A simple and sensitive enzymatic method for cholesterol quantification in macrophages and foam cells

Area of Science:

• Biochemistry
• Cell Biology
• Analytical Chemistry

Background:

• Accurate measurement of cellular cholesterol is crucial for understanding macrophage lipid metabolism.
• Existing enzymatic cholesterol assays are not optimized for solid-phase samples like cells due to solubilization issues.
• Endogenous peroxides in enzyme-compatible solvents interfere with cholesterol assays.

Purpose of the Study:

• To develop and validate a precise, sensitive, and high-throughput method for quantifying free and esterified cholesterol in cellular samples.
• To overcome limitations of existing enzymatic cholesterol assays for cell-based studies.
• To enable more efficient research into macrophage cholesterol dynamics.

Main Methods:

• Developed an efficient solubilization protocol for total cholesterol from cells compatible with enzymatic assays.
• Utilized catalase pretreatment to eliminate interfering endogenous peroxides.
• Validated the method against stable isotope dilution gas chromatography-mass spectrometry.

Main Results:

• The novel protocol efficiently solubilizes cellular cholesterol without saponification or chromatography.
• Catalase pretreatment significantly reduced assay background and increased sensitivity.
• Results obtained by the enzymatic method showed excellent agreement with gas chromatography-mass spectrometry.

Conclusions:

• A simple, sensitive, and high-throughput enzymatic method for cellular cholesterol quantification has been established.
• This method is suitable for complex biological matrices like macrophages.
• The developed assay facilitates research on cellular cholesterol metabolism and related diseases.