Detection of exosomes, microparticles, and other extracellular vesicles

Background

TEM image exosomes
Transmission electron microscopy image of extracellular vesicles from human urine.

Cells release vesicles, also called microparticles and exosomes, which are spherical particles enclosed by a phospholipid bilayer. The diameter of these extracellular vesicles typically ranges from 30 nm to 1 μm, the smallest being some 100-fold smaller than the smallest cells. Because cells release vesicles into their environment, body fluids such as blood and urine contain typically more than 10 billion vesicles per mL. It is becoming increasingly clear that most vesicles have specialized functions and play a key role in coagulation, intercellular signaling, and waste management. Consequently, there is a growing interest in the clinical applications of vesicles. Vesicles can potentially be used for prognosis, therapy, and biomarkers for health and disease.

Problem

The isolation and detection of extracellular vesicles from body fluids has proven to be difficult. On the one hand, due to the complexity of body fluids, the physical separation of vesicles from similar sized particles and cells is complicated. On the other hand, since vesicles have a low refractive index and are smaller than 1 μm, vesicles are below the detection range of many currently used techniques. Consequently, the extent to which vesicles really contribute to processes underlying physiology and pathology is virtually unexplored.

Aims

The aims of my research are (1) to improve vesicle detection in general and (2) to develop a device suitable for clinical use and capable of accurately determining the size and composition (proteins, lipids, RNA, DNA) of single vesicles at high throughput.