Localized conditional induction of brain arteriovenous malformations in a mouse model of hereditary hemorrhagic telangiectasia

BACKGROUND

Longitudinal mouse models of brain arteriovenous malformations (AVMs) are crucial for developing novel therapeutics and pathobiological mechanism discovery underlying brain AVM progression and rupture. The sustainability of existing mouse models is limited by ubiquitous Cre activation, which is associated with lethal hemorrhages resulting from AVM formation in visceral organs. To overcome this condition, we developed a novel experimental mouse model of hereditary hemorrhagic telangiectasia (HHT) with CreER-mediated specific, localized induction of brain AVMs.

METHODS

Hydroxytamoxifen (4-OHT) was stereotactically delivered into the striatum, parietal cortex, or cerebellum of R26CreER; Alk12f/2f (Alk1-iKO) littermates. Mice were evaluated for vascular malformations with latex dye perfusion and 3D time-of-flight magnetic resonance angiography (MRA). Immunofluorescence and Prussian blue staining were performed for vascular lesion characterization.

RESULTS

Our model produced two types of brain vascular malformations, including nidal AVMs (88%, 38/43) and arteriovenous fistulas (12%, 5/43), with an overall frequency of 73% (43/59). By performing stereotaxic injection of 4-OHT targeting different brain regions, Alk1-iKO mice developed vascular malformations in the striatum (73%, 22/30), in the parietal cortex (76%, 13/17), and in the cerebellum (67%, 8/12). Identical application of the stereotaxic injection protocol in reporter mice confirmed localized Cre activity near the injection site. The 4-week mortality was 3% (2/61). Seven mice were studied longitudinally for a mean (SD; range) duration of 7.2 (3; 2.3-9.5) months and demonstrated nidal stability on sequential MRA. The brain AVMs displayed microhemorrhages and diffuse immune cell invasion.

CONCLUSIONS

We present the first HHT mouse model of brain AVMs that produces localized AVMs in the brain. The mouse lesions closely resemble the human lesions for complex nidal angioarchitecture, arteriovenous shunts, microhemorrhages, and inflammation. The model's longitudinal robustness is a powerful discovery resource to advance our pathomechanistic understanding of brain AVMs and identify novel therapeutic targets.

Safety and Efficacy of Stereotaxic Surgery Combined with Urokinase in the Treatment of Ventricular Hemorrhage: A Retrospective Propensity-Matched Score Analysis

BACKGROUND

Intraventricular hemorrhage (IVH) is a severe and devastating stroke. Research on existing treatment options has been controversial. Therefore, we aimed to evaluate the safety and efficacy of minimally implanted stereotactic puncture combined with urokinase (uPA) in the treatment of IVH.

METHODS

The clinical data of 122 IVH patients admitted to our department from 2018 to 2022 were retrospectively analyzed. According to the modified RanKin score (mRS) after 30 days, the patients were divided into good prognosis (mRS 0-3) and poor prognosis (mRS 4-6), and the factors affecting the prognosis were screened by univariate and multivariate analysis, and then the tendency Score matching and paired patient screening were performed for comparative analysis between uPA and non-uPA groups.

RESULTS

Patients' age, uPA usage, initial Glasgow Coma Scale and primary blood volume all could affect the mRS score of patients. One hundred patients were finally included, including 50 cases in the uPA group and 50 cases in the non-uPA group. The analysis showed that at follow-up after 30 days, 46.0% of the patients in the uPA group and 28.0% in the non-uPA group had an mRS score of 0-3; however, they were not statistically significantly different. The postoperative hematoma clearance rate in the uPA group was significantly higher than that in the non-uPA group (P < 0.001), and the incidence of postoperative complications was not increased (P > 0.05).

CONCIUSIONS

uPA treatment can improve the treatment efficiency. However, its effect in improving patient outcomes does not appear to be significant.

Pinealectomy in Rats

The pinealectomy technique consists of the surgical removal of the superficial pineal gland. This procedure allows the ablation of circulating indoles produced by this gland. Withdrawal of systemic melatonin, a pineal hormone, affects animal circadian rhythms and induces several physiological changes that are the subject of many investigations. In this chapter, we describe the pinealectomy protocol adapted to rats. We describe the animal placement on the stereotaxic fixation system, and the procedure for the pineal gland removal and animal recovery from surgery.

Ratlas-LH: An MRI template of the Lister hooded rat brain with stereotaxic coordinates for neurosurgical implantations

There is currently no brain atlas available to specifically determine stereotaxic coordinates for neurosurgery in Lister hooded rats despite the popularity of this strain for behavioural neuroscience studies in the United Kingdom and elsewhere. We have created a dataset, which we refer to as ‘Ratlas-LH’ (for Lister hooded). Ratlas-LH combines in vivo magnetic resonance images of the brain of young adult male Lister hooded rats with ex vivo micro-computed tomography images of the ex vivo skull, as well as a set of delineations of brain regions, adapted from the Waxholm Space Atlas of the Sprague Dawley Rat Brain. Ratlas-LH was produced with an isotropic resolution of 0.15 mm. It has been labelled in such a way as to provide a stereotaxic coordinate system for the determination of distances relative to the skull landmark of bregma. We have demonstrated that the atlas can be used to determine stereotaxic coordinates to accurately target brain regions in the Lister hooded rat brain. Ratlas-LH is freely available to facilitate neurosurgical procedures in the Lister hooded rat.

A comprehensive macaque fMRI pipeline and hierarchical atlas

Functional neuroimaging research in the non-human primate (NHP) has been advancing at a remarkable rate. The increase in available data establishes a need for robust analysis pipelines designed for NHP neuroimaging and accompanying template spaces to standardize the localization of neuroimaging results. Our group recently developed the NIMH Macaque Template (NMT), a high-resolution population average anatomical template and associated neuroimaging resources, providing researchers with a standard space for macaque neuroimaging . Here, we release NMT v2, which includes both symmetric and asymmetric templates in stereotaxic orientation, with improvements in spatial contrast, processing efficiency, and segmentation. We also introduce the Cortical Hierarchy Atlas of the Rhesus Macaque (CHARM), a hierarchical parcellation of the macaque cerebral cortex with varying degrees of detail. These tools have been integrated into the neuroimaging analysis software AFNI to provide a comprehensive and robust pipeline for fMRI processing, visualization and analysis of NHP data. AFNI's new @animal_warper program can be used to efficiently align anatomical scans to the NMT v2 space, and afni_proc.py integrates these results with full fMRI processing using macaque-specific parameters: from motion correction through regression modeling. Taken together, the NMT v2 and AFNI represent an all-in-one package for macaque functional neuroimaging analysis, as demonstrated with available demos for both task and resting state fMRI.

Optogenetic Stimulation of the Central Amygdala Using Channelrhodopsin

Optogenetics allows for the targeted temporary inhibition or stimulation of specific brain regions in vivo with precise temporal resolution. Here, we describe the steps to perform intracranial optogenetic surgery in rodents as well as instructions to build an optogenetic headcap and set up an optogenetic testing environment to conduct experiments. Behavioral studies have implemented these methods to stimulate the central amygdala (CeA) to create an addictive-like preference for reward.

Method and Apparatus for the Automated Delivery of Continuous Neural Stem Cell Trails Into the Spinal Cord of Small and Large Animals

BACKGROUND

Immature neurons can extend processes after transplantation in adult animals. Neuronal relays can form between injected neural stem cells (NSCs) and surviving neurons, possibly improving recovery after spinal cord injury (SCI). Cell delivery methods of single or multiple bolus injections of concentrated cell suspensions thus far tested in preclinical and clinical experiments are suboptimal for new tract formation. Nonuniform injectate dispersal is often seen due to gravitational cell settling and clumping. Multiple injections have additive risks of hemorrhage, parenchymal damage, and cellular reflux and require additional surgical exposure. The deposition of multiply delivered cells boluses may be uneven and discontinuous.

OBJECTIVE

To develop an injection apparatus and methodology to deliver continuous cellular trails bridging spinal cord lesions.

METHODS

We improved the uniformity of cellular trails by formulating NSCs in hyaluronic acid. The TrailmakerTM stereotaxic injection device was automatized to extend a shape memory needle from a single-entry point in the spinal cord longitudinal axis to "pioneer" a new trail space and then retract while depositing an hyaluronic acid-NSC suspension. We conducted testing in a collagen spinal models, and animal testing using human NSCs (hNSCs) in rats and minipigs.

RESULTS

Continuous surviving trails of hNSCs within rat and minipig naive spinal cords were 12 and 40 mm in length. hNSC trails were delivered across semi-acute contusion injuries in rats. Transplanted hNSCs survived and were able to differentiate into neural lineage cells and astrocytes.

CONCLUSION

The TrailmakerTM creates longitudinal cellular trails spanning multiple levels from a single-entry point. This may enhance the ability of therapeutics to promote functional relays after SCI.

An improved protocol to establish experimental tuberculous meningitis in the rabbit

Tuberculous meningitis (TBM), caused by Mycobacterium tuberculosis (Mtb), is the deadliest form of tuberculosis in humans, particularly in children and the geriatric population. However, the host-pathogen interactions underlying TBM is not well understood. Rabbits are a valuable model system to study TB in humans. The rabbit model of TB recapitulates several pathophysiological characteristics, including heterogeneity, architecture, and development of granulomas at the site of infection as observed in Mtb-infected human organs. Previously, our group has established a rabbit model of TBM that has been used to understand the host immune response to Mtb infection and to evaluate novel intervention therapies for TBM. In this model, rabbits infected intracisternally with Mtb showed histopathologic manifestations in the brain and meninges that are hallmarks of TBM in humans, including inflammatory cell accumulation and thickening of the leptomeninges. However, in this model, a helmet made of dental acrylic was attached to rabbit's skull with screws under anesthesia. At 24 h post-procedure, the animals were injected intracisternally with Mtb using a spinal needle. The rabbits were necropsied at various experimental time points up to 2 weeks post-infection. Although this method has been successful in establishing TBM, placement of the dental acrylic helmet on rabbit skull with screws that stays until the experimental endpoint poses stress to the animals and increases the chances of secondary infection. To alleviate these issues, we have developed an improved protocol, in which sedated rabbits are placed on specialised stereotaxic equipment and injected with Mtb intracisternally. This method is less cumbersome, faster, and more efficient in delivering the bacteria. Besides, the animals are not stressed by this method, compared to the previous one.

Stereotaxic Targeting of Alpha-Synuclein Pathology in Mouse Brain Using Preformed Fibrils

The accumulation of intraneuronal inclusions containing misfolded alpha-synuclein (aSyn) within the central nervous system (CNS) is a common feature found in several neurodegenerative disorders including Parkinson's disease (PD). Emerging evidence indicates that aSyn amyloid fibrils, a configuration that is present within these characteristic inclusions, are capable of self-replicating by templating the conversion of endogenously expressed aSyn in neurons. Stereotaxic administration of synthetic α-synuclein preformed fibrils (PFFs) into the mouse brain has been shown to seed the formation of intracellular aSyn pathology reminiscent of Lewy body (LB) inclusions present in human PD and related synucleinopathies. Moreover, pathology can be targeted to specific CNS regions. This experimental approach provides a versatile platform for investigating PD-like LB pathology in vivo. We focus here on procedures for initiating aSyn inclusion formation at various regions of the mouse brain using computer-assisted motorized stereotaxic microinjection of aSyn PFFs and discuss appropriate strategies for controls and analysis.

Methodologic recommendations and possible interpretations of video-EEG recordings in immature rodents used as experimental controls: A TASK1-WG2 report of the ILAE/AES Joint Translational Task Force

The use of immature rodents to study physiologic aspects of cortical development requires high‐quality recordings electroencephalography (EEG) with simultaneous video recording (vEEG) of behavior. Normative developmental vEEG data in control animals are fundamental for the study of abnormal background activity in animal models of seizures or other neurologic disorders. Electrical recordings from immature, freely behaving rodents can be particularly difficult because of the small size of immature rodents, their thin and soft skull, interference with the recording apparatus by the dam, and other technical challenges. In this report of the TASK1 Working Group 2 (WG2) of the International League Against Epilepsy/American Epilepsy Society (ILAE/AES) Joint Translational Task Force, we provide suggestions that aim to optimize future vEEG recordings from immature rodents, as well as their interpretation. We focus on recordings from immature rodents younger than 30 days old used as experimental controls, because the quality and correct interpretation of such recordings is important when interpreting the vEEG results of animals serving as models of neurologic disorders. We discuss the technical aspects of such recordings and compare tethered versus wireless approaches. We also summarize the appearance of common artifacts and various patterns of electrical activity seen in young rodents used as controls as a function of behavioral state, age, and (where known) sex and strain. The information herein will hopefully help improve the methodology of vEEG recordings from immature rodents and may lead to results and interpretations that are more consistent across studies from different laboratories.

Computer-assisted stereotaxic navigation improves the accuracy of mechanical alignment and component positioning in total knee arthroplasty

INTRODUCTION

This study reports on a novel computer-assisted stereotaxic navigation (CASN) system that attempts to combine the accuracy of computer navigation with familiarity of conventional methods. We hypothesize that CASN would improve mechanical alignment and component positioning when compared to conventional instrumentation.

MATERIALS AND METHODS

145 patients (192 knees) retrospectively matched for age, BMI, gender and pre-operative scores, underwent total knee arthroplasty (TKA) using CASN (n = 92) or conventional instrumentation (n = 100). Pre- and post-operative radiological alignment [Acceptable ranges: mechanical axis (MA) 0° ± 3°, coronal femoral-component angle (CFA) and coronal tibia-component angle (CTA) 90° ± 3°] and clinical outcomes (Knee Society Scores, Oxford Knee Score and Short Form-36) at 6 months were examined.

RESULTS

The CASN group had significantly improved mean MA (1.9° ± 1.4°, versus 2.8° ± 2.0° in the conventional group, p = 0.001), CFA (1.6° ± 1.3°, versus 2.1° ± 1.5° in the conventional group, p = 0.035) and CTA (1.6° ± 1.2°, versus 2.1° ± 1.5° in the conventional group, p = 0.024). 91.3 % of knees in the CASN group were within 3° of a neutral mechanical axis, versus 74 % in the conventional group (p < 0.001). The duration of surgery was significantly longer in the CASN group (84 ± 22 vs 73 ± 15 min, p = 0.001) and cost an additional USD 850 per operation. There were no significant differences in clinical outcomes or satisfaction rates at 6 months post-operatively (p > 0.05).

CONCLUSIONS

CASN improved TKA mechanical alignment and component positioning, however, resulted in longer and costlier surgery with no benefits in short-term functional outcomes, despite providing familiarity to surgeons accustomed to conventional instrumentation.

LEVEL OF EVIDENCE

III.