Implanting a sensor to monitor inflammation continuously
A first-of-its-kind implantable sensor can track inflammation continuously in a rat model of diabetes.
Researchers at the Chan Zuckerberg Biohub Chicago and Northwestern University (both IL, USA) have created a tiny implantable microdevice that continuously monitors the concentrations of inflammatory proteins in real time. This sensor could offer deeper insights into inflammatory proteins and inflammation-associated diseases.
Inflammation is a natural response produced by the immune system; it is often a protective reaction against injuries and irritants, manifesting in different ways, such as swelling around a cut, fever or body aches. However, when triggered incorrectly, it can be harmful, resulting in the attack of the body’s own cells. This happens in cases of diabetes, rheumatoid arthritis and Crohn’s disease, as well as many other chronic illnesses.
Although researchers and doctors have long known the important role inflammation plays in health and disease, there wasn’t an adequate tool for monitoring inflammation. Previously, senior author Shana Kelley’s (Northwestern University) lab devised sensors that detect proteins in fluids such as saliva. Next, the team wanted to investigate if the sensors would be able to monitor inflammatory proteins in the fluid underneath the skin of animals, hence the creation of an implantable microdevice.
The team created a nanoscale device comprising an electrode and sensors engineered to detect two protein biomarkers of inflammation in a microneedle the width of three human hairs. Due to fluctuating electrical charges produced by the electrode, the sensors sway back and forth. This swaying motion provides enough force to throw off the bound protein, leaving the sensor vacant so another protein can attach.
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The researchers tested the nanoscale device on rat models of diabetes, a disease closely linked with inflammation. The microdevices were implanted on the rats’ skin to continuously monitor inflammatory proteins as the rats fasted and when they were injected with a substance – such as insulin – to agitate the immune system. They used ELISA to confirm the protein concentrations picked up by the sensors were accurate. Following statistical analyses of the ELISA and sensor data, it was found that the datasets agreed.
The sensor was highly sensitive, accurately reporting the concentrations of inflammatory proteins when the rats were fasting – inflammation was low – and when injected with insulin – inflammation increased. What’s more, the sensor was able to report the local spike in inflammation caused by the injection itself. Furthermore, the researchers confirmed that embedding the microdevice did not produce a widespread inflammatory response.
The team will continue their work in animal models, using the sensor to test how inflammation changes in response to different environments and food conditions. They also plan to conduct further research in instrumental tissues, which are tissue models of human organs embedded with thousands of sensors and probes to monitor cellular and molecular processes.
Much like the implantable glucose sensors worn by individuals with diabetes, “…this [inflammatory protein sensor] has the same potential to allow us to monitor, and even prevent, many diseases,” concluded Kelley. “With inflammation, the sky’s the limit with what you could do for your health by keeping a handle on it.”
