Establishment of a Reproducible Ischemic Stroke Model in Nestin-GFP Mice with High Survival Rates

An accumulation of evidence shows that endogenous neural stem/progenitor cells (NSPCs) are activated following brain injury such as that suffered during ischemic stroke. To understand the expression patterns of these cells, researchers have developed mice that express an NSPC marker, Nestin, which is detectable by specific reporters such as green fluorescent protein (GFP), i.e., Nestin-GFP mice. However, the genetic background of most transgenic mice, including Nestin-GFP mice, comes from the C57BL/6 strain. Because mice from this background strain have many cerebral arterial branches and collateral vessels, they are accompanied by several major problems including variable ischemic areas and high mortality when subjected to ischemic stroke by occluding the middle cerebral artery (MCA). In contrast, CB-17 wild-type mice are free from these problems. Therefore, with the aim of overcoming the aforementioned defects, we first crossed Nestin-GFP mice (C57BL/6 background) with CB-17 wild-type mice and then developed Nestin-GFP mice (CB-17 background) by further backcrossing the generated hybrid mice with CB-17 wild-type mice. Subsequently, we investigated the phenotypes of the established Nestin-GFP mice (CB-17 background) following MCA occlusion; these mice had fewer blood vessels around the MCA compared with the number of blood vessels in Nestin-GFP mice (C57BL/6 background). In addition, TTC staining showed that infarcted volume was variable in Nestin-GFP mice (C57BL/6 background) but highly reproducible in Nestin-GFP mice (CB-17 background). In a further investigation of mice survival rates up to 28 days after MCA occlusion, all Nestin-GFP mice (CB-17 background) survived the period, whereas Nestin-GFP mice (C57BL/6 background) frequently died within 1 week and exhibited a higher mortality rate. Immunohistochemistry analysis of Nestin-GFP mice (CB-17 background) showed that GFP⁺ cells were mainly obverted in not only conventional neurogenic areas, including the subventricular zone (SVZ), but also ischemic areas. In vitro, cells isolated from the ischemic areas and the SVZ formed GFP⁺ neurosphere-like cell clusters that gave rise to various neural lineages including neurons, astrocytes, and oligodendrocytes. However, microarray analysis of these cells and genetic mapping experiments by Nestin-CreERT2 Line4 mice crossed with yellow fluorescent protein (YFP) reporter mice (Nestin promoter-driven YFP-expressing mice) indicated that cells with NSPC activities in the ischemic areas and the SVZ had different characteristics and origins. These results show that the expression patterns and fate of GFP⁺ cells with NSPC activities can be precisely investigated over a long period in Nestin-GFP mice (CB-17 background), which is not necessarily possible with Nestin-GFP mice (C57BL/6 background). Thus, Nestin-GFP mice (CB-17 background) could become a useful tool with which to investigate the mechanism of neurogenesis via the aforementioned cells under pathological conditions such as following ischemic stroke.

3D Image Analysis of the Complete Ventricular-Subventricular Zone Stem Cell Niche Reveals Significant Vasculature Changes and Progenitor Deficits in Males Versus Females with Aging

With age, neural stem cell (NSC) function in the adult ventricular-subventricular zone (V-SVZ) declines, reducing memory and cognitive function in males; however, the impact on females is not well understood. To obtain a global view of how age and sex impact the mouse V-SVZ, we constructed 3D montages after multiplex immunostaining, and used computer-based 3D image analysis to quantify data across the entire niche at 2, 18, and 22 months. We discovered dramatic sex differences in the aging of the V-SVZ niche vasculature, which regulates NSC activity: females showed increased diameter but decreased vessel density with age, while males showed decreased diameter and increased tortuosity and vessel density. Accompanying these vascular changes, males showed significant decline in NSC numbers, progenitor cell proliferation, and more disorganized migrating neuroblast chains with age; however, females did not. By examining the entire 3D niche, we found significant sex differences, with females being relatively spared through very old age.

S phase entry of neural progenitor cells correlates with increased blood flow in the young subventricular zone

The postnatal subventricular zone (SVZ) contains proliferating neural progenitor cells in close proximity to blood vessels. Insults and drug treatments acutely stimulate cell proliferation in the SVZ, which was assessed by labeling cells entering S phase. Although G1-to-S progression is metabolically demanding on a minute-to-hour time scale, it remains unknown whether increased SVZ cell proliferation is accompanied by a local hemodynamic response. This neurovascular coupling provides energy substrates to active neuronal assemblies. Transcardial dye perfusion revealed the presence of capillaries throughout the SVZ that constrict upon applications of the thromboxane A₂ receptor agonist U-46119 in acute brain slice preparations. We then monitored in vivo blood flow using laser Doppler flowmetry via a microprobe located either in the SVZ or a mature network. U-46119 injections into the lateral ventricle decreased blood flow in the SVZ and the striatum, which are near the ventricle. A 1-hour ventricular injection of epidermal and basic fibroblast growth factor (EGF and bFGF) significantly increased the percentage of Sox2 transcription factor-positive cells in S phase 1.5 hours post-injection. This increase was accompanied by a sustained rise in blood flow in the SVZ but not in the striatum. Direct growth factor injections into the cortex did not alter local blood flow, ruling out direct effects on capillaries. These findings suggest that an acute increase in the number of G1-to-S cycling SVZ cells is accompanied by neurometabolic-vascular coupling, which may provide energy and nutrient for cell cycle progression.

The variations of the anterior choroidal artery: an intraoperative study

AIM

Increasing use of surgical magnification for operations in the territory of the anterior choroidal artery (AChA) has created a need for detailed knowledge of their anatomical variations. The aim of the present study is to examine the anatomical variations of the AChAin patients operated via pterional approach.

MATERIAL AND METHODS

The origin and branching pattern of AChAs were observed intraoperatively in 130 patients who were operated via a pterional approach at our center.

RESULTS

AChAs arose from the internal carotid artery (ICA) and distal to the posterior communicating artery (PCoA) at a ratio of 70%, from just distal to the original point of the PCoA in 20%, and from just proximal to the ICA bifurcation in 10% of the patients. In 95 cases, AChAs arose from the inferolateral aspect of the ICA in the posterolateral aspect in 27 and from its lateral part in 8 cases. AChAs were found as a single branch at the origins from ICA in 110 patients, as double in 17 cases and as triple in 3 patients.

CONCLUSION

Recognition of anatomical variations and microvascular relationships of AChA will allow neurosurgeons to construct a better and safer microdissection plan, to save time and can prevent postoperative neurological deficits.

Intraventricular haemorrhage caused by the rupture of a dural arteriovenous malformation of the middle cranial fossa

Dural arteriovenous malformations of the middle cranial fossa are very rare. Venous drainage flows either through superficial leptomeningeal veins or through the sphenoparietal, sphenopetrous and/or sphenobasilar sinuses. They often have an aggressive course and therefore poor outcome. It is essential to analyse and understand the angioarchitecture of the dural arteriovenous malformations in order to select and plan the correct treatments. We describe an exceptional case of intraventricular haemorrhage caused by the rupture of a dural arteriovenous malformation of the middle cranial fossa. To our knowledge, this is the first case report of such characteristics described in the literature.

Arterial supply and venous drainage of the choroid plexus of the human lateral ventricle in the prenatal period as revealed by vascular corrosion casts and SEM

The topography of the arterial supply and venous drainage was visualised by corrosion casting and scanning electron microscopy in the human foetal (20 weeks) choroid plexus of the lateral ventricle. Although secondary villi were not yet present at that developmental stage, the topography of the large arteries and veins almost fully corresponded to that described in adult individuals. The only major difference observed was a lack of the typical tortuosity of the lateral branch of the anterior choroidal artery and of the superior choroidal vein, which probably develops during further expansion of the vascular system associated with the formation of secondary villi.

Intraventricular meningioma with fatal haemorrhage: clinical and autopsy findings

Only a few cases of intraventricular meningioma have been reported and the association with intracranial haemorrhage is even rarer. More than ever, autopsy findings are scarce. Here, we report a case of primary intraventricular meningioma with intraventricular haemorrhage in a 57-year-old woman. A CT scan of the head initially suggested a malignant brain tumour as the lesion was quite inhomogeneous with hyper- and hypodense sections accompanied by fresh haemorrhage. At autopsy, the tumour was histologically diagnosed as a fibroblastic meningioma WHO-Grade I. The source of haemorrhage was most likely the tumour itself as it contained focally rather large angiomatous and additionally small cavernous vessels and acute haemorrhage in various sections. The assumptive adherence of the tumour to the choroid plexus was probably disrupted by the haematoma.

Description of Endoscopic Ventricular Anatomy in Myelomeningocele

OBJECTIVE

The purpose of this work is to present our endoscopic neuroanatomical findings of a series of myelomeningocele and hydrocephalus patients, treated with endoscopic third ventricular cisternostomy (ETVC), in order to describe ventricular configuration abnormalities in this group of patients, in which this neurosurgical procedure has limited performance.

METHOD

We checked the videos of 10 endoscopic third ventricular cisternostomies of myelomeningocele patients taken during 24 months as from December 1998. A previous guideline is designed to record anatomic variables in the lateral ventricles, IIIrd ventricle, and basal cisterns. The topic is analyzed in view of the necropsy and imaging background data.

RESULTS

The ETVC of lateral ventricles showed: absence of septum (9/10); absence of anteroseptal vein (8/10); absence of choroid plexus and thalamostriate vein (0/10); absence of fornix (1/10): small foramen of Monro (4/10). The ETVC of the IIIrd ventricle showed: impossibility of recognizing any mammillary bodies (4/10); presence of septations (5/10); presence of atypical veins in the floor (6/10); translucent floor (5/10); floor umbilications (5/10); absence of infundibulum (4/10); arachnoid adherences (7/10); and visual contact of basilar artery (4/10).

CONCLUSION

There are categorical structural alterations in the ventricular system of myelomeningocele patients that are well correlated with previous necropsy and imaging reports. The ventricular system of dysraphic children presents severe anatomic alterations, which alter the reference points of the classical endoscopic third ventricular cisternostomy.

Surgical approaches to the atrium of the lateral ventricle: microsurgical anatomy

BACKGROUND

Managing lesions situated in the atrium of the lateral ventricle remains a challenging neurosurgical problem. The purposes of this study were to examine the microsurgical anatomy of the atrium of the lateral ventricle and the optic radiation and to define the differences in the exposure obtained by various surgical approaches.

METHODS

Fifteen adult cadaveric specimens were studied using magnification x3 to x40 after perfusion of the arteries and veins with colored silicone. The microsurgical anatomy of the atrium of the lateral ventricle was examined. The relationship between the optic radiation and the atrium was studied using the white matter fiber dissection technique. Surgical approaches to the atrium of the lateral ventricle were examined in stepwise dissection.

RESULTS

The medial and inferior walls of the atrium were free from optic radiation fibers. Surgical approaches to the atrium of the lateral ventricle are divided into 3 routes: (1) anterior approach: transsylvian approach, (2) posterior approaches: posterior transcortical, posterior transcallosal, occipital, and supracerebellar transtentorial approaches, and (3) lateral approaches: transtemporal and subtemporal approaches.

CONCLUSION

Knowledge of the microsurgical anatomy of the atrium of the lateral ventricle and surrounding vital structures and the choice of an appropriate surgical approach will help surgeons perform safe and minimally invasive surgery.

Vascular changes in the subventricular zone after distal cortical lesions

One of the effects of cortical lesions is to produce cell proliferation in the subventricular zone (SVZ), a neurogenic zone of the adult brain distal from the lesion. The mechanisms of these effects are unknown. Recent evidence points to a relationship between the vasculature and neurogenesis both in vitro and in vivo. In the present study, we asked whether cortical lesions induced vascular modifications in the distal SVZ in vivo. Lesions of the frontoparietal cortex were produced by thermocoagulation of pial blood vessels, a method that leads to highly reproducible loss of all cortical layers, sparing the corpus callosum and underlying striatum. These lesions induced increased immunoreactivity for vascular endothelial growth factor (VEGF) around the walls of SVZ vessels, at a considerable distance from the lesion. Vascular permeability was markedly increased in both the SVZ and RMS by 3 days after the injury. A dramatic increase in endothelial proliferation was followed by expansion of the local SVZ vascular tree 7 days after the injury. This time course corresponded to the proliferative changes in the SVZ, and a tight correlation was observed between the number of blood vessels and the increase in SVZ cell number. The data demonstrate that thermocoagulatory cortical lesions induce distal vascular changes that could play a role in lesion-induced SVZ expansion.

Microanatomy of the subependymal arteries of the lateral ventricle

BACKGROUND

Scarce information about the anatomy of the subependymal arteries (SEAs) is present in the scientific literature.

METHODS

Twenty cerebral hemispheres with injected arteries were microdissected, and the magnetic resonance imaging scans of 100 patients with lacunar infarcts were examined.

RESULTS

The SEAs were found to range in diameter from 40 to 490 microm (mean, 149 microm) and in number between 3 and 12 (average, 5.2). Of these, numbers from 1 to 3 originated from the anterior choroidal artery (AChA), between 1 and 10 from the lateral posterior choroidal artery (LPChA), 1 from the medial posterior choroidal artery (MPChA), and 1 from the internal carotid artery. The SEAs most often arose from the choroidal branches (90%) and less frequently from the thalamic (30%), caudate (35%), or thalamocaudate twigs (20%). The SEAs of the AChA supplied the walls of the temporal horn (100%), the occipital horn (85%), and the atrium (35%). Those of the LPChA perfused the walls of the occipital horn (15%), the atrium (65%), the body of the ventricle (100%), and partially the frontal horn. The SEAs of the MPChA partially nourished the body and the frontal horn (10%). The SEAs may also occasionally supply the caudate nucleus (20%) and the stria terminalis. The anastomoses involving the SEAs were absent. In spite of this, ischemia in the territory of a single SEA was noticed in only 1% of our patients.

CONCLUSIONS

The SEAs are tiny vessels that supply the walls of the lateral ventricle, as well as the caudate nucleus and the stria terminalis occasionally. The obtained anatomic data can have important neurosurgical implications in intraventricular operations.