Ruben M. Sandoval

Fluorescent Dextrans in Intravital Multi-Photon Microscopy

Intravital Multi-photon microscopy stands unique among investigative tools because of the rich and dynamic information that can be rapidly collected and quickly analyzed. Additionally, data gathered from an intact in vivo subject in many cases is more meaningful than that derived from isolated in vitro methods that lack the complex interactions only found within intact organs. There are numerous fluorescent compounds that have been utilized in intravital microscopy studies to delineate compartments and label organelles. Dextrans are unique in that they are inert, are polymers and as such available in various sizes, and are easily modified to accept fluorophores. Here we describe how dextrans can be used to label different compartments within the kidney based solely on molecular weight. Parameters such as microvascular flow rates and vascular integrity, vesicular trafficking, and renal function can be studied using established techniques. Despite their broad versatility, precautions must be taken when using specified molecular weight sizes because preparations with a broad heterogeneity of their polymer sizes can lead to misinterpretation of data in parameters such as membrane integrity and renal function.