In Vivo Imaging Using Quantum Dot–Conjugated Probes

Recent advances in luminescent materials for super-resolution imaging via stimulated emission depletion nanoscopy

Recent progress on STED fluorophores for super-resolution imaging and also their characteristics are outlined here, thus providing some guidelines to select proper probes and even develop new materials for super-resolution imaging via STED nanoscopy.

Cellular Plasticity during Metastasis: New Insights Provided by Intravital Microscopy

Metastasis is a highly dynamic process during which cancer and microenvironmental cells undergo a cascade of events required for efficient dissemination throughout the body. During the metastatic cascade, tumor cells can change their state and behavior, a phenomenon commonly defined as cellular plasticity. To monitor cellular plasticity during metastasis, high-resolution intravital microscopy (IVM) techniques have been developed and allow us to visualize individual cells by repeated imaging in animal models. In this review, we summarize the latest technological advancements in the field of IVM and how they have been applied to monitor metastatic events. In particular, we highlight how longitudinal imaging in native tissues can provide new insights into the plastic physiological and developmental processes that are hijacked by cancer cells during metastasis.

Imaging mGluR5 dynamics in astrocytes using quantum dots

This unit describes the method that we have developed to clarify endogenous mGluR5 (metabotropic glutamate receptors 5) dynamics in astrocytes by single-particle tracking using quantum dots (QD-SPT). QD-SPT has been a powerful tool to examine the contribution of neurotransmitter receptor dynamics to synaptic plasticity. Neurotransmitter receptors are also expressed in astrocytes, the most abundant form of glial cell in the brain. mGluR5s, which evoke intracellular Ca(2+) signals upon receiving glutamate, contribute to the modulation of synaptic transmission efficacy and local blood flow by astrocytes. QD-SPT has previously revealed that the regulation of the lateral diffusion of mGluR5 on the plasma membrane is important for local Ca(2+) signaling in astrocytes. Determining how mGluR5 dynamics are regulated in response to neuronal input would enable a better understanding of neuron-astrocyte communication in future studies.

High accuracy 3D quantum dot tracking with multifocal plane microscopy for the study of fast intracellular dynamics in live cells

Single particle tracking in three dimensions in a live cell environment holds the promise of revealing important new biological insights. However, conventional microscopy-based imaging techniques are not well suited for fast three-dimensional (3D) tracking of single particles in cells. Previously we developed an imaging modality multifocal plane microscopy (MUM) to image fast intracellular dynamics in three dimensions in live cells. Here, we introduce an algorithm, the MUM localization algorithm (MUMLA), to determine the 3D position of a point source that is imaged using MUM. We validate MUMLA through simulated and experimental data and show that the 3D position of quantum dots can be determined over a wide spatial range. We demonstrate that MUMLA indeed provides the best possible accuracy with which the 3D position can be determined. Our analysis shows that MUM overcomes the poor depth discrimination of the conventional microscope, and thereby paves the way for high accuracy tracking of nanoparticles in a live cell environment. Here, using MUM and MUMLA we report for the first time the full 3D trajectories of QD-labeled antibody molecules undergoing endocytosis in live cells from the plasma membrane to the sorting endosome deep inside the cell.