Engineers have developed microscopic robots that swim through the lungs to deliver chemotherapy directly to lung tumors.

RT’s Three Key Takeaways:

  1. Engineers at UC San Diego have created microrobots that can swim through the lungs and deliver chemotherapy directly to metastatic lung tumors, improving drug distribution and retention.
  2. In studies with mice, the microrobots successfully inhibited tumor growth and spread, resulting in a longer median survival time compared to traditional treatments.
  3. The success of this approach in preclinical trials suggests potential for human clinical trials, aiming to offer a more effective and targeted treatment for lung cancer patients.

Engineers at the University of California San Diego have developed microscopic robots, known as microrobots, capable of swimming through the lungs to deliver cancer-fighting medication directly to metastatic tumors.

This approach has shown promise in mice, where it inhibited the growth and spread of tumors that had metastasized to the lungs, thereby boosting survival rates compared to control treatments.

The findings are detailed in a paper published in Science Advances.

Design and Functionality

To create the microrobots, 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, which are loaded with the chemotherapeutic drug doxorubicin and coated with red blood cell membranes. This coating serves a critical function: It protects the nanoparticles from the immune system, allowing them to stay in the lungs long enough to exert their anti-tumor effects.

“It acts as a camouflage,” said study co-first author Zhengxing Li, who is a nanoengineering PhD, student in the labs of Joseph Wang, PhD, and Liangfang Zhang, PhD, professors in the Aiiso Yufeng Li Family Department of Chemical and Nano Engineering at the UC San Diego Jacobs School of Engineering. “This coating makes the nanoparticle look like a red blood cell from the body, so it will not trigger an immune response.”

Safety and Previous Work

This formulation of nanoparticle-carrying algae is safe, the researchers note. The materials used to make the nanoparticles are biocompatible while the green algae employed, Chlamydomonas reinhardtii, are recognized as safe for use by the US 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,” says Wang in a release.

In previous work, the microrobots fought the spread of pneumonia-causing bacteria using a different drug and cell membrane combination for the nanoparticles. By tweaking these components, the team has now tailored the microrobots to fight the spread of cancer cells in the lungs.

Promising Results in Mice

“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,” says Zhang in a release.

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,” says Li in a release. “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.

Photo caption: Colored SEM image of a microrobot made of an algae cell (green) covered with drug-filled nanoparticles (orange) coated with red blood cell membranes.

Photo credit: Zhengxing Li