Abstract
Epidermal keratinocyte (KC) differentiation, which involves the process from proliferation to cell death for shedding the outermost layer of skin, is crucial for the barrier function of skin. Therefore, in dermatology, it is important to elucidate the epidermal KC differentiation process to evaluate the symptom level of diseases and skin conditions. Previous dermatological studies used staining or labelling techniques for this purpose, but they have technological limitations for revealing the entire process of epidermal KC differentiation, especially when applied to humans. Here, we demonstrate label-free visualization of three-dimensional (3D) intracellular morphological changes of ex vivo human epidermis during epidermal KC differentiation using stimulated Raman scattering (SRS) microscopy. Specifically, we observed changes in nuclei during the initial enucleation process in which the nucleus is digested prior to flattening. Furthermore, we found holes left behind by improperly digested nuclei in the stratum corneum, suggesting abnormal differentiation. Our findings indicate the great potential of SRS microscopy for discrimination of the degree of epidermal KC differentiation.
Highlights
IntroductionSkin is the largest organ in the body and has various functions that are essential to maintaining life activities, such as forming a barrier against dry environments (by preventing water evaporation) and harmful external substances
Skin is the largest organ in the body and has various functions that are essential to maintaining life activities, such as forming a barrier against dry environments and harmful external substances
Elucidation of the epidermal KC differentiation process is crucial in dermatology to evaluate the symptom level of diseases involving epidermal KC differentiation as well as skin conditions such as disorders related to epidermal metabolism
Summary
Skin is the largest organ in the body and has various functions that are essential to maintaining life activities, such as forming a barrier against dry environments (by preventing water evaporation) and harmful external substances. Many dermatological studies using fixation/staining or labelling with fluorescent dyes or proteins at the genetic level have had limited success in revealing epidermal maturation by focusing on natural moisturizing factors[4], barrier function[5], intercellular lipids[6], desquamation processes, and the molecular mechanism of epidermal terminal differentiation[7,8]. Such methods have been known to affect the main components www.nature.com/scientificreports/. We have continued these investigations and report the results in this paper
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