An Anthrobot is shown, depth colored, with a corona of cilia that provides locomotion for the bot. Credit: Gizem Gumuskaya, Tufts University
The multicellular bots move around and help heal “wounds” created in cultured neurons.
Researchers at Tufts University and Harvard University’s Wyss Institute have created tiny biological robots that they call Anthrobots from human tracheal cells that can move across a surface and have been found to encourage the growth of neurons across a region of damage in a lab dish.
The multicellular robots, ranging in size from the width of a human hair to the point of a sharpened pencil, were made to self-assemble and shown to have a remarkable healing effect on other cells. The discovery is a starting point for the researchers’ vision to use patient-derived biobots as new therapeutic tools for regeneration, healing, and treatment of disease.
Human tracheal skin cells self-assemble into multi-cellular, moving organoids called Anthrobots. These images show Anthrobots with cilia on their surface (yellow) distributed in different patterns. Surface patterns of cilia are correlated with different movement patterns: circular, wiggling, long curves, or straight lines. Credit: Gizem Gumuskaya, Tufts University
From Xenobots to Anthrobots: A Leap in Biobotics
This advancement builds upon previous research in the laboratories of Michael Levin, Vannevar Bush Professor of Biology at Tufts University School of Arts & Sciences, and Josh Bongard at the University of Vermont in which they created multicellular biological robots from frog embryo cells called Xenobots, capable of navigating passageways, collecting material, recording information, healing themselves from injury, and even replicating for a few cycles on their own. At the time, researchers did not know if these capabilities were dependent on their being derived from an amphibian embryo, or if biobots could be constructed from cells of other
Exploring the Capabilities of Anthrobots
In this case, researchers gave human cells, after decades of quiet life in the trachea, a chance to reboot and find ways of creating new structures and tasks. “We wanted to probe what cells can do besides create default features in the body,” said Gumuskaya, who earned a degree in architecture before coming into biology. “By reprogramming interactions between cells, new multicellular structures can be created, analogous to the way stone and brick can be arranged into different structural elements like walls, archways or columns.” The researchers found that not only could the cells create new multicellular shapes, but they could move in different ways over a surface of human neurons grown in a lab dish and encourage new growth to fill in gaps caused by scratching the layer of cells.
Exactly how the Anthrobots encourage growth of neurons is not yet clear, but the researchers confirmed that neurons grew under the area covered by a clustered assembly of Anthrobots, which they called a “superbot.”
“The cellular assemblies we construct in the lab can have capabilities that go beyond what they do in the body,” said Levin, who also serves as the director of the Allen Discovery Center at Tufts and is an associate faculty member of the Wyss Institute. “It is fascinating and completely unexpected that normal patient tracheal cells, without modifying their 
Gizem Gumuskaya working in the lab to make Anthrobots. Credit: Gizem Gumuskaya, Tufts University
The advantages of using human cells include the ability to construct bots from a patient’s own cells to perform therapeutic work without the risk of triggering an immune response or requiring immunosuppressants. They only last a few weeks before breaking down, and so can easily be re-absorbed into the body after their work is done.
In addition, outside of the body, Anthrobots can only survive in very specific laboratory conditions, and there is no risk of exposure or unintended spread outside the lab. Likewise, they do not reproduce, and they have no genetic edits, additions, or deletions, so there is no risk of their evolving beyond existing safeguards.
How Are Anthrobots Made?
Each Anthrobot starts out as a single cell, derived from an adult donor. The cells come from the surface of the trachea and are covered with hairlike projections called cilia that wave back and forth. The cilia help the tracheal cells push out tiny particles that find their way into air passages of the lung. We all experience the work of ciliated cells when we take the final step of expelling the particles and excess fluid by coughing or clearing our throats. Earlier studies by others had shown that when the cells are grown in the lab, they spontaneously form tiny multicellular spheres called organoids.
The researchers developed growth conditions that encouraged the cilia to face outward on organoids. Within a few days they started moving around, driven by the cilia acting like oars. They noted different shapes and types of movement – the first. important feature observed of the biorobotics platform. Levin says that if other features could be added to the Anthrobots (for example, contributed by different cells), they could be designed to respond to their environment, and travel to and perform functions in the body, or help build engineered tissues in the lab.
The team, with the help of Simon Garnier at the 
An aggregate of Anthrobots, or superbot (green), stimulates growth of neurons (red) where they had been mechanically stripped away. Credit: Gizem Gumuskaya, Tufts University