Applications of Second-Harmonic Generation Imaging Microscopy in Ovarian and Breast Cancer

Abstract

In this perspective, we discuss how the nonlinear optical technique of second-harmonic generation (SHG) microscopy has been used to greatly enhance our understanding of the tumor microenvironment (TME) of breast and ovarian cancer. Striking changes in collagen architecture are associated with these epithelial cancers, and SHG can image these changes with great sensitivity and specificity with submicrometer resolution. This information has not historically been exploited by pathologists but has the potential to enhance diagnostic and prognostic capabilities. We summarize the utility of image processing tools that analyze fiber morphology in SHG images of breast and ovarian cancer in human tissues and animal models. We also describe methods that exploit the SHG physical underpinnings that are effective in delineating normal and malignant tissues. First we describe the use of polarization-resolved SHG that yields metrics related to macromolecular and supramolecular structures. The coherence and corresponding phase-matching process of SHG results in emission directionality (forward to backward), which is related to sub-resolution fibrillar assembly. These analyses are more general and more broadly applicable than purely morphology-based analyses; however, they are more computationally intensive. Intravital imaging techniques are also emerging that incorporate all of these quantitative analyses. Now, all these techniques can be coupled with rapidly advancing miniaturization of imaging systems to afford their use in clinical situations including enhancing pathology analysis and also in assisting in real-time surgical determination of tumor margins.

Mechanical Properties of the Tumor Stromal Microenvironment Probed In Vitro and Ex Vivo by In Situ-Calibrated Optical Trap-Based Active Microrheology

“…Varying the initial collagen concentration regulated porosity, fiber width and fiber length and the microscale mechanics varied as a function of polymerization temperature (Figure 1). We found that pore area, fiber width, and fiber length decreased with increasing polymerization temperature and achieved distributions of fiber widths, lengths and porosity comparable to those described by others (Figure 1)(Bredfeldt, Liu, Conklin, et al, 2014; Bredfeldt, Liu, Pehlke, et al, 2014; Khanna et al, 2015; Tilbury & Campagnola, 2015). …”

“…Using confocal reflection microscopy we achieved ~250 nm optical resolution (lateral). The ctFIRE algorithm employed here has been used extensively to quantify fiber properties(Bredfeldt, Liu, Conklin, et al, 2014; Bredfeldt, Liu, Pehlke, et al, 2014; Khanna, Wells, Puré, & Volk, 2015; Tilbury & Campagnola, 2015). Varying the initial collagen concentration regulated porosity, fiber width and fiber length and the microscale mechanics varied as a function of polymerization temperature (Figure 1).…”

Peptide Nanophotonics: From Optical Waveguiding to Precise Medicine and Multifunctional Biochips

“…These new materials such as 3‐methyl‐4‐methoxy‐4′‐nitrostilbene self‐assembled into hexagonal microprisms and 2,7‐diphenyl‐9 H‐fluoren‐9‐one microfibers have been already introduced as effective nonlinear photonic waveguides. As shown in the former sections, both biological fibers and bioinspired peptide nanostructures FF‐PNT and FFF‐PNTp exhibit nonlinear second order optical response, and thus make them possible to guide second harmonic frequency wave in their noncentrosymmetric clad both for medical diagnostics and device applications . To test their waveguiding property, vertically aligned FF‐PNT were fabricated by the breath figure method .…”

Tumor Microenvironment and Models of Ovarian Cancer

“…In his group's work, stromal remodeling was investigated along the continuum of ovarian pathology from normal stroma, to benign tumors, to low-and high-grade tumors using a biomedical engineering approach. 11,12 Interestingly, stromal characteristics are unique among the pathology types, and characterization of the stromal architecture can predict the subtype of epithelial cell pathology. In addition to tumor cells impacting stromal behavior, multiple investigators reported on the effects of stromalderived signals on tumor cells.…”