It might be a little hard to stomach, but using maggots to clean up wounds is a technique that has been in use for centuries. By selectively devouring dead flesh and leaving healthy tissue intact, these loathsome larvae have offered a cheap way of treating wounds, but not necessarily a quicker one. Now scientists are looking to hasten the healing process by genetically modifying maggots to produce a human growth factor while they go about their business.

Known as maggot debridement therapy (MDT), the wound treatment method was approved by the US Food and Drug Administration in 2004, though it had been applied in various forms throughout history long before that, from Napoleon's army to experiments in World War I. While the maggots assist in healing by cleaning the wound and keeping them clean by secreting anti-microbial factors, there's no evidence to suggest that they actively fast-track the regeneration of healthy cells.

Looking to rectify this, engineers at North Carolina State University (NC State) genetically engineered green bottle fly larvae (Lucilia sericata) to secrete a growth factor called PDGF-BB, which is a protein known to boost healing by driving cell growth and survival.

But designing a mechanism to draw the PDGF-BB from the maggots was a little tricky. First, the team integrated a heat trigger whereby shocking the larvae with temperatures of 37° C (98.6° F) resulted in production of the protein. While it could be detected in the maggots, this approach wasn't enough to have them actually secrete it from their bodies, sending the researchers back to the drawing board.

The team then engineered the larvae to produce PDGF-BB when raised on a diet that didn't include an antibiotic called tetracycline. The researchers found that this approach resulted in high levels of PDGF-BB in the excretions and secretions of the maggots, and say the approach could prove particularly useful as a low-cost alternative where more common treatments aren't available.

"A vast majority of people with diabetes live in low- or middle-income countries, with less access to expensive treatment options," says Max Scott, an NC State professor of entomology. "We see this as a proof-of-principle study for the future development of engineered L. sericata strains that express a variety of growth factors and anti-microbial peptides with the long-term aim of developing a cost-effective means for wound treatment that could save people from amputation and other harmful effects of diabetes."

The research was published in the journal BMC Biotechnology.

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