3249 Defining the Extracellular Vesicle Content of Interstitial Fluid for Blood-Free Diagnostics; Extraction Methods and Initial Characterization

OBJECTIVES/SPECIFIC AIMS: Recent advances in microneedle technology have enabled practical, in vivo dermal interstitial fluid (ISF) sampling. These minimally-invasive techniques allow for collection of ISF without damage to adjacent tissues and do not rely on blister formation. Initial reports of extracellular vesicle (EV) isolation from dermal ISF and paired blood samples suggest that EVs may be more abundant in ISF. Analysis of ISF-derived EVs may allow for more detailed study of intercellular communication at the tissue level, particularly in acute inflammatory conditions. The objective of this study is to describe the isolation and initial characterization of interstitial fluid-derived exosomes. METHODS/STUDY POPULATION: We apply electron microscopy, nanoparticle tracking analysis (NTA), immuochemical, and sequencing methods to describe and distinguish the EV content of interstitial fluid. We include apparently healthy adult human subjects with no active skin disease. We also study immunocompetent, CD-hairless rats to demonstrate the generalizability of the methods. RESULTS/ANTICIPATED RESULTS: We successfully isolated EVs from human and rat interstitial fluid using commercially available precipitation methods. The EVs were initially characterized using UV/Vis spectroscopy, electron microscopy, and NTA. While the study is ongoing, initial results suggest that the concentration and size distribution of EVs differs significantly between blood fractions and ISF. Further immunochemical and sequencing characterization is ongoing. DISCUSSION/SIGNIFICANCE OF IMPACT: We present here the initial characterization of EVs isolated from dermal interstitial fluid. This appears to be the first report of EV characterization using ISF collection methods that do not perturb adjacent tissues (such as with blister or microdialysis methods). The present study lays a foundation for further examination of ISF-derived EVs in acute inflammatory disease such as cellulitis or infectious neuritis. This may enable minimally invasive diagnostics and new research tools to understand intercellular communication in living organisms with increased spatial and temporal resolution.