(Second) Harmonic Disharmony: Nonlinear Microscopy Shines New Light on the Pathology of Atherosclerosis

Abstract

There has been increasing interest in second harmonic generation (SHG) imaging approaches for the investigation of atherosclerosis due to the deep penetration and three-dimensional sectioning capabilities of the nonlinear optical microscope. Atherosclerosis involves remodeling or alteration of the collagenous framework in affected vessels. The disease is often characterized by excessive collagen deposition and altered collagen organization. SHG has the capability to accurately characterize collagen structure, which is an essential component in understanding atherosclerotic lesion development and progression. As a structure-based imaging modality, SHG is most impactful in atherosclerosis evaluation in conjunction with other, chemically specific nonlinear optics (NLO) techniques to identify additional components of the lesion. These include the use of coherent anti-Stokes Raman scattering and two-photon excitation fluorescence for studying atherosclerosis burden, and application of stimulated Raman scattering to image cholesterol crystals. However, very few NLO studies have attempted to quantitate differences in control versus atherosclerotic states or to correlate the application to clinical situations. This review highlights the potential of SHG imaging to directly and indirectly describe atherosclerosis as a pathological condition.

Biomechanical relevance of the microstructure in artery walls with a focus on passive and active components

“…The same was found for the intima and adventitia The microstructure, in particular in the collagen fabric in diseased tissues, is remarkably different from that of a healthy tissue, as in the case of, e.g., an atherosclerotic tissue; see Fig. 3 modified from [82]. dispersion in walls of abdominal aortic aneurysms (AAAs) is significantly higher than for tis-sues obtained from healthy samples [56].…”

Visualization of Monocytic Cells in Regressing Atherosclerotic Plaques by Intravital 2-Photon and Positron Emission Tomography–Based Imaging—Brief Report

“…Fluorescence emission was passed through 480-nm and 560-nm dichroic mirrors placed in series and detected as red (>560 nm), green (480 to 560 nm), and blue (<480 nm). Two-photon excitation produces a second harmonic signal from collagen within aortic arch wall 13 . Video-rate and time-lapse recordings were acquired using ImageWarp acquisition program (A&B Software).…”

Pterostilbene reduces endothelial cell apoptosis by regulation of the Nrf2‑mediated TLR‑4/MyD88/NF‑κB pathway in a rat model of atherosclerosis

“…Atherosclerosis is a chronic inflammatory disease of the vascular wall associated with lipid deposition and plaque fibrosis (1)(2)(3). As a chronic inflammatory disease, the mortality rate caused by atherosclerosis is rising worldwide (4).…”