(Nanowork News) Engineers at the University of California, San Diego have developed a pill that releases microscopic robots, or microrobots, into the colon to treat inflammatory bowel disease (IBD). Experimental treatments administered orally have shown success in mice. This significantly reduced IBD symptoms and promoted healing of damaged colon tissue without causing toxic side effects.
This study Scientific Robotics (“Biohybrid microrobots modulate colonic cytokine levels and regulate epithelial barrier restoration in inflammatory bowel disease”).
![Color SEM image of a microrobot made of algae cells (green) covered with macrophage-mimicking nanoparticles (red).](https://www.nanowerk.com/nanotechnology-news3/id65438_1.jpg)
IBD, an autoimmune disease characterized by chronic intestinal inflammation, affects millions of people worldwide and causes severe abdominal pain, rectal bleeding, diarrhea and weight loss. This occurs when immune cells known as macrophages become overactive and produce excessive amounts of pro-inflammatory proteins called pro-inflammatory cytokines. These cytokines, in turn, bind to receptors on macrophages, triggering them to produce more cytokines, thereby perpetuating the inflammatory cycle that causes the debilitating symptoms of IBD.
Now researchers have developed a treatment that successfully maintains these cytokine levels. A team led by Liangfang Zhang and Joseph Wang, the Aiiso Yufeng Li Family Professor of Chemistry and Nanoengineering at UC San Diego, designed a microrobot comprised of inflammation-fighting nanoparticles chemically attached to green algae cells. Nanoparticles absorb and neutralize intestinal pro-inflammatory cytokines. Meanwhile, green algae use their natural swimming ability to efficiently distribute nanoparticles throughout the colon and accelerate cytokine clearance, helping to heal inflamed tissue.
What makes these nanoparticles so effective is their biomimetic design. This product is made of biodegradable polymer nanoparticles coated with macrophage cell membranes and can act as a macrophage bait. These baits naturally bind to inflammatory cytokines rather than triggering them to produce more, disrupting the inflammatory cycle.
“The advantage of this approach is that it doesn’t require drugs,” Zhang said. We simply leverage natural cell membranes to absorb and neutralize pro-inflammatory cytokines,” Zhang said.
![Illustration of a microrobot that neutralizes inflammatory cytokines to treat inflammatory bowel caused by IBD.](https://www.nanowerk.com/nanotechnology-news3/id65438_2.jpg)
Researchers ensured that the biohybrid microrobot met stringent safety standards. The nanoparticles are made of biocompatible materials, and the green algae cells used in this study have been recognized as safe for consumption by the U.S. Food and Drug Administration (FDA).
The microrobot is packaged inside a liquid capsule with a pH-responsive coating. This coating remains intact in the acidic environment of the stomach, but dissolves when it reaches the neutral pH of the colon. This allows microrobots to be selectively released where they are most needed.
“We can send microrobots to the location of the disease without affecting other organs,” Wang said. “This way we can minimize toxicity.” The capsules keep the functionalized algae in a liquid state until released.
The capsules were administered orally to rats suffering from IBD. This treatment reduced stool bleeding, improved stool consistency, reversed weight loss due to IBD, and reduced colon inflammation, all without any apparent side effects.
The research team is currently focusing on translating microrobotic therapy into clinical research.