Label-Free Detection of Lipid Accumulation in Cells Using Magnetic Levitation.

Dysfunction in adipose tissue can cause serious health problems, including obesity, type-2 diabetes, and cardiovascular disease, significantly reducing human life expectancy. Differences in differentiation and lipid accumulation in adipocytes reflect their functional status, making it important to characterize adipocytes by monitoring biophysical changes during adipogenic differentiation. However, there is currently no specific cell surface marker to separate mature adipocytes from non-adipose cells based on their lipid content, and separation of mature adipocytes is challenging due to handling limitations without fixation, antibody staining, or particle conjugation. Here, we report a biomarker-free, magnetic levitation-based method to detect density changes and quantify the accumulation of lipid-rich droplets within differentiating adipogenic cells. Magnetic levitation revealed density changes within preadipocytes differentiating towards mature adipocytes, with density decreasing over time as cells accumulated lipids. We then used lipid droplets as an intracellular marker to quantify lipid accumulation in single adipocytes during adipogenesis. The significant density changes correlated with cell morphology and lipid droplet morphology within the cytoplasm. For the first time, free-floating lipid vesicle density was measured using magnetic levitation. This unique method enables efficient detection and quantification of dynamically evolving lipid droplets in cells, proving beneficial for modeling lipid storage-related diseases and drug screening applications.