Experimental investigation of encephalomyosynangiosis using gyrencephalic brain of the miniature pig: histopathological evaluation of dynamic reconstruction of vessels for functional anastomosis. Laboratory investigation

Affinity of structural white matter tracts between infant and adult pig

BACKGROUND

The piglet brain has been increasingly used as an excellent surrogate for investigation of pediatric neurodevelopment, nutrition, and traumatic brain injuries. This study intends to establish a piglet brain's structural connectivity model and compare it with the adult pig, enhancing its application for structurally guided functional analysis.

METHODS

In this study, diffusion-weighted (DW)-MRI data from piglets (n=11, 3-week-old) was used to establish piglet model and compare with adult pigs. We employed a data-driven independent component analysis (ICA) method to derive piglet-specific tracts. Pearson correlations and Kullback-Leibler (KL) divergences was employed to identify common tracts and unique tracts for piglet. Common tracts were then used in a blueprint connectome study to highlight differences in regions of interest (ROI).

RESULTS

The data-driven approach applied to piglet brains revealed 17 common tracts, showing high similarity with adult pigs' white matter (WM) tracts, and identified 3 tracts unique to piglets and 10 negative marker tracts. Additionally, the study highlighted notable differences in 3 ROIs associated with blueprint connectome.

COMPARING WITH EXISTING METHODS

This study marks a significant shift from surface-based to voxel-based methodologies in analyzing pig brain structural connectivity and generating connectome blueprints. Additionally, it sheds light on the use of the piglet model for developmental studies, offering new perspectives in this area.

CONCLUSION

This study established a piglet brain tract model and conducts a comparative analysis of adult pig's and piglet's structural connectivity. These findings underscore the potential use of the piglet brain model in employing piglet model for developmental studies.

Predictive value of the hemispheric magnetic resonance angiography score on the development of indirect pial synangiosis after combined revascularization surgery for adult moyamoya disease

PURPOSE

It is difficult to precisely predict indirect bypass development in the context of combined bypass procedures in moyamoya disease (MMD). We aimed to investigate the predictive value of magnetic resonance angiography (MRA) signal intensity in the peripheral portion of the major cerebral arteries for indirect bypass development in adult patients with MMD.

METHODS

We studied 93 hemispheres from 62 adult patients who underwent combined direct and indirect revascularization between 2005 and 2019 and genetic analysis for RNF213 p.R4810K. The signal intensity of the peripheral portion of the major intracranial arteries during preoperative MRA was graded as a hemispheric MRA score (0-3 in the middle cerebral artery and 0-2 in the anterior cerebral and posterior cerebral arteries, with a high score representing low visibility) according to each vessel's visibility. Postoperative bypass development was qualitatively evaluated using MRA, and we evaluated the correlation between preoperative factors, including the hemispheric MRA score and bypass development, using univariate and multivariate analyses.

RESULTS

A good indirect bypass was observed in 70% of the hemispheres. Hemispheric MRA scores were significantly higher in hemispheres with good indirect bypass development than in those with poor indirect bypass development (median: 3 vs. 1; p < 0.0001). Multiple logistic regression analysis revealed hemispheric MRA score as an independent predictor of good indirect bypass development (odds ratio, 2.1; 95% confidence interval, 1.3-3.6; p < 0.01). The low hemispheric MRA score (< 2) and wild-type RNF213 predicted poor indirect bypass development with a specificity of 0.92.

CONCLUSION

Hemispheric MRA score was a predictive factor for indirect bypass development in adult patients who underwent a combined bypass procedure for MMD. Predicting poor indirect bypass development may lead to future tailored bypass surgeries for MMD.

Future of Endovascular and Surgical Treatments of Atherosclerotic Intracranial Stenosis

Intracranial atherosclerotic disease and resultant intracranial stenosis is a global leading cause of stroke, and poses an ongoing treatment challenge. Among patients with intracranial stenosis, those with hemodynamic compromise are at high risk for recurrent stroke despite medical therapy and risk factor modification. Revascularization of the hypoperfused territory is the most plausible treatment strategy for these high-risk patients, yet surgical and endovascular therapies have not yet shown to be sufficiently safe and effective in randomized controlled trials. Advances in diagnostic and therapeutic technologies have led to a resurgence of interest in surgical and endovascular treatment strategies, with a growing body of evidence to support their further evaluation in the treatment of select patient populations. This review outlines the current and emerging endovascular and surgical treatments and highlights promising future management strategies.

Adult Moyamoya Disease and Syndrome: Current Perspectives and Future Directions: A Scientific Statement From the American Heart Association/American Stroke Association

Adult moyamoya disease and syndrome are rare disorders with significant morbidity and mortality. A writing group of experts was selected to conduct a literature search, summarize the current knowledge on the topic, and provide a road map for future investigation. The document presents an update in the definitions of moyamoya disease and syndrome, modern methods for diagnosis, and updated information on pathophysiology, epidemiology, and both medical and surgical treatment. Despite recent advancements, there are still many unresolved questions about moyamoya disease and syndrome, including lack of unified diagnostic criteria, reliable biomarkers, better understanding of the underlying pathophysiology, and stronger evidence for treatment guidelines. To advance progress in this area, it is crucial to acknowledge the limitations and weaknesses of current studies and explore new approaches, which are outlined in this scientific statement for future research strategies.

Proteome Profiling of the Dura Mater in Patients with Moyamoya Angiopathy

Moyamoya angiopathy (MMA) is an uncommon cerebrovascular disease characterized by a progressive steno-occlusive lesion of the internal carotid artery and the compensatory development of an unstable network of collateral vessels. These vascular hallmarks are responsible for recurrent ischemic/hemorrhagic strokes. Surgical treatment represents the preferred procedure for MMA patients, and indirect revascularization may induce a spontaneous angiogenesis between the brain surface and dura mater (DM), whose function remains rather unknown. A better understanding of MMA pathogenesis is expected from the molecular characterization of DM. We performed a comprehensive, label-free, quantitative mass spectrometry-based proteomic characterization of DM. The 30 most abundant identified proteins were located in the extracellular region or exosomes and were involved in extracellular matrix organization. Gene ontology analysis revealed that most proteins were involved in binding functions and hydrolase activity. Among the 30 most abundant proteins, Filamin A is particularly relevant because considering its well-known biochemical functions and molecular features, it could be a possible second hit gene with a potential role in MMA pathogenesis. The current explorative study could pave the way for further analyses aimed at better understanding such uncommon and disabling intracranial vasculopathy.

Association of RNF213 polymorphism and cortical hyperintensity sign on fluid-attenuated inversion recovery images after revascularization surgery for moyamoya disease: possible involvement of intrinsic vascular vulnerability

A cortical hyperintensity on fluid-attenuated inversion recovery images (FLAIR cortical hyperintensity (FCH)) is an abnormal finding after revascularization surgery for moyamoya disease. This study aimed to investigate the pathophysiology of FCH through genetic analyses of RNF213 p.R4810K polymorphism and perioperative hemodynamic studies using single-photon emission computed tomography. We studied 96 hemispheres in 65 adults and 47 hemispheres in 27 children, who underwent combined direct and indirect revascularization. Early or late FCH was defined when it was observed on postoperative days 0-2 and 6-9, respectively. FCH scores (range: 0-6) were evaluated according to the extent of FCH in the operated hemisphere. FCHs were significantly more prevalent in adult patients than pediatric patients (early: 94% vs. 78%; late: 97% vs. 59%). In pediatric patients, FCH scores were significantly improved from the early to late phase regardless of the RNF213 genotype (mutant median [IQR]: 2 [1-5] vs. 1 [0-2]; wild-type median: 4 [0.5-6] vs. 0.5 [0-1.75]). In adults, FCH scores were significantly improved in patients with the wild-type RNF213 allele (median: 4 [2-5.25] vs. 2 [2, 3]); however, they showed no significant improvement in patients with the RNF213 mutation. FCH scores were significantly higher in patients with symptomatic cerebral hyperperfusion than those without it (early median: 5 [4, 5] vs. 4 [2-5]; late median: 4 [3-5] vs. 3 [2-4]). In conclusion, the RNF213 p.R4810K polymorphism was associated with prolonged FCH, and extensive FCH was associated with symptomatic cerebral hyperperfusion in adult patients with moyamoya disease.

Outcomes after superficial temporal artery–middle cerebral artery anastomosis combined with multiple burr hole surgery and dural inversion synangiosis for moyamoya disease in adults

Objective

Several forms of cerebral revascularization have been carried out to treat moyamoya disease, however, the existing methods are accompanied by a variety of complications. In this study, the authors aimed to evaluate the clinical and angiographic outcomes of a new surgical procedure: superficial temporal artery–middle cerebral artery (STA-MCA) anastomosis combined with multiple burr hole (MBH) surgery and dural inversion synangiosis for the treatment of moyamoya disease in adults.

Methods

Patients treated for moyamoya disease from August 2019 to July 2021 were retrospectively reviewed. Clinical data, including perioperative complications and follow-up outcomes, were noted. Preoperative and postoperative angiograms were compared, and the diameters of the frontal branch of the superficial temporal artery (F-STA), the deep temporal artery (DTA), the distal superficial temporal artery (STA) before the bifurcation and the middle meningeal artery (MMA) were measured on preoperative and postoperative angiograms. Meanwhile, a Matsushima score was assigned from postoperative angiograms.

Results

This study included 66 patients (67 hemispheres). During the follow-up period, a median of 18 (IQR, 13–21) months, no stroke or death occurred in any of the patients. The clinical outcomes were excellent in 27 patients (40.9%), good in 34 patients (51.6%), fair in 4 patients (6.0%), and poor in 1 patient (1.5%); the overall rate of favorable clinical outcomes (excellent and good) was 92.5%. The modified Rankin Scale (mRS) score was significantly improved at follow-up (P < 0.001). There were 41 hemispheres imaged by cerebral angiography after the operation, at a median postoperative interval of 9 (IQR, 8–12) months; among them, 34 (82.9%) hemispheres had Matsushima scores of grade A and grade B. The average postoperative diameters in the STA, DTA and MMA were increased significantly in 41 hemispheres at follow-up (P < 0.001). Sixteen (24.2%) patients suffered from perioperative complications, including focal hyperperfusion syndrome (HS) in 8 (12.2%) patients, cerebral infarction in 3 (4.5%) patients (including one case accompanied by wound infection), cerebral hemorrhage in 2 (3.0%) patients, seizures in 2 (3.0%) patients, and subdural effusion in 1 (1.5%) patient.

Conclusions

The procedure of STA-MCA anastomosis combined with MBH surgery and dural inversion synangiosis may be a safe and effective treatment for adult patients with moyamoya disease.

Experimental Animal Models for Moyamoya Disease: A Species-Oriented Scoping Review

Moyamoya disease (MMD) is a rare cerebrovascular disease characterized by progressive stenosis of large intracranial arteries and a hazy network of basal collaterals called moyamoya vessels. The etiology and pathogenesis of MMD are still obscure. The biggest obstacles in the basic research of MMD are difficulty in obtaining specimens and the lack of an animal model. It is necessary to use appropriate and rationally designed animal models for the correct evaluation. Several animal models and methods have been developed to produce an effective MMD model, such as zebrafish, mice and rats, rabbits, primates, felines, canines, and peripheral blood cells, each with advantages and disadvantages. There are three mechanisms for developing animal models, including genetic, immunological/inflammatory, and ischemic animal models. This review aims to analyze the characteristics of currently available models, providing an overview of the animal models framework and the convenience of selecting model types for MMD research. It will be a great benefit to identify strategies for future model generations.

Experimental animal models for moyamoya disease and treatment: a pathogenesis-oriented scoping review

OBJECTIVE

Moyamoya disease (MMD) is an intracranial steno-occlusive pathology characterized by progressive narrowing of proximal large vessels, including the terminal internal carotid arteries (ICAs), middle cerebral arteries, or anterior cerebral arteries. Named for the "puff of smoke" appearance of the anomalous vascularization visualized on cerebral angiography, MMD lacks a well-defined etiology, although significant insights have been made, including the identification of a susceptibility gene, RNF213, in humans with the disease. A limitation to advancing the understanding and treatment of MMD has been the lack of experimental animal models that authentically reflect the clinical pathogenesis. In an effort to analyze characteristics of currently available models and identify strategies for future model generation, the authors performed a scoping review of experimental animal models that have been used to study MMD.

METHODS

A systematic search of PubMed, Web of Science, and Scopus was performed to identify articles describing animal models used to study MMD. Additional articles were identified via citation searching. Study selection and data extraction were performed by two independent reviewers based on defined inclusion and exclusion criteria.

RESULTS

A total of 44 articles were included for full-text review. The methods used to generate these animal models were broadly classified as surgical (n = 25, 56.8%), immunological (n = 7, 15.9%), genetic (n = 6, 13.6%), or a combination (n = 6, 13.6%). Surgical models typically involved permanent ligation of one or both of the common carotid arteries or ICAs to produce chronic cerebral hypoperfusion. Genetic models utilized known MMD or cerebrovascular disease-related genes, such as RNF213 or ACTA2, to induce heritable cerebral vasculopathy. Finally, immunological models attempted to induce vasculitis-type pathology by recapitulating the inflammatory milieu thought to underlie MMD.

CONCLUSIONS

Models generated for MMD have involved three general approaches: surgical, immunological, and genetic. Although each reflects a key aspect of MMD pathogenesis, the failure of any individual model to recapitulate the development, progression, and consequences of the disease underscores the importance of future work in developing a multietiology model.

Detecting functional connectivity disruptions in a translational pediatric traumatic brain injury porcine model using resting-state and task-based fMRI

Functional magnetic resonance imaging (fMRI) has significant potential to evaluate changes in brain network activity after traumatic brain injury (TBI) and enable early prognosis of potential functional (e.g., motor, cognitive, behavior) deficits. In this study, resting-state and task-based fMRI (rs- and tb-fMRI) were utilized to examine network changes in a pediatric porcine TBI model that has increased predictive potential in the development of novel therapies. rs- and tb-fMRI were performed one day post-TBI in piglets. Activation maps were generated using group independent component analysis (ICA) and sparse dictionary learning (sDL). Activation maps were compared to pig reference functional connectivity atlases and evaluated using Pearson spatial correlation coefficients and mean ratios. Nonparametric permutation analyses were used to determine significantly different activation areas between the TBI and healthy control groups. Significantly lower Pearson values and mean ratios were observed in the visual, executive control, and sensorimotor networks for TBI piglets compared to controls. Significant differences were also observed within several specific individual anatomical structures within each network. In conclusion, both rs- and tb-fMRI demonstrate the ability to detect functional connectivity disruptions in a translational TBI piglet model, and these disruptions can be traced to specific affected anatomical structures.

Critical role of platelet-derived growth factor-α in angiogenesis after indirect bypass in a murine moyamoya disease model

OBJECTIVE

This study aimed to clarify the underlying mechanism of pathognomonic angiogenesis between the temporal muscle and neocortex after indirect bypass for moyamoya disease by shedding light on the role of platelet-derived growth factor receptor-α (PDGFRα) in angiogenesis.

METHODS

The gene for PDGFRα was systemically inactivated in adult mice (α-KO mice). The Pdgfra-preserving mice (Flox mice) and α-KO mice were exposed to bilateral common carotid artery stenosis (BCAS) by using microcoils. One week later the animals underwent encephalomyosynangiosis (EMS) on the right side. Cerebral blood flow (CBF) was serially measured using a laser Doppler flowmeter. Histological analysis was performed on the distribution of CD31-positive vessels and collagen deposit at 28 days after BCAS. Reverse transcription polymerase chain reaction (RT-PCR) was performed to assess the expression of collagen mRNA in the skin fibroblasts derived from Flox and α-KO mice.

RESULTS

BCAS significantly reduced CBF up to approximately 70% of the control level at 28 days after the onset. There was no significant difference in CBF between Flox and α-KO mice. EMS significantly enhanced the improvement of CBF on the ipsilateral side of Flox mice, but not α-KO mice. EMS significantly induced the development of CD31-positive vessels in both the neocortex and temporal muscle on the ipsilateral side of Flox mice, but not α-KO mice. Deposition of collagen was distinctly observed between them in Flox mice, but not α-KO mice. Expression of mRNA of collagen type 1 alpha 1 (Col1a1) and collagen type 3 alpha 1 (Col3a1) was significantly downregulated in the skin fibroblasts from α-KO mice.

CONCLUSIONS

This is the first study that denotes the role of a specific growth factor in angiogenesis after EMS for moyamoya disease by inactivating its gene in mice. The findings strongly suggest that PDGFRα signal may play an important role in developing spontaneous angiogenesis between the temporal muscle and neocortex after EMS in moyamoya disease.

An integrative multivariate approach for predicting functional recovery using magnetic resonance imaging parameters in a translational pig ischemic stroke model

Magnetic resonance imaging (MRI) is a clinically relevant, real-time imaging modality that is frequently utilized to assess stroke type and severity. However, specific MRI biomarkers that can be used to predict long-term functional recovery are still a critical need. Consequently, the present study sought to examine the prognostic value of commonly utilized MRI parameters to predict functional outcomes in a porcine model of ischemic stroke. Stroke was induced via permanent middle cerebral artery occlusion. At 24 hours post-stroke, MRI analysis revealed focal ischemic lesions, decreased diffusivity, hemispheric swelling, and white matter degradation. Functional deficits including behavioral abnormalities in open field and novel object exploration as well as spatiotemporal gait impairments were observed at 4 weeks post-stroke. Gaussian graphical models identified specific MRI outputs and functional recovery variables, including white matter integrity and gait performance, that exhibited strong conditional dependencies. Canonical correlation analysis revealed a prognostic relationship between lesion volume and white matter integrity and novel object exploration and gait performance. Consequently, these analyses may also have the potential of predicting patient recovery at chronic time points as pigs and humans share many anatomical similarities (e.g., white matter composition) that have proven to be critical in ischemic stroke pathophysiology. The study was approved by the University of Georgia (UGA) Institutional Animal Care and Use Committee (IACUC; Protocol Number: A2014-07-021-Y3-A11 and 2018-01-029-Y1-A5) on November 22, 2017.

Preservation of spatial memory and neuroprotection by the fatty acid amide hydrolase inhibitor URB597 in a rat model of vascular dementia

Background

Chronic cerebral hypoperfusion (CCH) is a major risk factor for vascular dementia (VaD). There are currently no broadly effective prevention or treatment strategies for VaD, but recent studies have reported promising results following vascular bypass surgery and pharmacomodulation of the brain endocannabinoid system (ECS). In this study, early effects of encephalomyosynangiosis (EMS) bypass surgery and augmented endocannabinoid signaling on CCH-induced cognitive dysfunction and neuronal damage were investigated.

Methods

An animal model of VaD was established by bilateral common carotid artery occlusion (BCCAO). Cannabinoid signaling was upregulated by treatment with the fatty acid amide hydrolase inhibitor URB597 (URB). Spatial learning and memory, cerebral blood flow (CBF), revascularization, brain-derived neurotrophic factor (BDNF)-tropomyosin receptor kinase B (TrkB) signaling, and apoptosis were compared among Sham, BCCAO, BCCAO + EMS, BCCAO + URB, and BCCAO + URB + EMS groups. Spatial learning and memory were evaluated using the Morris water maze (MWM). The CBF in cortex and hippocampus was evaluated by 3-dimensional arterial spin labeling. The neovascularization was visualized by CD34 immunofluorescence staining, and BDNF-TrkB signaling protein expression levels were assessed by Western blotting.

Results

Treatment with URB597 but not EMS alone reversed the spatial learning and memory deficits induced by BCCAO. Neovascularization was enhanced after EMS surgery but not by URB597. Alternatively, there were no significant differences in CBF among treatment groups. Expression levels of BDNF and TrkB were significantly reduced by CCH compared to Sham treatment, and downregulation of both proteins was reversed by URB597 treatment but not EMS. BCCAO enhanced neuronal apoptosis, which was also reversed by URB597.

Conclusions

Augmentation of endogenous cannabinoid signaling but not EMS protects against CCH-induced neurodegeneration and preserves spatial learning and memory, possibly by activating BDNF-TrkB signaling.

Intracisternal administration of tanshinone IIA-loaded nanoparticles leads to reduced tissue injury and functional deficits in a porcine model of ischemic stroke

Background

The absolute number of new stroke patients is annually increasing and there still remains only a few Food and Drug Administration (FDA) approved treatments with significant limitations available to patients. Tanshinone IIA (Tan IIA) is a promising potential therapeutic for ischemic stroke that has shown success in pre-clinical rodent studies but lead to inconsistent efficacy results in human patients. The physical properties of Tan-IIA, including short half-life and low solubility, suggests that Poly (lactic-co-glycolic acid) (PLGA) nanoparticle-assisted delivery may lead to improve bioavailability and therapeutic efficacy. The objective of this study was to develop Tan IIA-loaded nanoparticles (Tan IIA-NPs) and to evaluate their therapeutic effects on cerebral pathological changes and consequent motor function deficits in a pig ischemic stroke model.

Results

Tan IIA-NP treated neural stem cells showed a reduction in SOD activity in in vitro assays demonstrating antioxidative effects. Ischemic stroke pigs treated with Tan IIA-NPs showed reduced hemispheric swelling when compared to vehicle only treated pigs (7.85 ± 1.41 vs. 16.83 ± 0.62%), consequent midline shift (MLS) (1.72 ± 0.07 vs. 2.91 ± 0.36 mm), and ischemic lesion volumes (9.54 ± 5.06 vs. 12.01 ± 0.17 cm³) when compared to vehicle-only treated pigs. Treatment also lead to lower reductions in diffusivity (-37.30 ± 3.67 vs. -46.33 ± 0.73%) and white matter integrity (-19.66 ± 5.58 vs. -30.11 ± 1.19%) as well as reduced hemorrhage (0.85 ± 0.15 vs 2.91 ± 0.84 cm³) 24 h post-ischemic stroke. In addition, Tan IIA-NPs led to a reduced percentage of circulating band neutrophils at 12 (7.75 ± 1.93 vs. 14.00 ± 1.73%) and 24 (4.25 ± 0.48 vs 5.75 ± 0.85%) hours post-stroke suggesting a mitigated inflammatory response. Moreover, spatiotemporal gait deficits including cadence, cycle time, step time, swing percent of cycle, stride length, and changes in relative mean pressure were less severe post-stroke in Tan IIA-NP treated pigs relative to control pigs.

Conclusion

The findings of this proof of concept study strongly suggest that administration of Tan IIA-NPs in the acute phase post-stroke mitigates neural injury likely through limiting free radical formation, thus leading to less severe gait deficits in a translational pig ischemic stroke model. With stroke as one of the leading causes of functional disability in the United States, and gait deficits being a major component, these promising results suggest that acute Tan IIA-NP administration may improve functional outcomes and the quality of life of many future stroke patients.

Neuroregeneration and functional recovery after stroke: advancing neural stem cell therapy toward clinical application

Stroke is a main cause of death and disability worldwide. The ability of the brain to self-repair in the acute and chronic phases after stroke is minimal; however, promising stem cell-based interventions are emerging that may give substantial and possibly complete recovery of brain function after stroke. Many animal models and clinical trials have demonstrated that neural stem cells (NSCs) in the central nervous system can orchestrate neurological repair through nerve regeneration, neuron polarization, axon pruning, neurite outgrowth, repair of myelin, and remodeling of the microenvironment and brain networks. Compared with other types of stem cells, NSCs have unique advantages in cell replacement, paracrine action, inflammatory regulation and neuroprotection. Our review summarizes NSC origins, characteristics, therapeutic mechanisms and repair processes, then highlights current research findings and clinical evidence for NSC therapy. These results may be helpful to inform the direction of future stroke research and to guide clinical decision-making.

The trend of indirect anastomosis formation in a 2-vessel occlusion plus encephalo-myo-synangiosis rat model

Background

Basic research on the factors influencing indirect anastomosis formation in a 2-vessel occlusion plus encephalo-myo-synangiosis (2VO + EMS) rat model is conducive to improving the efficacy of indirect revascularization surgery in the clinic. However, the time point at which anastomosis between the rat temporal muscle (TM) and brain naturally has the greatest effect after encephalo-myo-synangiosis (EMS) remains unknown. Therefore, we conducted this study to explore the peak time of indirect anastomosis formation in the 2VO + EMS rat model.

Methods

Forty 2VO + EMS rats were randomly divided into five groups (n=8) according to the length of time (by week) after EMS, and 2VO rats were used as the control group (n=8). The expression of vascular endothelial growth factor (VEGF) and CD31 on the EMS side of the brain, perfusion ratio [improvement of cerebral blood perfusion (CBP) on the EMS side] and Morris water maze (MWM) results were compared between groups. Furthermore, the trends of the above variables were explored over weeks.

Results

Overall, the expression of VEGF and CD31, the perfusion ratio and the cognitive improvement in the 2VO + EMS rat model gradually increased over weeks after EMS. The VEGF and CD31 expression (as detected by immunofluorescence), perfusion ratio and number of times crossing the platform area peaked at 4 weeks after EMS. In addition, both the escape latency and the time spent in the target quadrant peaked in the fifth week after EMS.

Conclusions

After establishing the 2VO + EMS rat model, the degree of endothelial cell (EC) proliferation and CBP improvement on the EMS side of the brain peaked at 4 weeks after EMS, whereas the cognitive improvement peaked in the fifth week.

Limits and pitfalls of indirect revascularization in moyamoya disease and syndrome

Moyamoya vasculopathy is a rare chronic cerebrovascular disorder characterized by the stenosis of the terminal branches of the internal carotid arteries and the proximal tracts of anterior and middle cerebral arteries. Although surgical revascularization does not significantly change the underlying pathogenic mechanisms, it plays a pivotal role in the management of affected individuals, allowing to decrease the risk of ischemic and hemorrhagic complications. Surgical approaches may be direct (extracranial-intracranial bypass), indirect, or a combination of the two. Several indirect techniques classifiable according to the tissue (muscle, periosteum, galea, dura mater, and extracranial tissues) or vessel (artery) used as a source of blood supply are currently available. In this study, we reviewed the pertinent literature and analyzed the advantages, disadvantages, and pitfalls of the most relevant indirect revascularization techniques. We discussed the technical aspects and the therapeutical implications of each procedure, providing a current state-of-the-art overview on the limits and pitfalls of indirect revascularization in the treatment of moyamoya vasculopathy.

Relevance of Porcine Stroke Models to Bridge the Gap from Pre-Clinical Findings to Clinical Implementation

In the search of animal stroke models providing translational advantages for biomedical research, pigs are large mammals with interesting brain characteristics and wide social acceptance. Compared to rodents, pigs have human-like highly gyrencephalic brains. In addition, increasingly through phylogeny, animals have more sophisticated white matter connectivity; thus, ratios of white-to-gray matter in humans and pigs are higher than in rodents. Swine models provide the opportunity to study the effect of stroke with emphasis on white matter damage and neuroanatomical changes in connectivity, and their pathophysiological correlate. In addition, the subarachnoid space surrounding the swine brain resembles that of humans. This allows the accumulation of blood and clots in subarachnoid hemorrhage models mimicking the clinical condition. The clot accumulation has been reported to mediate pathological mechanisms known to contribute to infarct progression and final damage in stroke patients. Importantly, swine allows trustworthy tracking of brain damage evolution using the same non-invasive multimodal imaging sequences used in the clinical practice. Moreover, several models of comorbidities and pathologies usually found in stroke patients have recently been established in swine. We review here ischemic and hemorrhagic stroke models reported so far in pigs. The advantages and limitations of each model are also discussed.

Perinatal Docosahexaenoic Acid Supplementation Improves Cognition and Alters Brain Functional Organization in Piglets

Epidemiologic studies associate maternal docosahexaenoic acid (DHA)/DHA-containing seafood intake with enhanced cognitive development; although, it should be noted that interventional trials show inconsistent findings. We examined perinatal DHA supplementation on cognitive performance, brain anatomical and functional organization, and the brain monoamine neurotransmitter status of offspring using a piglet model. Sows were fed a control (CON) or a diet containing DHA (DHA) from late gestation throughout lactation. Piglets underwent an open field test (OFT), an object recognition test (ORT), and magnetic resonance imaging (MRI) to acquire anatomical, diffusion tensor imaging (DTI), and resting-state functional MRI (rs-fMRI) at weaning. Piglets from DHA-fed sows spent 95% more time sniffing the walls than CON in OFT and exhibited an elevated interest in the novel object in ORT, while CON piglets demonstrated no preference. Maternal DHA supplementation increased fiber length and tended to increase fractional anisotropy in the hippocampus of offspring than CON. DHA piglets exhibited increased functional connectivity in the cerebellar, visual, and default mode network and decreased activity in executive control and sensorimotor network compared to CON. The brain monoamine neurotransmitter levels did not differ in healthy offspring. Perinatal DHA supplementation may increase exploratory behaviors, improve recognition memory, enhance fiber tract integrity, and alter brain functional organization in offspring at weaning.

Large Craniotomy Increases the Risk of Minor Perioperative Complications in Revascularization Surgery for Moyamoya Disease

OBJECTIVE

Larger craniotomy is expected to increase blood flow over a wider range after indirect revascularization. However, the optimal size of craniotomy has not been established. In this study perioperative complications in revascularization surgery for moyamoya disease are evaluated, focusing on craniotomy size.

METHODS

We retrospectively analyzed 87 hemispheres in 65 patients with moyamoya disease who had undergone revascularization surgery. Areas and types of craniotomy were classified as 1-piece craniotomy in the middle cerebral artery (MCA) territory (1-piece group) in 54 hemispheres (mean area of craniotomy, 40.6 ± 13.5 cm²); 2-piece craniotomy in the MCA territory with anterior cerebral artery (ACA) territory (2-piece group) in 16 hemispheres (mean area of craniotomy, 55.4 ± 12.0 cm²); and 1-piece craniotomy in both MCA and ACA territories (large group) in 17 hemispheres (mean area of craniotomy, 84.2 ± 11.0 cm²). Perioperative complication rates in each craniotomy group were analyzed.

RESULTS

Perioperative complications occurred in 45 hemispheres (52%). Transient, moderate, and severe complications occurred in 38 hemispheres, 3 hemispheres, and 4 hemispheres, respectively. Complication rates in the 1-piece, 2-piece, and large groups were 41%, 63%, and 76%, respectively. Large craniotomy was associated with a significantly higher frequency of complications (P = 0.01). However, no significant difference was found among groups when limiting analysis to moderate and severe complications. Multivariate analysis showed large craniotomy as the only factor independently related to complications (odds ratio, 2.93; 95% confidence interval, 1.08-7.92; P = 0.034).

CONCLUSIONS

Large craniotomy is associated with more frequent perioperative complications, especially transient symptoms.

Characterization of tissue and functional deficits in a clinically translational pig model of acute ischemic stroke

The acute stroke phase is a critical time frame used to evaluate stroke severity, therapeutic options, and prognosis while also serving as a major tool for the development of diagnostics. To further understand stroke pathophysiology and to enhance the development of treatments, our group developed a translational pig ischemic stroke model. In this study, the evolution of acute ischemic tissue damage, immune responses, and functional deficits were further characterized. Stroke was induced by middle cerebral artery occlusion in Landrace pigs. At 24 h post-stroke, magnetic resonance imaging revealed a decrease in ipsilateral diffusivity, an increase in hemispheric swelling resulting in notable midline shift, and intracerebral hemorrhage. Stroke negatively impacted white matter integrity with decreased fractional anisotropy values in the internal capsule. Like patients, pigs showed a reduction in circulating lymphocytes and a surge in neutrophils and band cells. Functional responses corresponded with structural changes through reductions in open field exploration and impairments in spatiotemporal gait parameters. Characterization of acute ischemic stroke in pigs provided important insights into tissue and functional-level assessments that could be used to identify potential biomarkers and improve preclinical testing of novel therapeutics.

Large animal ischemic stroke models: replicating human stroke pathophysiology

The high morbidity and mortality rate of ischemic stroke in humans has led to the development of numerous animal models that replicate human stroke to further understand the underlying pathophysiology and to explore potential therapeutic interventions. Although promising therapeutics have been identified using these animal models, with most undergoing significant testing in rodent models, the vast majority of these interventions have failed in human clinical trials. This failure of preclinical translation highlights the critical need for better therapeutic assessment in more clinically relevant ischemic stroke animal models. Large animal models such as non-human primates, sheep, pigs, and dogs are likely more predictive of human responses and outcomes due to brain anatomy and physiology that are more similar to humans-potentially making large animal testing a key step in the stroke therapy translational pipeline. The objective of this review is to highlight key characteristics that potentially make these gyrencephalic, large animal ischemic stroke models more predictive by comparing pathophysiological responses, tissue-level changes, and model limitations.

Risk factors for and outcomes of postoperative complications in adult patients with moyamoya disease

OBJECTIVE

The risk factors and clinical significance of postoperative complications in moyamoya disease are still unclear. The aim of this study was to investigate the predictors of postoperative complications in moyamoya disease and examine the impact of complications on outcomes.

METHODS

The authors reviewed consecutive cases involving adult moyamoya disease patients who underwent indirect, direct, or combined bypass surgery in their hospital between 2009 and 2015. Preoperative clinical characteristics and radiographic features were recorded. Postoperative complications within 14 days after surgery were examined. Multivariate logistic regression analyses were performed to identify the risk factors for either postoperative ischemia or postoperative cerebral hyperperfusion. Outcome data, including recurrent strokes and neurological status (modified Rankin Scale [mRS]) during follow-up, were collected. Outcomes were compared between patients who had complications with those without complications, using propensity-score analysis to account for between-group differences in baseline characteristics.

RESULTS

A total of 500 patients (610 hemispheres) were included in this study. Postoperative complications were observed in 74 operations (12.1%), including new postoperative ischemia in 30 cases (4.9%), hyperperfusion in 27 (4.4%), impaired wound healing in 12 (2.0%), and subdural effusion in 6 (1.0%). The complication rates for different surgery types were as follows: 12.6% (n = 25) for indirect bypass, 12.7% (n = 37) for direct bypass, and 10.0% (n = 12) for combined bypass (p = 0.726). Postoperative ischemic complications occurred in 30 hemispheres (4.9%) in 30 different patients, and postoperative symptomatic hyperperfusion occurred after 27 procedures (4.4%). Advanced Suzuki stage (OR 1.669, 95% CI 1.059-2.632, p = 0.027) and preoperative ischemic presentation (OR 5.845, 95% CI 1.654-20.653, p = 0.006) were significantly associated with postoperative ischemia. Preoperative ischemic presentation (OR 5.73, 95% CI 1.27-25.88, p = 0.023) and admission modified Rankin Scale (mRS) score (OR 1.81, 95% CI 1.06-3.10, p = 0.031) were significantly associated with symptomatic postoperative cerebral hyperperfusion syndrome (CHS). Compared with patients without postoperative complications, patients who experienced any postoperative complications had longer hospital stays and worse mRS scores at discharge (both p < 0.0001). At the final follow-up, no significant differences in functional disability (mRS score 3-6, 11.9% vs 4.5%, p = 0.116) and future stroke events (p = 0.513) between the 2 groups were detected.

CONCLUSIONS

Advanced Suzuki stage and preoperative ischemic presentation were independent risk factors for postoperative ischemia; the mRS score on admission and preoperative ischemic presentation were independently associated with postoperative CHS. Although patients with postoperative complications had worse neurological status at discharge, postoperative complications had no associations with future stroke events or functional disability during follow-up.

The pig as a preclinical traumatic brain injury model: current models, functional outcome measures, and translational detection strategies

Traumatic brain injury (TBI) is a major contributor of long-term disability and a leading cause of death worldwide. A series of secondary injury cascades can contribute to cell death, tissue loss, and ultimately to the development of functional impairments. However, there are currently no effective therapeutic interventions that improve brain outcomes following TBI. As a result, a number of experimental TBI models have been developed to recapitulate TBI injury mechanisms and to test the efficacy of potential therapeutics. The pig model has recently come to the forefront as the pig brain is closer in size, structure, and composition to the human brain compared to traditional rodent models, making it an ideal large animal model to study TBI pathophysiology and functional outcomes. This review will focus on the shared characteristics between humans and pigs that make them ideal for modeling TBI and will review the three most common pig TBI models-the diffuse axonal injury, the controlled cortical impact, and the fluid percussion models. It will also review current advances in functional outcome assessment measures and other non-invasive, translational TBI detection and measurement tools like biomarker analysis and magnetic resonance imaging. The use of pigs as TBI models and the continued development and improvement of translational assessment modalities have made significant contributions to unraveling the complex cascade of TBI sequela and provide an important means to study potential clinically relevant therapeutic interventions.

Noninvasive Assessment of Hemodynamic Stress Distribution after Indirect Revascularization for Pediatric Moyamoya Vasculopathy

BACKGROUND AND PURPOSE

Indirect revascularization surgery is an effective treatment in children with Moyamoya vasculopathy. In the present study, we hypothesized that DSC-PWI may reliably assess the evolution of CBF-related parameters after revascularization surgery, monitoring the outcome of surgical pediatric patients with Moyamoya vasculopathy. Thus, we aimed to evaluate differences in DSC-PWI parameters, including the hemodynamic stress distribution, in surgical and nonsurgical children with Moyamoya vasculopathy and to correlate them with long-term postoperative outcome.

MATERIALS AND METHODS

Pre- and postoperative DSC parameters of 28 patients (16 females; mean age, 5.5 ± 4.8 years) treated with indirect revascularization were compared with those obtained at 2 time points in 10 nonsurgical patients (6 females; mean age, 6.9 ± 4.7 years). We calculated 4 normalized CBF-related parameters and their percentage variance: mean normalized CBF of the MCA territory, mean normalized CBF of the proximal MCA territory, mean normalized CBF of cortical the MCA territory, and hemodynamic stress distribution. The relationship between perfusion parameters and postoperative outcomes (poor, fair, good, excellent) was explored using 1-way analysis of covariance (P < .05).

RESULTS

A significant decrease of the mean normalized CBF of the proximal MCA territory and hemodynamic stress distribution and an increase of the mean normalized CBF of the cortical MCA territory were observed after revascularization surgery (P < .001). No variations were observed in nonsurgical children. Postoperative hemodynamic stress distribution and its percentage change were significantly different in outcome groups (P < .001).

CONCLUSIONS

DSC-PWI indices show postoperative hemodynamic changes that correlate with clinical outcome after revascularization surgery in children with Moyamoya disease.

Human Neural Stem Cell Extracellular Vesicles Improve Recovery in a Porcine Model of Ischemic Stroke

BACKGROUND AND PURPOSE

Recent work from our group suggests that human neural stem cell-derived extracellular vesicle (NSC EV) treatment improves both tissue and sensorimotor function in a preclinical thromboembolic mouse model of stroke. In this study, NSC EVs were evaluated in a pig ischemic stroke model, where clinically relevant end points were used to assess recovery in a more translational large animal model.

METHODS

Ischemic stroke was induced by permanent middle cerebral artery occlusion (MCAO), and either NSC EV or PBS treatment was administered intravenously at 2, 14, and 24 hours post-MCAO. NSC EV effects on tissue level recovery were evaluated via magnetic resonance imaging at 1 and 84 days post-MCAO. Effects on functional recovery were also assessed through longitudinal behavior and gait analysis testing.

RESULTS

NSC EV treatment was neuroprotective and led to significant improvements at the tissue and functional levels in stroked pigs. NSC EV treatment eliminated intracranial hemorrhage in ischemic lesions in NSC EV pigs (0 of 7) versus control pigs (7 of 8). NSC EV-treated pigs exhibited a significant decrease in cerebral lesion volume and decreased brain swelling relative to control pigs 1-day post-MCAO. NSC EVs significantly reduced edema in treated pigs relative to control pigs, as assessed by improved diffusivity through apparent diffusion coefficient maps. NSC EVs preserved white matter integrity with increased corpus callosum fractional anisotropy values 84 days post-MCAO. Behavior and mobility improvements paralleled structural changes as NSC EV-treated pigs exhibited improved outcomes, including increased exploratory behavior and faster restoration of spatiotemporal gait parameters.

CONCLUSIONS

This study demonstrated for the first time that in a large animal model novel NSC EVs significantly improved neural tissue preservation and functional levels post-MCAO, suggesting NSC EVs may be a paradigm changing stroke therapeutic.

Clinical and angiographic outcomes after combined direct and indirect bypass in adult patients with moyamoya disease: A retrospective study of 76 procedures

The present retrospective study was performed to evaluate the clinical outcome, as well as post-operative collateral formation and revascularization patterns in combined bypass. Surgical revascularization has been the mainstay of treatment for moyamoya patients. A total of 76 hemispheres from 64 moyamoya patients undergoing combined superficial temporal artery-middle cerebral artery (STA-MCA) anastomosis and encephalo-duro-myo-synangiosis (EDMS) were retrospectively reviewed. Computed tomography perfusion and DSA were routinely performed. Modified Rankin scale (mRS) scoring and Kaplan-Meier analysis were performed, and post-operative collateral grading on digital subtraction angiography (DSA), reconstruction patterns and vessel diameter were measured to evaluate the revascularization area and vascular compensatory effect. During the follow-up period, the chief complaint was partially alleviated in 57/64 patients (89.1%). In all patients, mRS was significantly decreased after the operation. Good revascularization was established in most patients at 6 months after the surgery: 92.1% of sides were scored as 2 and 77.6% were scored as 3 by post-operative collateral grading on DSA. Dominant collateral revascularization originating from EDMS was more frequent than that from STA-MCA anastomosis (31 vs. 19 hemispheres) at 6-month follow-up. Morphologically, the calibers of the STA main trunk (2.60±0.65 mm) increased profoundly at the first 10 post-operative days (3.32±1.05 mm) and shrank back to pre-operative status at 6 months (2.20±1.01 mm) and 12 months (2.36±0.73 mm) according to DSA examination. Middle meningeal artery (MMA) and deep temporal artery (DTA) demonstrated continuous augmentation during the follow-up time (from 1.30±0.46 to 1.87±0.69 mm for MMA and 1.11±0.25 to 2.11±1.16 mm for DTA). These results strongly suggested that combined STA-MCA bypass and EDMS provided efficient revascularization and reduced acute cerebral events. The direct STA-MCA bypass provided early augmentation of cerebral perfusion, whereas the indirect EDMS provided a more durable long-term revascularization, indicating a complementary association between the two revascularization methods.

Chronologic Evaluation of Cerebral Hemodynamics by Dynamic Susceptibility Contrast Magnetic Resonance Imaging After Indirect Bypass Surgery for Moyamoya Disease

OBJECTIVE

Although indirect bypass surgery is an effective treatment option for patients with ischemic-onset moyamoya disease (MMD), the time point after surgery at which the patient's hemodynamic status starts to improve and the time point at which the improvement reaches a maximum have not been known. The objective of the present study is to evaluate the hemodynamic status time course after indirect bypass surgery for MMD, using dynamic susceptibility contrast-magnetic resonance imaging (DSC-MRI).

METHODS

We retrospectively analyzed the cases of 25 patients with MMD (37 sides; mean age, 14.7 years; range, 3-36 years) who underwent indirect bypass surgery and repeated DSC-MRI measurement within 6 months after the operation. The difference in the mean transit time (MTT) between the target regions and the control region (cerebellum) was termed the MTT delay, and we measured the MTT delay's chronologic changes after surgery.

RESULTS

The postoperative MTT delay was 1.81 ± 1.16 seconds within 1 week after surgery, 1.57 ± 1.01 at weeks 1-2, 1.55 ± 0.68 at weeks 2-4, 1.32 ± 0.68 at months 1-2, 0.95 ± 0.32 at months 2-3, and 0.77 ± 0.33 at months 3-6. Compared with the preoperative value (2.11 ± 0.98 seconds), the MTT delay decreased significantly from 2 to 4 weeks after surgery (P < 0.05).

CONCLUSIONS

The amelioration of cerebral hemodynamics by indirect bypass surgery began soon after surgery and gradually reached a maximum at 3 months after surgery. DSC-MRI detected small changes in hemodynamic improvement, which are suspected to be caused by the initiation of angiogenesis and arteriogenesis in the early postoperative period.

Combined gene therapy with vascular endothelial growth factor plus apelin in a chronic cerebral hypoperfusion model in rats

OBJECTIVE

The aim of this study was to evaluate whether combined gene therapy with vascular endothelial growth factor (VEGF) plus apelin during indirect vasoreconstructive surgery enhances brain angiogenesis in a chronic cerebral hypoperfusion model in rats.

METHODS

A chronic cerebral hypoperfusion model induced by the permanent ligation of bilateral common carotid arteries (CCAs; a procedure herein referred to as “CCA occlusion” [CCAO]) in rats was employed in this study. Seven days after the CCAO procedure, the authors performed encephalo-myo-synangiosis (EMS) and injected plasmid(s) into each rat's temporal muscle. Rats were divided into 4 groups based on which plasmid was received (i.e., LacZ group, VEGF group, apelin group, and VEGF+apelin group). Protein levels in the cortex and attached muscle were assessed with enzyme-linked immunosorbent assay (ELISA) on Day 7 after EMS, while immunofluorescent analysis of cortical vessels was performed on Day 14 after EMS.

RESULTS

The total number of blood vessels in the cortex on Day 14 after EMS was significantly larger in the VEGF group and the VEGF+apelin group than in the LacZ group (p < 0.05, respectively). Larger vessels appeared in the VEGF+apelin group than in the other groups (p < 0.05, respectively). Apelin protein on Day 7 after EMS was not detected in the cortex for any of the groups. In the attached muscle, apelin protein was detected only in the apelin group and the VEGF+apelin group. Immunofluorescent analysis revealed that apelin and its receptor, APJ, were expressed on endothelial cells (ECs) 7 days after the CCAO.

CONCLUSIONS

Combined gene therapy (VEGF plus apelin) during EMS in a chronic cerebral hypoperfusion model can enhance angiogenesis in rats. This treatment has the potential to be a feasible option in a clinical setting for patients with moyamoya disease.

First autopsy analysis of a neovascularized arterial network induced by indirect bypass surgery for moyamoya disease: case report

The object of this study was to analyze the pathology of collateral vessels newly induced by indirect bypass surgery for moyamoya disease (MMD). An autopsy analysis was conducted on a 39-year-old woman with MMD who had died of a brainstem infarction. The patient had undergone bilateral indirect bypass surgeries 22 years earlier. Sufficient revascularization via bilateral external carotid arterial systems was confirmed by cerebral angiography before her death. Macroscopic observation of the operative areas revealed countless meandering vessels on the internal surface of the dura mater connected with small vessels on the brain surface and in the subpial brain tissue. Notably, microscopic analysis of these vessels revealed the characteristic 3-layer structure of an arterial wall. This autopsy analysis was the first to confirm that indirect bypass surgery had induced the formation of a new arterial network (arteriogenesis) and that this network had been maintained for more than 20 years to compensate for the chronic cerebral ischemia caused by the MMD.

Collaterals: Implications in cerebral ischemic diseases and therapeutic interventions

Despite the tremendous progress made in the treatment of cerebrovascular occlusive diseases, many patients suffering from ischemic brain injury still experience dismal outcomes. Although rehabilitation contributes to post-stroke functional recovery, there is no doubt that interventions that promote the restoration of blood supply are proven to minimize ischemic injury and improve recovery. In response to the acutely decreased blood perfusion during arterial occlusion, arteriogenesis, the compensation of blood flow through the collateral circulation during arterial obstructive diseases can act not only in a timely fashion but also much more efficiently compared to angiogenesis, the sprouting of new capillaries, and a mechanism occurring in a delayed fashion while increases the total resistance of the vascular bed of the affected territory. Interestingly, despite the vast differences between the two vascular remodeling mechanisms, some crucial growth factors and cytokines involved in angiogenesis are also required for arteriogenesis. Understanding the mechanisms underlying vascular remodeling after ischemic brain injury is a critical step towards the development of effective therapies for ischemic stroke. The present article will discuss our current views in vascular remodeling acutely after brain ischemia, namely arteriogenesis, and some relevant clinical therapies available on the horizon in augmenting collateral flow that hold promise in treating ischemic brain injury. This article is part of a Special Issue entitled SI: Cell Interactions In Stroke.

Steroids and Immunosuppressant Agents Do Not Affect Indirect Revascularization in Quasi-Moyamoya Disease Associated with Pure Red Cell Aplasia: A Case Report

A 31-year-old woman with pure red cell aplasia presented with motor aphasia and right homonymous hemianopia due to a left temporal and parietal lobe infarction. Magnetic resonance angiography revealed an occlusion of the left anterior and middle cerebral artery, with the development of moyamoya vessels. She was diagnosed with quasi-moyamoya disease and subsequently underwent direct and indirect anastomosis surgery, while continuing steroid and immunosuppressant therapy for pure red cell aplasia. The postoperative course was uneventful, and follow-up cerebral angiography 6 months after the surgery revealed the development of neovascularization through an indirect anastomosis. Neovascularization can be induced while the patient is receiving steroid and immunosuppressant therapy in quasi-moyamoya disease.

Myoblast-mediated gene therapy improves functional collateralization in chronic cerebral hypoperfusion

BACKGROUND AND PURPOSE

Direct extracranial-intracranial bypass surgery for treatment of cerebral hemodynamic compromise remains hindered by complications but alternative simple and safe indirect revascularization procedures, such as an encephalomyosynangiosis (EMS), lack hemodynamic efficiency. Here, the myoblast-mediated transfer of angiogenic genes presents an approach for induction of therapeutic collateralization. In this study, we tested the effect of myoblast-mediated delivery of vascular endothelial growth factor-A (VEGF) to the muscle/brain interface of an EMS in a model of chronic cerebral hypoperfusion.

METHODS

Permanent unilateral internal carotid artery-occlusion was performed in adult C57/BL6 mice with or without (no EMS) surgical grafting of an EMS followed by implantation of monoclonal mouse myoblasts expressing either VEGF164 or an empty vector (EV). Cerebral hemodynamic impairment, transpial collateralization, angiogenesis, mural cell investment, microvascular permeability, and cortical infarction after ipsilateral stroke were assessed by real-time laser speckle blood flow imaging, 2- and 3-dimensional immunofluorescence and MRI.

RESULTS

VEGF-expressing myoblasts improved hemodynamic rescue by day 14 (no EMS 37±21%, EV 42±9%, VEGF 48±12%; P<0.05 for VEGF versus no EMS and versus EV), together with the EMS take rate (VEGF 60%, EV 18.2%; P<0.05) and angiogenesis of mature cortical microvessels below the EMS (P<0.05 for VEGF versus EV). Importantly, functional and morphological results were paralleled by a 25% reduction of cortical infarction after experimental stroke on the side of the EMS.

CONCLUSIONS

Myoblast-mediated VEGF supplementation at the target site of an EMS could help overcome the clinical dilemma of poor surgical revascularization results and provide protection from ischemic stroke.

In vivo evaluation of angiogenic activity and its correlation with efficacy of indirect revascularization surgery in pediatric moyamoya disease

Indirect revascularization is the most widely used treatment to induce angiogenesis in pediatric moyamoya disease (MMD). Molecular imaging methods targeted for angiogenesis have recently been developed. We performed angiogenesis imaging in indirect revascularization surgery for MMD to evaluate angiogenic activity and its correlation with treatment efficacy.

METHODS

Twelve patients with pediatric MMD were prospectively enrolled. Encephaloduroarteriosynangiosis surgery was conducted, and (68)Ga-Arg-Gly-Asp (RGD) PET was performed 3.7 ± 1.0 mo after surgery. Basal perfusion and stress perfusion (PStr) in the middle cerebral artery territory were evaluated by acetazolamide-stress brain perfusion SPECT using statistical probabilistic anatomic mapping, at preoperative, early postoperative, and long-term follow-up states. Angiogenic activity was assessed on the images in terms of maximal uptake ratio, volume of increased uptake, and uptake-volume product.

RESULTS

Basal perfusion and PStr were significantly improved after surgery. Increased angiogenic activity was observed in the revascularized area, mainly around the bony flap. Angiogenic activity gradually decreased with time and significantly correlated with the postoperative time interval (P = 0.0015 for maximal uptake ratio and 0.0069 for volume of increased uptake). It was estimated to normalize at 6.3 mo after surgery. Uptake-volume product was inversely correlated with PStr improvement at the early postoperative state (r = -0.5960, P = 0.0409) and also weakly correlated with PStr improvement at long-term follow-up (r = -0.5010, P = 0.1165).

CONCLUSION

Angiogenesis PET imaging with (68)Ga-RGD was successfully used for the assessment of angiogenic activity in indirect revascularization surgery for MMD, and angiogenic activation measured at approximately 3.7 mo after surgery was inversely correlated with perfusion improvement. The assessment of angiogenic activity using (68)Ga-RGD PET is expected to be effective for evaluating the mechanism or efficacy of revascularization treatment.

Expression of circulating vascular endothelial growth factor-antagonizing cytokines and vascular stabilizing factors prior to and following bypass surgery in patients with moyamoya disease

The aim of the present study was to investigate the levels of vascular endothelial growth factor (VEGF)-antagonizing cytokines and VEGF-influenced vascular stabilizing cytokines in patients with moyamoya disease (MMD) and the association with postoperative collateral vessel formation. The study population included 53 MMD patients that had undergone indirect bypass surgery and 50 healthy controls. Serum levels of VEGF, thrombospondin-1 (TSP-1), TSP-2, soluble VEGF receptor-1 (sVEGFR-1), sVEGFR-2, endostatin, angiopoietin-1 (Ang-1) and Ang-2 were measured at the baseline (preoperative) and at day seven following surgery. Postoperative collateralization assessment was conducted upon the six-month follow-up cerebral angiography. Cytokine levels were compared between patients with good or poor collateral formation. Compared with the healthy controls, MMD patients exhibited lower baseline levels of sVEGFR-1 (P<0.0001) and sVEGFR-2 (P<0.0001), but higher VEGF expression (P<0.0001). Ang-1 and Ang-2 levels did not exhibit any difference between the two groups. On day seven following surgery, MMD patients exhibited an almost unchanged sVEGFR-1 and sVEGFR-2 expression level, but upregulated expression of VEGF (P<0.0001), Ang-1 (P<0.0001) and TSP-2 (P<0.0001). The six-month follow-up angiographies revealed that 21 patients (45.65%) that had undergone the same surgical procedure achieved good collateralization. Patients with good collateral formation appeared to have lower sVEGFR-1 and sVEGFR-2 levels prior to (P=0.029 and P=0.045, respectively) and at day seven (P=0.044 and P=0.047, respectively) following bypass surgery when compared with the patients with worse collateralization. Therefore, sVEGFR-1 and sVEGFR-2 may play a role in the pathogenesis of MMD. Lower levels of sVEGFR-1 and sVEGFR-2 indicated better postoperative collateralization in the six months following indirect bypass surgery. However, Ang-1 and Ang-2 may not be specifically involved in the course of MMD.

Development and characterization of a Yucatan miniature biomedical pig permanent middle cerebral artery occlusion stroke model

BACKGROUND

Efforts to develop stroke treatments have met with limited success despite an intense need to produce novel treatments. The failed translation of many of these therapies in clinical trials has lead to a close examination of the therapeutic development process. One of the major factors believed to be limiting effective screening of these treatments is the absence of an animal model more predictive of human responses to treatments. The pig may potentially fill this gap with a gyrencephalic brain that is larger in size with a more similar gray-white matter composition to humans than traditional stroke animal models. In this study we develop and characterize a novel pig middle cerebral artery occlusion (MCAO) ischemic stroke model.

METHODS

Eleven male pigs underwent MCAO surgery with the first 4 landrace pigs utilized to optimize stroke procedure and 7 additional Yucatan stroked pigs studied over a 90 day period. MRI analysis was done at 24 hrs and 90 days and included T2w, T2w FLAIR, T1w FLAIR and DWI sequences and associated ADC maps. Pigs were sacrificed at 90 days and underwent gross and microscopic histological evaluation. Significance in quantitative changes was determined by two-way analysis of variance and post-hoc Tukey's Pair-Wise comparisons.

RESULTS

MRI analysis of animals that underwent MCAO surgery at 24 hrs had hyperintense regions in T2w and DWI images with corresponding ADC maps having hypointense regions indicating cytotoxic edema consistent with an ischemic stroke. At 90 days, region of interest analysis of T1 FLAIR and ADC maps had an average lesion size of 59.17 cc, a loss of 8% brain matter. Histological examination of pig brains showed atrophy and loss of tissue, consistent with MRI, as well as glial scar formation and macrophage infiltration.

CONCLUSIONS

The MCAO procedure led to significant and consistent strokes with high survivability. These results suggest that the pig model is potentially a robust system for the study of stroke pathophysiology and potential diagnostics and therapeutics.

Effectiveness of burr holes for indirect revascularization in patients with moyamoya disease-a review of the literature

OBJECTIVE

Moyamoya disease (MMD) has inspired the development and refinement of numerous surgical techniques to induce revascularization in hypoperfused territories. Over the last 3 decades, the use of burr hole surgery has progressively gained popularity. Used either in combination with another direct or indirect procedure or as the sole method for revascularization, burr hole surgery can be tailored to each patient's specific needs. We reviewed the conceptual progress, the technical evolution, and the clinical and radiological data following burr hole surgery.

METHODS

Pubmed and Medline databases were searched for publications from 1970 to 2012 relating to the use of burr holes in the surgical management of MMD. The reference sections of each article were reviewed, and pertinent articles were identified.

RESULTS

A review of case reports and case series using burr hole surgery for MMD testifies to the progressive refinement in the decision process and key technical aspects of this procedure. Favorable clinical and angiographic results have been documented in the pediatric and adult MMD population after burr holes, used either in combination with direct or indirect revascularization techniques, or more recently alone in the setting of multiple burr holes. The superficial temporal artery and middle meningeal artery have both been found to contribute to revascularization via burr holes.

CONCLUSIONS

Burr hole surgery is an important and versatile tool in the armamentarium of surgeons treating children and adults with MMD, allowing tailoring of the revascularization. Further studies should help to determine factors that may help predict optimal revascularization from this surgical technique.

Bilateral internal carotid arteries ligation temporary impairs brain vasculaturev in young rats

Bilateral internal carotid artery ligation (BICL) rat model is one of the chronic cerebral hypoperfusion animal models used for investigating brain dysfunction related diseases. Cerebral blood flow decreases in different cerebral regions in a time-dependent manner after the BICL. However little is known about the cerebral vasculature change in the brain after the BICL. In the current study, the bilateral internal carotid arteries of the juvenile rats were permanently ligated and the change of the cerebral vasculature was studied 7, 14 and 21 days after the BICL. In the juvenile rats, 7 days after the BICL, the functional vascular area was decreased significantly in the anterior half of the cerebral cortex, but it had only little decrease in the posterior half of the cerebral cortex and hippocampus. However, at the time points of 14 and 21 days after the surgery, the functional vascular area throughout the whole cerebral cortex and hippocampus was almost similar to those in the sham control rats. In conclusion, the results from our current study showed that in the BICL hypoperfusion model in young rats, the brain functional vascular area was impaired initially in certain brain regions after the artery ligation, but likely to be quickly self-recovered late after. The results suggest that the brain vasculature in young rats has plasticity to external insult caused by cerebral hypoperfusion.

Intracranial arterial stenoses: current viewpoints, novel approaches, and surgical perspectives

Ten percent of all strokes occurring in the USA are caused by intracranial arterial stenosis (IAS). Symptomatic IAS carries one of the highest rates of recurrent stroke despite intensive medical therapy (25 % in high-risk groups). Clinical results for endovascular angioplasty and stenting have been disappointing. The objectives of this study were to review the contemporary understanding of symptomatic IAS and present potential alternative treatments to resolve factors not addressed by current therapies. We performed a literature review on IAS pathophysiology, natural history, and current treatment. We present an evaluation of the currently deficient aspects in its treatment and explore the role of alternative surgical approaches. There is a well-documented interrelation between hemodynamic and embolic factors in cerebral ischemia caused by IAS. Despite the effectiveness of medical therapy, hemodynamic factors are not addressed satisfactorily by medications alone. Collateral circulation and severity of stenosis are the strongest predictors of risk for stroke and death. Indirect revascularization techniques, such as encephaloduroarteriosynangiosis, offer an alternative treatment to enhance collateral circulation while minimizing risk of hemorrhage associated with hyperemia and endovascular manipulation, with promising results in preliminary studies on chronic cerebrovascular occlusive disease. Despite improvements in medical management for IAS, relevant aspects of its pathophysiology are not resolved by medical treatment alone, such as poor collateral circulation. Surgical indirect revascularization can improve collateral circulation and play a role in the treatment of this condition. Further formal evaluation of indirect revascularization for IAS is a logical and worthy step in the development of intracranial atherosclerosis treatment strategies.

SSEA4-positive pig induced pluripotent stem cells are primed for differentiation into neural cells

Neural cells derived from induced pluripotent stem cells (iPSCs) have the potential for autologous cell therapies in treating patients with severe neurological disorders or injury. However, further study of efficacy and safety are needed in large animal preclinical models that have similar neural anatomy and physiology to humans such as the pig. The pig model for pluripotent stem cell therapy has been made possible for the first time with the development of pig iPSCs (piPSCs) capable of in vitro and in vivo differentiation into tissues of all three germ layers. Still, the question remains if piPSCs are capable of undergoing robust neural differentiation using a system similar to those being used with human iPSCs. In this study, we generated a new line of piPSCs from fibroblast cells that expressed pluripotency markers and were capable of embryoid body differentiation into all three germ layers. piPSCs demonstrated robust neural differentiation forming βIII-TUB/MAP2+ neurons, GFAP+ astrocytes, and O4+ oligodendrocytes and demonstrated strong upregulation of neural cell genes representative of all three major neural lineages of the central nervous system. In the presence of motor neuron signaling factors, piPSC-derived neurons showed expression of transcription factors associated with motor neuron differentiation (HB9 and ISLET1). Our findings demonstrate that SSEA4 expression is required for piPSCs to differentiate into neurons, astrocytes, and oligodendrocytes and furthermore develop specific neuronal subtypes. This indicates that the pigs can fill the need for a powerful model to study autologous neural iPSC therapies in a system similar to humans.

Granulocyte colony-stimulating factor enhances the angiogenetic effect of indirect bypass surgery for chronic cerebral hypoperfusion in a rat model

BACKGROUND

Granulocyte colony-stimulating factor (G-CSF) mobilizes hematopoietic bone marrow cells into systemic circulation and has been used clinically to treat chemotherapy-induced neutropenia. Recently, G-CSF was shown to have neuroprotective and angiogenetic effects in acute cerebral infarction.

OBJECTIVE

To evaluate the effects of G-CSF for angiogenesis after indirect bypass surgery.

METHODS

: Chronic cerebral hypoperfusions were induced in male Wistar rats by permanent bilateral internal carotid artery occlusion (BICAO). After BICAO, unilateral indirect bypass and encephalogaleosynangiosis (EGS) were performed, and human recombinant G-CSF (10 μg/kg) or saline was injected intramuscularly for 5 consecutive days. We measured regional cerebral blood flow (rCBF) by laser Doppler flowmetry and performed immunohistochemical analysis 21 days after BICAO.

RESULTS

BICAO decreased rCBF to 62.52% ± 5.8% of control (P < .01). The rCBF increased significantly 21 days after BICAO in all treatment groups (n = 10; P < .05) except the G-E- group. The rCBF increase observed in the G+E+ group was significantly higher than that observed in other groups. Both G-CSF and EGS treatments significantly increased the number of small vessels (P < .01), and G-CSF and EGS showed additive effect in increasing the number of small vessels.

CONCLUSION

Combined use of G-CSF and indirect bypass surgery induces an increase in rCBF and angiogenesis under conditions of cerebral chronic hypoperfusion. This is the first report to demonstrate that G-CSF can enhance angiogenesis induced by indirect bypass surgery, and that this combined therapy is a safe and easy method of treatment.