【文章名】Microencapsulation of inorganic nanocrystals into PLGA microsphere vaccines enables their intracellular localization in dendritic cells by electron and fluorescence microscopy
Microencapsulation of inorganic nanocrystals into PLGA microsphere vaccines enables their intracellular localization in dendritic cells by electron and fluorescence microscopy
作者
Schliehe, C; Schliehe, C; Thiry, M; Tromsdorf, UI; Hentschel, J; Weller, H; Groettrup, M
[摘要]:Biodegradable poly-(D,L-lactide-co-glycolide) microspheres (PLGA-MS) are approved as a drug delivery system in humans and represent a promising antigen delivery device for immunotherapy against cancer. Immune responses following PLGA-MS vaccination require cross-presentation of encapsulated antigen by professional antigen presenting cells (APCs). While the potential of PLGA-MS as vaccine formulations is well established, the intracellular pathway of cross-presentation following phagocytosis of PLGA-MS is still under debate. A part of the controversy stems from the difficulty in unambiguously identifying PLGA-MS within cells. Here we show a novel strategy for the efficient encapsulation of inorganic nanocrystals (NCs) into PLGA-MS as a tool to study their intracellular localization. We microencapsulated NCs as an electron dense marker to study the intracellular localization of PLGA-MS by transmission electron microscopy (TEM) and as fluorescent labels for confocal laser scanning microscopy. Using this method, we found PLGA-MS to be rapidly taken up by dendritic cells and macrophages. Co-localization with the lysosomal marker LAMP1 showed a lysosomal storage of PLGA-MS for over two days after uptake, long after the initiation of cross-presentation had occurred. Our data argue against an escape of PLGA-MS from the endosome as has previously been suggested as a mechanism to facilitate cross-presentation of PLGA-MS encapsulated antigen. (C) 2011 Elsevier B.V. All rights reserved.