The miracles of modern medicine strike again: Scientists have managed to generate a modified version of algae capable of carrying tiny, antibiotic-filled capsules into the bodies of mice to fight off deadly lung infections. The results help raise hopes that a similar therapy could one day cure critically ill human patients who suffer from the same type of bacterial infection.
The key to this work is in drug-delivering nanoparticles, which are tens to tens of thousands’ times smaller than the width of a single hair. Researchers at the University of California San Diego found that their nanoparticle-infused algae were able to fight off pneumonia infections in mice and allow them to survive for several weeks after treatment—in stark contrast to the untreated mice that died within three days. The team’s work was published Thursday in Nature Materials.
The effectiveness of antibiotics is limited, ironically, by the body’s own metabolism and immune system. When we take pills orally or receive antibiotics intravenously, these drugs embark on a journey to get where they need to go. They must cross numerous barriers and membranes, all while evading detection by patrolling cells. The UCSD researchers wanted to use nanoparticles to give antibiotics a shortcut to the infection site. Their size coupled with a coating to mimic a type of immune cell would spell safe passage for the drugs hidden within.
“With an IV injection, sometimes only a very small fraction of antibiotics will get into the lungs,” study co-author and UCSD pharmacy researcher Victor Nizet said in a press release. This is why very sick patients will die from pneumonia, even with antibiotic treatment. This nanoparticle therapy, said Nizet, has the potential to wipe out these deadly bacteria and save patients’ lives.
The researchers’ nanoparticles can’t move on their own—they need some assistance to travel around the body, as well as avoid getting captured by the body’s immune system. So the scientists embedded the tiny, drug-filled capsules into a species of single-cell green algae, and let the swimmers loose in the tracheae of 12 mice infected with Pseudomonas aeruginosa, a nasty bacterial pneumonia. The algae managed to evade capture by immune cells called macrophages by swimming away and instead heading for sites of infection—and avoid getting gobbled up by the macrophages like stand-alone nanoparticles would.
All 12 mice that were given the algae-nanoparticle combination remained alive after 30 days, while untreated mice died within three days. And to boot, this new method outperformed intravenous treatment of the same antibiotic given at an equal concentration; it took an IV dose with 3,000 times as much antibiotics to produce the same effects.
Moreover, the researchers found that the nanoparticles and algae had no harmful effects on the mice’s cells and degraded after releasing the antibiotics. “Nothing toxic is left behind,” said study co-author and UCSD nanoengineering researcher Joseph Wang in the press release.
Currently, the scientists are conducting further research into how the algae-nanoparticle duos interact with organisms’ immune systems. Eventually, they hope to turn the therapy into a life-saving treatment for ICU patients. That is, if people can stomach the thought of injecting tiny algae into their lungs.