Microrobots Target Lung Tumor Metastasis in Mice with Cancer Drugs

Researchers at the University of California San Diego have engineered microscopic robots, termed microrobots, designed to navigate through the lungs and deliver cancer medications directly to metastatic tumors. Initial tests in mice have shown promising results, effectively curbing tumor growth and spread, thereby enhancing survival rates compared to standard treatments.

These microrobots represent a fusion of biological and nanotechnological innovation, the product of collaborative efforts between the labs of Joseph Wang and Liangfang Zhang from the UC San Diego Jacobs School of Engineering. The researchers combined green algae cells with drug-filled nanoparticles to craft these microrobots. The algae serve as a propulsion mechanism, enabling the microrobots to move efficiently within the lungs and locate tumors.

The nanoparticles utilized in this technology are designed with a clever structure. They are biodegradable polymer spheres loaded with the chemotherapeutic drug doxorubicin and coated with red blood cell membranes. This particular coating is crucial as it camouflages the nanoparticles, preventing detection and destruction by the immune system. According to Zhengxing Li, a key contributor to the study, this coating makes the nanoparticles appear like red blood cells, thus evading an immune response.

Safety is a significant consideration in this study. The materials used for the nanoparticles are biocompatible, and the green algae Chlamydomonas reinhardtii, used in the microrobots, is approved by the U.S. Food and Drug Administration for safe use.

This cutting-edge research builds on previous work by Wang and Zhang's teams, who have successfully tested similar microrobots against pneumonia in mice. The earlier versions combated bacterial infections in the lungs using a distinct drug and cell membrane combination for the nanoparticles. The researchers modified these components to create microrobots tailored to fight lung cancer cells in the current study. Zhang describes this as a versatile platform technology capable of effectively delivering treatments throughout lung tissues to tackle various deadly diseases.

In the recent study, mice with melanoma that had metastasized to the lungs were treated with the microrobots. These microrobots were introduced into the lungs via a tube inserted into the windpipe. Mice receiving this treatment showed a median survival time of 37 days, a significant improvement over the 27-day median survival time observed in untreated mice and those treated with either the drug alone or drug-filled nanoparticles without algae.

The active swimming capability of the microrobots plays a critical role in enhancing drug distribution to deep lung tissues and extending the drug's retention time in the lungs. This improved distribution and retention enabled the researchers to lower the required drug dosage, potentially minimizing side effects while maintaining high efficacy in enhancing survival rates.

Looking ahead, the team aims to advance this microrobot therapy to trials in larger animals, with the ultimate goal of conducting human clinical trials. The study titled "Biohybrid microrobots locally and actively deliver drug-loaded nanoparticles to inhibit the progression of lung metastasis" underscores the potential of this technology to revolutionize lung cancer treatment.