P11 Noninvasive skin stretch-activated extraction of interstitial fluid biomarkers

Abstract Introduction and aims Dermal interstitial fluid (ISF) offers a promising alternative to blood-based sampling procedures for biomarker analysis due to its rich chemical composition. However, existing ISF extraction methods are invasive. Skin stretching through the topical application of vacuum pressure can transiently increase the permeability of the skin barrier. This study aimed to understand whether skin stretching can noninvasively extract ISF and the types of biomarkers it contains. Methods Two types of stretching devices were employed: one that stretches by forming a skin dome (dome) and another that suppresses dome formation (flat), both driven by vacuum pressure. The ability of the devices to extract ISF from the forearm skin of healthy human volunteers was tested. The bicinchoninic acid assay determined ISF extraction volumes to calculate protein concentration as a surrogate for ISF volume. A panel of nine cytokines were quantified using a Mesoscale device in the ISF extracted using the two devices. Results The flat skin stretching was more tolerable and extracted significantly more ISF than domed stretching using 10 min of −4.5 psi vacuum pressure (1.58 µL ± 0.36 vs. 0.67 µL ± 0.23, P < 0.001). TEWL demonstrated reversible permeabilization of the tissue. Flat stretching detected all nine cytokines in the Mesoscale discovery assay, but dome stretching detected only two. Of the two cytokines detected by both stretching approaches, significantly higher levels were detected with the flat device [interleukin (IL)-17: domed 0.4274 fg ± 1.047, flat 14.34 ± 8.909; P = 0.003; IL-1β: domed 1462 fg ± 1144, flat 11315 fg ± 7541; P = 0.0092]. Conclusions The flat skin stretching device allowed extraction of significantly more ISF and cytokine biomarkers than the dome device. This suggests skin stretching without vertical displacement is more suitable for biomarker extraction. Future work will focus on using the flat device to assess biomarkers in health and disease.