1. General introduction 21 1. PRECLINICAL AND CLINICAL METHODOLOGY In this thesis the clinical applicability of EPI-assisted jet injections in severe and recalcitrant keloids was studied using a variety of research techniques and designs. Prior to starting clinical research in patients with keloids, preclinical studies were performed using cutting-edge imaging techniques to provide a better understanding of the deposition and distribution of drugs in severe keloids after EPI-assisted drug delivery. Previous work of Bik et al. has provided comprehensive information of how drugs are distributed in skin after EPI-assisted injection.29,63 However, these experiments were limited to in vivo animal- and ex vivo human studies with normal skin. To gain more insights in the distribution of EPI-assisted jet injections in diseased tissue such as keloids, an ex vivo study that visualized distribution of EPI-assisted jet injections using the 3DFluorescent Imaging Cryomicrotome System (3D-FICS) in severe keloids was performed. The 3D-FICS (Figure 5) is an innovative 3D imaging technique that enables visualization of fluorescent markers representing the biodistribution of fluorescent labeled-fluids. Various imaging techniques can be used to visualize the layers of the skin, including high frequency ultrasound, optical coherence tomography, and confocal microscopy. A. B. Figure 5. A. The 3D-Fluorescent Imaging Cryomicrotome System (3D-FICS), a custom-built innovative 3D imaging technique that enables visualization of fluorescent markers representing the biodistribution of fluorescent labeled-fluids. B. A 3D image representing the biodistribution of fluorescent labeled triamcinolone acetonide administered in a keloid sample. 0.5 cm
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