Current Mouse Models of Intracranial Aneurysms: Analysis of Pharmacological Agents Used to Induce Aneurysms and Their Impact on Translational Research

A modified surgical approach to induce circle Willis perforation in mice using the common carotid artery

The Circle of Willis perforation (cWp) mouse model is widely used in subarachnoid hemorrhage (SAH) research but involves sacrificing the external carotid artery (ECA), which may have a potential affect on the hemodynamic in the carotid arteries and cortical perfusion. We propose a modified approach using needle puncture via the common carotid artery (CCA) to preserve carotid vascular integrity. Twenty-seven C57BL/6 mice were randomly assigned into three groups and underwent cWp surgery in three procedures: sham (n = 3), ECA (n = 12), and CCA (n = 12). Surgical duration, success rate, intraoperative intracranial pressure (ICP) fluctuations, 24-hour mortality, and neurological deficits were assessed. The CCA approach achieved a 100% success rate and shorter surgical duration than the ECA approach (ECA 73 ± 18 vs. CCA 36 ± 10 min, P < 0.05). ICP fluctuations and mortality rates were comparable between the ECA and CCA groups (P > 0.05), indicating that the CCA approach shared a similar pattern with the ECA approach. Neurological outcomes were similar across SAH groups (CCA SAH induction and ECA SAH induction) but worse than sham (P < 0.05) in terms of body weight loss, open-filed test and Rotarod test performances. This modified cWp CCA approach, which preserves the carotid structures, helps eliminate hemodynamic bias and offers a potentially more efficient alternative with a shorter surgical duration compared to the classical ECA approach. It may prove to be a valuable option for broader application in SAH preclinical research.

Neutrophils extracellular traps myeloperoxidase and elastase predict cerebral vasospasms after aneurysmal subarachnoid hemorrhage

Aneurysmal subarachnoid hemorrhage (aSAH) is a highly fatal and morbid disease. Despite successful coiling or clipping of a ruptured aneurysm, the patients suffer post-aSAH complications, including early brain injury, cerebral vasospasm (CVS), delayed cerebral ischemia (DCI), and systemic infections that mainly determine the clinical outcomes. Diagnostic biomarkers to predict accurately post-aSAH complications are needed. In this prospective exploratory study, we investigated the predictive value of neutrophil extracellular traps (NETs) components for CVS after aSAH. In the study, 62 patients with aSAH, 17 patients with unruptured cerebral aneurysms, and 12 healthy controls were included. The serum levels of myeloperoxidase (MPO), elastase (ELA), and citrullinated histone H3 (cH3) on day 1 and day 4 of hospital admission were measured with ELISA. Data were scaled using the Yeo-Johnson transformation. Values in two groups were compared using a t-test and in multiple groups using ANOVA. Logistic regression was used to model the outcome probability, including CVS, as the function of ELISA values. Among the patients with aneurysms, those who suffered aSAH had significantly higher levels of MPO (113.9 ± 294.4 vs. 422.3 ± 319.0 ng/ml, p < 0.05), ELA (84.8 ± 221.0 vs. 199.2 ± 218.9 ng/ml, p < 0.05), and cH3 (0.0 ± 0.0 vs. 2.8 ± 1.5, ng/ml, p < 0.05) on day one after aSAH, suggesting the involvement of NETs components in pathophysiology of aSAH and the events following aSAH. Individually, MPO and ELA levels taken on day 1 after SAH did not differ between patients with CVS and patients without CVS. However, when taken together into a logistic model, they allowed for predicting CVS with high sensitivity (91 %) and specificity (79 %). MPO and ELA, along with other clinical parameters, can be used as early predictors of CVS in aSAH patients and can serve as guidance during treatment decisions in the management of aSAH.

Dimethyl Fumarate Mediates Sustained Vascular Smooth Muscle Cell Remodeling in a Mouse Model of Cerebral Aneurysm

Cerebral aneurysms (CA) are a type of vascular disease that causes significant morbidity and mortality with rupture. Dysfunction of the vascular smooth muscle cells (VSMCs) from circle of Willis (CoW) vessels mediates CA formation, as they are the major cell type of the arterial wall and play a role in maintaining vessel integrity. Dimethyl fumarate (DMF), a first-line oral treatment for relapsing-remitting multiple sclerosis, has been shown to inhibit VSMC proliferation and reduce CA formation in a mouse model. Potential unwanted side effects of DMF on VSMC function have not been investigated yet. The present study characterizes the impact of DMF on VSMC using single-cell RNA-sequencing (scRNA-seq) in CoW vessels following CA induction and further explores its role in mitochondrial function using in vitro VSMC cultures. Two weeks of DMF treatment following CA induction impaired the transcription of the glutathione redox system and downregulated mitochondrial respiration genes in VSMCs. In vitro, DMF treatment increased lactate formation and enhanced the mitochondrial production of reactive oxygen species (ROS). These effects rendered VSMCs vulnerable to oxidative stress and led to mitochondrial dysfunction and enhancement of apoptosis. Taken together, our data support the concept that the DMF-mediated antiproliferative effect on VSMCs is linked to disturbed antioxidative functions resulting in altered mitochondrial metabolism. This negative impact of DMF treatment on VSMCs may be linked to preexisting alterations of cerebrovascular function due to renal hypertension. Therefore, before severe adverse effects emerge, it would be clinically relevant to develop indices or biomarkers linked to this disturbed antioxidative function to monitor patients undergoing DMF treatment.

Tobacco smoke condensate-induced senescence in endothelial cells was ameliorated by colchicine treatment via suppression of NF-κB and MAPKs P38 and ERK pathways activation

Smoking is the major cause of cardiovascular diseases and cancer. It induces oxidative stress, leading to DNA damage and cellular senescence. Senescent cells increase the expression and release of pro-inflammatory molecules and matrix metalloproteinase, which are known to play a vital role in the initiation and progression of cardiovascular diseases and metastasis in cancer. The current study investigated the smoking induced cellular senescence and employed colchicine that blocked senescence in endothelial cells exposed to tobacco smoke condensate. Colchicine prevented oxidative stress and DNA damage in tobacco smoke-condensate-treated endothelial cells. Colchicin reduced β-gal activity, improved Lamin B1, and attenuated cell growth arrest markers P21 and P53. Colchicine also ameliorated the expression of SASP factors and inhibited the activation of NF-kB and MAPKs P38 and ERK. In summary, colchicine inhibited tobacco smoke condensate-induced senescence in endothelial cells by blocking the activation of NF-kB and MAPKs P38 and ERK.