In vivo confocal Raman spectroscopy for intrinsic aging and photoaging assessment

• Published in: Journal of dermatological science 2017-11, Vol.88 (2), p.199-206
• Main Authors: de Vasconcelos Nasser Caetano, Livia, de Oliveira Mendes, Thiago, Bagatin, Edileia, Amante Miot, Helio, Marques Soares, Juliana Laudiceia, Simoes e Silva Enokihara, Milvia Maria, Abrahao Martin, Airton
• Format: Article
• Language: English
• Subjects: Adult; Aged; Aged, 80 and over; Collagen Type I - analysis; Collagen Type I - chemistry; Dermis - anatomy & histology; Dermis - chemistry; Dermis - diagnostic imaging; Dermis - radiation effects; Female; Forearm; High frequency ultrasound; Histology; Humans; Light - adverse effects; Microscopy, Confocal - methods; Middle Aged; Photoaging; Raman spectroscopy; Skin aging; Skin Aging - radiation effects; Spectrum Analysis, Raman - methods; Ultrasonography - methods
• ISSN: 0923-1811; 1873-569X
• DOI: 10.1016/j.jdermsci.2017.07.011

•The 855cm−1 and 938cm−1 band intensities were inversely correlated with dermal collagen content in the non-photoexposed region.•The 1275cm−1/1450cm−1 intensity ratio correlated with the dermal collagen content in the photoexposed region.•In vivo confocal Raman spectroscopy is a promising non-invasive tool for intrinsic and extrinsic aging assessment. In vivo confocal Raman spectroscopy is a non-invasive method to assess either the epidermis or the dermis composition. Few studies have focused on dermis collagen alterations through intrinsic aging and photoaging. This study evaluated the in vivo Raman spectra from the dermis of a photoexposed site versus a non-photoexposed region in different age groups, and evaluated the correlation between peak intensities and age, photoaging score and the amount of collagen assessed with histology and high frequency ultrasound (HFUS). Fifteen volunteers aged 28–82 years were divided into three groups according to forearm photoaging degree. In vivo Raman spectra from the dermis were collected on the dorsal forearm (chronically photoexposed skin) and on the proximal medial arm (non-photoexposed skin). Cross-sectional images of the skin were obtained using a 20MHz ultrasound unit exactly on the same sites, which were further submitted to punch biopsies for histologic study (collagen I immunohistochemistry, picrosirius red staining and Verhoeff). Principal Component Analysis (PCA) and Orthogonal Partial Least Squares Discriminant Analysis (OPLS-DA) were taken in the spectral region of 796cm−1–996cm−1 to determine its potential to discriminate between different groups. The Spearman rank correlation coefficient of individual peak intensities and ratios with age, clinical score and the amount of collagen assessed by ultrasound and histology were calculated. PCA of pairs of groups and OPLS-DA could discriminate the intrinsically from the photoaged skin and the young group from the elderly one, with important contribution of the 938cm−1 and 855cm−1 peaks intensities. The intensity of the peaks in 855cm−1 and/or 938cm−1 presented moderate correlation with age (rho=0.579, p=0.049) and moderate to high inverse correlation with HFUS echogenicity (rho=−0.710, p=0.010) and collagen I immunohistochemistry (rho=−0.833, p=0.005) in the non-photoexposed region. The I1275/I1450 intensities ratio presented moderate to high correlation coefficients with age (rho=−0.730, p=0.007), photoaging score (rho=−0.594, p=0.042), HFUS echogenicity (rho=