Differential Nanoparticle Sequestration by Macrophages and Scavenger Endothelial Cells Visualized in Vivo in Real-Time and at Ultrastructural Resolution

TY - JOUR

T1 - Differential Nanoparticle Sequestration by Macrophages and Scavenger Endothelial Cells Visualized in Vivo in Real-Time and at Ultrastructural Resolution

AU - Hayashi, Yuya

AU - Takamiya, Masanari

AU - Jensen, Pia Bomholt

AU - Ojea-Jiménez, Isaac

AU - Claude, Hélicia

AU - Antony, Claude

AU - Kjaer-Sorensen, Kasper

AU - Grabher, Clemens

AU - Boesen, Thomas

AU - Gilliland, Douglas

AU - Oxvig, Claus

AU - Strähle, Uwe

AU - Weiss, Carsten

PY - 2020/1

Y1 - 2020/1

N2 - Despite the common knowledge that the reticuloendothelial system is largely responsible for blood clearance of systemically administered nanoparticles, the sequestration mechanism remains a "black box". Using transgenic zebrafish embryos with cell type-specific fluorescent reporters and fluorescently labeled model nanoparticles (70 nm SiO2), we here demonstrate simultaneous three-color in vivo imaging of intravenously injected nanoparticles, macrophages, and scavenger endothelial cells (SECs). The trafficking processes were further revealed at ultrastructural resolution by transmission electron microscopy. We also find, using a correlative light-electron microscopy approach, that macrophages rapidly sequester nanoparticles via membrane adhesion and endocytosis (including macropinocytosis) within minutes after injection. In contrast, SECs trap single nanoparticles via scavenger receptor-mediated endocytosis, resulting in gradual sequestration with a time scale of hours. Inhibition of the scavenger receptors prevented SECs from accumulating nanoparticles but enhanced uptake in macrophages, indicating the competitive nature of nanoparticle clearance in vivo. To directly quantify the relative contributions of the two cell types to overall nanoparticle sequestration, the differential sequestration kinetics was studied within the first 30 min post-injection. This revealed a much higher and increasing relative contribution of SECs, as they by far outnumber macrophages in zebrafish embryos, suggesting the importance of the macrophage:SECs ratio in a given tissue. Further characterizing macrophages on their efficiency in nanoparticle clearance, we show that inflammatory stimuli diminish the uptake of nanoparticles per cell. Our study demonstrates the strength of transgenic zebrafish embryos for intravital real-time and ultrastructural imaging of nanomaterials that may provide mechanistic insights into nanoparticle clearance in rodent models and humans.

AB - Despite the common knowledge that the reticuloendothelial system is largely responsible for blood clearance of systemically administered nanoparticles, the sequestration mechanism remains a "black box". Using transgenic zebrafish embryos with cell type-specific fluorescent reporters and fluorescently labeled model nanoparticles (70 nm SiO2), we here demonstrate simultaneous three-color in vivo imaging of intravenously injected nanoparticles, macrophages, and scavenger endothelial cells (SECs). The trafficking processes were further revealed at ultrastructural resolution by transmission electron microscopy. We also find, using a correlative light-electron microscopy approach, that macrophages rapidly sequester nanoparticles via membrane adhesion and endocytosis (including macropinocytosis) within minutes after injection. In contrast, SECs trap single nanoparticles via scavenger receptor-mediated endocytosis, resulting in gradual sequestration with a time scale of hours. Inhibition of the scavenger receptors prevented SECs from accumulating nanoparticles but enhanced uptake in macrophages, indicating the competitive nature of nanoparticle clearance in vivo. To directly quantify the relative contributions of the two cell types to overall nanoparticle sequestration, the differential sequestration kinetics was studied within the first 30 min post-injection. This revealed a much higher and increasing relative contribution of SECs, as they by far outnumber macrophages in zebrafish embryos, suggesting the importance of the macrophage:SECs ratio in a given tissue. Further characterizing macrophages on their efficiency in nanoparticle clearance, we show that inflammatory stimuli diminish the uptake of nanoparticles per cell. Our study demonstrates the strength of transgenic zebrafish embryos for intravital real-time and ultrastructural imaging of nanomaterials that may provide mechanistic insights into nanoparticle clearance in rodent models and humans.

KW - ACCUMULATION

KW - CIRCULATION

KW - CLEARANCE

KW - COLOCALIZATION

KW - IMAGE

KW - LIVER

KW - PROTEIN ADSORPTION

KW - SILICA

KW - SIZE

KW - ZEBRAFISH

KW - correlative light-electron microscopy

KW - intravital confocal microscopy

KW - macrophage polarization

KW - nanoparticles

KW - transmission electron microscopy

KW - uptake kinetics

KW - zebrafish embryos

KW - Zebrafish embryos

KW - Macrophage polarization

KW - Correlative light-electron microscopy

KW - Uptake kinetics

KW - Nanoparticles

KW - Intravital confocal microscopy

KW - Transmission electron microscopy

U2 - 10.1021/acsnano.9b07233

DO - 10.1021/acsnano.9b07233

M3 - Journal article

C2 - 31922724

SN - 1936-0851

VL - 14

SP - 1665

EP - 1681

JO - ACS Nano

JF - ACS Nano

IS - 2

ER -