Imaging dermal blood flow through the intact rat skin with an optical clearing method

Abstract

Impairment of skin microcirculation is one of the main features in advanced clinical stages of peripheral vascular disease. Recently, some noninvasive methods have been available to investigate skin microcirculation in clinical settings as well as improve disease management, i.e., capillaroscopy allows the investigation of skin capillary morphology and density, laser Doppler fluxmetry allows real-time assessment of perfusion of skin volume, and transcutaneous measurement of oxygen tension provides continuous information about skin oxygenation.¹ However, none of them can provide both structural and functional information of dermal vessels simultaneously. In contrast, laser speckle contrast imaging (LSCI), a full-field optical technique, can produce a two-dimensional map of blood flow with high spatio-temporal resolution,^{2, 3, 4, 5, 6, 7} which plays an important role in studying cerebral blood flow,^{7, 8} mesentery microcirculation,⁹ etc. Unfortunately, it suffers from a limited penetration depth of light in turbid tissues, as the previous investigations were restricted within the image of blood flow in transparent tissues.