Whole-body drugs can be too much of a shotgun approach, damaging cells that aren’t meant to be targeted. Hiding drugs inside red blood cells could help guide powerful but toxic antibiotics to target bacteria, a new study has found.
Bacteria are growing develop resistance to our best antibiotics, leaving doctors with less and fewer treatment options. In many cases, we are reduced to our drugs of last resortsuch as those that induce serious side effects in the body.
But there may be ways to target these drugs more precisely. A few years ago, scientists at McMasters University in Canada developed what they called “superhuman red blood cells– Essentially, they extract the innards of normal blood cells and stuff them with drugs instead. immune attack them.
In the new study, the team tackled an unresolved problem: how to get the hybrid blood cells to go to the desired target? They coated the outside of blood cells with an antibody that targeted the species of bacteria they were trying to kill, causing them to cluster around insects and deliver their drug payload more precisely.
The researchers tested the drug delivery system with an antibiotic called polymyxin B (PmB), which is effective at killing bacteria resistant to other drugs. But it comes at a cost to healthy cells, with the potential for kidney damage, neurological problems, and other serious side effects. As such, it is considered an antibiotic of last resort.
In in vitro cell culture tests, the team loaded blood cells with PmB and targeted them to drug-resistant bacteria. E.coli. They found that the cells had a loading efficiency of around 90% and were effective at delivering PmB to bacteria at levels high enough to kill them. To test targeting, the team also exposed a different bacterium, Klebsiella aerogeneshybrid cells coated with E.coli antibodies, and found that they were insufficient to kill the insects. This, the team says, shows that selective targeting works.
The researchers say this approach has a number of advantages. Not only does this prevent the drug’s payload from affecting healthy cells, but since red blood cells have a long lifespan of around 120 days, they have plenty of time to reach targeted sites. The technique could also reduce the number of doses required and the amount of drug per dose.
“Essentially, we’re using red blood cells to hide this antibiotic inside so that it can no longer interact with or harm healthy cells as it passes through the body,” said Hannah Krivic, lead author of the study. “We designed these red blood cells so that they can only target the bacteria we want them to target.”
The team says future work will investigate the potential of the technique to deliver drugs across the blood-brain barrier to the brain to help treat neurological conditions such as Alzheimer’s disease.
The research was published in the journal SCA Infectious Diseases.
Source: McMaster University