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Journal of Biomedical Optics • Open Access

Raman spectroscopic analysis of human skin tissue sections ex-vivo: evaluation of the effects of tissue processing and dewaxing
Author(s): Syed M. Ali; Franck Bonnier; Ali Tfayli; Helen A. Lambkin; Kathleen Flynn; Vincent McDonagh; Claragh Healy; T. Clive Lee; Fiona M. Lyng; Hugh J. Byrne

Paper Abstract

Raman spectroscopy coupled with K-means clustering analysis (KMCA) is employed to elucidate the biochemical structure of human skin tissue sections and the effects of tissue processing. Both hand and thigh sections of human cadavers were analyzed in their unprocessed and formalin-fixed, paraffin-processed (FFPP), and subsequently dewaxed forms. In unprocessed sections, KMCA reveals clear differentiation of the stratum corneum (SC), intermediate underlying epithelium, and dermal layers for sections from both anatomical sites. The SC is seen to be relatively rich in lipidic content; the spectrum of the subjacent layers is strongly influenced by the presence of melanin, while that of the dermis is dominated by the characteristics of collagen. For a given anatomical site, little difference in layer structure and biochemistry is observed between samples from different cadavers. However, the hand and thigh sections are consistently differentiated for all cadavers, largely based on lipidic profiles. In dewaxed FFPP samples, while the SC, intermediate, and dermal layers are clearly differentiated by KMCA of Raman maps of tissue sections, the lipidic contributions to the spectra are significantly reduced, with the result that respective skin layers from different anatomical sites become indistinguishable. While efficient at removing the fixing wax, the tissue processing also efficiently removes the structurally similar lipidic components of the skin layers. In studies of dermatological processes in which lipids play an important role, such as wound healing, dewaxed samples are therefore not appropriate. Removal of the lipids does however accentuate the spectral features of the cellular and protein components, which may be more appropriate for retrospective analysis of disease progression and biochemical analysis using tissue banks.

Paper Details

Date Published: 2 November 2012
PDF: 12 pages
J. Biomed. Opt. 18(6) 061202 doi: 10.1117/1.JBO.18.6.061202
Published in: Journal of Biomedical Optics Volume 18, Issue 6
Show Author Affiliations
Syed M. Ali, Dublin Institute of Technology (Ireland)
Franck Bonnier, Dublin Institute of Technology (Ireland)
Ali Tfayli, Univ. Paris-Sud 11 (France)
Helen A. Lambkin, Dublin Institute of Technology (Ireland)
Kathleen Flynn, Dublin Institute of Technology (Ireland)
Vincent McDonagh, Royal College of Surgeons in Ireland (Ireland)
Claragh Healy, Royal College of Surgeons in Ireland (Ireland)
T. Clive Lee, Royal College of Surgeons in Ireland (Ireland)
Fiona M. Lyng, Dublin Institute of Technology (Ireland)
Hugh J. Byrne, Dublin Institute of Technology (Ireland)

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