Characterization of breast duct epithelia: a Raman spectroscopic study

Abstract

Spectroscopic characterization of normal breast duct epithelia is the basis for understanding the spectral information obtained from epithelium-derived breast tumors. In this study, healthy breast tissue samples were examined by means of Raman spectroscopy with an excitation wavelength of 840 nm. Raman spectra of breast ducts were acquired using a microscopic mapping approach, and mapping measurements of breast duct epithelium were performed at a lateral resolution that enabled investigation of single epithelial cells. Different cellular compounds within the epithelial layer such as nuclei and cytoplasm were identified by principal components analysis (PCA) and K-means cluster analysis applied to their Raman spectra. Furthermore, spectra of breast secretion fluid that was found to cover the epithelium in most samples were analyzed. They contained mainly signal contributions from lipids. Two different classes of lipid secretion spectra were identified and both spectral classes could be found in the same sample. Spatially resolved analysis of breast duct fluid could provide new insights into breast secretion biochemistry in normal and pathological conditions.