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Sham control groups are essential in experimental animal studies to reduce the influence of surgical intervention. The intraluminal filament procedure is one of the most common models of middle cerebral artery occlusion (MCAO) used in the study of brain ischemia. However, a sham group is usually not included in the experimental design of these studies. In this study, we aimed to evaluate the relevance of the sham group by analyzing and comparing the brain protein profiles of the sham and MCAO groups. In the sham group, 98 dysregulated proteins were detected, compared to 171 in the ischemic group. Moreover, a comparative study of protein profiles revealed the existence of a pool of 57 proteins that appeared to be dysregulated in both sham and ischemic animals. These results indicated that the surgical procedure required for the intraluminal occlusion of the middle cerebral artery (MCA) induces changes in brain protein expression that are not associated with ischemic lesions. This study highlights the importance of including sham control groups in the experimental design, to ensure that surgical intervention does not affect the therapeutic target under study.

Background: Ischemic stroke is the most common cerebrovascular disease and is caused by interruption of blood supply to the brain. To date, recombinant tissue plasminogen activator (rtPA) has been the main pharmacological treatment in the acute phase. However, this treatment has some drawbacks, such as a short half-life, low reperfusion rate, risk of hemorrhagic transformations, and neurotoxic effects. To overcome the limitations of rtPA and improve its effectiveness, we recently designed sonosensitive sub-micrometric capsules (SCs) loaded with rtPA with a size of approximately 600 nm, synthesized using the layer-by-layer (LbL) technique, and coated with gelatine for clot targeting. In this study, we evaluated the rtPA release of ultrasound (US)-responsive SCs in healthy mice and the therapeutic effect in a thromboembolic stroke model., Results: In healthy mice, SCs loaded with rtPA 1 mg/kg responded properly to external US exposure, extending the half-life of the drug in the blood stream more than the group treated with free rtPA solution. The gelatine coating also contributed to stabilizing the encapsulation and maintaining the response to US. When the same particles were administered in the stroke model, these SCs appeared to aggregate in the ischemic brain region, probably generating secondary embolisms and limiting the thrombolytic effect of rtPA. Despite the promising results of these thrombolytic particles, at least under the dose and size conditions used in this study, the administration of these capsules represents a risk factor for stroke., Conclusions: This is the first study to report the aggregation risk of a drug carrier in neurological pathologies such as stroke. Biocompatibility analysis related to the use of nano-and microparticles should be deeply studied to anticipate the limitations and orientate the design of new nanoparticles for translation to humans., (© 2022. The Author(s).)

Endothelial cells represent the first biological barrier for compounds, including nanoparticles, administered via the intravascular route. In the case of ischemic stroke and other vascular diseases, the endothelium overexpresses specific markers, which can be used as molecular targets to facilitate drug delivery and imaging. However, targeting these markers can be quite challenging due to the presence of blood flow and the associated hydrodynamic forces, reducing the likelihood of adhesion to the vessel wall. To overcome these challenges, various parameters including size, shape, charge or ligand coating have been explored to increase the targeting efficiency. Geometric shape can modulate nanoparticle binding to the cell, especially by counteracting part of the hydrodynamic forces of the bloodstream encountered by the classical spherical shape. In this study, the binding affinity of polystyrene nanoparticles with two different shapes, spherical and rod-shaped, were compared. First, vascular adhesion molecule-1 (VCAM-1) was evaluated as a vascular target of inflammation, induced by lipopolysaccharide (LPS) stimulation. To evaluate the effect of nanoparticle shape on particle adhesion, nanoparticles were coated with anti-VCAM-1 and tested under static conditions in cell culture dishes coated with cerebral microvasculature cells (bEnd.3) and under dynamic flow conditions in microfluidic channels lined with hCMEC/D3 cells. Effect of particle shape on accumulation was also assessed in two in vivo models including systemic inflammation and local brain inflammation. The elongated rod-shaped particles demonstrated greater binding ability in vitro, reaching a 2.5-fold increase in the accumulation for static cultures and 1.5-fold for flow conditions. Anti-VCAM-1 coated rods exhibited a 3.5-fold increase in the brain accumulation compared to control rods. These results suggest shape offers a useful parameter in future design of drug delivery nanosystems or contrast agents for neurovascular pathologies., (Copyright © 2019 The Authors. Published by Elsevier B.V. All rights reserved.)