Human Platelet-Derived Extracellular Vesicles Are Internalized by Human Induced Pluripotent Stem Cell-Derived Neurons Under Control and Hypoxic Conditions.

Ischaemic brain stroke is among the leading causes of death and disability worldwide. However, the current treatments have a limited time window and regeneration potential. Clinically relevant human platelet-derived extracellular vesicles (EVs) offer potential neuroprotective treatment for stroke. Here, the neuronal uptake of carboxyfluorescein succinimidyl ester (CFSE)-labelled EVs was confirmed by confocal imaging and three-dimensional (3D) image analysis with Imaris software. The results showed that human induced pluripotent stem cell (hiPSC)-derived neurons can internalize EVs. We also show the colocalization of EVs with cellular organelles: early endosomes and lysosomes. We used an in vitro human model of stroke to study the effects of hypoxia on neurons. After hypoxia, the activity of the neurons, including spiking and bursting, decreased. However, the activity was restored after 72 h of reperfusion. EVs did not affect neuronal activity acutely, but during long-term follow-up, neurons showed increased activity. Together, our findings provide insights into the effects of platelet-derived EVs on neuronal uptake, morphology and functionality and changes after hypoxic insult in an in vitro human model.