Generations of laboratory mice like these recently became host to microscopic robot swarms.Photo: Getty Images (Getty Images)
In a mind-bending development, a team of researchers in China have managed to treat brain tumors in mice by delivering drugs to the tissues using microscopic robots. The robots jumped from the mice’s bloodstreams into their brains by being coated in E. coli, which tricked the rodents’ immune systems into attacking them, absorbing the robots and the cancer-fighting drugs in the process.
The team’s research was published today in the journal Science Robotics. It comes on the heels of previous research by members of the same team, which saw liquid-coated nanorobots remotely propelled through the jelly-like fluid of the eye. Besides being an obvious recipe for an episode of “The Magic School Bus,” the research had obvious applications for ophthalmological research and medical treatments.
“It’s not just the blood-brain barrier,” said lead author Zhiguang Wu, a chemist at the Harbin Institute for Technology in China, in an email. “Most barriers in dense tissues are difficult obstacles to overcome in moving microrobots around a body.”
The crafts are magnetic, and the researchers use a rotating magnetic field to pull them around remotely. On microscales—we’re talking incremental movements about 1% the width of a hair—the researchers were able to make the hybrid bio-bots wend paths like in the video game Snake. They’re dubbed “neutrobots” because they infiltrate the brain in the casing of neutrophils, a type of white blood cell.
“The biggest challenge of the work was how to achieve a swarm intelligence of neutrobots,” Wu said. “Like robot swarms in the macroscale world, the micro/nanorobot swarms enable sophisticated manipulation to accomplish complex tasks.”
It ultimately took Wu’s team eight years to actualize the microscopic robot swarms capable of bridging the gap between the rodent bloodstream in the animal’s tail, where the bots were injected, and its brain, where gliomas—tumors that emerge from the brain’s glial cells—resided. Part of the issue is that the mice’s white blood cells didn’t dig the flavor of the magnetic robots. To overcome that issue, Wu’s team coated the bots in bits of E. coli membrane, which the white blood cells easily recognize as a unwelcome invader. That made the robots much more palatable, and the white blood cells enveloped them. From inside those cells, the robots were then able to roll the cells toward the brain; a Trojan horse for the 21st century (in this case, one that benefits the residents of Troy). The neutrobots made it into the brains and were able to deliver the drug directly to the targeted tumors.
Wu said the applications of the robots are manifold, and more breakthroughs could be on the horizon. “The neutrobots are not exclusively designed for the treatment of glioma,” he said, explaining that they’re “a platform for active delivery for the therapy of various brain diseases such as cerebral thrombosis, apoplexy, and epilepsy.”
A neutrobot nestled up against a glioma tumor in a mouse brain.Image: Zhang et al., Sci Robot. 6, eaaz9519 (2021)
Whether it’s surgery or drug delivery, robots are slowly but surely making their way into our most personal of domains. Of course, they’re still just in mouse brains for now, but future applications in humans seem increasingly likely.
“The use of neutrophils in microrobot design is a fascinating strategy for overcoming biological barriers,” wrote robotic engineers Junsun Hwang and Hongsoo Choi, who weren’t affiliated with the new work, in an accompanying article. “However, bench-to-bedside translation with respect to targeted drug delivery by neutrobots or microrobots is still some way off.”
Currently, experts lack the ability to see what the robots are doing clearly in real time, which would be vital for any medical use of the droids down the line. But in the rat race of robotics research, it’s clear that humans are pushing their inanimate swarms in the direction of progress.