Permeability of the blood-brain barrier through the phases of ischaemic stroke and relation with clinical outcome: protocol for a systematic review

Therapeutic Nanoparticles for the Different Phases of Ischemic Stroke

Stroke represents the second leading cause of mortality and morbidity worldwide. Ischemic strokes are the most prevalent type of stroke, and they are characterized by a series of pathological events prompted by an arterial occlusion that leads to a heterogeneous pathophysiological response through different hemodynamic phases, namely the hyperacute, acute, subacute, and chronic phases. Stroke treatment is highly reliant on recanalization therapies, which are limited to only a subset of patients due to their narrow therapeutic window; hence, there is a huge need for new stroke treatments. Nonetheless, the vast majority of promising treatments are not effective in the clinical setting due to their inability to cross the blood-brain barrier and reach the brain. In this context, nanotechnology-based approaches such as nanoparticle drug delivery emerge as the most promising option. In this review, we will discuss the current status of nanotechnology in the setting of stroke, focusing on the diverse available nanoparticle approaches targeted to the different pathological and physiological repair mechanisms involved in each of the stroke phases.

Biocompatible BSA-MnO2 nanoparticles for in vivo timely permeability imaging of blood-brain barrier and prediction of hemorrhage transformation in acute ischemic stroke

Hemorrhage transformation (HT) is a frequent but maybe fatal complication following acute ischemic stroke due to severe damage of the blood-brain barrier (BBB). Quantitative BBB permeability imaging is a promising method to predict HT in stroke patients for a favorable prognosis. However, clinical gadolinium chelate-based magnetic resonance (MR) imaging of the stroke suffers from a relatively low sensitivity and potential side effects of nephrogenic systemic fibrosis and intracranial gadolinium deposition. Herein, BSA-MnO2 nanoparticles (BM NPs) fabricated by a facile disinfection-mimic method were employed for the permeability imaging of BBB in the stroke for the first time. The BM NPs showed a high T1 relaxivity (r1 = 5.9 mM-1 s-1), remarkable MR imaging ability, and good biocompatibility, allowing the noninvasive timely visualization of BBB permeability in the model rats of middle cerebral artery occlusion (MCAO). Furthermore, increased peak intensity, extended imaging duration, and expanded imaging region indicated by BM NPs in MR imaging showed a good prediction for the onset of HT in MCAO rats. Therefore, BM NPs hold an attractive potential to be an alternative biocompatible MR contrast agent for the noninvasive BBB permeability imaging in vivo, benefiting the fundamental research of diverse neurological disorders and the clinical treatment for stroke patients.