Exosomes and Microvesicles

Challenge

Understanding Exosomes

Exosomes and other extracellular vesicles (EVs) are key contributors to cell-to-cell communication. EVs can cross biological barriers such as the blood-brain barrier and be internalized within the cell with a high degree of specificity. For these reasons, they are of significant interest as therapeutic agents, drug delivery vehicles and diagnostic biomarkers.

EVs typically have a hydrodynamic diameter of 30-2000nm; for the exosomes sub-group, this value is thought to be 30-120nm, which is smaller than the theoretical best resolution for an optical microscope. To fully understand exosomes requires instrumentation that is both sensitive enough to detect them and has sufficient resolution to visualize them.

Exosome

Case Study

Exosome uptake in HeLa Cells

The Nanoimager was used to study the uptake of exosomes in a HeLa cell. As a control, the GFP-labeled exosomes were first imaged in solution using single-particle tracking (SPT) to measure their size. The size histogram indicated that the exosomes were 80-100nm in diameter with some larger particles present.

The exosomes were next added to HeLa cells and visualized diffusing in solution before entering the cell. The color bar in the image indicates a dramatic drop in diffusion once exosomes bound to or entered the cell. Further experiments will be undertaken with multiple colors to understand which molecules are involved in the uptake process and to measure the timescale for this process.

In summary, the Nanoimager offers:

> Super-resolution multi-color imaging with 20nm resolution to understand the interaction of exosomes with other cellular components.

> Tracking of vesicles inside cells and in solution (3D single-molecule dual color single-particle tracking (SPT).

> Single-molecule sensitivity for both organic dyes and fluorescent proteins.



Read more about the Nanoimager's NimOS software and its other applications such as vesicle & single-particle tracking in cells and viral particle imaging.

Exosome imaging

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