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Brain-Derived Microparticles in Patients with Severe Isolated TBI

ABSTRACT Primary Objective: to investigate the presence of circulating microparticles (MPs) of brain tissue origin in the systemic and cerebrovenous blood of patients with severe traumatic brain injury (TBI). Research Design: Prospective observational study in 15 consecutive patients with severe isolated TBI. Methods and Procedures: We repeatedly measured concentrations of MPs expressing glial fibrillary acidic protein (GFAP), neuron-specific enolase (NSE) and aquaporin-4 (AQP4), in arterial and cerebrovenous blood at admittance to hospital and up to 72 hours after the injury. Main Outcomes and Results: Concentrations of MPs expressing GFAP and AQP4 were significantly higher in the TBI group compared with healthy controls: GFAP 2.0 [1.1–7.9] vs. 1.3 [1–2.1] × 106/mL, p < 0.001; AQP4 0.1 [0.07–0.22] vs. 0.08 [0.06–0.11] × 106/mL, p < 0.001 (median, range). No transcranial gradients were found. Levels of NSE-expressing MPs were also higher in the TBI group compared with healthy controls: 0.4 [0.25–2.1] vs. 0.26 [0.13–0.98] × 106/mL, p < 0.05; however, regarding NSE-positive non-platelet MPs, there were no differences between patients and controls. Conclusions: Patients with TBI have higher numbers of brain-derived MPs. Further studies are needed, however, to identify specific and sensitive MP markers of brain injury.