A neurodevelopmental epigenetic programme mediated by SMARCD3-DAB1-Reelin signalling is hijacked to promote medulloblastoma metastasis

How abnormal neurodevelopment relates to the tumour aggressiveness of medulloblastoma (MB), the most common type of embryonal tumour, remains elusive. Here we uncover a neurodevelopmental epigenomic programme that is hijacked to induce MB metastatic dissemination. Unsupervised analyses of integrated publicly available datasets with our newly generated data reveal that SMARCD3 (also known as BAF60C) regulates Disabled 1 (DAB1)-mediated Reelin signalling in Purkinje cell migration and MB metastasis by orchestrating cis-regulatory elements at the DAB1 locus. We further identify that a core set of transcription factors, enhancer of zeste homologue 2 (EZH2) and nuclear factor I X (NFIX), coordinates with the cis-regulatory elements at the SMARCD3 locus to form a chromatin hub to control SMARCD3 expression in the developing cerebellum and in metastatic MB. Increased SMARCD3 expression activates Reelin-DAB1-mediated Src kinase signalling, which results in a MB response to Src inhibition. These data deepen our understanding of how neurodevelopmental programming influences disease progression and provide a potential therapeutic option for patients with MB.

Radiosurgery to the spinal dorsal root ganglion induces fibrosis and inhibits satellite glial cell activation while preserving axonal neurotransmission

OBJECTIVE

Stereotactic radiosurgery (SRS) has been used to treat trigeminal neuralgia by targeting the cisternal segment of the trigeminal nerve, which in turn triggers changes in the gasserian ganglion. In the lumbar spine, the dorsal root ganglion (DRG) is responsible for transmitting pain sensitivity and is involved in the pathogenesis of peripheral neuropathic pain. Therefore, radiosurgery to the DRG might improve chronic peripheral pain. This study evaluated the clinical and histological effects of high-dose radiosurgery to the DRG in a rodent model.

METHODS

Eight Sprague-Dawley rats received either 40- or 80-Gy SRS to the fifth and sixth lumbar DRGs using the Leksell Gamma Knife Icon. Animals were euthanized 3 months after treatment, and the lumbar spine was dissected and taken for analysis. Simple histology was used to assess collagen deposition and inflammatory response. GFAP, Neu-N, substance P, and internexin were used as a measure of peripheral glial activation, neurogenesis, pain-specific neurotransmission, and neurotransmission in general, respectively. The integrity of the spinothalamic tract was assessed by means of the von Frey test.

RESULTS

The animals did not exhibit any signs of motor or sensory deficits during the experimentation period. Edema, fibrosis, and vascular sclerotic changes were present on the treated, but not the control, side. SRS reduced the expression of GFAP without affecting the expression of Neu-N, substance P, or internexin. The von Frey sensory perception elicited equivalent results for the control side and both radiosurgical doses.

CONCLUSIONS

SRS did not alter sensory or motor function but reduced the activation of satellite glial cells, a pathway for DRG-mediated pain perpetuation. Radiosurgery provoked changes equivalent to the effects of focal radiation on the trigeminal ganglion after SRS for trigeminal neuralgia, suggesting that radiosurgery could be successful in relieving radiculopathic pain.

Evaluation of Clinical and Histologic Effects of High-Dose Radiosurgery on Rat Dorsal Root Ganglion

BACKGROUND

Stereotactic radiosurgery (SRS) is an effective technique to create lesions of the trigeminal nerve to treat refractory trigeminal neuralgia. In the lumbar spine, the dorsal root ganglion (DRG) contains the body of the sensory neurons responsible for pain sensitivity. Neuromodulation of the DRG might therefore improve chronic peripheral pain. This study was performed to determine the feasibility, clinical, and histologic effects of delivering high-dose SRS targeted to the lumbar DRG in a rat model.

METHODS

Four Sprague Dawley male rats underwent 80 Gy maximum-dose single-fraction SRS to the left L5 and L6 DRG using the Leksell Gamma Knife Icon (Elekta, Atlanta, Georgia, USA). The right L5 and L6 DRGs served as controls. The animals were evaluated for motor and sensory deficits every 2 weeks and were sacrificed at 3 and 6 months after SRS. Common histologic techniques were used to assess for fibrosis and demyelination at the target levels.

RESULTS

No detectable motor or sensory deficits were seen in any animal. Histologic changes including fibrosis and loss of myelin were noted to the left L5 and L6 DRGs, but not the right side control DRGs. Fibrotic changes within the vertebral body were also evident on the treated sides of the vertebral bodies.

CONCLUSIONS

We were able to detect a demyelinating response from SRS delivered to the DRG in rats. Because such changes mimic those seen after trigeminal SRS in experimental animals, we hypothesize that radiosurgery may be a potential option in chronic spinal radicular pain amenable to neuromodulation.

Toward Improving Safety in Neurosurgery with an Active Handheld Instrument

Microsurgical procedures, such as petroclival meningioma resection, require careful surgical actions in order to remove tumor tissue, while avoiding brain and vessel damaging. Such procedures are currently performed under microscope magnification. Robotic tools are emerging in order to filter surgeons' unintended movements and prevent tools from entering forbidden regions such as vascular structures. The present work investigates the use of a handheld robotic tool (Micron) to automate vessel avoidance in microsurgery. In particular, we focused on vessel segmentation, implementing a deep-learning-based segmentation strategy in microscopy images, and its integration with a feature-based passive 3D reconstruction algorithm to obtain accurate and robust vessel position. We then implemented a virtual-fixture-based strategy to control the handheld robotic tool and perform vessel avoidance. Clay vascular phantoms, lying on a background obtained from microscopy images recorded during petroclival meningioma surgery, were used for testing the segmentation and control algorithms. When testing the segmentation algorithm on 100 different phantom images, a median Dice similarity coefficient equal to 0.96 was achieved. A set of 25 Micron trials of 80 s in duration, each involving the interaction of Micron with a different vascular phantom, were recorded, with a safety distance equal to 2 mm, which was comparable to the median vessel diameter. Micron's tip entered the forbidden region 24% of the time when the control algorithm was active. However, the median penetration depth was 16.9 μm, which was two orders of magnitude lower than median vessel diameter. Results suggest the system can assist surgeons in performing safe vessel avoidance during neurosurgical procedures.

The influence of suturectomy on age-related changes in cerebral blood flow in rabbits with familial bicoronal suture craniosynostosis: A quantitative analysis

Background

Coronal suture synostosis is a condition which can have deleterious physical and cognitive sequelae in humans if not corrected. A well-established animal model has previously demonstrated disruptions in intracranial pressure and developmental abnormalities in rabbits with congenital craniosynostosis compared to wild type rabbits.

Objective

The current study aimed to measure the cerebral blood flow (CBF) in developing rabbits with craniosynostosis who underwent suturectomy compared to those with no intervention and compared to wild type rabbits.

Methods

Rabbits with early onset coronal suture synostosis were assigned to have suturectomy at 10 days of age (EOCS-SU, n = 15) or no intervention (EOCS, n = 18). A subset of each group was randomly selected for measurement at 10 days of age, 25 days of age, and 42 days of age. Wild type rabbits (WT, n = 18) were also randomly assigned to measurement at each time point as controls. Cerebral blood flow at the bilateral hemispheres, cortices, thalami, and superficial cortices was measured in each group using arterial spin-labeling MRI.

Results

At 25 days of age, CBF at the superficial cortex was significantly higher in EOCS rabbits (192.6 ± 10.1 mL/100 mg/min on the left and 195 ± 9.5 mL/100 mg/min on the right) compared to WT rabbits (99.2 ± 29.1 mL/100 mg/min on the left and 96.2 ± 21.4 mL/100 mg/min on the right), but there was no significant difference in CBF between EOCS-SU (97.6 ± 11.3 mL/100 mg/min on the left and 99 ± 7.4 mL/100 mg/min on the right) and WT rabbits. By 42 days of age the CBF in EOCS rabbits was not significantly different than that of WT rabbits.

Conclusion

Suturectomy eliminated the abnormally increased CBF at the superficial cortex seen in EOCS rabbits at 25 days of age. This finding contributes to the evidence that suturectomy limits abnormalities of ICP and CBF associated with craniosynostosis.

Human Connectome-Based Tractographic Atlas of the Brainstem Connections and Surgical Approaches

BACKGROUND

The brainstem is one of the most challenging areas for the neurosurgeon because of the limited space between gray matter nuclei and white matter pathways. Diffusion tensor imaging-based tractography has been used to study the brainstem structure, but the angular and spatial resolution could be improved further with advanced diffusion magnetic resonance imaging (MRI).

OBJECTIVE

To construct a high-angular/spatial resolution, wide-population-based, comprehensive tractography atlas that presents an anatomical review of the surgical approaches to the brainstem.

METHODS

We applied advanced diffusion MRI fiber tractography to a population-based atlas constructed with data from a total of 488 subjects from the Human Connectome Project-488. Five formalin-fixed brains were studied for surgical landmarks. Luxol Fast Blue-stained histological sections were used to validate the results of tractography.

RESULTS

We acquired the tractography of the major brainstem pathways and validated them with histological analysis. The pathways included the cerebellar peduncles, corticospinal tract, corticopontine tracts, medial lemniscus, lateral lemniscus, spinothalamic tract, rubrospinal tract, central tegmental tract, medial longitudinal fasciculus, and dorsal longitudinal fasciculus. Then, the reconstructed 3-dimensional brainstem structure was sectioned at the level of classic surgical approaches, namely supracollicular, infracollicular, lateral mesencephalic, perioculomotor, peritrigeminal, anterolateral (to the medulla), and retro-olivary approaches.

CONCLUSION

The advanced diffusion MRI fiber tracking is a powerful tool to explore the brainstem neuroanatomy and to achieve a better understanding of surgical approaches.

ABBREVIATIONS

CN, cranial nerveCPT, corticopontine tractCST, corticospinal tractCTT, central tegmental tractDLF, dorsal longitudinal fasciculusHCP, Human Connectome ProjectML, medial lemniscusMLF, medial longitudinal fasciculusRST, rubrospinal tractSTT, spinothalamic tract.

Tip Design for Safety of Steerable Needles for Robot-Controlled Brain Insertion

Background

Current practice in neurosurgical needle insertion is limited by the straight trajectories inherent with rigid probes. One technique allowing curvilinear trajectories involves flexible bevel-tipped needles, which bend during insertion due to their asymmetry. In the brain, safety will require avoidance of the sharp tips often used in laboratory studies, in favor of a more rounded profile. Steering performance, on the other hand, requires maximal asymmetry. Design of safe bevel-tipped brain needles thus involves management of this tradeoff by adjusting needle gauge, bevel angle, and fillet (or tip) radius to arrive at a design that is suitably asymmetrical while producing strain, strain rate, and stress below the levels that would damage brain tissue.

Methods

Designs with a variety of values of needle radius, bevel angle, and fillet radius were evaluated in finite-element simulations of simultaneous insertion and rotation. Brain tissue was modeled as a hyperelastic, linear viscoelastic material. Based on the literature available, safety thresholds of 0.19 strain, 10 s^-1 strain rate, and 120 kPa stress were used. Safe values of needle radius, bevel angle, and fillet radius were selected, along with an appropriate velocity envelope for safe operation. The resulting needle was fabricated and compared with a Sedan side-cutting brain biopsy needle in a study in the porcine model in vivo (N=3).

Results

The prototype needle selected was 1.66 mm in diameter, with bevel angle of 10° and fillet radius of 0.25 mm. Upon examination of postoperative CT and histological images, no differences in tissue trauma or hemorrhage were noted between the prototype needle and the Sedan needle.

Conclusions

The study indicates a general design technique for safe bevel-tipped brain needles based on comparison with relevant damage thresholds for strain, strain rate, and stress. The full potential of the technique awaits the determination of more exact safety thresholds.

The influence of surgical correction on white matter microstructural integrity in rabbits with familial coronal suture craniosynostosis

OBJECT Craniosynostosis is a condition in which one or more of the calvarial sutures fuses prematurely. In addition to the cosmetic ramifications attributable to premature suture fusion, aberrations in neurophysiological parameters are seen, which may result in more significant damage. This work examines the microstructural integrity of white matter, using diffusion tensor imaging (DTI) in a homogeneous strain of rabbits with simple, familial coronal suture synostosis before and after surgical correction. METHODS After diagnosis, rabbits were assigned to different groups: wild-type (WT), rabbits with early-onset complete fusion of the coronal suture (BC), and rabbits that had undergone surgical correction with suturectomy (BC-SU) at 10 days of age. Fixed rabbit heads were imaged at 12, 25, or 42 days of life using a 4.7-T, 40-cm bore Avance scanner with a 7.2-cm radiofrequency coil. For DTI, a 3D spin echo sequence was used with a diffusion gradient (b = 2000 sec/mm(2)) applied in 6 directions. RESULTS As age increased from 12 to 42 days, the DTI differences between WT and BC groups became more pronounced (p < 0.05, 1-way ANOVA), especially in the corpus callosum, cingulum, and fimbriae. Suturectomy resulted in rabbits with no significant differences compared with WT animals, as assessed by DTI of white matter tracts. Also, it was possible to predict to which group an animal belonged (WT, BC, and BC-SU) with high accuracy based on imaging data alone using a linear support vector machine classifier. The ability to predict to which group the animal belonged improved as the age of the animal increased (71% accurate at 12 days and 100% accurate at 42 days). CONCLUSIONS Craniosynostosis results in characteristic changes of major white matter tracts, with differences becoming more apparent as the age of the rabbits increases. Early suturectomy (at 10 days of life) appears to mitigate these differences.

Premetastatic soil and prevention of breast cancer brain metastasis

BACKGROUND

As therapies for systemic cancer improve and patients survive longer, the risk for brain metastases increases. We evaluated whether immune mechanisms are involved in the development of brain metastasis.

METHODS

We conducted our studies using BALB/c mice bearing syngeneic 4T1 mammary adenocarcinoma cells in the mammary gland.

RESULTS

The brains of mice bearing 4T1 tumors at day 14 had no detectable metastatic tumor cells but presented with marked accumulation of bone marrow-derived CD11b(+)Gr1(+) myeloid cells, which express high levels of inflammatory chemokines S100A8 and S100A9. In vitro, S100A9 attracts 4T1 cells through Toll-like receptor 4 and CD11b(+)Gr1(+) myeloid cells through Toll-like receptor 4 and the receptor for advanced glycation end-products. Systemic treatment of 4T1-bearing mice with anti-Gr1 (RB6-8C5) monoclonal antibody reduces accumulation of CD11b(+)Gr1(+) myeloid cells in the day-14 premetastatic brain as well as subsequent brain metastasis of 4T1 cells detected on day 30. Furthermore, treatment of 4T1 tumor-bearing mice with the cyclooxygenase-2 inhibitor celecoxib or genetic disruption of cyclooxygenase-2 in 4T1 cells inhibits the inflammatory chemokines and infiltration of CD11b(+)Gr1(+) myeloid cells in the premetastatic brain and subsequent formation of brain metastasis.

CONCLUSIONS

Our results suggest that the primary tumor induces accumulation of CD11b(+)Gr1(+) myeloid cells in the brain to form "premetastatic soil" and inflammation mediators, such as S100A9, that attract additional myeloid cells as well as metastatic tumor cells. Celecoxib and anti-Gr1 treatment may be useful for blockade of these processes, thereby preventing brain metastasis in patients with breast cancer.

Morris water maze function and histologic characterization of two age-at-injury experimental models of controlled cortical impact in the immature rat

PURPOSE

Controlled cortical impact (CCI) is commonly used in adult animals to study focal traumatic brain injury (TBI). Our study aims to further study injury mechanisms in children and variable models of pathology in the developing brain.

METHODS

Develop a focal injury model of experimental TBI in the immature, postnatal days (PND) 7 and 17 rats that underwent a CCI at varying depths of deflection, 1.5-2.5 mm compared with sham and then tested using the Morris water maze (MWM) beginning on post-injury day (PID) 11. Histopathologic analysis was performed at PID 1 and 28.

RESULTS

In PND 7, the 1.75- and 2.0-mm deflections (diameter (d) = 3 mm; velocity = 4 m/s; and duration = 500 ms) resulted in significant MWM deficits while the 1.5-mm injury did not produce MWM deficits vs. sham controls. In PND 17, all injury levels resulted in significant MWM deficits vs. sham controls with a graded response; the 1.5-mm deflection (d = 6 mm; velocity = 4 m/s; and duration = 500 ms) produced significantly less deficits as compared WITH the 2.0- and 2.5-mm injuries. Histologically, a graded injury response was also seen in both ages at injury with cortical and more severe injuries, hippocampal damage. Cortical contusion volume increased in most injury severities from PID 1 to 28 in both ages at injury while hippocampal volumes subsequently decreased.

CONCLUSIONS

CCI in PND 7 and 17 rat results in significant MWM deficits and cortical histopathology providing two different and unique experimental models of TBI in immature rats that may be useful in further investigations into the mechanisms and treatments of pediatric TBI.

Dipyrone inhibits neuronal cell death and diminishes hypoxic/ischemic brain injury

BACKGROUND

Dipyrone is an analgesic and antipyretic drug usually prescribed for patients with inflammatory conditions. We recently identified dipyrone as an antiapoptotic agent by screening a library of 1040 compounds for their ability to inhibit cytochrome c release from isolated mitochondria.

OBJECTIVE

We investigated the potential neuroprotective properties of dipyrone in cerebral ischemia.

METHODS

We evaluated the protective effects of dipyrone in experimental models of neuronal hypoxia/ischemia, including an oxygen/glucose deprivation model in primary cerebrocortical neurons and a focal cerebral ischemia model in mice.

RESULTS

Dipyrone reduced hypoxia/ischemia injury in both cellular and animal models. Dipyrone inhibited the release of cytochrome c and other mitochondrial apoptogenic factors from mitochondria into the cytoplasm, and attenuated subsequent caspase-9 and caspase-3 activation both in vitro and in vivo. Moreover, dipyrone prevented ischemia-induced changes in Bcl-2 and tBid, and ameliorated oxygen/glucose deprivation-mediated loss of mitochondrial membrane potential. Dipyrone also inhibited ischemia-induced reactive microgliosis. In the cellular models evaluated, dipyrone did not inhibit oxygen/glucose deprivation-induced cyclooxygenase-2 activation.

CONCLUSION

Dipyrone is remarkably neuroprotective in cerebral ischemia, and its cyclooxygenase-independent protective properties are, at least in part, due to the inhibition of mitochondrial cell death cascades.

Injection Parameters Affect Cell Viability and Implant Volumes in Automated Cell Delivery for the Brain

The technique of central nervous system cell implantation can affect the outcome of preclinical or clinical studies. Our goal was to evaluate the impact of various injection parameters that may be of consequence during the delivery of solute-suspended cells. These parameters included ( 1 ) the type and concentration of cells used for implantation, ( 2 ) the rate at which cells are injected (flow rate), ( 3 ) the acceleration of the delivery device, ( 4 ) the period of time between cell loading and injection into the CNS (delay), and ( 5 ) the length and gauge of the needle used to deliver the cells. Neural progenitor cells (NPCs) and bone marrow stromal cells (BMSCs) were injected an automated device. These parameters were assessed in relation to their effect on the volume of cells injected and cell viability. Longer and thinner cannulae and higher cell concentrations were detrimental for cell delivery. Devices and techniques that optimize these parameters should be of benefit.

Abstract 1788: COX-2 blockade suppresses gliomagenesis by inhibiting CCL2-mediated accumulation of myeloid-derived suppressor cells

Recent reports in epidemiology suggest yet unexplained roles of immunosurveillance in gliomagenesis and survival of glioma patients. For example, the use of nonsteroidal anti-inflammatory drugs (NSAIDs) has been shown to be associated with reduced occurrence of malignant glioma in humans. NSAIDs mediate their biological effects partially by suppression of cyclooxygenase (COX)-2 and its product prostaglandin (PG) E2, both of which are known to induce immunoregulatory cells, such as myeloid-derived suppressor cells (MDSCs) and regulatory T cells, in tumor-bearing hosts. In the current study, using a novel Sleeping Beauty transposon-mediated de novo mouse glioma model, we evaluated our hypothesis that COX-2 blockade by NSAIDs would suppress gliomagenesis by altering chemokine expression and immune cell attraction in glioma microenvironment, thereby promoting anti-glioma immunosurveillance. We chose acetylsalicylic acid (ASA; a non-selective COX-2 inhibitor) and celecoxib (a selective COX-2 inhibitor) as candidates of therapeutic agents. In wild type (WT) mice with developing gliomas, ASA-based treatment delayed glioma development only if the treatment was initiated simultaneously with glioma induction, but not after the tumor was established. In contrast, celecoxib-based treatment inhibited glioma development even if the treatment was initiated later. These data indicate that COX-2 plays an important role in gliomagenesis. Consistently, C57BL/6-background mice deficient for COX-2 gene (Cox2-deficient mice) demonstrated a significant delay in tumor growth when compared with the WT mice. Of importance, both the NSAID-treated and Cox2-deficient mice exhibited a decrease in systemic PGE2 levels when compared with the controls, which was concomitant with decreases in CCL2 and CD11b+Ly6CloLy6G+ MDSCs but increases in CXCL10 and CD8+CD107a+ CTLs in the glioma microenvironment. In addition, MDSC depletion by anti-Gr1 antibody treatment prolonged the survival of the WT mice developing gliomas, suggesting that COX2-induced MDSCs play an important role in gliomagenesis. We finally addressed the impacts of CCL2 and CXCL10 on the attraction of MDSCs and CTLs as well as gliomagenesis. With developing gliomas, Ccl2-deficient mice exhibited a decrease in MDSC accumulation in the glioma microenvironment, whereas Cxcl10-deficient mice exhibited a decrease in CTL accumulation. Taken together, these findings indicate important roles of the COX-2 pathway in gliomagenesis through CCL2-mediated MDSC accumulation and a reduction of CXCL10-mediated CTL infiltration into the glioma microenvironment, and suggest a possibility to develop NSAID-based prophylactic strategies for gliomas.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 1788. doi:10.1158/1538-7445.AM2011-1788

Manual vs automated delivery of cells for transplantation: accuracy, reproducibility, and impact on viability

BACKGROUND

Cellular transplantation holds promise for the management of a variety of neurological disorders. However, there is great variability in cell type, preparation methods, and implantation technique, which are crucial to clinical outcomes.

OBJECTIVE

We compared manual injection with automated injection using a prototype device to determine the possible value of a mechanized delivery system.

METHODS

Neural progenitor cells and bone marrow stromal cells were injected using manual or automated methods. Consistency of injection volumes and cell number and viability were evaluated immediately or 1 day after injection.

RESULTS

When cells were delivered as a series of 3 manual injections from the same syringe, the variation in fluid volume was greater than for single manual injections. Automated delivery of a series of 3 injections resulted in a lower variability in the amount of delivery than manual injection for both cell lines (1.2%-2.6% coefficient of variability for automated delivery vs 4.3%-24.0% for manual delivery). The amount delivered from injection 1 to injection 3 increased significantly with manual injections, whereas the amount injected did not vary over the 3 injections for the automated unit. Cell viability 1 day after injection was typically 30% to 40% of the value immediately after injection for the bone marrow stromal cells and 30% to 70% for the neural progenitor cells. There were no significant differences in viability attributed to the method of injection.

CONCLUSION

The automated delivery device led to enhanced consistency of volumetric cell delivery but did not improve cell viability in the methods tested. Automated techniques could be useful in standardizing reproducible procedures for cell transplantation and improve both preclinical and clinical research.

COX-2 blockade suppresses gliomagenesis by inhibiting myeloid-derived suppressor cells

Epidemiologic studies have highlighted associations between the regular use of nonsteroidal anti-inflammatory drugs (NSAID) and reduced glioma risks in humans. Most NSAIDs function as COX-2 inhibitors that prevent production of prostaglandin E₂ (PGE₂). Because PGE₂ induces expansion of myeloid-derived suppressor cells (MDSC), we hypothesized that COX-2 blockade would suppress gliomagenesis by inhibiting MDSC development and accumulation in the tumor microenvironment (TME). In mouse models of glioma, treatment with the COX-2 inhibitors acetylsalicylic acid (ASA) or celecoxib inhibited systemic PGE₂ production and delayed glioma development. ASA treatment also reduced the MDSC-attracting chemokine CCL2 (C-C motif ligand 2) in the TME along with numbers of CD11b(+)Ly6G(hi)Ly6C(lo) granulocytic MDSCs in both the bone marrow and the TME. In support of this evidence that COX-2 blockade blocked systemic development of MDSCs and their CCL2-mediated accumulation in the TME, there were defects in these processes in glioma-bearing Cox2-deficient and Ccl2-deficient mice. Conversely, these mice or ASA-treated wild-type mice displayed enhanced expression of CXCL10 (C-X-C motif chemokine 10) and infiltration of cytotoxic T lymphocytes (CTL) in the TME, consistent with a relief of MDSC-mediated immunosuppression. Antibody-mediated depletion of MDSCs delayed glioma growth in association with an increase in CXCL10 and CTLs in the TME, underscoring a critical role for MDSCs in glioma development. Finally, Cxcl10-deficient mice exhibited reduced CTL infiltration of tumors, establishing that CXCL10 limited this pathway of immunosuppression. Taken together, our findings show that the COX-2 pathway promotes gliomagenesis by directly supporting systemic development of MDSCs and their accumulation in the TME, where they limit CTL infiltration.

Cellular transplantation for the nervous system: impact of time after preparation on cell viability and survival

OBJECT

Cell transplantation has shown promise for the treatment of various neurological disorders, but the factors that influence cell survival and integration following transplantation are poorly understood. In fact, little is known regarding how simple but potentially critical variables, including the method of cellular preparation and administration, might affect transplant success. The goal of the present study was to determine the impact of time between tissue preparation and implantation on cellular viability. Time can vary with cell preparation, delivery to the operating room, and surgical technique. This study was also designed to evaluate the sensitivity of various methods of assessing implant viability.

METHODS

Cell lines of neural progenitor cells and bone marrow stromal cells were generated from healthy adult mice. On the day of experimentation, the cells were collected, suspended in a balanced salt solution, and sequentially assessed for viability for up to 3.5 hours based on their appearance under phase-contrast microscopy, their ability to retain a fluorescent dye, and their attachment to a cultivation surface for 24 hours.

RESULTS

When viability was measured based on the ability of cells to retain a fluorescent dye, there was a decrease in viability of 10-15% each hour. Based on the ability of the cells to attach to a culture surface and grow for 24 hours, viability decreased more rapidly at approximately 20% per hour. In addition, only about one-third of the cells judged viable based on phase-contrast microscopy or acute dye retention were found to be viable based on plating, and only 10% of the cells initially judged as viable were still capable of survival after 3 hours in suspension.

CONCLUSIONS

The authors' results indicate that that there can be significant losses in viability between preparation and implantation and that more sophisticated methods of evaluation, such as the ability of cells to attach to a substrate and grow, may be required to detect decreases in viability. The time between preparation and implantation will be an important factor in clinical trial design.

Resveratrol attenuates behavioral impairments and reduces cortical and hippocampal loss in a rat controlled cortical impact model of traumatic brain injury

Resveratrol (3,5,4'-trihydroxystilbene) is a plant-derived small molecule that is protective against multiple neurological and systemic insults. To date, no studies have explored the potential for resveratrol to provide behavioral protection in adult animals in the setting of traumatic brain injury (TBI). Using 50 male Sprague-Dawley rats, we employed the controlled cortical impact (CCI) model to ascertain whether post-injury administration of resveratrol would reduce the severity of the well-described cognitive and motor deficits associated with the model. Contusion volumes and hippocampal neuronal numbers were also measured to characterize the tissue and neuronal-sparing properties, respectively, of resveratrol. We found that 100 mg/kg, but not 10 mg/kg, of intraperitoneal resveratrol administered after injury provides significant behavioral protection in rats sustaining CCI. Specifically, rodents treated with 100 mg/kg of resveratrol showed improvements in motor performance (beam balance and beam walking) and testing of visuospatial memory (Morris water maze). Behavioral protection was correlated with significantly reduced contusion volumes, preservation of CA1 and CA3 hippocampal neurons, and protection from overt hippocampal loss as a result of incorporation into the overlying cortical contusion in resveratrol-treated animals. Although the mechanisms by which resveratrol mediates its neuroprotection is unclear, the current study adds to the growing literature identifying resveratrol as a potential therapy for human brain injury.

Flumazenil administration attenuates cognitive impairment in immature rats after controlled cortical impact

Evidence suggests that the gamma-aminobutyric acid (GABA)ergic system may be involved in cognitive dysfunction following traumatic brain injury (TBI). We investigated the effect of flumazenil treatment, a benzodiazepine antagonist approved by the U.S. Food and Drug Administration, on learning and memory in the immature rat following experimental brain injury. Post-natal day 17 rats were injured using controlled cortical impact. Systemic treatment with flumazenil at 1, 5, and 10 mg/kg was initiated on post-injury day 1 and administered for 13 days via daily intraperitoneal injections. Morris water maze (MWM) testing was used to measure latency to find a submerged platform and the results from experimental and control animals were compared. We demonstrated a significant dose-dependent improvement in MWM performance in drug-treated animals. This is the first study demonstrating the efficacy of flumazenil in reducing post-TBI cognitive deficits and we propose that these effects may be related to modulation of the GABA(A) receptor.

Identification of ATP citrate lyase as a positive regulator of glycolytic function in glioblastomas

Glioblastomas, the most malignant type of glioma, are more glycolytic than normal brain tissue. Robust migration of glioblastoma cells has been previously demonstrated under glycolytic conditions and their pseudopodia contain increased glycolytic and decreased mitochondrial enzymes. Glycolysis is suppressed by metabolic acids, including citric acid which is excluded from mitochondria during hypoxia. We postulated that glioma cells maintain glycolysis by regulating metabolic acids, especially in their pseudopodia. The enzyme that breaks down cytosolic citric acid is ATP citrate lyase (ACLY). Our identification of increased ACLY in pseudopodia of U87 glioblastoma cells on 1D gels and immunoblots prompted investigation of ACLY gene expression in gliomas for survival data and correlation with expression of ENO1, that encodes enolase 1. Queries of the NIH's REMBRANDT brain tumor database based on Affymetrix data indicated that decreased survival correlated with increased gene expression of ACLY in gliomas. Queries of gliomas and glioblastomas found an association of upregulated ACLY and ENO1 expression by chi square for all probe sets (reporters) combined and correlation for numbers of probe sets indicating shared upregulation of these genes. Real-time quantitative PCR confirmed correlation between ACLY and ENO1 in 21 glioblastomas (p < 0.001). Inhibition of ACLY with hydroxycitrate suppressed (p < 0.05) in vitro glioblastoma cell migration, clonogenicity and brain invasion under glycolytic conditions and enhanced the suppressive effects of a Met inhibitor on cell migration. In summary, gene expression data, proteomics and functional assays support ACLY as a positive regulator of glycolysis in glioblastomas.

Therapeutic efficacy of a herpes simplex virus with radiation or temozolomide for intracranial glioblastoma after convection-enhanced delivery

The herpes simplex virus-1 (HSV-1)-infected cell protein 0 (ICP0) is an E3 ubiquitin ligase implicated in cell cycle arrest and DNA repair inhibition. Convection-enhanced delivery (CED) of either the replication-defective, ICP0-producing HSV-1 mutant, d106, or the recombinant d109, devoid of all viral genome expression, was performed to determine the in vivo efficacy of ICP0 in combination with ionizing radiation (IR) or systemic temozolomide (TMZ) in the treatment of glioblastoma multiforme (GBM). Intracranial U87-MG xenografts were established in athymic nude mice. Animal survival was determined after mice underwent intracranial CED of either the replication-defective d106 or d109 viruses, or Hanks' balanced salt solution (HBSS), before a single session of whole-brain irradiation or TMZ treatment. Median survival for animals that underwent treatment with HBSS alone, d109 alone, d106 alone, HBSS + IR, HBSS + TMZ, d109 + IR, d106 + IR, and d106 + TMZ was 28, 35, 41, 39, 44, 39, 68 (P < 0.01), and 66 days (P < 0.01), respectively. Intracerebral d106 CED resulted in a significant increase in athymic nude mouse survival when combined with IR or TMZ. d106 CED allows for distribution of HSV-1 in human GBM xenografts and persistent viral infection.

Toll like receptor-3 ligand poly-ICLC promotes the efficacy of peripheral vaccinations with tumor antigen-derived peptide epitopes in murine CNS tumor models

Background

Toll-like receptor (TLR)3 ligands serve as natural inducers of pro-inflammatory cytokines capable of promoting Type-1 adaptive immunity, and TLR3 is abundantly expressed by cells within the central nervous system (CNS). To improve the efficacy of vaccine strategies directed against CNS tumors, we evaluated whether administration of a TLR3 ligand, polyinosinic-polycytidylic (poly-IC) stabilized with poly-lysine and carboxymethylcellulose (poly-ICLC) would enhance the anti-CNS tumor effectiveness of tumor peptide-based vaccinations.

Methods

C57BL/6 mice bearing syngeneic CNS GL261 glioma or M05 melanoma received subcutaneous (s.c.) vaccinations with synthetic peptides encoding CTL epitopes- mEphA2 (671–679), hgp100 (25–33) and mTRP-2 (180–188) for GL261, or ovalbumin (OVA: 257–264) for M05. The mice also received intramuscular (i.m.) injections with poly-ICLC.

Results

The combination of subcutaneous (s.c.) peptide-based vaccination and i.m. poly-ICLC administration promoted systemic induction of antigen (Ag)-specific Type-1 CTLs expressing very late activation antigen (VLA)-4, which confers efficient CNS-tumor homing of vaccine-induced CTLs based on experiments with monoclonal antibody (mAb)-mediated blockade of VLA-4. In addition, the combination treatment allowed expression of IFN-γ by CNS tumor-infiltrating CTLs, and improved the survival of tumor bearing mice in the absence of detectable autoimmunity.

Conclusion

These data suggest that poly-ICLC, which has been previously evaluated in clinical trials, can be effectively combined with tumor Ag-specific vaccine strategies, thereby providing a greater index of therapeutic efficacy.

Testing causal mechanisms of nonsyndromic craniosynostosis using path analysis of cranial contents in rabbits with uncorrected craniosynostosis

OBJECTIVE

Various causal mechanisms of familial nonsyndromic craniosynostosis have been presented. One hypothesis suggests that overproduction of bone at the suture is the primary origin of craniosynostosis, which affects brain and cranial growth secondarily through altered intracranial pressure (Primary Suture Fusion Model). Other hypotheses suggest that decreased cranial base growth or abnormal brain growth are the primary cause of craniosynostosis (Cranial Base, Brain Parenchyma Models, respectively). This study was designed to investigate which model best describes neurocranial changes associated with craniosynostosis in a rabbit model through multivariate path analysis.

DESIGN

Serial magnetic resonance imaging scans and intracranial pressure measurements were obtained at 10, 25, and 42 days of age from 18 rabbits: six controls, six with delayed-onset synostosis, and six with early-onset synostosis. Five variables were collected from each rabbit: calvarial thickness at the affected suture, cranial base length, brain volume, cerebrospinal fluid volume, and intracranial pressure. This data set was used to test causal pathway relationships generated by the proposed models. Goodness of fit was measured by experimental group for each model.

RESULTS

Primary Suture Fusion Model best explained the variables in both delayed-onset and early-onset synostotic rabbits (Goodness of fit = 93%, 97%, respectively). Cranial Base Model (Goodness of fit = 94%) best explained the data in control rabbits.

CONCLUSION

Results suggest that the primary site of craniosynostosis in craniosynostotic rabbits is most likely the synostosed suture. Other cranial vault anomalies are most likely secondary compensatory changes. Results of the present study may provide insight regarding the causal pathway of craniosynostosis.

Sensitivity to radiation-induced apoptosis and neuron loss declines rapidly in the postnatal mouse neocortex

Therapeutic brain irradiation can cause progressive decline in cognitive function, particularly in children, but the reason for this effect is unclear. The study explored whether age-related differences in apoptotic sensitivity might contribute to the increased vulnerability of the young brain to radiation. Postnatal day 1 (P1) to P30 mice were treated with 0-16 Gy whole-body X-irradiation. Apoptotic cells were identified and quantified up to 48 h later using the TdT-UTP nick end-labelling method (TUNEL) and immunohistochemistry for activated caspase-3. The number of neuron-specific nuclear protein (NeuN)-positive and -negative cells were also counted to measure neuronal and non-neuronal cell loss. Significantly greater TUNEL labelling occurred in the cortex of irradiated P1 animals relative to the other age groups, but there was no difference among the P7, P14 and P30 groups. Irradiation decreased the %NeuN-positive cells in the mice irradiated on P1, whereas in P14 animals, irradiation led to an increase in the %NeuN-positive cells. These data demonstrate that neocortical neurons of very young mice are more susceptible to radiation-induced apoptosis. However, this sensitivity decreases rapidly after birth. By P14, acute cell loss due to radiation occurs primarily in non-neuronal populations.

Age-related changes in lateral ventricle morphology in craniosynostotic rabbits using magnetic resonance imaging

BACKGROUND AND AIMS

Craniosynostosis occurs in 300-500 per 1,000,000 live births and results in secondary craniofacial, ocular, and intracranial anomalies. Neurologic problems associated with craniosynostosis include changes in intracranial morphology such as dilation of the cerebral ventricles, however, clinical studies are confounded by small sample sizes, heterogenous samples, and lack of age-matched controls. The present study was designed to assess age-related changes in the lateral ventricle volume of the brain in normal rabbits and rabbits with naturally-occurring coronal suture synostosis using serial magnetic resonance imaging.

METHODS

Eighteen rabbits (6 wild-type controls, 6 with early-onset [ approximately 21 days gestation], and 6 with delayed-onset [approximately 25 days post-gestation] coronal suture synostosis) had magnetic resonance imaging (MRI) at 10, 25, and 42 days of age.

RESULTS

The results demonstrate that rabbits with early-onset synostosis had significantly (p<0.001) dilated and larger lateral ventricles (by 77% at 10 days of age) than wild-type and delayed-onset synostosis rabbits, which progressively worsened by day 42.

CONCLUSION

This finding suggests that uncorrected coronal suture synostosis may have early effects on lateral ventricle volume hypertrophy, possibly through obstructed cerebrospinal fluid and/or venous drainage and circulation.

Hippocampal neurotransplantation evaluated in the rat kainic acid epilepsy model

OBJECTIVE

Neurotransplantation has focused on disorders that involve subcortical brain targets. We evaluated the concepts of epileptic focus repair and changes in animal behavior through replacement of lost hippocampal neurons. The safety of hippocampal neurotransplantation was assessed in the rat kainic acid (KA) epilepsy model.

METHODS

Sixty-three rats were studied and classified into six groups: KA plus 40,000 LBS-Neurons (Layton BioScience, Sunnyvale, CA; n = 13); KA plus 80,000 cells (n = 12); KA plus media (n = 9); no-KA plus 40,000 cells (n = 12); no-KA plus 80,000 cells (n = 12); and no-KA plus media (n = 5). Clinical observation (2 h daily) and electroencephalogram recording (3 h every other week) were performed to check for seizures until Week 11 after KA injection. On Week 12, the Morris water maze test was performed to assess spatial learning and memory.

RESULTS

Four rats were excluded because of intracranial hematoma or abscess. In the clinical observation of seizures, the no-KA plus media group had significantly fewer seizures than rats that received KA followed by injection of 40,000 cells, 80,000 cells, or media (P = 0.001, 0.0004, and 0.004, respectively). On electroencephalographic analysis, there was no significant difference between any of the groups. Transplanted rats with KA-induced epilepsy did not have an increased number of seizures. In the Morris water maze test, the hidden platform task showed that the KA plus 80,000 cell group had significantly longer swim latencies than groups with no-KA plus 40,000 cells (P = 0.035) or no-KA plus 80,000 cells (P = 0.015), demonstrating the behavioral deficits caused by KA injection. The probe trial showed no significant difference for the percentage of time in the target quadrant between any of the groups. Histological studies showed that 26 (59%) of 44 transplanted rats had evidence of graft survival.

CONCLUSION

The safety of cortical neurotransplantation was demonstrated, even in an animal model predisposed to epilepsy. We did not find evidence for cessation of seizures or improvement in behavior using this model.

Treatment of rat gliosarcoma brain tumors by HSV-based multigene therapy combined with radiosurgery

Our laboratory has employed replication-defective herpes simplex virus type 1 gene transfer vectors for treatment of animal models of human malignant glioblastoma. The base vectors were defective for the immediate early (IE) genes ICP4, ICP27, and ICP22 but expressed the IE gene ICP0, which can arrest tumor cell division, and an IE thymidine kinase (alpha-tk) gene construct that mediates suicide gene therapy (SGT) in the presence of ganciclovir (GCV). Previously, we reported that SGT using ICP0/alpha-tk vectors in nude mouse models of glioblastoma was improved by coexpression of the gap-junction-forming protein connexin43 (Cx43) or human tumor necrosis factor alpha (TNF alpha). We also showed that further gains in therapeutic outcome could be achieved by combining TNF alpha-enhanced SGT with gamma-knife radiosurgery (GKR). To expand these observations, we have first repeated these studies in immunocompetent rats with brain tumors derived from implanted 9L gliosarcoma cells and second compared the most efficient vector from this study with a new recombinant vector, NUREL-C2, which expressed both TNF alpha and Cx43 along with ICP0 and alpha-tk. Results from the first part indicated that our ICP0/alpha-tk/TNF alpha vector in combination with GKR provides an effective therapy although this treatment was not statistically better than GKR combined with the ICP0/alpha-tk/Cx43 vector. Our observations in the second part suggested that NUREL-C2 may be more effective than the ICP0/alpha-tk/TNF alpha vector in combination treatments with GCV (P = 0.08) or GCV plus GKR (P = 0.10). GKR significantly enhanced the efficacy of NUREL-C2/GCV treatment (P = 0.02) as well as other virus/GCV treatments (P < or = 0.05). Conversely, the efficacy of GKR was significantly improved by both the ICP0/alpha-tk/TNF alpha vector and NUREL-C2 in combination with GCV (P = 0.02 and P < 0.01, respectively). Together these results indicate that NUREL-C2 may be an attractive candidate for Phase I gene-therapy safety studies in patients with recurrent malignant glioblastoma.

Increased intracranial pressure after coronal suturectomy in craniosynostotic rabbits

It has been suggested that the complications associated with intracranial hypertension in craniosynostotic infants may be managed with surgical release of the synostosed sutures. However, both postoperative increases and decreases in intracranial pressure (ICP) have been reported in heterogeneous samples of infants with syndromic and nonsyndromic craniosynostoses. The present study was designed to describe longitudinal changes in ICP in a homogeneous sample of rabbits with uncorrected and corrected familial coronal suture synostosis and compare them with age-matched normal control rabbits. Fifty-three rabbits were divided into three groups: normal rabbits (n = 28), rabbits with uncorrected bilateral coronal suture synostosis (n = 9), and rabbits with bilateral coronal suture synostosis with coronal suturectomy at 25 days of age (n = 16). ICP was measured at 25 and 42 days of age using a Codman epidural microtransducer. Results revealed that rabbits with uncorrected craniosynostosis had significantly (P < 0.05) higher ICP at 25 days of age than normal control rabbits by approximately 86%. However, by 42 days of age, ICP in normal rabbits increased by 75%, whereas ICP in rabbits with uncorrected craniosynostosis decreased by 69% over the same time. Synostotic rabbits with coronal suturectomy showed a 50% decrease in ICP immediately after surgical release and then followed the normal, age-related ICP pattern, which significantly increased by 75% at 42 days of age. Results suggest that, in the rabbit model, the postsuturectomy rise in ICP may simply be normal, age-related changes, although a longer follow-up will be needed to determine the recurrence of pathological ICP. Possible multifactorial explanations for intracranial decompression and compensation in the craniosynostotic rabbit model are also discussed.

A rabbit model of human familial, nonsyndromic unicoronal suture synostosis. II. Intracranial contents, intracranial volume, and intracranial pressure

This two-part study reviews data from a recently developed colony of New Zealand white rabbits with familial, nonsyndromic unilateral coronal suture synostosis, and this second part presents neuropathological findings and age-related changes in intracranial volume (ICV) and intracranial pressure (ICP) in 106 normal rabbits and 56 craniosynostotic rabbits from this colony. Brain morphology and anteroposterior length were described in 44 rabbit fetuses and perinates (27 normal; 17 synostosed). Middle meningeal artery patterns were qualitatively assessed from 2-D PCC MRI VENC scans and endocranial tracings from 15, 126-day-old rabbits (8 normal, 7 rabbits with unicoronal synostosis). Brain metabolism was evaluated by assessing 18F-FDG uptake with high-resolution PET scanning in 7, 25-day-old rabbits (3 normal, 4 with unicoronal or bicoronal synostosis). Intracranial contents and ICV were assessed using 3-D CT scanning of the skulls of 30 rabbits (20 normal,10 with unicoronal synostosis) at 42 and 126 days of age. Serial ICP data were collected from 66 rabbits (49 normal; 17 with unicoronal synostosis) at 25 and 42 days of age. ICP was assessed in the epidural space using a Codman NeuroMonitor microsensor transducer. Results revealed that cerebral cortex morphology was similar between normal and synostosed fetuses around the time of synostosis. Significantly (P<0.05) decreased A-P cerebral hemisphere growth rates and asymmetrical cortical remodeling were noted with increasing age in synostotic rabbits. In addition, rabbits with unicoronal suture synostosis exhibited asymmetrical middle meningeal artery patterns, decreased and asymmetrical brain metabolism, a "beaten-copper" intracranial appearance, significantly (P<0.05) decreased ICV, and significantly (P<0.01) elevated ICP compared with normal control rabbits. The advantages and disadvantages of these rabbits as a model for human familial, nonsyndromic unicoronal suture synostosis are discussed, especially in light of recent clinical neuropathological, ICV, and ICP findings recorded in human craniosynostotic studies.