9 research outputs found
In vivo imaging of cytotoxic T cell infiltration and elimination of a solid tumor
Although the immune system evolved to fight infections, it may also attack and destroy solid tumors. In most cases, tumor rejection is initiated by CD8+ cytotoxic T lymphocytes (CTLs), which infiltrate solid tumors, recognize tumor antigens, and kill tumor cells. We use a combination of two-photon intravital microscopy and immunofluorescence on ordered sequential sections to analyze the infiltration and destruction of solid tumors by CTLs. We show that in the periphery of a thymoma growing subcutaneously, activated CTLs migrate with high instantaneous velocities. The CTLs arrest in close contact to tumor cells expressing their cognate antigen. In regions where most tumor cells are dead, CTLs resume migration, sometimes following collagen fibers or blood vessels. CTLs migrating along blood vessels preferentially adopt an elongated morphology. CTLs also infiltrate tumors in depth, but only when the tumor cells express the cognate CTL antigen. In tumors that do not express the cognate antigen, CTL infiltration is restricted to peripheral regions, and lymphocytes neither stop moving nor kill tumor cells. Antigen expression by tumor cells therefore determines both CTL motility within the tumor and profound tumor infiltration
Tracking Targeted Bimodal Nanovaccines: Immune Responses and Routing in Cells, Tissue, and Whole Organism
Dendritic cells (DCs) are the most
potent antigen-presenting cells
(APCs), involved in the induction of immunity and currently exploited
for antitumor immunotherapies. An optimized noninvasive imaging modality
capable of determining and quantifying DC-targeted nanoparticle (NP)
trajectories could provide valuable information regarding therapeutic
vaccine outcome. Here, targeted poly(d,l-lactide-<i>co</i>-glycolide) nanoparticles (PLGA NPs) recognizing DC receptors
were equipped with superparamagnetic iron oxide particles (SPIO) or
gold nanoparticles with fluorescently labeled antigen. The fluorescent
label allowed for rapid analysis and quantification of DC-specific
uptake of targeted PLGA NPs in comparison to uptake by other cells.
Transmission electron microscopy (TEM) showed that a fraction of the
encapsulated antigen reached the lysosomal compartment of DCs, where
SPIO and gold were already partially released. However, part of the
PLGA NPs localized within the cytoplasm, as confirmed by confocal
microscopy. DCs targeted with NPs carrying SPIO or fluorescent antigen
were detected within lymph nodes as early as 1 h after injection by
magnetic resonance imaging (MRI). Despite the fact that targeting
did not markedly affect PLGA NP biodistribution on organism and tissue
level, it increased delivery of NPs to DCs residing in peripheral
lymph nodes and resulted in enhanced T cell proliferation. In conclusion,
two imaging agents within a single carrier allows tracking of targeted
PLGA NPs at the subcellular, cellular, and organismal levels, thereby
facilitating the rational design of in vivo targeted vaccination strategies
Tracking targeted bimodal nanovaccines: immune responses and routing in cells, tissue, and whole organism
Item does not contain fulltextDendritic cells (DCs) are the most potent antigen-presenting cells (APCs), involved in the induction of immunity and currently exploited for antitumor immunotherapies. An optimized noninvasive imaging modality capable of determining and quantifying DC-targeted nanoparticle (NP) trajectories could provide valuable information regarding therapeutic vaccine outcome. Here, targeted poly(d,l-lactide-co-glycolide) nanoparticles (PLGA NPs) recognizing DC receptors were equipped with superparamagnetic iron oxide particles (SPIO) or gold nanoparticles with fluorescently labeled antigen. The fluorescent label allowed for rapid analysis and quantification of DC-specific uptake of targeted PLGA NPs in comparison to uptake by other cells. Transmission electron microscopy (TEM) showed that a fraction of the encapsulated antigen reached the lysosomal compartment of DCs, where SPIO and gold were already partially released. However, part of the PLGA NPs localized within the cytoplasm, as confirmed by confocal microscopy. DCs targeted with NPs carrying SPIO or fluorescent antigen were detected within lymph nodes as early as 1 h after injection by magnetic resonance imaging (MRI). Despite the fact that targeting did not markedly affect PLGA NP biodistribution on organism and tissue level, it increased delivery of NPs to DCs residing in peripheral lymph nodes and resulted in enhanced T cell proliferation. In conclusion, two imaging agents within a single carrier allows tracking of targeted PLGA NPs at the subcellular, cellular, and organismal levels, thereby facilitating the rational design of in vivo targeted vaccination strategies