The Skin Reservoir Model: A Tool for Evaluating Microdialysis Sampling of Large Biomarkers from Human Skin
Katrine Baumann, Sidsel Falkencrone, Niels Peter Hell Knudsen, Anders Woetmann, Sally Dabelsteen, Per Stahl Skov
Microdialysis is a well-established technique for sampling of small molecules from the human skin, but larger molecules are more difficult to recover. Consequently, sampling feasibility must be evaluated before microdialysis is used in vivo. This report presents a tool for estimating the recovery of large biomarkers from human skin by microdialysis, using previously frozen human skin specimens as reservoirs for biomarker reference solutions. Recovery of the following 17 biomarkers was assessed: CCL27/CTACK, CXCL1/GROα, CXCL7/NAP-2, CXCL10/IP-10, EGF, GM-CSF, IFN-γ, IL-1α, IL-6, IL-8, IL-17, IL-22, IL-23, MIF, TNF-α, TSLP and VEGF. The relative skin recoveries of 13/17 biomarkers were successfully determined in the range 4.0–18.4%. Sampling in the skin reservoir model was not associated with probe leakage, as fluid recovery was stable, at between 80% and 110%. Furthermore, the skin reservoir model enabled studies and optimization of different parameters known to affect biomarker recovery, including flow rate and perfusate composition.
Microdialysis is a minimally-invasive technique to study skin reactions by sampling of molecules from the tissue; however, not all molecules are easily recovered. Therefore, we propose a new model to investigate the sampling efficiency of larger biomarkers: the skin reservoir model. This model simulates the sampling situation in living human beings by using previously frozen excised human skin as a reservoir for biomarker solutions. Thus, it serves as a tool to carefully validate and optimize sampling of the target molecules before the use of microdialysis; for example, in clinical studies.