Attracted to death:apoptotic cell-derived extracellular vesicles towards a basic characterisation

Abstract

Apoptosis, the tightly regulated process of cell death, plays an essential role in health and disease. Although ill-defined, extracellular vesicles derived from dying cells (ACdEV) are known to modulate immune responses. Little work has been carried out into these potentially important mediators, work here aims to provide a foundational basis for understanding of ACdEV. Here, apoptosis was induced in different cell lines and ACdEV size was determined, as well as concentration and zeta potential. ACdEV were characterised by Tuneable Resistive Pulse Sensing, with the kinetics of apoptosis being defined using flow cytometric analysis. we provide substantial evidence for the presence of exosomes in ACdEV isolations. Functional studies were performed assessing the role of ACdEV and their secretome in MØ migration and differentiation, T-cell proliferation, wound closure,bystander effect. The uptake of ACdEV by macrophage-like cells was also assessed. Key functional differences were identified between early and late ACdEV. Furthermore the complexity of apoptotic cell secretomes was highlighted. The development of a zeta potential based method for phenotyping of extracellular vesicles is carried out, proving the ability of TRPS to identify changes in zeta potential. This method once developed further can be applied to phenotyping of extracellular vesicles derived from biological samples. Data presented here suggests that ACdEV may be a complex mechanism of communication utilised by dying cells to make clear their location and their stage of death as well as modulating immune responses to the dead cell.