A small animal model for early cerebral aneurysm pathology

The composition of landmark vein of Galen malformation research: the emergence of endovascular treatments

BACKGROUND

Since the advent of endovascular treatment, the long-term prognosis of vein of Galen malformation (VOGM) has markedly improved; however, the nature of research leading to this point is unclear. The objective of this study was to define the composition of VOGM research to date, by means of a bibliometric analysis of the 100 most cited VOGM articles.

METHODS

An electronic search of Elsevier's Scopus database was performed to identify the 100 most cited articles on VOGM screened against predetermined criteria. Data were then compared.

RESULTS

The 100 most cited VOGM articles were published between 1974 and 2017 in 38 unique journals and originated from 16 unique countries. Mean citation count and rate were 59.4 citations and 2.9 citations/year, respectively. The USA (n = 42); Hôpital de Bicêtre, France (n = 15); and Dr. Pierre Lasjaunias (n = 16) were the largest individual country, institutional, and author contributors. Compared to the older articles (published < 2000), key differences for newer articles were statistically higher citation rates (P < 0.01), more authors (P < 0.01), higher proportion of endovascular treatment descriptions (P = 0.01), and more originating from Asia Pacific (P < 0.01).

CONCLUSIONS

From the 100 most cited VOGM articles to date, there has been a noticeable shift from diagnosing VOGM based on the foundational work by Dr. Lasjaunias to understanding how we can model clinical outcomes now that endovascular treatment has become the standard of care. Significant shifts in prognosis are pending, and the current bibliometric data implicate we are on the precipice of more recent works making an impact in the near future.

Identification and Validation of TREM2 in Intracranial Aneurysms

Background: Intracranial aneurysm (IA) is a cerebrovascular disease that seriously endangers human heath and life. However, the pathogenesis of IA has not been clarified. Objective: In this study, we explored the role of the triggering receptor expressed on myeloid cells-2 (TREM2) gene to explore a novel mechanism underlying IA. Methods: First, we verified the role of the candidate gene, TREM2 in a modified mouse model of IA. Second, we verified elevated expression of TREM2 using the Gene Expression Omnibus (GEO) database (GSE54083 and GSE75436) and developed protein interaction (PPI) network analysis using the top one hundred DEGs from GSE75436 dataset. Finally, we predicted a likely mechanism by which TREM2 is involved in the pathology of IA using single-gene Gene Set Enrichment Analysis (GSEA). Results: The expression of TREM2 and inflammatory factors was significantly increased in the modified mouse IA model, and showed a positive correlation. Elevated expression of TREM2 was also found in IA patients tissues from the GSE54083 and GSE75436 data sets. PPI network analyses suggested that the DEGs were involved in a variety of inflammatory processes. The GSEA results suggest that TREM2 may participate in IA progression by regulating macrophage function. Conclusion: TREM2 is highly expressed in both human and mouse IA tissues, and may participate in IA progression by regulating macrophage function and inflammatory factor expression. The molecular mechanism of TREM2 involvement in the IA process can be further studied using our modified mouse IA model.

Endogenous animal models of intracranial aneurysm development: a review

The pathogenesis and natural history of intracranial aneurysm (IA) remains poorly understood. To this end, animal models with induced cerebral vessel lesions mimicking human aneurysms have provided the ability to greatly expand our understanding. In this review, we comprehensively searched the published literature to identify studies that endogenously induced IA formation in animals. Studies that constructed aneurysms (i.e., by surgically creating a sac) were excluded. From the eligible studies, we reported information including the animal species, method for aneurysm induction, aneurysm definitions, evaluation methods, aneurysm characteristics, formation rate, rupture rate, and time course. Between 1960 and 2019, 174 articles reported endogenous animal models of IA. The majority used flow modification, hypertension, and vessel wall weakening (i.e., elastase treatment) to induce IAs, primarily in rats and mice. Most studies utilized subjective or qualitative descriptions to define experimental aneurysms and histology to study them. In general, experimental IAs resembled the pathobiology of the human disease in terms of internal elastic lamina loss, medial layer degradation, and inflammatory cell infiltration. After the early 2000s, many endogenous animal models of IA began to incorporate state-of-the-art technology, such as gene expression profiling and 9.4-T magnetic resonance imaging (MRI) in vivo imaging, to quantitatively analyze the biological mechanisms of IA. Future studies aimed at longitudinally assessing IA pathobiology in models that incorporate aneurysm growth will likely have the largest impact on our understanding of the disease. We believe this will be aided by high-resolution, small animal, survival imaging, in situ live-cell imaging, and next-generation omics technology.

Preclinical Intracranial Aneurysm Models: A Systematic Review

Intracranial aneurysms (IA) are characterized by weakened cerebral vessel walls that may lead to rupture and subarachnoid hemorrhage. The mechanisms behind their formation and progression are yet unclear and warrant preclinical studies. This systematic review aims to provide a comprehensive, systematic overview of available animal models for the study of IA pathobiology. We conducted a systematic literature search using the PubMed database to identify preclinical studies employing IA animal models. Suitable articles were selected based on predefined eligibility criteria following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Included studies were reviewed and categorized according to the experimental animal and aneurysm model. Of 4266 returned results, 3930 articles were excluded based on the title and/or abstract and further articles after screening the full text, leaving 123 studies for detailed analysis. A total of 20 different models were found in rats (nine), mice (five), rabbits (four), and dogs (two). Rat models constituted the most frequently employed intracranial experimental aneurysm model (79 studies), followed by mice (31 studies), rabbits (12 studies), and two studies in dogs. The most common techniques to induce cerebral aneurysms were surgical ligation of the common carotid artery with subsequent induction of hypertension by ligation of the renal arteries, followed by elastase-induced creation of IAs in combination with corticosterone- or angiotensin-induced hypertension. This review provides a comprehensive summary of the multitude of available IA models to study various aspects of aneurysm formation, growth, and rupture. It will serve as a useful reference for researchers by facilitating the selection of the most appropriate model and technique to answer their scientific question.

Association between surgical repair of aortic aneurysms and the diagnosis of intracranial aneurysms

OBJECTIVE

Aortic aneurysms (AAs) and intracranial aneurysms (IAs) share several clinical risk factors, a genetic predisposition, and molecular signaling pathways. Nonetheless, associations between IAs and AAs remain to be thoroughly validated in large-scale studies. In addition, no effective medical therapies exist for unruptured IAs or AAs.

METHODS

Data for this nationwide, population-based, retrospective, cohort study described herein were obtained from the National Health Insurance Research Database in Taiwan. The study outcomes assessed were (1) the cumulative incidence of IAs, which was compared between AA and patients without an AA and (2) the cumulative incidence of IAs in patients with AAs during the 13-year follow-up period, which was further compared among those who underwent open surgical repair (OSR), endovascular aneurysm repair or nonsurgical treatment (NST).

RESULTS

Our analyses included 20,280 patients with an AA and 20,280 propensity score-matched patients without an AA. Compared with the patients without an AA, patients with AA exhibited a significantly increased risk of an IA diagnosis (adjusted hazard ratio [HR], 3.395; P < .001). Furthermore, 6308 patients with AAs were treated with surgical intervention and another 6308 propensity score-matched patients with AAs were not. Patients with an AA who underwent OSR had a significantly lower risk of being diagnosed with an IA than patients with an AA who underwent endovascular aneurysm repair or NST (adjusted HR, 0.491 [P < .001] and adjusted HR, 0.473 [P < .001], respectively).

CONCLUSIONS

We demonstrated an association between IAs and AAs, even after adjusting for several comorbidities. We also found that OSR was associated with fewer recognized IAs than NST.