Scientists at Tufts University and the Wyss Institute announced on Mar. 16 the creation of a novel living organism, called a neurobot, which features a primitive nervous system developed from frog cells. The findings were recently published in Advanced Science.
The development of neurobots marks an advance in understanding how cell collectives adapt and organize to form complex structures under new conditions. This research could have implications for synthetic biology and regenerative medicine.
The team, led by Michael Levin, Vannevar Bush Professor of Biology at Tufts, and Haleh Fotowat, senior scientist at the Wyss Institute, began by using precursor skin cells from early embryos of the African clawed frog (Xenopus laevis). These cells spontaneously formed small spherical structures known as xenobots that can swim through water using cilia. The researchers then implanted clusters of neural precursor cells into these biobots during their formation. The neural cells matured into neurons that extended axons and dendrites throughout the bots.
“We wanted to find out what would happen if we provided these biobots with the raw materials needed to build a nervous system,” said Levin, who is also director of the Allen Discovery Center at Tufts. He added that this approach allows scientists to observe behavior in a biological body rather than just in tissue samples or lab dishes.
Fotowat said creating neurobots helps examine fundamental rules for how nervous systems form: “I’ve tried to understand neuronal behavior in existing animals like zebrafish, and how they give rise to behavior, but neurobots are about reverse engineering,” she said. “Can we build a nervous system from the start? What happens if you put neurons in a completely novel context? What are the basic, innate rules for them to organize and form networks?”
Microscopy showed that neurons inside neurobots developed hallmark features such as axons and dendrites. Protein markers associated with synapses were identified, and calcium imaging confirmed electrical activity within primitive neural networks. Neurobots grew larger than non-neural biobots and displayed more complex movement patterns. When exposed to pentylenetetrazole—a drug affecting brain activity—neurobots’ movements changed differently compared to non-neural bots, suggesting their simple nervous systems influenced behavior.
Levin noted that genes involved in visual perception were activated within neurobots: “We don’t know, but my hypothesis is that these neurobots are up-regulating parts of the genome that could be useful for novel functions down the line,” he said. “If they lived longer, would they then also develop photoreceptors? It’s a fascinating question that we are actively studying.”
This research opens new possibilities for building living machines capable of self-organization and adaptation.
