Creating elastase aneurysms in rabbits: a video primer.

The New Zealand rabbit elastase-induced arterial aneurysm of the right common carotid artery remains a widely used model for assessing the effectiveness and safety of new neuroendovascular devices.1 This model offers a simple and reliable platform for pre-clinical investigations, crucial for comprehending the biological processes underlying aneurysm healing after endovascular treatment.2 Notably, the induced aneurysm exhibits morphological, hemodynamic, and histological characteristics similar to human intracranial aneurysms.

WEB shape modifications: angiography-histopathology correlations in rabbits.

Background: WEB Shape Modification (WSM) over time is frequent after aneurysm treatment. In this study, we explored the relationship between histopathological changes and angiographic evolution over time in experimental aneurysms in rabbits treated with the Woven EndoBridge (WEB) procedure.

Methods: Quantitative WSM was assessed using flat-panel computed tomography (FPCT) during follow-up by calculating height and width ratio (HR, WR), defined as the ratio between either measurement at an index time point and the measurement immediately after WEB implantation.

L-Arginine reduces downstream vascular contractility after flow-diverting device deployment: A preliminary study in a rabbit model.

Background: Flow diverters (FDs) are an effective treatment for intracranial aneurysms, though not free from hemorrhagic complications. A previous study demonstrated increased vascular contractility after FD-implantation as a potential mechanism of distal complications. Our study aimed to investigate whether L-arginine medication affects vascular contractility following FD deployment in a rabbit model.

A novel rabbit thromboembolic occlusion model.

Background: To develop a preclinical thromboembolic occlusion model for studying revascularization strategies.

Methods: Clot analog with barium sulfate was injected into the distal aorta in 9 New Zealand white rabbits. The situation of aorta occlusion was compared among fibrin-rich (n=4), red blood cell (RBC)-rich (n=3), and whole blood clot analogs (n=2) using digital subtraction angiography.

Characterizing thrombus with multiple red blood cell compositions by optical coherence tomography attenuation coefficient.

Embolectomy is one of the emergency procedures performed to remove emboli. Assessing the composition of human blood clots is an important diagnostic factor and could provide guidance for an appropriate treatment strategy for interventional physicians. Immunostaining has been used to identity compositions of clots as a gold-standard procedure, but it is time-consuming and cannot be performed in situ.

Characterizing blood clots using acoustic radiation force optical coherence elastography and ultrasound shear wave elastography.

Thromboembolism in a cerebral blood vessel is associated with high morbidity and mortality. Mechanical thrombectomy (MT) is one of the emergenc proceduresperformed to remove emboli. However, the interventional approaches such as aspiration catheters or stent retriever are empirically selected.

Cellular responses to flow diverters in a tissue-engineered aneurysm model.

Background: Notwithstanding the widespread implementation of flow diverters (FDs) in the treatment of intracranial aneurysms, the exact mechanism of action of these devices remains elusive. We aimed to advance the understanding of cellular responses to FD implantation using a 3D tissue-engineered in vitro aneurysm model.

Methods: Aneurysm-like blood vessel mimics (aBVMs) were constructed by electrospinning polycaprolactone nanofibers onto desired aneurysm-like geometries.

Characterization of thrombus composition with multimodality CT-based imaging: an in-vitro study.

Background: CT is the most commonly used imaging modality for acute ischemic stroke evaluation. There is growing interest to use pre-operative imaging to characterize clot composition in stroke. We performed an in-vitro study examining the ability of various CT techniques in differentiation between different clot types.

Downstream vascular changes after flow-diverting device deployment in a rabbit model.

Background: Flow diverters (FDs) are increasingly used in the treatment of intracranial aneurysms, and carry the risk of thromboembolic complications, even in patients treated with dual antiplatelet therapy. The effect of FDs on the downstream vascular is unknown. The aim of the study was to investigate vascular wall pulse wave velocity (PWV) and contractility changes following FD treatment in a rabbit model.

Hemodynamic characteristics of stable and unstable vertebrobasilar dolichoectatic and fusiform aneurysms.

Background And Purpose: Vertebrobasilar dolichoectatic and fusiform aneurysms (VBDAs) are known to have a poor natural history, with high rates of growth, rupture, and stroke. The purpose of this study was to identify hemodynamic characteristics that differ between VBDAs associated with growth, rupture, and stroke.

Materials And Methods: VBDAs with CT angiography or MR angiography followed longitudinally without treatment were studied.

Assessment of endothelialization of aneurysm wall over time in a rabbit model through CD31 scoring.

Background: Intracranial aneurysms represent a significant health concern and are poorly understood despite decades of research. Our study focused on understanding temporal patterns of endothelial cell distribution in different spatial locations within the aneurysm early after creation in a rabbit model.

Methods: Elastase induced saccular aneurysms were created in rabbits and harvested on day 1 (n=3) and after 2 (n=5), 4 (n=4), 8 (n=5), and 12 (n=6) weeks.

Rabbit aneurysm models mimic histologic wall types identified in human intracranial aneurysms.

Background: Semiquantitative scales correlate histopathologic findings in the walls of human aneurysms with rupture status.

Objective: To apply a semiquantitative scale to the rabbit elastase-induced aneurysm model to determine whether rabbit histologic types mimic the full range of histologic subtypes of humans.

Materials And Methods: Twenty-seven elastase-induced female rabbit aneurysms were studied, harvested at 2 weeks (n=5) and 12 weeks (n=22).

Autologous adipose-derived mesenchymal stem cells improve healing of coiled experimental saccular aneurysms: an angiographic and histopathological study.

Purpose: Long-term occlusion of coiled aneurysms frequently fails, probably because of poor intrasaccular healing and inadequate endothelialization across the aneurysm neck. The purpose of this study was to determine if attachment of autologous mesenchymal stem cells (MSCs) to platinum coils would improve the healing response in an elastase-induced aneurysm model in rabbits.

Materials And Methods: With approval from the institutional animal care and use committee, aneurysms were created in rabbits and embolized with control platinum coils (Axium; Medtronic) (n=6) or coils seeded ex vivo with autologous adipose-tissue MSCs (n=7).

Increased X-ray Visualization of Shape Memory Polymer Foams by Chemical Incorporation of Iodine Motifs.

Shape memory polymers can be programmed into a secondary geometry and recovered to their primary geometry with the application of a controlled stimulus. Porous shape memory polymer foam scaffolds that respond to body temperature show particular promise for embolic medical applications. A limitation for the minimally invasive delivery of these materials is an inherent lack of X-ray contrast.

Concomitant aneurysm detection in an intracranial dolichoectasia mouse model using a MicroFil polymer perfusion technique.

Objective: To assess the feasibility of using MicroFil polymer perfusion to detect concomitant saccular aneurysms in an intracranial arterial dolichoectasia (IADE) model in mice, and to report detailed histomorphometric features of these aneurysms.

Materials And Methods: IADE models were created in C57/BL6 mice via microsurgical injection of 25 mU elastase into the cisterna magna. The cerebral vasculature was perfused with MicroFil polymer and harvested at 1, 3, and 7 days, and 2 and 4 weeks (n=8 for each group).

Concomitant coiling reduces metalloproteinase levels in flow diverter-treated aneurysms but anti-inflammatory treatment has no effect.

Background And Purpose: Flow diverters (FD) can cause rare but devastating delayed aneurysm ruptures in which matrix metalloproteinases (MMPs) have been potentially implicated. Concomitant coiling or anti-inflammatory medications have been proposed to prevent the risk of delayed ruptures. The aim of this study was to evaluate concomitant coiling and ciclosporin in regulating the expression of MMPs in FD-treated aneurysms.

Statins are not associated with short-term improved aneurysm healing in a rabbit model of unruptured aneurysms.

Background: Owing to their anti-inflammatory effects and ability to stimulate production of extracellular matrix and chemotactic migration of mesenchymal progenitor cells, statins could potentially improve aneurysm healing after endovascular treatment.

Objective: To test the hypothesis that systemic administration of simvastatin would improve aneurysm healing in a rabbit model of unruptured intracranial aneurysms.

Methods: Experimental aneurysms were created in female rabbits and were embolized with platinum coils.

Experimental testing of the dual-layer Woven EndoBridge device using an elastase-induced aneurysm model in rabbits.

The dual-layer Woven EndoBridge (WEB) device (WEB II) is designed to improve the performance of the first-generation WEB device. This study was performed to evaluate the acute and chronic performance of WEB II for aneurysm occlusion in an elastase-induced aneurysm model in rabbits. We implanted WEB II devices in 36 elastase-induced aneurysms and followed up for one, three, six, and 12 months.

Histopathological findings following pipeline embolization in a human cerebral aneurysm at the basilar tip.

We report histopathological findings from a human cerebral aneurysm following treatment with a flow diverter. A 75-year-old male underwent flow diversion treatment (Pipeline Embolization Device (PED)) and coil embolization for treatment of an aneurysm at the basilar tip. At four months, angiography showed complete aneurysm occlusion; at 12 months angiography demonstrated that the aneurysm had reopened.

Characterizing patterns of endothelialization following coil embolization: a whole-mount, dual immunostaining approach.

Background: The extent, rate, and source of endothelialization following coil embolization of saccular aneurysms remains poorly understood. We performed a whole tissue mount, dual immunohistochemical analysis of experimental aneurysms to characterize the state of endothelialization over time after platinum coil embolization.

Method And Material: Elastase-induced rabbit aneurysms were created and treated with bare platinum coils.

Elastase-induced intracranial dolichoectasia model in mice.

Background: Intracranial dolichoectasia is associated with high morbidity, and its pathophysiology remains poorly understood.

Objective: To develop a technique for the creation of a murine model of dolichoectasia.

Methods: C57/BL6 mice were injected with 0 milliunit (mu) (control, n = 5), 15 mu (n = 7), 25 mu (n = 10), 35 mu (n = 10), and 55 mu (n = 6) of elastase in the cisterna magna.

Relationship between aneurysm occlusion and flow diverting device oversizing in a rabbit model.

Background And Purpose: Implanted, actual flow diverter pore density is thought to be strongly influenced by proper matching between the device size and parent artery diameter. The objective of this study was to characterize the correlation between device sizing, metal coverage, and the resultant occlusion of aneurysms following flow diverter treatment in a rabbit model.

Methods: Rabbit saccular aneurysms were treated with flow diverters (iso-sized to proximal parent artery, 0.

Gene expression comparison of flow diversion and coiling in an experimental aneurysm model.

Background And Purpose: Mechanisms of both healing and complications, including spontaneous aneurysm rupture, remain unclear following flow diverter treatment. The aim of this study was to compare gene expression of various key molecules involved in the healing of aneurysms, between aneurysms treated with microcoils and flow diverters.

Methods: Saccular aneurysms were created in rabbits.

Strategy for analysis of flow diverting devices based on multi-modality image-based modeling.

Quantification and characterization of the hemodynamic environment created after flow diversion treatment of cerebral aneurysms is important to understand the effects of flow diverters and their interactions with the biology of the aneurysm wall and the thrombosis process that takes place subsequently. This paper describes the construction of multi-modality image-based subject-specific CFD models of experimentally created aneurysms in rabbits and subsequently treated with flow diverters. Briefly, anatomical models were constructed from 3D rotational angiography images, flow conditions were derived from Doppler ultrasound measurements, stent models were created and virtually deployed, and the results were compared with in vivo digital subtraction angiography and Doppler ultrasound images.

Cellular mechanisms of aneurysm occlusion after treatment with a flow diverter.

Purpose: To characterize the progression of healing across aneurysm necks following treatment with a flow diverter in a rabbit aneurysm model.

Materials And Methods: With institutional animal care and use committee approval, saccular aneurysms were created in 20 rabbits and treated with flow diverters. On days 1, 3, and 7 and weeks 4 and 8 after implantation, the aneurysm and the device-implanted vessel were harvested.