Alterations of the extracellular matrix in ovarian cancer studied by Second Harmonic Generation imaging microscopy

<p>Abstract</p> <p>Background</p> <p>Remodeling of the extracellular matrix (ECM) has been implicated in ovarian cancer, and we hypothesize that these alterations may provide a better optical marker of early disease than currently available imaging/screening methods and that understanding their physical manifestations will provide insight into invasion.</p> <p>Methods</p> <p>For this investigation we use Second Harmonic Generation (SHG) imaging microcopy to study changes in the structure of the ovarian ECM in human normal and malignant ex vivo biopsies. This method directly visualizes the type I collagen in the ECM and provides quantitative metrics of the fibrillar assembly. To quantify these changes in collagen morphology we utilized an integrated approach combining 3D SHG imaging measurements and bulk optical parameter measurements in conjunction with Monte Carlo simulations of the experimental data to extract tissue structural properties.</p> <p>Results</p> <p>We find the SHG emission attributes (directionality and relative intensity) and bulk optical parameters, both of which are related to the tissue structure, are significantly different in the tumors in a manner that is consistent with the change in collagen assembly. The normal and malignant tissues have highly different collagen fiber assemblies, where collectively, our findings show that the malignant ovaries are characterized by lower cell density, denser collagen, as well as higher regularity at both the fibril and fiber levels. This further suggests that the assembly in cancer may be comprised of newly synthesized collagen as opposed to modification of existing collagen.</p> <p>Conclusions</p> <p>Due to the large structural changes in tissue assembly and the SHG sensitivity to these collagen alterations, quantitative discrimination is achieved using small patient data sets. Ultimately these measurements may be developed as intrinsic biomarkers for use in clinical applications.</p

Implementation of 3D SHG imaging microscopy for tissue characterization and disease diagnostics: Experiment and simulations

This work encompasses the integrated use of 3D Second Harmonic Generation (SHG) imaging microcopy, Monte Carlo simulations and novel heuristic and phenomenological models to quantifiably characterize biological tissues and develop diagnostics for diseased states. Experimental techniques are utilized to obtain 3D SHG images and laser-tissue interaction descriptors, Monte Carlo techniques in conjunction with physical based models are used to determine bulk optical components (through inverse Monte Carlo techniques) and deconvolve the inter-related mechanisms responsible for the measured data. Utilizing this approach SHG creation attributes including efficiency and initial directionality are obtained which when combined with experimental data establish a comparative diagnostic suitable to quantifiably differentiate normal from the diseased tissues attributable to changes in the physical properties of the respective extracellular matrix (ECM). The analytical tool is developed and applied toward Osteogenesis Imperfecta in mice and Ovarian Cancer in humans, and a quantifiable diagnostic is developed. In addition this analytical tool is also utilized to better understand optical clearing of tissues which has the potential to achieve greater penetration into specimens of skeletal muscle tissue.