Optical diagnosis of gallbladder cancers via two-photon excited fluorescence imaging of unstained histological sections

Two-photon excited fluorescence (TPEF) microscopy, based on signal from cells, can provide detailed information on tissue architecture and cellular morphology in unstained histological sections to generate subcellular-resolution images from tissue directly. In this paper, we used TPEF microscopy to image microstructure of human normal gallbladder and three types of differentiated carcinomas in order to investigate the morphological changes of tissue structure, cell, cytoplasm, and nucleus without hematoxylin and eosin (H&E) staining. It displayed that TPEF microscopy can well image the stratified normal gallbladder tissue, including the mucosa, the muscularis, and the serosa. The typical cancer cell, characterized by cellular and nuclear pleomorphism, enlarged nuclei, and augmented nucleolus, can be identified in histological sections without H-E staining as well. The quantitative results showed that the areas of the nucleus and the nucleolus in three types of cancerous cells were all significantly greater than those in normal gallbladder columnar epithelial cells derived from TPEF microscopic images. The studies demonstrated that TPEF microscopy has the ability to characterize tissue structures and cell morphology of gallbladder cancers differentiated from a normal gallbladder in a manner similar to traditional histological analysis. As a novel tool, it has the potential for future retrospective studies of tumor staging and migration by utilizing histological section specimens without H-E staining.