Space & Innovation

Maggots Modified to Heal Wounds Faster

New genetically modified maggots are designed to secrete a healing growth factor as they eat away dead tissue.

When a wound won't heal, send in the maggots.

Researchers at North Carolina State University have genetically engineered larvae (i.e. maggots) of the green bottle fly so they secrete human growth factor molecules shown to boost healing.

It may sound icky, but using maggots to promote healing isn't new - the wormy insects have been placed on wounds for more than a century. The maggots eat dead tissue and leave living tissue alone. The young insects also secrete antimicrobial compounds that help keep the wound clean.

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It's a cheap way to treat wounds, but until now some have doubted the treatment's effectiveness. Past clinical trials have failed to show that maggots actually speed up a wound's healing time.

That's where genetic engineering comes in.

The North Carolina team created two brands of maggots - one was engineered to produce human platelet derived growth factor-BB when the maggots were warmed to 37 degrees Celsius (98.6° F). The second group was designed to release the growth factor when their diet lacked a specific antibiotic.

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The lab results showed the first group did not end up releasing adequate amounts of the healing growth factor, but the second group with the antibiotic-limited diet did.

The next step is to test the modified maggots in clinical trials.

While placing maggots on a wound may sound gross, it holds out particular promise for Diabetes patients who often suffer from long-lasting ulcers on their legs and feet.

"A vast majority of people with diabetes live in low- or middle-income countries, with less access to expensive treatment options," said author Max Scott, an NC State professor of entomology in a press release. Scott said the engineered maggots could offer "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.

Genetically modified green bottle flies produce and secrete a human growth factor that helps wound healing.

Americans on average share their homes with 100, and up to 211, different types of tiny animals known as arthropods, according to a new study. The study, published in the journal PeerJ, is the first to evaluate the biodiversity of such little creatures in U.S. homes. Arthropods are animals that have protective external coverings, segmented bodies and jointed limbs. They include insects, spiders, mites, centipedes and more. "I was surprised by the number of specimens we collected from very typical homes, as well as how many rooms we found them in," lead author Matt Bertone told Discovery News. "For instance I didn't expect some groups to be in every home we sampled, and I would not have expected, for example, cobweb spiders to be found in 65 percent of rooms." Bertone, an entomologist at North Carolina State University, and his colleagues also found a lot of ants, such as this search party of little black ants that succeeded in finding a morsel of food on a couch. He explained, "A variety of ants (Formicidae) can commonly be found in homes. These social insects often form trails of workers looking for food and water."

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Bertone and his team visited 50 free-standing houses within 30 miles of Raleigh, N.C., between May and October of 2012. The scientists went room to room, collecting all of the arthropods that they could find. These included both living and dead specimens. The scientists identified no fewer than 579 different types of arthropods during the survey. While the location of a home is a factor, it is expected that houses across the United States will have most, if not all, of the arthropods included on this list. One such creature is the book louse. "Book lice (Liposcelididae) are tiny insects found in many habitats, often in animal nests and human homes," Bertone said. "They are related to true parasitic lice but instead of blood and skin, book lice feed on molds, dead insects, stored food products, and other bits of organic matter."

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Entire families of some arthropods in various life stages can exist in a given home. This image shows the larvae of carpet beetles. "Like tiny pipe cleaners, carpet beetle larvae (Dermestidae) are covered in many hairs," Bertone said. "These hairs are specially modified to interfere with predators, clogging up the mouths of would-be hunters. Carpet beetle larvae typically feed on wool and other hair, feathers, and dead insects." He added that the vast majority of arthropods found in homes are not pest species. They are either peaceful cohabitants, or accidental visitors.

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Many of the tiny animals detected by the researchers had clearly wandered in from outdoors or were brought in on something, such as cut flowers. Not all accidental visitors or arrivals survive for very long indoors. Some drop dead pretty quickly. Cellar spiders, which do well in homes, help to consume some of the newly arrived, and newly dead. "Cellar spiders (Pholcidae), sometimes called daddy-longlegs, are thin legged and reside in webs," Bertone said. "They are often found in basements and crawl spaces, but can be found elsewhere in homes. Although they feed on small arthropods that they capture in their webs, they are also known to invade the webs of other spiders to eat the residents."

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A surprising finding from the study was that only five of the 554 rooms surveyed by the researchers did not contain any arthropods. Bertone said that we tend to think of our homes as sterile environments, but that they actually provide good evidence for biodiversity. One creature living in your midst is probably the dark-winged fungus gnat. "Many come from the soil of overwatered houseplants or compost bins," Bertone said. "They can be an annoyance, but do not bite."

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Many spiders live out their entire life cycles in homes, as numerous human residents could attest. Spitting spiders are common. They have an extra pair of silk glands in their head, attached to their venom glands, which enable them to spit a venomous silk on prey. They then tie the victim up, Bertone said, "so the spider can delicately bite the food item." Cobweb spiders (Theridiidae), like this male (left) and female (right) house spider (

Parasteatoda tepidariorum

), are also common members of U.S. households. "They create irregular webs, which have trip wires to the ground," Bertone said. "When crawling insects come into contact with these tight strands, the connection is broken and the prey gets pulled into the web."

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Certain non-human, non-pet residents of homes go in and outside of the house from time to time. Ground beetles, for example, sometimes willingly wander into homes, looking for prey. They might then crawl back outside. "They will feed on many types of small arthropods, ripping them apart with powerful mandibles," Bertone said. Homes with gardens clearly facilitate this indoor/outdoor lifestyle. While the researchers did not conduct the survey in apartments, they suspect that fewer such arthropods associated with outdoor environments would be found, but "maybe more pests," Bertone guessed.

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Different types of silverfish, such as the gray silverfish and the four-lined silverfish, are common in U.S. homes. "Silverfish (Lepismatidae) are ancient insects that lack wings and have shiny scales all over their body," Bertone said. "They are well adapted to living in homes because they can survive on low nutrient materials such as crumbs, dead insects and even glues, paper and leather."

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Also called drain flies, moth flies (Psychodidae) are similar to small moths, but are in fact true flies, Bertone said. "Their larvae inhabit pipes and drains, where they feed on the muck and organic matter that builds up. For this reason, adults are often found in bathrooms. The adults are harmless and do not bite." Flies, in general, constituted one of the most commonly collected groups of arthropods in homes. Outside of arthropods, U.S. homes contain still more different types of non-pet animals. Bertone explained that these other small creatures often commonly require high humidity or moisture to survive. "These types of animals, including various worms, snails, and slugs, may be present in some basements, but would be absent from the main parts of homes," he added.

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The well-named ghost spider exemplifies many of the tiny animals that the researchers found. It lurks around homes, mostly unseen, and spends a fair amount of time searching for food. Ghost spiders, like other so-called hunting spiders, do not make webs. "These types of spiders can be common in homes, crawling along the floor or up the walls," Bertone said. Entomologist Michelle Trautwein of the California Academy of Sciences, said that the new study provides "only a first glimpse into the species that live in our homes, and more work needs to be done to flesh this picture out." In the future, she hopes that more will be learned about how the tiny animals benefit, harm or otherwise affect ecosystems and human health. She also hopes their traits will be explored, to see if they share evolutionary characteristics that have made them better suited to live with humans. Bertone believes that the study's biggest take home message is that while the findings may be a little frightening to some people, "Most of the arthropods we found are harmless to humans and are very small and inconspicuous. They go about their lives and rarely interfere with ours."

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