Comparison of the size of a microneedle plaster for the extraction of interstitial fluid with an injection needle for collecting blood samples.

The fluid between your cells can help reveal health problems

By Karina Shah

A microneedle plaster for extracting interstitial fluid (left) and a needle for taking blood samples (right)

Allison Carter, Georgia Institute of Technology

The fluid between our cells could be used to diagnose and monitor health conditions. A patch made of tiny needles can remove this fluid and may be easier to use and less invasive than normal blood tests.

Interstitial fluid, also known as tissue fluid, is the fluid that surrounds all of our cells. This fluid leaks from our blood vessels into the cells of our body to provide essential nutrients while removing waste products.

“The fluid that fills the spaces between cells in tissue makes up almost a quarter of our body fluids,” says Mark Prausnitz of the Georgia Institute of Technology.

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Prausnitz and his colleagues developed a plaster made from five stainless steel microneedles that can puncture a person’s skin. The researchers tested the patch on 21 people by taking small amounts of interstitial fluid from the body and comparing it with blood samples.

The team found similar amounts of key compounds – including glucose, caffeine, and vitamin D – in both samples. The researchers say this means the approach could be used to test these compounds and identify health problems related to their amounts like diabetes diagnose. Because the needles in the patch are much smaller than normal needles, the skin can heal from the punctures in a day.

Previous methods of drawing interstitial fluid from the body have had problems with blood contamination. To counteract this, Prausnitz and his team gently increased the suction pressure of the patch so as not to damage nearby blood vessels.

“[This approach] This may be more acceptable than blood tests – especially in pediatric medicine, ‚ÄĚsays Timothy Miles Rawson of Imperial College London. Additionally, it could be used for continuous monitoring because the interstitial fluid doesn’t clot, he says.

Journal reference: Science Translational Medicine, DOI: 10.1126 / scitranslmed.aaw0285

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