Frontiers in intravital multiphoton microscopy of cancer

Abstract

Background Cancer is a highly complex disease, which involves the cooperation of tumor cells with multiple types of host cells and the extracellular matrix. Cancer studies that rely solely on static measurements of individual cell types are insufficient to dissect this complexity. In the last two decades, intravital microscopy has established itself as a powerful technique that can significantly improve our understanding of cancer by revealing the dynamic interactions governing cancer initiation, progression, and treatment effects in living animals. This review focuses on intravital multiphoton microscopy (IV‐MPM) applications in mouse models of cancer. Recent findings IV‐MPM studies have already enabled a deeper understanding of the complex events occurring in cancer at the molecular, cellular, and tissue levels. Multiple cell types present in different tissues influence cancer cell behavior via activation of distinct signaling pathways. As a result, the boundaries in the field of IV‐MPM are continuously being pushed to provide an integrated comprehension of cancer. We propose that optics, informatics, and cancer (cell) biology are coevolving as a new field. We have identified four emerging themes in this new field. First, new microscopy systems and image processing algorithms are enabling the simultaneous identification of multiple interactions between the tumor cells and the components of the tumor microenvironment. Second, techniques from molecular biology are being exploited to visualize subcellular structures and protein activities within individual cells of interest and relate those to phenotypic decisions, opening the door for “in vivo cell biology”. Third, combining IV‐MPM with additional imaging modalities or omics studies holds promise for linking the cell phenotype to its genotype, metabolic state, or tissue location. Finally, the clinical use of IV‐MPM for analyzing efficacy of anticancer treatments is steadily growing, suggesting a future role of IV‐MPM for personalized medicine. Conclusion IV‐MPM has revolutionized visualization of tumor‐microenvironment interactions in real time. Moving forward, incorporation of novel optics, automated image processing, and omics technologies in the study of cancer biology, will not only advance our understanding of the underlying complexities but will also leverage the unique aspects of IV‐MPM for clinical use.

Multidimensional Imaging of Mammary Gland Development: A Window Into Breast Form and Function

“…Indeed, the light-scattering adipose stroma that shrouds the mammary epithelial tree poses significant challenges for high-resolution in vivo imaging of normal and pre-neoplastic ductal structures. Nevertheless, continual improvements in imaging tools, including multiphoton lasers (Andresen et al, 2009), adaptive optics (Rueckel et al, 2006), sensitive detectors and image processing methods (Gligorijevic et al, 2014;Weigert et al, 2018;Perrin et al, 2019) hold great promise for future IVM studies into mammary gland development. The burgeoning application of the multidimensional imaging approaches described herein to the mammary gland will undoubtedly herald a new era in our investigation and understanding of breast biology.…”

“…This facilitates tracking of individual cells in live tissues over extended periods of time in near physiological conditions (Alieva et al, 2014). Cell type-specific fluorescent reporters, optogenetic tools and dyes can be combined for simultaneous imaging by multi-color IVM, allowing dynamic interactions between different mammary cell types and cellular structures to be visualized in situ (Ellenbroek and Van Rheenen, 2014;Nobis et al, 2018;Perrin et al, 2019). The majority of IVM studies rely on multiphoton modalities for deep tissue imaging (Pittet and Weissleder, 2011;Ellenbroek and Van Rheenen, 2014;Perrin et al, 2019).…”

“…Cell type-specific fluorescent reporters, optogenetic tools and dyes can be combined for simultaneous imaging by multi-color IVM, allowing dynamic interactions between different mammary cell types and cellular structures to be visualized in situ (Ellenbroek and Van Rheenen, 2014;Nobis et al, 2018;Perrin et al, 2019). The majority of IVM studies rely on multiphoton modalities for deep tissue imaging (Pittet and Weissleder, 2011;Ellenbroek and Van Rheenen, 2014;Perrin et al, 2019). Nevertheless, the increased surface epithelial mass and lower adipocyte content of lactating mammary tissues and tumors, for example, make these contexts more acquiescent to confocal IVM (Ebrahim and Weigert, 2019).…”

Influence of pump beam shaping and noise on performance of a direct diode-pumped ultrafast Ti:sapphire laser

“…Having the capability of generating femtosecond pulses with broad spectral tuning range starting from ∼650-1100 nm, the ultrafast Ti:S lasers play a major role in the development of many biophotonic imaging technologies, like optical coherence tomography [1][2][3] and multiphoton imaging [4][5][6], for the diagnosis of different types of early stage cancers [7][8][9]. In these applications, the intensity noise of the Ti:S laser play an important role in order to achieve a high signal-to-noise level and good image contrast [10,11] Traditionally, frequency-doubled diode-pumped solid-state lasers (DPSSLs) operating in the green wavelength region have been used for pumping of the Ti:S lasers.…”

Three‐dimensional intravital imaging in bone research

“…Intravital imaging (IVI) that allows observing biological processes in live animals (in vivo) at a high resolution makes studying the behavior of cells in their natural environment possible . These days, intravital imaging has been applied in many biological fields with the development of imaging techniques, such as neurobiology, tumor biology, immunology and bone biology . As one example of milestone discoveries based on IVI, the lung was found to be an important site of platelet biogenesis (accounting for about 50% of total platelet production), and a reservoir for hematopoietic progenitors that can migrate and repopulate the bone marrow, when thrombocytopenia or relative stem cell deficiency occurs there .…”