Microscopic robots made from white blood cells using light could treat life-threatening illnesses

GUANGZHOU, China — Using light, scientists have created microscopic robots out of white blood cells which could treat and prevent life-threatening illnesses. The tiny machines are made of cells called neutrophils and researchers believe they could revolutionize modern medicine.

“Neutrobots” can deliver drugs to precise locations in the body under the direction of laser beams. Other devices developed to perform similar tasks contain synthetic materials, raising the risk of serious side-effects.

“The neutrophil microcrafts can be remotely activated by light and then navigated to the target position along a designated route,” researchers write in the journal ACS Central Science.

In experiments on zebrafish, the Chinese team used scanning optical tweezers (SOTs) to perform three potential applications on the animals’ tails. This included cell therapy, targeted nanomedicine, and removal of debris or organic waste that can trigger disease.

“By integrating the noninvasive manipulation of optical tweezers and innate immunologic function of neutrophils, the proposed neutrophil microcraft provides new insight for the construction of native medical microdevices for precision medicine in vivo.”

The robot cells could carry drug payloads directly to a tumor, blood clot, or infection. SOTs point a highly focused beam to hold and move microscopic and sub-microscopic particles in a manner similar to tweezers.

“The neutrophil microcraft can be activated or recovered in a controlled manner, and the migration of the activated neutrophil microcraft is fully steerable, just like driving a vehicle,” study authors write.

A noninvasive version of nanotechnology

Ordinary neutrophils can spring into action as an inflammatory response, but they are often slow and move in the wrong direction.

“With the development of optically manipulated neutrophil microcraft, the behaviors of natural neutrophil can now be actively controlled,” study authors report.

This includes remote activation by SOTs at a desired time and location. Researchers add this allows them to precisely move the cells along a designed route and at a specific speed. The light beam enabled multi-functional manipulation of the neutrophils by irradiating the fish using a specialized mirror and microscope.

“The zebrafish was selected as the animal model in this study due to its high genome homology with humans and readily observable blood circulation in the zebrafish tail for optical manipulation, in which the neutrophils were clearly identified through fluorescence labeling,” researchers explain in their report.

Medical microrobots currently in development would require injections or the consumption of capsules to get them inside an animal or person. However, researchers have found the objects trigger immune reactions in small animals, resulting in their removal before they can perform their jobs.

Neutrophils are a non-invasive alternative as they are already in the body picking up dead nanoparticles. They travel through vessels into adjacent tissues. The study marks the first time lasers have guided the tiny robots within living animals.

blood cell robot
(Credit: ACS Cent. Sci. 2022)

Neutrobots could be faster and smarter blood cells

The light-driven microrobot can move with a velocity of 1.3 microns a second — three times faster than a neutrophil naturally moves. In one test, a neutrobot moved through a blood vessel wall into the surrounding tissue.

Another picked up and transported a plastic nanoparticle, showing its potential for carrying medicine. When the team pushed one toward red blood cell debris, it engulfed the pieces. Surprisingly, at the same time, a different neutrophil which wasn’t controlled by a laser, tried to naturally destroy it.

“Unlike traditional medical microdevices, this neutrophil microcraft is free from artificial microstructures and invasive implantation processes, thus avoiding complicated preparation technology and unavoidable tissue damage,” researchers conclude.

“Meanwhile, it exhibits high biocompatibility due to the endogenous nature and minor immunogenicity. This concept of a native neutrophil microcraft, coupled with the intelligent control of multiplexed assignment execution, could hold great promise for the active execution of complex medical tasks in vivo, with great potential utility in the treatment of inflammatory diseases.”

South West News Service writer Mark Waghorn contributed to this report.

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