Cell density can affect cholesteryl ester accumulation in the human THP-1 macrophage

Area of Science:

• Cell biology
• Biochemistry
• Atherosclerosis research

Background:

• Foam cell formation is a key process in atherosclerosis.
• Macrophage cholesterol metabolism is crucial in foam cell development.
• Scavenger receptors play a significant role in cellular cholesterol uptake.

Purpose of the Study:

• To investigate the effect of cell density on esterified cholesterol accumulation in THP-1 macrophages.
• To determine how cell density influences scavenger receptor expression and activity.
• To explore the role of cell density in modulating macrophage lipid metabolism.

Main Methods:

• THP-1 macrophages were cultured at varying cell densities and exposed to acetylated LDL (acLDL).
• Esterified cholesterol (EC) mass and [14C]oleate incorporation were quantified.
• 125I-labeled acLDL degradation and scavenger receptor mRNA/protein expression were analyzed.
• Fatty acid supplementation and beta-VLDL exposure were used to assess non-scavenger receptor pathways.

Main Results:

• Lower cell density (1.0 x 10^6 cells/dish) resulted in a 5-fold increase in EC mass compared to higher density (4.0 x 10^6 cells/dish).
• Decreasing cell number enhanced [14C]oleate incorporation into EC and acLDL degradation.
• Higher cell density correlated with a 2-fold reduction in scavenger receptor mRNA and protein expression.
• Fatty acid supplementation increased EC formation in densely plated cells, suggesting non-scavenger receptor involvement.

Conclusions:

• Macrophage cell density is a critical factor regulating esterified cholesterol accumulation.
• Cell density modulates both scavenger and non-scavenger receptor-mediated cholesterol uptake pathways.
• Findings suggest that cell density influences foam cell formation in THP-1 macrophages.