In vivo confocal Raman spectroscopic imaging of the human skin extracellular matrix degradation due to accumulated intrinsic and extrinsic aging.

Abstract

Skin aging is a dynamic process that affects the entire body, marked by molecular and structural changes. Type I collagen is the most abundant structural component and accounts 80% of total collagen in human skin. The amount of proline and hydroxyproline reflect the quantity and quality of the collagen fiber in the extracellular matrix of skin, which is alerted due to accumulated effects of intrinsic and extrinsic aging. Extrinsic aging is driven by ultraviolet radiation-induced reactive oxygen species production that activates the matrix metalloproteinase and disrupts the extracellular matrix of skin dermis, while intrinsic aging is the non-enzymatic process resulting in advanced glycation end products (AGEs). In the presence of pentosidine-AGEs, aging process is accelerated. In vivo Raman spectra of human dermis were collected from forearms of 30 volunteers and were divided into three groups: 10 young adult 25±5years, 10 old adult 65±10years and 10 diabetic old adult 65±10years old male participants. Density functional theory was performed to compute the vibration modes of AGEs, pentosidine, and glucosepane. In vivo confocal Raman spectroscopy detects the specific changes in the proline and hydroxyproline conformation, collagen fiber degradation of type I collagen and AGE protein contribution to specific Raman bands in the aged dermis because of Intrinsic and Extrinsic aging. Statistical t test marked significant differences (P<.01) in Raman peaks of proline and hydroxyproline among young adult, old adult, and diabetic old adult participants at wavenumbers 855, 875, 922, and 938cm-1 . In vivo confocal Raman spectroscopy is a useful tool to detect the AGE markers in the old adult and diabetic old adult male participants, which interacts with the ultraviolet radiations and accelerates the aging process resulting in the extracellular matrix degradation.