Microrobots cross the blood-brain barrier, opening up anti-cancer R&D opportunities

MRI brain scan
Researchers have devised an approach that inhibited the proliferation of tumor cells more effectively than a traditional injection. (Ildar Imashev / Getty Images)

Researchers have created microrobots that could deliver therapeutic payloads across the blood-brain barrier. The researchers based their microrobots on neutrophil white blood cells and used rotating magnetic fields to propel them to targets in the brain. 

Difficulties getting molecules across the blood-brain barrier have stymied efforts to treat diseases that affect the brain, including cancers and neurological disorders. Cell-based microrobots are one avenue of research but have triggered immune attacks, leading to their clearance. The limitations of existing microrobots led a team at the Harbin Institute of Technology in China to add a twist to the idea.

Writing in Science Robotics, the researchers describe how they loaded the cancer drug paclitaxel into magnetic nanogels and coated the particles with Escherichia coli. When neutrophils, a type of white blood cell, detected the E. coli membrane, they swallowed up the particles. The process created magnetic, neutrophil-based microrobots.

As part of a neutrophil, the drug-loaded nanogels passed along the bloodstream of mice and into the brain without triggering the sort of immune responses that limit the utility of other microbots. The use of magnetic nanogels enabled the researchers to control the movement of the nanobots. Rather than wait for nanobots to passively reach the brain, the researchers actively moved them toward the target using a rotating magnetic field.

The approach inhibited the proliferation of tumor cells more effectively than a traditional injection of the drug. If successfully translated into humans, the microrobots could facilitate the delivery of high, therapeutic doses of anti-cancer drugs to the brain without exposing healthy tissues to intolerable levels of the molecules.

Work needs to be done to get the approach ready for the clinic. In an accompanying editorial, two robotic engineers not involved in the projects said “bench-to-bedside translation with respect to targeted drug delivery by neutrobots or microrobots is still some way off.”