Interstitial fluid (ISF) is the liquid surrounding the cells in the human body and has attracted much interest as a diagnostic substance. Its value as a biomarker is comparable to blood but safer and less painful to collect.
Existing methods for sampling dermal ISF are time-consuming, require specialized equipment, need to be performed by trained medical professionals and often yield volumes that are too small for biomolecular analysis using conventional diagnostic assays.
“We have developed a sampling technique that yields an average of 20.8 microliters of dermal ISF within 25 minutes, which is a six-fold improvement over existing sampling techniques,” said Peter Lillehoj, Shankle Chair and Associate Professor of Mechanical Engineering (MECH) at Rice.
A paper outlining his research, “Microneedle-based sampling of dermal interstitial fluid using a vacuum-assisted skin patch,” has been published in Cell Reports Physical Science.
“The technique we’re reporting is minimally invasive,” Lillehoj said, “and doesn’t require specialized equipment or electricity, which makes it amenable to widespread use in research and clinical settings. We want to make diagnostic testing easier and less costly.”
The researchers used a microneedle array to make minute pores in the skin from which ISF is extracted using a vacuum-assisted skin patch. Analysis of dermal ISF collected from volunteers resulted in the identification of 610 medically relevant biomarkers. More than half of them had not been previously detected in ISF.
“ISF contains a wealth of biomolecules, yet it has been underutilized for diagnostic testing because there has been a lack of simple, rapid techniques for collecting abundant amounts of fluid,” Lillehoj said. “Because of the increased sample volume yielded using our method, we have demonstrated for the first time the use of dermal ISF for diagnostic testing using commercial immunoassays.”
Lillehoj’s co-authors are Xue Jiang, research scientist at Spear Bio, Inc; Elizabeth C. Wilkirson, fourth-year MECH doctoral student at Rice; Aaron O. Bailey and William K. Russell, University of Texas Mass Spectrometry Facility, Galveston.