Engineers at the University of California San Diego have developed microscopic robots, known as microrobots, that can swim through the lungs and deliver cancer-fighting medication directly to metastatic tumors. These innovative microrobots, a collaborative effort between the labs of Joseph Wang and Liangfang Zhang, professors in the Aiiso Yufeng Li Family Department of Chemical and Nano Engineering at the UC San Diego Jacobs School of Engineering, have shown promise in mice by inhibiting the growth and spread of tumors that had metastasized to the lungs, thereby improving survival rates compared to control treatments.
The findings, detailed in a paper published on June 12 in Science Advances, showcase the potential of this novel approach in the fight against cancer.
A Fusion of Biology and Nanotechnology
The microrobots are a clever combination of biology and nanotechnology. To create them, researchers chemically attached drug-filled nanoparticles to the surface of green algae cells. The algae, which provide the microrobots with their movement, enable the nanoparticles to efficiently swim around in the lungs and deliver their therapeutic payload to tumors.
The nanoparticles are made of tiny biodegradable polymer spheres, loaded with the chemotherapeutic drug doxorubicin and coated with red blood cell membranes. This coating serves a crucial function: it protects the nanoparticles from the immune system, allowing them to remain in the lungs long enough to exert their anti-tumor effects. “It acts as a camouflage,” said study co-first author Zhengxing Li, a nanoengineering Ph.D. student in both Wang and Zhang’s research groups. “This coating makes the nanoparticle look like a red blood cell from the body, so it will not trigger an immune response.”
Safe and Effective Treatment
The researchers noted that this formulation of nanoparticle-carrying algae is safe. The materials used to make the nanoparticles are biocompatible, while the green algae employed, Chlamydomonas reinhardtii, are recognized as safe for use by the U.S. Food and Drug Administration.
This study builds on prior work by Wang and Zhang’s teams using similar microrobots to treat deadly pneumonia in mice. “Those were the first microrobots to be safely tested in the lungs of live animals,” said Wang.
In the current study, mice with melanoma that had metastasized to the lungs were treated with the microrobots, which were administered to the lungs through a small tube inserted into the windpipe. Treated mice experienced a median survival time of 37 days, an improvement over the 27-day median survival time observed in untreated mice, as well as mice that received either the drug alone or drug-filled nanoparticles without algae.
“The active swimming motion of the microrobots significantly improved distribution of the drug to the deep lung tissue, while prolonging retention time,” said Li. “This enhanced distribution and prolonged retention time allowed us to reduce the required drug dosage, potentially reducing side effects while maintaining high survival efficacy.”
Moving forward, the team is working on advancing this microrobot treatment to trials in larger animals, with the ultimate goal of human clinical trials. “We demonstrate that this is a platform technology that can actively and efficiently deliver therapeutics throughout the entire lung tissue to combat different types of deadly diseases in the lungs,” said Zhang.
