In Vivo Dendritic Cell Tracking Using Fluorescence Lifetime Imaging and Near-Infrared-Emissive Polymersomes

Noninvasive in vivo cell-tracking techniques are necessary to advance the field of cellular-based therapeutics as well as to elucidate mechanisms governing in vivo cell biology. Fluorescence is commonly used for in vitro and postmortem biomedical studies but has been limited by autofluorescence at the whole-animal level. In this report, we demonstrate the ability of in vivo fluorescent lifetime imaging to remove autofluorescence and thereby enable in vivo dendritic cell tracking in na < ve mice. Specifically, we track mature dendritic cells (DCs) labeled internally with near-infrared-emissive polymersomes (NIR-DCs). We establish the ability to detect labeled cells in vivo and image NIR-DC trafficking after both intravenous and subcutaneous delivery. In addition, we demonstrate the longitudinal capacity of this method by characterizing NIR-DC migration kinetics in the popliteal lymph node. This work provides a tool to evaluate dendritic-cell-based immunotherapy and generates novel opportunities for in vivo fluorescence imaging.