Xenobots

The book is made of wood. But she is not a tree, its dead cells have been transformed for other needs. Similarly, a group of scientists repurposed living cells taken from embryos of African frogs (Xenopus laevis, hence the name "xenobots"), and assembled them into completely new life forms. These "xenobots" with a width of a millimeter can move towards the target, possibly carrying a therapeutic load (for example, a medicine that needs to be delivered to a certain part of the patient's body), and independently recover from damage.

The new living machines, as their creators call them, are neither robots in the traditional sense, nor a known animal species. This is a new class of artifacts: a living, programmable organism.

The living robots were developed on a supercomputer at the University of Vermont, and then assembled and tested by biologists at Tufts University, USA. The possibilities of using these living robots are diverse, for example, searching for harmful compounds or radioactive contamination, collecting microplastics in the oceans, cleaning the lumen of arteries, etc.

Live systems to order

Researchers have designed fully biological robots from scratch for the first time. To do this, a search was carried out for several months using an evolutionary algorithm to create thousands of variants of projects of new life forms. Trying to complete a task set by scientists, for example, moving in one direction, the computer collected several hundred simulated cells into countless forms over and over again. After a hundred independent runs of the algorithm, the most promising projects were selected for testing.

Then computer models were assembled based on the projects. At first, stem cells from frog embryos were used. They were separated into separate cells and left for incubation. After that, the cells were separated with microscopic forceps and reassembled in exact accordance with the design determined earlier by the computer.

Cells assembled into structures that had never been found in nature began to interact with each other. Skin cells have formed a more passive architecture, while once random contractions of cardiomyocytes were involved in creating an orderly forward movement due to the formation of a spontaneous self-organizing structure. Researchers have shown how these reconfigurable organisms are able to move in concert and explore their liquid environment for several days or weeks, feeding on embryonic energy reserves.

Later tests showed that groups of xenobots move in a circle, pushing pellets into a central place – spontaneously and collectively. Some xenobots were built with a hole in the center to reduce fluid resistance. In the simulated versions, they were able to use this hole as a pocket for successful cargo transfer.

Xenobots are completely biodegradable, and after seven days they become just dead cells.

In their experiments, scientists inflicted damage to xenobots and observed their reaction: they cut the robot almost in half, but it regenerated and continued to work.

Crack the code

The authors write that the potential of the collected information about the interaction of cells inside xenobots is huge both for computational science and for understanding life.

In order for the body to develop and function, there is a constant exchange of information and cooperation in cells and between them. These properties are determined by bioelectric, biochemical and biomechanical processes that take place on a platform defined by DNA, and they are reconfigurable to create new forms of life. The cells from which xenobots are built have 100% frog DNA, but they are not frogs. What determines the anatomy of a living organism? What else are these cells capable of building?

Researchers have demonstrated that frog cells can be used to create interesting living forms that are completely different from the default anatomy. The creation of xenobots is a small step towards cracking the so–called "morphogenetic code" and a deeper understanding of the organization of living structures.

Article S.Kriegman et al. A scalable pipeline for designing reconfigurable organizations is published in the journal PNAS.

Aminat Adzhieva, portal "Eternal Youth" http://vechnayamolodost.ru based on UVM materials: Team Builds the First Living Robots.