Night of the Living Robots

Using human cells, scientists have developed tiny “biological robots” that possess the potential to promote and speed up cell regeneration and repair.

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In 2010, developmental biologist and professor at the Tufts’ School of Arts and Science Michael Levin and his colleagues used skin cells and myocardial (heart) cells sourced from embryos of the African frog Xenopus laevis to construct “xenobots,” tiny artificial “living” creatures. They have been aiming to delve deeper into bioengineering to produce not only artificial organs but also biological robots. The xenobots had many lifelike characteristics, such as being spontaneously locomotive at their own will without any external influencing factors; when under observation, they swam through a protein-rich gel in a group. Nevertheless, they were dismissed for not having the qualities of “biological robots.” Since amphibians can often regenerate severed parts of their bodies, some researchers hypothesized that perhaps clustered frog cells could regenerate into a seemingly living organism as well; therefore, they were just exhibiting amphibian behavior rather than a form of bioengineered behavior. However, Levin defended xenobots by stating that he didn’t think this had anything to do with being a frog but rather was a result of the fact that they originated from a biological organism.

Levin and his colleagues at Tufts University conducted further research, and in November 2023, they successfully created “living robots” from human cells. They were much more widely accepted amongst biologists as biological robots since human cells don’t regenerate and move around after they have been severed. These contraptions, dubbed “anthrobots,” range in size from 30 to 500 micrometers and are made from spheroids of adult human tracheal tissue cultured in a protein-rich gel called Matrigel. The tracheal tissue is responsible for sending mucus through the lungs. After growing in the gel for two weeks, the cells were set in a less viscous, or thick, liquid to grow for another week. The second liquid caused the thin protein appendages called cilia that originally lined the inside of the tracheal cells to move out and coat the cells’ exteriors. Anthrobots are spontaneously locomotive because their outer cilial linings can propel them through various mediums. The cultured cells were then clumped into small groups by themselves, with each clump containing around 100 cells. These were the final anthrobots, exhibiting all different characteristics. For instance, some had the regular tendency to move in straight lines, while others swam in arcs or circles and others simply moved about in utter chaos.

A remarkable discovery made about anthrobots is that they have the ability to promote fundamental wound healing in surrounding human cells. In order to test their healing skills and anthrobot collaboration, Levin and his team first placed several anthrobots together in a petri dish, where they proceeded to come together to form a “superbot” for reasons that scientists have yet to discover. Next, the super bot was placed on a piece of neural tissue with a small abrasion, detached from any human. Within three days, the wound was completely healed using the super bot—an astonishing feat considering that it generally takes weeks for soft corneal abrasions to recover. The anthrobots accomplished this by creating a makeshift bridge across the damaged sections, which made it significantly easier and quicker for neuron regeneration to repair the injury. The organism-like qualities that anthrobots possess can be used as a “biorobotics platform” to genetically engineer the plasticity of anthrobots into creatures that can repair damaged tissue on a larger scale; plasticity is the ability of cells to adapt different structures in response to environmental changes. 

One application of this technology is the treatment of strokes. Strokes often occur when blood vessels burst. This deprives areas of the brain from receiving oxygen and leads to brain damage. Anthrobots could be used to speed up the blood vessel repair and brain tissue regeneration processes, allowing for rapid recovery. Another potential application of anthrobots’ healing capabilities is in amyotrophic lateral sclerosis (ALS), a neurodegenerative disease that occurs due to the degeneration of motor neurons. ALS can begin at any age and severely shortens the lifespan of those who have it—the life expectancy after diagnosis is only an additional four to five years at best. Perhaps anthrobots could be utilized to regenerate those motor neurons at a faster pace than they degenerate, giving the patient a longer lifespan. 

Though anthrobots are in the early stages of research and development, they’re likely to become prominent in treating medical conditions in the near future. However, further research is needed to ensure that they are safe for human applications, given the fact that they haven’t been tested on humans as wound healers. There is still the possibility that the human body could have an immune response towards these “invaders,” or that the inner environment of the human body could be unideal for anthrobot survival. Test runs still need to be conducted, but administering humans or animals with anthrobots comes with ethical concerns as well since they could certainly create unexpected reactions in organisms. Anthrobots are exploring the future of morphospace, or are all the possible phenotypes an organism can adapt throughout its life, expanding the possibilities when it comes to outrunning the biological clock and treating medical conditions before they cause fatal damage. Hopefully one day, these biological robots will be able to help us heal faster than ever.