Engineers at the University of California San Diego in the United States have developed a new pill that releases microscopic robots, or microrobots, into the colon to treat inflammatory bowel disease (IBD). The experimental treatment, given orally, has shown success in mice, as it significantly reduced IBD symptoms and promoted the healing of damaged colon tissue without causing toxic side effects.
Millions of people worldwide are affected by IBD, an autoimmune disorder characterized by chronic inflammation of the gut, which causes severe abdominal pain, rectal bleeding, diarrhea and weight loss. It occurs when immune cells known as macrophages become overly activated, producing excessive levels of inflammation-causing proteins called pro-inflammatory cytokines. These cytokines, in turn, bind to receptors on macrophages, triggering them to produce more cytokines, and thereby perpetuating a cycle of inflammation that leads to the debilitating symptoms of IBD.
The new pill was shown to successfully keep these cytokine levels in check. The scientists behind the pill engineered microrobots composed of inflammation-fighting nanoparticles chemically attached to green algae cells. While the green algae use their natural swimming abilities to efficiently distribute the nanoparticles throughout the colon, which accelerates cytokine removal and helps heal inflamed tissue.
Effectiveness of the nanoparticles is due to the principles of engineering, chemistry and biology that are employed in the design and synthesis of the pill. Made up of biodegradable polymer nanoparticles coated with macrophage cell membranes, the pills are able to act as macrophage decoys that naturally bind pro-inflammatory cytokines, thereby breaking the inflammatory cycle.
Researchers behind the pill emphasized that their biohybrid microrobots meet rigorous safety standards. The nanoparticles are made of biocompatible materials, and the green algae cells used in this study are recognized as safe for consumption by the Food and Drug Administration (FDA) in the United States.
The microrobots are packed inside a liquid capsule with a pH-responsive coating. This coating remains intact in the acidic environment of the stomach acid, but dissolves upon reaching the neutral pH of the colon. This ensures that the microrobots are selectively released where they are needed most thereby minimizing toxicity.
The treatment administered orally to mice reduced fecal bleeding, improved stool consistency, reversed IBD-induced weight loss and reduced inflammation in the colon, all without apparent side effects. The research team is now reported to be focusing on translating their microrobot treatment into clinical studies in order to eventually make the pills available to patients with IBD.
