Extracellular Vesicles: Biology and Their Use as Potential Biomarkers in Hematopoietic Post-Transplant Complications

Abstract

Extracellular vesicles (EVs) are membranous particles constitutively released by all cells into biological fluids which play an essential role in inter-cellular communications as carriers of bioactive molecules, such as lipids, proteins, peptides, DNA, RNA, and sugars, thereby also influencing recipient cell functions. EVs are an highly heterogeneous group of particles including microvesicles and exosomes, which differ for dimensions and cellular origin. Furthermore, the EV lipid bilayer protects the luminal content from degradation by extracellular proteases and nucleases and they are stable under storage conditions. Furthermore, EVs cargo composition can differ among EVs subpopulations depending on the originating cell type, therefore this vast heterogeneity could be responsible for different biological effects mediated by EVs subgroups. Owing to all these characteristics, EVs are considered a very attractive targets for diagnostic applications and several studies suggested that EV alterations may also be used as biomarkers of disease progression or therapeutic response in many physiological and pathological processes. In fact, EVs have been recently investigated as a promising new category of biomarkers in different scenarios (such as in cancer, inflammation and autoimmune diseases), including hematopoietic stem cell transplantation (HSCT). This chapter will provide a brief introduction of allogeneic-HSCT and their main complications: relapse, Graft-vs-Host Disease, and early complication of endothelial origin. Afterward, it will describe EVs subtypes, composition, uptake, and clearance in human body, as well as the common EVs purification and characterization methods. We will introduce “the minimal information for studies of extracellular vesicles 2018 or MISEV, which are a set of guidelines updated intermittently that supplies a framework for researchers to report their EV studies in a uniform and transparent manner, thereby facilitating data comparison and reproducibility across different laboratories and experimental conditions. Eventually, we will discuss EVs potential application as biomarkers for the main allogeneic-HSCT complications.