Atherosclerosis
The progression of atherosclerosis depends on the amount of lipid
accumulation in the intima of the arteries. The increased amount of
lipid accumulation creates a risk of sudden rupture or rupture of
plaques characterized by high extracellular lipid content, abundant
macrophages, small amounts of smooth muscle cells, and relatively low
concentrations of collagen and
glycosaminoglycans.[7,232,233] This ultimately
results in the crystallization of mineral crystals. Raman spectroscopy
can accurately quantify the relative amounts of calcium salts,
cholesterol, triglycerides, and phospholipids in arterial tissue
(Figure 9a ). There are large differences in the construction of
conventional atherosclerotic mouse models, while the sclerotic plaques
are not easily localized. And the
differences in Raman spectroscopy results in that cause atherosclerotic
lesion sites suggest that the causes of atherosclerosis are
diverse.[234–236] Apolipoprotein E/low-density
lipoproteins (ApoE/LDLR) knockout was used as an indicator for the
construction of atherosclerosis model mice.[62,7]The Raman spectroscopy imaging method was adjusted to distinguish the
main biomolecules present in this atherosclerotic tissue to reveal the
relationship between apatite, cholesterol, and triglycerides
(Figure 9b ).[135,237,238] Besides, Raman
spectroscopy was used to analyze the pharmacological effects of drugs in
the atherosclerotic plaque in situ, providing a strong basis for the
development of drugs for atherosclerosis
treatment.[234,239]
In addition to the analysis of the causes of atherosclerosis, Raman
spectroscopy can be also utilized as a diagnostic tool for
atherosclerosis due to the specific chemical composition of
atherosclerotic plaques. Stimulated Raman scattering microscopy combined
with second harmonic generation microscopy effectively distinguishes
between cholesterol monocrystals, aliphatic lipids, structural proteins
of the tissue matrix, and other condensed
structures.[240,241] Some researchers reported a
fiber-optic Raman spectroscopy method to achieve in vivoatherosclerosis detection with a specificity and sensitivity of 79% and
85%.[235,242] To increase the detection time and
accuracy of atherosclerosis, techniques such as fluorescence lifetime
imaging and fluorescence imaging are used in combination with Raman
spectroscopy for lesion site
identification.[238,243–245]
Atherosclerosis is highly individualized, which greatly limits the study
of its triggering mechanisms. Moreover, the presence of hemoglobin leads
to strong tissue autofluorescence and interference with Raman
spectroscopy results. All these problems need to be addressed in
subsequent studies.