Coaxing bacteria into producing medicines for humans’ benefit has been a common quest. But the goal of getting those bacteria to drop loads of medicine at a specific target inside the body is more unusual.
According to research presented Tuesday at the American Chemical Society meeting in Anaheim, California, that goal is now within sight. The researchers, led by William Bentley of the University of Maryland, say their engineered bacteria could serve as on-the-go nanofactories inside the body, both to produce illness-fighting agents and to deliver them to the correct spots.
They developed a prototype using a strain of the E. coli bacterium specially engineered with a targeting molecule attached to its outer surface. The bacterium cruises around, finds its target, attaches to it, and begins producing preprogrammed drugs. In the laboratory, in vitro, the prototype was able both to find targeted intestinal cells and to produce chemical signals that triggered nearby bacteria to produce proteins they typically don’t make.
“We envision a cell that seeks out a cancer tumor and locks on to it, then starts to create its own antitumor drug and deliver it on the spot,” said Bentley. He said this method could also treat conditions such as other gastrointestinal illnesses or vitamin deficiency. “One thing that is different from other treatments is that this is site-specific,” he said. “Most medicines kill all the cells or tissue, while this system only delivers drugs to one spot.”
The bacterial drug factories could also produce signaling molecules to communicate with natural bacteria and keep them from starting an infection. They could, Bentley said, be injected or swallowed as probiotics—beneficial live organisms—though clinical applications of the technology are years away.
Other researchers say that transferring the process from the lab to a person can be difficult. “Getting a lab strain of E. coli to survive the stomach is going to be tricky,” says J. Christopher Anderson, a bioengineering professor at the University of California, Berkeley. “There are issues to the genetic stability of the organisms, and depending on the specific goal, the ability to get enough bacteria into the intestines to do something could be tricky.” Anderson says that the intestine is a good place to start for engineered bacteria therapy because E. coli last longer in the intestines than in other parts of the body.
Getting bacterial dirigibles past regulatory hurdles could also be problematic, Anderson says. “Treating chronic diseases with gastrointestinal engineered bacteria will necessarily result in environmental release. Since these bacteria produce biologically active chemicals or proteins to be functional, there are likely to be significant safety concerns and thereby barriers to getting them approved.”