Circulating Microglia-derived Extracellular Vesicles Predict Recovery After Rehabilitation in Stroke Survivors

Timely intensive rehabilitation is crucial to contrast the negative escalation of events that follow a stroke injury, to promote tissue regeneration, and to restore the physiological function. This study aimed to identify measurable blood biomarkers that could be predictive of functional recovery in stroke survivors. 30 sub-acute stroke subjects were enrolled at Fondazione Don Gnocchi (Italy) during the observation prospective study EXO4STROKE (NCT05370105). Following clinical assessment, cytokines, neurofilaments and circulating Extracellular Vesicles (EVs) were evaluated in the serum of patients at admission (T0) and at discharge (T1) in intensive rehabilitation unit. Multiplexed SPRi analysis of circulating EVs allowed detection of brain (neurons, astrocytes, microglia) and non-brain (endothelium, skeletal muscle, and platelets) derived EVs, and the relative quantification of markers of pathological or regenerative processes. Machine learning-based analysis complemented the study by integrating statistically significant features in a cross-validated prediction model targeting functional recovery at T1 from T0 data. The results of the present study demonstrate that high serum levels of IL-6 and Neurofilament Light Chain at T0 were associated with higher residual disability at T1. In contrast, elevated circulating levels of EVs from neurons (CD171+) and microglia (CD11b+) were associated with better recovery after rehabilitation. Moreover, the overexpression of the VEGF receptor on microglial EVs was associated with higher functional improvement. Alternatively, the overexpression of TGF-beta receptor on IB4 + EVs post-stroke was found associated with increased stroke severity. In conclusion, this study identifies a panel of few circulating biomarkers able to objectively assess post-stroke status and potentially predict functional recovery after rehabilitation.