Third Harmonic Generation microscopy distinguishes malignant cell grade in human breast tissue biopsies

Evangelia Gavgiotaki,Savvas Bovasianos,Sofia Agelaki,Maria Tzardi,Vasilios Georgoulias,George Filippidis,George Kenanakis,Irene Athanassakis,Vassilis Tsafas

doi:10.1038/s41598-020-67857-y

Evangelia Gavgiotaki, Savvas Bovasianos + Show 7 more

Open Access

https://doi.org/10.1038/s41598-020-67857-y

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Abstract

The ability to distinguish and grade malignant cells during surgical procedures in a fast, non-invasive and staining-free manner is of high importance in tumor management. To this extend, Third Harmonic Generation (THG), Second Harmonic Generation (SHG) and Fourier-Transform Infrared (FTIR) spectroscopy were applied to discriminate malignant from healthy cells in human breast tissue biopsies. Indeed, integration of non-linear processes into a single, unified microscopy platform offered complementary structural information within individual cells at the submicron level. Using a single laser beam, label-free THG imaging techniques provided important morphological information as to the mean nuclear and cytoplasmic area, cell volume and tissue intensity, which upon quantification could not only distinguish cancerous from benign breast tissues but also define disease severity. Simultaneously, collagen fibers that could be detected by SHG imaging showed a well structured continuity in benign tumor tissues, which were gradually disoriented along with disease severity. Combination of THG imaging with FTIR spectroscopy could provide a clearer distinction among the different grades of breast cancer, since FTIR analysis showed increased lipid concentrations in malignant tissues. Thus, the use of non-linear optical microscopy can be considered as powerful and harmless tool for tumor cell diagnostics even during real time surgery procedures.

Highlights

The application of this technology has been proposed in clinical studies, while it has been used for intravital imaging in biological models[11,12]
Various studies have shown the potential of label free non-linear imaging for cancer research, this is the first time that Third Harmonic Generation (THG) microscopy was employed for accurate imaging and signal quantification in breast cancer tissues
In an effort to examine whether THG imaging could distinguish malignant from healthy cells within breast tissues and provide information as to the severity of tumor invasion, paraffin embedded sections were submitted to qualitative and quantitative non-linear imaging as well as FTIR analysis

Summary

Introduction

The application of this technology has been proposed in clinical studies, while it has been used for intravital imaging in biological models[11,12]. THG and other non-linear optical modalities were utilized to shed light on the above features and examine their potential use in diagnosis for differentiating malignant from benign breast tissue samples and discriminating among the different grades of cancer. This technique has been used in the study of more complex systems, of tissues and clinical samples, including breast cancer biopsies[25,26,27,28,29,30]. The findings presented suggest that non-linear optical imaging techniques could define the tumor, evaluate the grade and the malignant or benign nature of the outgrowth, while FTIR spectra analysis could provide valuable complementary chemical information

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