Introduction: Most studies on extracellular vesicles (EVs) in the context of the brain has been informed by in vitro models, in situ methods or biofluids, limiting insight into EV function and composition relative to neuroanatomical origin or parental cell type. Here, we assess whether a human - mouse chimeric transplantation model could be used to study EVs released by human neural cells engrafted into the striatum, and isolate human EVs from both brain and peripheral circulation.
Methods: Human pluripotent stem cell–derived neural progenitors were implanted into the striatum of immune-deficient nude mice. EVs were isolated from mouse plasma and brain using IZON qEV2 35nm Gen2 SEC columns. EV proteins were quantified, digested, and analysed via label free data independent acquisition LC-MS/MS proteomics. Spectra were searched against Homo sapiens and Mus musculus Uniprot databases in Spectronaut, and species-specific peptides were validated using NCBI BLAST tool.
Results: Human neural grafts were successfully integrated into the striatum of immune-deficient mice over six months. EVs secreted by the human grafts were detectable in both mouse brain and systemic circulation. Species-specific peptides were identified via LC–MS/MS spectral searches, allowing distinguishing peptides from human- and mouse -derived EVs.
Conclusion: This in vivo model enables studying EVs originating from a neuroanatomical region implicated in neurodegenerative disease. It provides a platform to investigate the spatial distribution of EVs, their role in the propagation of pathogenic proteins, and to characterise EV cargo reflecting early molecular alterations associated with transplanted patient-derived cells.