Involvement of endocytosis in uptake of phosphatidylserine-coated single-walled cargon nanotubes by RAW 264.7 macrophages.
Feng-W; Konduru-NV; Tyurina-YY; Clark-K; Stolz-DB; Bayir-H; Fadeel-B; Shvedova-AA; Kagan-VE
Toxicologist 2008 Mar; 102(1):213
Collapse of phospholipid membrane asymmetry and exposure of phosphatidylserine (PS) on the surface of apoptotic cells is essential for recognition and removal of apoptotic cells by phagocytes. Previously, we hypothesized and confirmed that coating of single walled carbon nanotubes (SWCNTs) with PS stimulated their recognition and uptake by macrophages, dendritic cells and microglia. However, the mechanisms of the uptake remain unknown. To study the uptake mechanisms of SWCNTs by phagocytic cells, RAW 264.7 macrophages were incubated with nanotubes coated with fluorescently labeled phospholipids- nitrobenzoxadiazole (NBD)-PS or NBD-phosphatidylcholine (NBD-PC) for different periods of time (12.5ug SWCNTs/0.5x105 cells). By using confocal microscopy, we found that NBD-PS-SWCNTs but not NBD-PC-SWCNTs were recognized and taken-up by macrophages. We also demonstrated that PS-coated nanotubes were localized in the lysosomes as evidenced by co-localization of fluorescence responses from NBD-PSSWCNTs and Lyso-Tracker Red. The intravesicular localization of PS-SWCNTs in macrophages was confirmed by transmission electron microscopy. Further, the uptake of NBD-PS-SWCNTs was suppressed by a cocktail of endocytosis inhibitors (chlorpromazine, nystatin, genistein and brefeldin A). This suggests that endocytosis is involved in the uptake of SWCNTs by macrophages. We conclude that PScoated SWCNT can be used for targeted delivery of specialized cargos - regulators, inhibitors into macrophages to control their functions and this strategy could be utilized for therapeutic regulation of immune responses.
Particulates; Quantitative-analysis; Immunology; Immune-system-disorders; Immunochemistry; Immune-reaction; Therapeutic-agents; Cell-transformation; Cellular-reactions; Cell-biology; Cellular-uptake; Cell-function; Nanotechnology
The Toxicologist. Society of Toxicology 47th Annual Meeting and ToxExpo, March 16-20, 2008, Seattle, Washington
University of Pittsburgh at Pittsburgh