Spectroscopic characterization of oral epithelial dysplasia and squamous cell carcinoma using multiphoton autofluorescence micro-spectroscopy

Rahul Pal, Kert Edward, Liang Ma, Suimin Qiu, Gracie Vargas

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3 Scopus citations

Abstract

Objective: Multiphoton autofluorescence microscopy (MPAM) has shown potential in identifying features that are directly related to tissue microstructural and biochemical changes throughout epithelial neoplasia. In this study, we evaluate the autofluorescence spectral characteristics of neoplastic epithelium in dysplasia and oral squamous cell carcinoma (OSCC) using multiphoton autofluorescence spectroscopy (MPAS) in an in vivo hamster model of oral neoplasia in order to identify unique signatures that could be used to delineate normal oral mucosa from neoplasia. Materials/Methods: A 9,10-dimethyl-1,2-benzanthracene (DMBA) hamster model of oral precancer and OSCC was used for in vivo MPAM and MPAS. Multiphoton Imaging and spectroscopy were performed with 780nm excitation while a bandpass emission 450-650nm was used for MPAM. Autofluorescence spectra was collected in the spectral window of 400-650nm. Results: MPAS with fluorescence excitation at 780nm revealed an overall red shift of a primary blue-green peak (480-520nm) that is attributed to NADH and FAD. In the case of oral squamous cell carcinoma (OSCC) and some high-grade dysplasia an additional prominent peak at 635nm, attributed to PpIX was observed. The fluorescence intensity at 635nm and an intensity ratio of the primary blue-green peak versus 635nm peak, showed statistically significant difference between control and neoplastic tissue. Discussion: Neoplastic transformation in the epithelium is known to alter the intracellular homeostasis of important tissue metabolites such as NADH, FAD, and PpIX, which was observed by MPAS in their native environment. A combination of deep tissue microscopy owing to higher penetration depth of multiphoton excitation and depth resolved spectroscopy could prove to be invaluable in identification of cytologic as well as biomolecular spectral characteristic of oral epithelial neoplasia.

Original languageEnglish (US)
JournalLasers in Surgery and Medicine
DOIs
StateAccepted/In press - 2017

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Keywords

  • Animal model
  • Multiphoton autofluorescence spectroscopy
  • Multiphoton microscopy
  • Oral cancer
  • Protoporphyrin IX
  • Two-photon fluorescence

ASJC Scopus subject areas

  • Surgery
  • Dermatology

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