From cells to extracellular vesicles
Cellular diagnostics have been the gold standard for diagnostics of many diseases in laboratory medicine and pathology for many years. Absolute and relative count of blood cells and qualitative features like size, morphology, biochemical and genetic characteristics have been and are still the basis for the diagnosis of a vast variety of diseases ranging from anemia, infections, sepsis, leukemia and lymphoma to coagulation disorders. Similarly, histopathological tissue diagnostics in pathology relies on morphological and molecular biological changes of cells in their organ compounds.
In contrast, subcellular particles have been considered as cellular waste. Likewise non-coding regions in the genome were greatly underestimated until the Encode Project revealed that this abundant genetic material is essential for regulation and fine-tuning of genomic transcription, silencing and activation of genomic regions and repair processes [1]. With the advent of new highly sensitive and high-resolution technologies, research interest in these subcellular particles has increased tremendously and has provided fascinating insights into their structure, biology, cellular release and function. Far beyond „just waste“, their key role for the cell-to-cell communication, the maintenance of the physiological balance within the organism and adaptation to external challenges as well as for the pathogenesis and progression of a plenitude of diseases has been recognized [2].
Heterogeneous group of EVs
Extracellular vesicles (EVs) are considered as particles with a lipid bilayer membrane naturally released from cells [3]. They comprise a wide spectrum of heterogeneous subcellular vesicles and vary greatly in size, density, surface composition, biochemical content, mechanism of formation, release from cells and biological functions that can be used for further sub-classification (Figure 1) [3,4].
