Adipocyte Differentiation Investigated by Stimulated Raman Microscopy Based on Femtosecond Laser Sources

Lipids are fundamental pillar for cells, acting as signalling mediators, components of cellular membranes, and reservoirs for intracellular energy storage. Lipids are packed into specific intracellular organelles, termed lipid droplets (LDs), having a crucial role in regulating the storage and the turnover of neutral lipids. Recently, extensive studies demonstrate the significant role of LDs in pathogenesis of several metabolic diseases, for example obesity, diabetes, atherosclerosis as well as cancer. Stimulated Raman scattering (SRS) microscopy is able to perform label-free imaging of lipids with high sensitivity, high spatial and spectral resolution, 3D sectioning, and fast time of image acquisition, i.e., a few seconds. In this paper, SRS microscopy, as a label-free method to image LDs in 3T3-L1 adipocyte cells, is used, and adipocyte differentiation is investigated. Our results demonstrate the ability of SRS imaging technique to monitor the maturation of LDs during the adipocyte differentiation. Finally, a fully 3D volume reconstruction of lipids droplets distribution, in adipocyte cells is demonstrated.