Noninvasive Continuous Monitoring of Adipocyte Differentiation: From Macro to Micro Scales.

3T3-L1 cells serve as model systems for studying adipogenesis and research of adipose tissue-related diseases, e.g. obesity and diabetes. Here, we present two novel and complementary nondestructive methods for adipogenesis analysis of living cells which facilitate continuous monitoring of the same culture over extended periods of time, and are applied in parallel at the macro- and micro-scales. At the macro-scale, we developed visual differences mapping (VDM), a novel method which allows to determine level of adipogenesis (LOA)-a numerical index which quantitatively describes the extent of differentiation in the whole culture, and percentage area populated by adipocytes (PAPBA) across a whole culture, based on the apparent morphological differences between preadipocytes and adipocytes. At the micro-scale, we developed an improved version of our previously published image-processing algorithm, which now provides data regarding single-cell morphology and lipid contents. Both methods were applied here synergistically for measuring differentiation levels in cultures over multiple weeks. VDM revealed that the mean LOA value reached 1.11 ± 0.06 and the mean PAPBA value reached >60%. Micro-scale analysis revealed that during differentiation, the cells transformed from a fibroblast-like shape to a circular shape with a build-up of lipid droplets. We predict a vast potential for implementation of these methods in adipose-related pharmacological research, such as in metabolic-syndrome studies.