Visualization of the important components in tumor microenvironment of breast cancer using multiphoton microscopy

Tumor microenvironment (TME) is composed of tumor cells, stromal cells and the extracellular matrix (ECM), that it plays an important role in the occurrence and development of tumors, such as promoting local drug resistance, immune escape, and distal metastasis. Based on second harmonic generation (SHG) and two-photon excited fluorescence (TPEF), multiphoton microscopy (MPM) has the ability to label-freely visualize extracellular matrix and cells in the TME. In addition, combined SHG and TPEF imaging can be used to generate similar pathological images, providing additional information for pathologists and even surgeons. Cancer cells, adipocytes, microvessel, collagen fibers, and tumor-infiltrating lymphocytes (TILs) which were the important components in the TME were imaged using MPM in this study. The results showed that MPM can clearly present the tissue structure and cell morphology in the microenvironment. With the development and widely used of MPM, in the future, MPM imaging may be able to perform clinical imaging of the tumor microenvironment without the need for invasive operations. MPM may become a novel imaging tool for imaging various prognostic factors in breast cancer.