Characterization of cholesterol crystals in atherosclerotic plaques using
stimulated Raman scattering and second-harmonic generation microscopy.
Authors Suhalim JL, Chung CY, Lilledahl MB, Lim RS, Levi M, Tromberg BJ, Potma EO
Submitted By Moshe Levi on 9/17/2012
Status Published
Journal Biophysical journal
Year 2012
Date Published 4/18/2012
Volume : Pages 102 : 1988 - 1995
PubMed Reference 22768956
Abstract Cholesterol crystals (ChCs) have been identified as a major factor of plaque
vulnerability and as a potential biomarker for atherosclerosis. Yet, due to the
technical challenge of selectively detecting cholesterol in its native tissue
environment, the physiochemical role of ChCs in atherosclerotic progression
remains largely unknown. In this work, we demonstrate the utility of
hyperspectral stimulated Raman scattering (SRS) microscopy combined with
second-harmonic generation (SHG) microscopy to selectively detect ChC. We show
that despite the polarization sensitivity of the ChC Raman spectrum, cholesterol
monohydrate crystals can be reliably discriminated from aliphatic lipids, from
structural proteins of the tissue matrix and from other condensed structures,
including cholesteryl esters. We also show that ChCs exhibit a nonvanishing SHG
signal, corroborating the noncentrosymmetry of the crystal lattice composed of
chiral cholesterol molecules. However, combined hyperspectral SRS and SHG
imaging reveals that not all SHG-active structures with solidlike morphologies
can be assigned to ChCs. This study exemplifies the merit of combining SRS and
SHG microscopy for an enhanced label-free chemical analysis of crystallized
structures in diseased tissue.

Investigators with authorship
Moshe LeviGeorgetown University