Blood-filled synthetic skin spares human volunteers itchy bites
In an effort to understand and help combat insect-borne diseases, many a human has sacrificed an arm in a tank full of mosquitos. Now, thanks to a new artificial skin impregnated with real blood, researchers might be able to spare humans the itchy bites, while gaining an even greater understanding of what makes mosquitoes tick.
The synthetic skin was made out of a hydrogel, the water-rich gummy-like wonder material that's being investigated to do everything from purifying water to replacing human cartilage. It was pioneered by bioengineers at Rice University and 3D-printed at Tulane University's School of Public Health and Tropical Medicine. The hydrogel patches are filled with channels that mimic blood vessels, which can be injected with a variety of liquids, including blood from humans and other species.
To test the system, researchers injected the hydrogels with warm human blood, and placed six patches of them in a plastic box filled with mosquitoes. The box was also outfitted with cameras pointing at each patch of synthetic skin. The team then used a machine-learning model to analyze the video footage and identify whether or not particular mosquitos had fed on the blood inside the hydrogels or not. The program was effective at distinguishing between the two mosquito states 92.5% of the time.
Next, the researchers coated some hydrogels in the popular repellent DEET, others in a plant-based repellent, and left some of them uncoated. They found that in the tank with uncoated patches of synthetic skin, 13.8% of the mosquitos fed on the blood. Even though this is a fairly low rate, the researchers believe it might simply be an issue of scaling up the size of the patches to encourage more feeding behavior. Another possibility they propose is heating the hydrogels in addition to the blood, as mosquitoes are attracted to warm surfaces.
In the tanks where the DEET and the plant-based repellents were used, none of the mosquitos fed.
"It’s a huge game changer," said Dawn Wesson, associate professor of tropical medicine at Tulane’s School of Public Health and Tropical Medicine. "If we can study how they (mosquitoes) feed, what they do in the process of feeding, we can better understand their potential for transmitting diseases and possibly do things to stop them from feeding."
The researchers say their breakthrough can allow labs to do more experiments at a reduced cost, as they won't need to hire study participants or purchase test animals. They also say the development could bring a more standardized approach to infectious disease transmission testing.
"It provides a consistent and controlled method of observation," said Omid Veiseh, the study’s corresponding author and an assistant professor of bioengineering at Rice. "The hope is researchers will be able to use that to identify ways to prevent the spread of disease in the future."
Although the hydrogel and machine learning system is already in use in Wesson's lab to study the transmission of dengue, a possible future step would be using the artificial skin patches in the wild, and tuning the fluids inside the hydrogels to take a look at how mosquitoes who feed on other species behave. The team may also look at studying other mosquito species.
"All of the experiments used lab strains of mosquitoes, and the majority involved one particular species: Aedes aegypti, the vector of the yellow fever virus, dengue virus, Zika virus, and others," Wesson told Frontiers Science News. "It may take time to optimize our experimental platform and machine learning model to study other species. Also, since the behavior of laboratory strains sometimes differs from that of mosquitoes found in the wild, it would be important to validate our results on wild mosquito populations."
"Overall, our results suggest that our experimental platform could be scaled up and adapted to screen different compounds for their effects on mosquitoes," added Veiseh.
The following video offers more insight into the study from the researchers involved.
The research has been published in the journal Frontiers in Bioengineering and Biotechnology.