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theses

The skin barrier is responsible for regulating water loss and preventing penetration of exogenous substances into the body. Traditional measurement techniques rely on invasive sampling through biopsy or the measurement of macroscopic parameters. Non-invasive skin measurement methodologies which probe skin biology and biophysics are therefore needed to expand our understanding of disease and non-disease states and to establish methods for assessing therapies targeted towards skin barrier. The goal of this work is to identify quantitative physiological and functional parameters of skin barrier suitable for non-invasive measurement, and establish the usefulness of these parameters to monitor barrier quality through in-vivo proof-of-principle studies utilizing models of controlled barrier disruption. Specifically, we investigate changes in endpoints related to epidermal morphology and endpoints related to composition and molecular order of stratum corneum (SC) lipids. Through controlled disruption of skin barrier function and measurement of morphological and compositional parameters by non-invasive microscopy and spectroscopy techniques, the contribution of these parameters to skin barrier function may be quantified. To evaluate the morphological contribution to skin barrier function, we utilize a tape stripping methodology to partially remove the SC. We observe that in addition to the expected increase in water loss resulting from altering the diffusion gradient across the SC, morphological changes are induced in the viable epidermis immediately after tape stripping and continue to evolve in the days following the tape stripping barrier insult. Thus, monitoring the cell size and epidermal layer thickness may provide insight into the immediate and longer term responses of the skin, including lamellar body degranulation, proliferation, and differentiation. We also probed the contribution of the composition and organization of the SC barrier lipids to overall skin barrier function. In vivo infrared spectroscopy and fluorescence microscopy were used to demonstrate the impact of disordering SC lipids and link the molecular interaction of exogenous agents with SC lipids to the resulting changes in barrier function. Through this work, methodologies were developed utilizing non-invasive multimodal microscopy and spectroscopy techniques to quantify skin properties at the molecular and cellular level and to relate these endpoints to the overall skin barrier function.

ETD_6826

Ph.D.

Includes bibliographical references

by Mary Catherine Mack

doi:10.7282/T3XS5XCD

ETD doctoral

The author owns the copyright to this work.