Unexplored Body Fluid: Novel Source of Biomarkers

A new minimally invasive technique has been developed which takes a sample of a largely unexplored body fluid called dermal interstitial fluid which can potentially provide a new source of information for routine diagnostic testing and for clinical monitoring. Tiny needles which were too small to see were developed by the researchers.

The study was published in the journal Science Translational Medicine and conducted by researchers at Georgia Institute of Technology and Emory University.

‘Dermal interstitial fluid (ISF) can help in diagnosis, clinical monitoring and identification of potential toxins absorbed through the skin. The fluid is collected by pressing a patch which has microscopic needles on the skin. This technique is useful for continuous glucose monitoring.’

The laboratory tests which are performed use mainly blood which constitutes 6 percent of body fluid. However important information can be derived from other body fluids which are not used routinely.

The researchers have developed a new method to collect the dermal interstitial fluid which circulates between the cells in the body tissues mainly in the skin.

By using through-the-skin technique, researchers could study the metabolic products of the skin, obtain various diagnostic markers, and identify toxins which are absorbed by the skin.

The dermal interstitial fluid does not clot like blood. This method can also be useful for continuous glucose monitoring and for various other health related problems.

Mark Prausnitz, Regents Professor and J. Erskine Love Jr. Chair in Georgia Tech's School of Chemical and Biomolecular Engineering said that,"Interstitial fluid originates in the blood and then leaks out of capillaries to bring nutrients to cells in the body's tissues. Because interstitial fluid is in direct communication with the cells, it should have information about the tissues themselves beyond what can be measured from testing the blood. This microneedle-based technique could provide a minimally invasive and simple way to access this interstitial fluid to make it available for medical diagnostic and research applications."

ISF is difficult to collect. There are instruments available for glucose monitoring in the ISF. But the techniques available are not suitable for routine diagnostic use.

The first author of the study Pradnya Samant along with other researchers used a patch having five solid stainless steel microneedles, hundredth of an inch in length. The patch was pressed at a particular angle into the skin of the 50 human subjects creating a shallow micropores in the outer layer of the skin containing the ISF.

The collection required about 20 minutes for each of the test subject. The microscopic pores healed within a day and minimal irritation of the skin was seen.

On analyzing the data, 10,000 unique compounds were found most of which were also present in the blood samples. 12 percent of the compounds found were not present in the blood and few others were found in higher levels in the ISF than in the blood.

Prausnitz said, "The skin is metabolically active, and it is full of cells that are changing the fluid. We found that some of the compounds were unique to the ISF, or enriched there, and that is what we were hoping to find."

Components of products which are applied to skin like hand lotions and certain pesticides that enters the body through the skin were found. This could help in further studies of this technique for dermatological and toxicological field.

Prausnitz said, "If you want to look at what accumulates in the skin over time, this may provide a way to obtain information about those kinds of exposures. These are materials that may accumulate in the tissues of our body, but are not found in the bloodstream."

He added,"We were encouraged that we found a good correlation between the blood and interstitial fluid glucose, which suggests we might be able to have a continuous glucose monitoring system based on this technology."

Continuous glucose monitoring is a technique which measures blood glucose level 24 hours a day using a device.

Dr Prausnitz wants to conduct further research to reduce the collection time and also simplify the process.

He said," We'd like to make this microneedle-based technique available to the research community to make ISF routinely available for study. Tissue interstitial fluid could be a novel source of biomarkers that complements conventional sources. This research provides a means to study this further."

Source: Medindia