Femtosecond CARS Microscopy to characterize lipid droplets in Engineered Adipose Tissue

Abstract

Adipose tissue is a type of connective tissue whose purpose was once thought to be limited to fat storage but is now understood to be a key factor in the pathogenesis of different metabolic diseases, including obesity and type-II diabetes. Adipose tissue consists largely of adipocytes, cells responsible for fat and releasing energy in form of lipids. Different classes of fatty acids, such as saturated and unsaturated have different biological effects on adipocytes. Lipid droplets are the primary organelles in adipocytes that store these fatty acids in form of lipids, and the development of engineered adipose tissues would benefit from improved techniques for analysis of lipid droplet composition, distributions, and dynamics based as a function of fatty acid saturation. Conventional microscopic techniques, such as fluorescence microscopy, provides excellent selectivity of lipid-based structures inside adipose tissue cellular structures based on staining with compound dyes. However, fluorescence staining limits multiplex imaging, and requires time consuming steps in preparing the samples for imaging. Therefore, developing a label-free, high resolution imaging platform with sensitivity to lipid composition could enable analysis of structural and compositional differentiation of lipid droplets within adipocytes during differentiation could give valuable insights into the importance of lipid droplets role in metabolism. As an important step towards achieving this goal, a femtosecond based CARS microscopy imaging platform has been developed to perform in vitro, label-free, imaging of fatty acid composition within engineered adipose tissues.