TY - JOUR T1 - A carbon nanotube optical reporter maps endolysosomal lipid flux JF - bioRxiv DO - 10.1101/134999 SP - 134999 AU - Prakrit V. Jena AU - Daniel Roxbury AU - Thomas V. Galassi AU - Leila Akkari AU - Christopher P. Horoszko AU - David B. Iaea AU - Januka Budhathoki-Uprety AU - Nina H. Pipalia AU - Abigail S. Haka AU - Jackson D. Harvey AU - Jeetain Mittal AU - Frederick R. Maxfield AU - Johanna A. Joyce AU - Daniel A. Heller Y1 - 2017/01/01 UR - http://biorxiv.org/content/early/2017/08/28/134999.abstract N2 - Lipid accumulation within the lumen of endolysosomal vesicles is observed in various pathologies including atherosclerosis, liver disease, neurological disorders, lysosomal storage disorders, and cancer. Current methods cannot measure lipid flux specifically within the lysosomal lumen of live cells. We developed an optical reporter, composed of a photoluminescent carbon nanotube of a single chirality, which responds to lipid accumulation via modulation of the nanotube’s optical bandgap. The engineered nanomaterial, composed of short-single stranded DNA and a single nanotube chirality, localizes exclusively to the lumen of endolysosomal organelles without adversely affecting cell viability or proliferation, or organelle morphology, integrity, or function. The emission wavelength of the reporter can be spatially resolved from within the endolysosomal lumen to generate quantitative maps of lipid content in live cells. Endolysosomal lipid accumulation in cell lines, an example of drug-induced phospholipidosis (DIPL), was observed for multiple drugs in macrophages, and measurements of patient-derived Niemann-Pick type C fibroblasts identified lipid accumulation and phenotypic reversal of this lysosomal storage disease. Single-cell measurements using the reporter discerned sub-cellular differences in equilibrium lipid content, illuminating significant intracellular heterogeneity among endolysosomal organelles of differentiating bone marrow-derived monocytes. Single-cell kinetics of lipoprotein-derived cholesterol accumulation within macrophages revealed rates that differed among cells by an order of magnitude. This carbon nanotube optical reporter of endolysosomal lipid content in live cells confers new capabilities for drug development processes and the investigation of lipid-linked diseases. ER -