Xenobots created a year ago from stem cells have learned to reproduce

US scientists, who created the world’s first living robots, called xenobots, say that a new form of life can now reproduce itself in a way that has not previously been observed in plants or animals.

We’ve previously written about the development of tiny artificial organisms in 2020. Formed from the stem cells of the African clawed frog (Xenopus laevis), from which they get their name, xenobots measure no more than one millimeter. Experiments have shown that they can move independently, work together in groups, and self-heal from injury.

In a new paper published December 7, 2021, in PNAS (Proceedings of the National Academy of Sciences of the United States of America), scientists at the University of Vermont, Tufts University, and the Wyss Institute for Biologically Inspired Engineering at Harvard University said they had discovered a completely new a form of biological reproduction previously unknown to science, which differs from reproduction in animals and plants.

“It’s amazing,” – says Michael Levin, professor of biology and director of the Allen Discovery Center at Tufts University, and one of the lead authors of the new study. “These cells have a frog genome, but we have saved them from the need to turn into tadpoles. In the end, they use their collective intelligence and plasticity to create something amazing. These cells can work together on such a new task as assembling individual stem cells and then grouping them into their own functioning copies.”

During earlier experiments, scientists were impressed that xenobots could perform simple tasks. Now researchers are amazed that these created biological objects, which are, in fact, computer-selected clusters of cells, can spontaneously reproduce themselves.

Robot or living organism?

Stem cells are non-specialized cells that can develop into any type of cell in the body. To create xenobots, the researchers incubated selected embryonic stem cells that would naturally evolve into the skin of a tadpole. This relatively simple procedure does not involve any manipulation of genes.

“Most people think of robots as artificial machines made of metal and ceramic. But the point is not so much what the robot is made of as it is guided by a human,” – said Professor Josh Bongard, a computer technology and robotics specialist at the University of Vermont (UVM), one of the leaders of the new study. “In this sense, it is a robot, but it is also clearly a living organism made from genetically unmodified frog cells.”

Bongard says they found that xenobots, initially spherical and made up of about 3,000 cells, can reproduce. However, this happened rarely and only under certain circumstances. According to Bongard, xenobots used “kinematic replication”, a process is known to take place at the molecular level and has never been seen before at the scale of cells or entire organisms.

“They can create children, but after that, the system usually dies. It’s actually very difficult to get this system to continue to reproduce,” – says Sam Kriegman, lead author of the study and a Ph.D. at the Bongard Laboratory at the University of Vermont. He is currently a Research Fellow at the Allen Discovery Center at Tufts University and the Wyss Institute of Bioengineering at Harvard University.

Form determines behavior

Using an artificial intelligence program running on the Deep Green supercomputer cluster at the University of Vermont’s Advanced Computing Core, an evolutionary algorithm was able to test billions of body shapes in simulation – triangle, square, pyramid, starfish – to find those that would allow cells to be more efficient when established. On the motion of kinematic replication reported in a new study.

After several months of computation, the supercomputer came up with a C-shaped model of the organism, reminiscent of Pac-Man, a 1980s video game character. Scientists have found that such a xenobot can find tiny stem cells in a Petri dish, collect hundreds of them in the “mouth”, and after a few days, the cells grouped in this way turned into new xenobots.

“Parents” -xenobots collect a large group of stem cells from which new xenobots-“children” will be formed.

“Artificial intelligence has not programmed these creatures in the way that we usually understand the way of writing code. He designed and created the Pacman form,” – Bongard said. “Form is, in essence, the program. Form affects the behavior of xenobots, enhancing this incredibly amazing property.”

Practical use

Xenobot creation is a nascent technology with no practical application like computers in the 1940s. However, according to the researchers, this combination of molecular biology and artificial intelligence can potentially be used to solve many problems related to both medicine and the environment. Potential uses for xenobots could include harvesting microplastics in the oceans, inspecting plant root systems, and uses in regenerative medicine.

 Prevention of possible risks

While the prospect of self-replicating biotechnology may cause public concern, the researchers said the living robots were kept in a laboratory under complete control and easily destroyed because they are biodegradable and ethics experts regulate the research process.