policymakers can decide which is the best course of action,” said Sam Kriegman, member of the team from the University of Vermont.
Although the team calls them ‘alive’, this denomination may depend on how we define living creatures. These xenobots cannot evolve on their own, as they have no reproductive organs and they can’t multiply, so when cells run out of nutrients, they become dead cells.
Could they turn into biological weapons? For the moment being, they are far from posing a threat to humanity.
Reference: 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