Extracellular vesicle properties and functions are defined by cell fitness status

Recent research has focused on understanding the influence of dying cells on immune function and the surrounding microenvironment. Apoptotic cells release a variety of extracellular vesicles (EVs), such as exosomes and microvesicles, and form apoptotic bodies through membrane blebbing. Despite increasing interest in EVs, the effects of apoptotic cell- versus live cell-derived EVs, have been poorly studied. Here, via transmission electron microscopy, nanoparticle tracking analysis, proteomics, and flow cytometry, we characterise the distinct features of EVs from live versus apoptotic cells. Using a model of Schistosoma mansoni infection, characterised by the presence of dying cells due to parasite egg accumulation, we demonstrated that adoptive transfer of apoptotic T cell-derived EVs attenuates liver pathology, in contrast to EVs from live T cells. Analysis of the transcriptomic profile of target macrophages and in vitro functional assays revealed that apoptotic cell-derived EVs activate NO-related pathways, which modulate macrophage function. Furthermore, these EVs specifically promoted fibroblast-mediated wound healing in vitro. Collectively, our findings highlight that cell fitness influences EV properties and their immune regulatory function. Investigating the differences between EVs from living and apoptotic cells is essential for advancing our understanding of immune regulation and optimising the development of EV-based therapeutic strategies.