Raman microspectroscopy of intracellular cholesterol crystals in cultured bovine coronary artery endothelial cells

Raman microspectroscopy is presented as a promising technique for the in situ characterization of intracellular cholesterol crystals. Crystal characterization is the first step in investigating the effects of various stimuli on their formation and in determining their role in the development of atherosclerosis. Treatment of cultured bovine coronary artery endothelial cells with 22-hydroxycholesterol (220HC) stimulated the production of intracellular crystals, a phenomenon that did not occur in the absence of viable cells. These crystals were identified as a combination of the 220HC starting material and cholesterol. The best fit to the average Raman spectrum of the microscopic crystals was achieved with a combination of 70% Raman contribution from 220HC and 30% from cholesterol. GC/MS analysis of the crystals confirmed the presence of both compounds. These results demonstrate the potential of Raman microspectroscopy as a powerful tool in lipid research, particularly for the in situ characterization of intracellular crystals.