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Primary central nervous system lymphoma (PCNSL) is a rare lymphoma, and the disease course is often aggressive with poor prognosis outcomes. PCNSL undergoes germinal center reactions and impairs B-cell maturation. However, angiogenesis is also involved in the tumorigenesis and progression of PCNSL. This study investigated the effects of the tumor microenvironment and angiogenesis-associated genomic alterations on the outcomes of PCNSL. The analysis also evaluated the influence of treatment modality and timing on PCNSL survival using partial least squares variance-based path modeling (PLS-PM). PLS-PM can be used to evaluate the complex relationship between prognostic variables and disease outcomes with a small sample of measurements and structural models. A total of 19 immunocompetent PCNSL samples were analyzed by exome sequencing. Our results suggest that the timing of radiotherapy and mutations of ROBO1 and KAT2B are potential indicators of PCNSL outcomes and may be affected by baseline characteristics such as age and sex. Our results also showed that patients with no mutations of ROBO1 and KAT2B, SubRT subgroup showed favorable survival outcomes compared with no SubRT subgroup in short-term follow-up. All SubRT patients have received high-dose methotrexate induction chemotherapy in the initial treatment. Therefore, initial induction chemotherapy combined with subsequent radiotherapy might improve survival outcomes in PCNSL patients who have no ROBO1 and KAT2B somatic mutations in short-term follow-up. The overall findings suggest that the tumor microenvironment and angiogenesis-associated genomic alterations and treatment modalities are potential indicators of overall survival and may be affected by the baseline characteristics of PCNSL patients., Competing Interests: The authors declare that there is no conflict of interest regarding the publication of this paper., (Copyright © 2021 Hui-Ching Wang et al.)

Background: Diffusion and perfusion MRI can invasively define physical properties and angiogenic features of tumors, and guide the individual treatment. The purpose of this study was to investigate whether the diffusion and perfusion MRI parameters of primary central nervous system lymphomas (PCNSLs) are related to the tumor locations., Methods: We retrospectively reviewed the diffusion, perfusion, and conventional MRI of 68 patients with PCNSLs at different locations (group 1: cortical gray matter, group 2: white matter, group 3: deep gray matter). Relative maximum cerebral blood volume (rCBV max ) from perfusion MRI, minimum apparent diffusion coefficients (ADC min ) from DWI of each group were calculated and compared by one-way ANOVA test. In addition, we compared the mean apparent diffusion coefficients (ADC mean ) in three different regions of control group., Results: The rCBV max of PCNSLs yielded the lowest value in the white matter group, and the highest value in the cortical gray matter group (P < 0.001). However, the ADC min of each subgroup was not statistically different. The ADC mean of each subgroup in control group was not statistically different., Conclusion: Our study confirms that rCBV max of PCNSLs are related to the tumor location, and provide simple but effective information for guiding the clinical practice of PCNSLs.

BACKGROUND This study aimed to compare the magnetic resonance imaging (MRI) findings of primary diffuse large B-cell lymphoma (DLBCL) of the central nervous system (CNS) with delayed contrast enhancement and histological microvessel density (MVD). T1-weighted and T2-weighted contrast-enhanced and non-enhanced brain imaging were used. CNS lymphoma tissue was evaluated using primary antibodies to endothelial cells and smooth muscle cells, and histochemical staining for reticulin fibers and basement membrane, which allowed quantification of the MVD. MATERIAL AND METHODS Twenty-one patients with histologically confirmed primary DLBCL of the CNS underwent pre-contrast-enhanced and postcontrast-enhanced MRI. Histology of the CNS lymphoma tissue included immunohistochemical staining with antibodies to CD34 for vascular endothelial cells and alpha smooth muscle actin (ASMA) for vascular smooth muscle cells, and histochemical staining included periodic acid-Schiff (PAS) and silver staining for reticulin fibers to evaluate microvessel density (MVD). RESULTS In primary DLBCL of the CNS, a positive correlation was found between the degree of necrosis and the size of the lymphoma (r=0.546, P=0.01). Delayed imaging enhancement was significantly correlated with the number of mature vessels, MVD, basement membrane, and reticulin fibers (r=0.593, 0.466, 0.446 and 0.497, respectively). Standardized ß regression coefficient analysis showed that the MVD, PAS-positive structures, the number of mature vessels, and reticulin fibers, were significantly associated with delayed enhancement on MRI (ß values, 0.425, 0.409, 0.295, and 0.188, respectively). CONCLUSIONS In primary DLBCL of the CNS, delayed imaging enhancement on MRI may be due to reduced neovascularization and vascular infiltration by lymphoma cells.

Research of various diseases of the nervous system has shown that VEGF has direct neuroprotective effects in the central and peripheral nervous systems, and indirect effects on improving neuronal vessel perfusion which leads to nerve protection. In the tumors of the nervous system, VEGF plays a critical role in tumor angiogenesis and tumor progression. The effect of anti-VEGF treatment on nerve protection and function has been recently reported - by normalizing the tumor vasculature, anti-VEGF treatment is able to relieve nerve edema and deliver oxygen more efficiently into the nerve, thus reducing nerve damage and improving nerve function. This review aims to summarize the divergent roles of VEGF in diseases of the nervous system and the recent findings of anti-VEGF therapy in nerve damage/regeneration and function in tumors, specifically, in Neurofibromatosis type 2 associated schwannomas., (Copyright © 2017. Published by Elsevier Inc.)

Hemangiopericytoma (HPC) is a highly vascularized mesenchymal tumor. Local recurrence and distant metastasis are common features of HPC. Considering the remarkable hyper-vasculature phenotype of HPC, we assumed that dysregulated angiogenic signaling pathways were involved in HPC. The key components of angiogenic signaling pathways including VEGF-VEGF-R2, EphrinB2-EphB4 and DLL4-Notch were examined by real-time RT-PCR, Western blotting and immunostaining in 17 surgical specimens of HPC patients and in 6 controls. A significant upregulation of VEGF and VEGF-R2 associated with elevated levels of p-Akt and proliferating cell nuclear antigen (PCNA) was detected in HPC. Moreover, a dramatic increase in the mRNA and protein expression of EphB4 and its downstream factor p-Erk1/2 was found in HPC. A massive activation of core-components of DLL4-Notch signaling was detected in HPC. Double-immunofluorescent staining confirmed the expression of these upregulated key factors in the endothelial cells of tumor vessels. The present study identified the activation of multiple and crucial angiogenic signaling pathways, which could function individually and/or synergistically to stimulate angiogenesis in HPC and eventually contribute to tumor growth and progression. Our findings emphasize the importance to target multiple angiogenic signaling pathways when an anti-angiogenic therapy is considered for this highly vascularized tumor.

Because tumors require a vascular supply for their survival and growth, angiogenesis is considered an important therapeutic target in most human cancers including cancer of the central nervous system. Antiangiogenic therapy has focused on inhibitors of the vascular endothelial growth factor (VEGF) signaling pathway. VEGF pathway-targeted drugs have shown therapeutic efficacy in several CNS tumors and have been tried most frequently in glioblastoma. These therapies, however, have been less effective than anticipated as some patients do not respond to therapy and some receive only modest benefit. Underlying this suboptimal response are multiple mechanisms of drug resistance involving changes in both tumor cells and their microenvironment. In this review, we discuss the multiple proposed mechanisms by which neurological tumors evolve to become resistant to antiangiogenic therapies. A better understanding of these mechanisms, their context, and their interplay will likely facilitate improvements in pharmacological strategies for the targeted treatment of neurological tumors.

Chemokines are peptides that function as chemoattractant cytokines in cell activation, differentiation and trafficking. Endothelin B receptor (ETBR) is a receptor for endothelin, which is known to function as a vasoconstrictor. In the present study, to clarify the immune escape mechanism of primary central nervous system lymphomas (PCNSLs), the expression of ETBR and of subsets of chemokines (CXCL12, 13) in 24 PCNSLs was investigated. CXCL12 was expressed by lymphoma cells in different resident brain cell populations in 22/24 cases. CXCL13 expression was identified in tumor cells in 19/24 cases, but was only expressed by tumor cells and by proliferating vascular endothelial cells. In addition, tumor-infiltrated lymphocytes (TILs) accumulated in areas with expression of chemokines, particularly of CXCL13. ETBR expression was detected in 12/24 cases. Positive ETBR cases were associated with a paucity of TILs, particularly of cytotoxic T cells, whereas negative ETBR cases were associated with an abundance of TILs. The combined data indicate that CXCL12 and CXCL13 up-regulation may be differently linked to the development of PCNSLs and to the accumulation of TILs. In addition, ETBR expression by lymphoma and endothelial cells may mediate trafficking of TILs, which may explain the immune escape processes of PCNSLs.

Malignant gliomas are the most common primary brain tumor found in adults. Unfortunately, the prognosis for these type of tumors remains dismal despite aggressive treatment with surgical resection, radiation and chemotherapy. Therefore, therapeutics aimed at disrupting the angiogenesis of these tumors is being utilized in to improve survival outcomes and quality of life. This paper reviews the history of antiangiogenic agents in malignant gliomas, discusses the FDA approval of bevacizumab as monotherapy in recurrent glioblastoma and the subsequent controversy, and analyzes the most recent newly diagnosed trials of RTOG 0825 and AVAglio. Additionally, the results of the latest trials with antiangiogenic agents and possible biomarkers are reviewed. Multiple questions remain regarding the potential benefit of antiangiogenic treatments in patients with glioblastoma. Future clinical trials should be designed to learn more about these drugs, to optimize their future use.

Loss-of-function mutations in genes encoding KRIT1 (also known as CCM1), CCM2 (also known as OSM and malcavernin) or PDCD10 (also known as CCM3) cause cerebral cavernous malformations (CCMs). These abnormalities are characterized by dilated leaky blood vessels, especially in the neurovasculature, that result in increased risk of stroke, focal neurological defects and seizures. The three CCM proteins can exist in a trimeric complex, and each of these essential multi-domain adaptor proteins also interacts with a range of signaling, cytoskeletal and adaptor proteins, presumably accounting for their roles in a range of basic cellular processes including cell adhesion, migration, polarity and apoptosis. In this Cell Science at a Glance article and the accompanying poster, we provide an overview of current models of CCM protein function focusing on how known protein-protein interactions might contribute to cellular phenotypes and highlighting gaps in our current understanding.

Current antiangiogenic therapies have led to the observation that such agents can lead to improved tumor vessel structure and function termed "vascular normalization" which reduces tumor burden. However, vessel normalization is a transient process, and patients often develop resistance/poor response to anti-vascular strategies that remains an important clinical challenge. Therefore, increasing effort has been made to better understand the cellular and molecular mechanisms of vascular normalization and its contribution to immunomodulation. Herein, we summarize the recent effort to better understand the cellular and molecular mechanisms of vascular normalization with a focus on preclinical genetic models. These studies remain important directions for a mechanistic understanding of the complexities of the maintenance of BBB integrity and the impact of its breakdown on tumor dissemination and pharmaco-distribution of therapeutics.

The extracellular matrix (ECM) protein tenascin-C (TN-C) is upregulated within glioma tissues and cultured glioma cell lines. TN-C possesses a multi-modular structure and a variety of functional properties have been reported for its domains. We describe five novel monoclonal antibodies identifying different domains of TN-C. The epitopes for these antibodies were investigated by using recombinantly expressed fibronectin type III domains of TN-C. The biological effects of TN-C fragments on glioma cell proliferation and adhesion were analyzed. The expression pattern of TN-C in human glioma tissue sections and in glioma cell lines was studied with the novel library of monoclonal antibodies. The immunocytochemical analyses of the established human glioma cell lines U-251-MG, U-373-MG and U-87-MG revealed distinct staining patterns for each antibody. Robust expression of TN-C was found within the tumor mass of surgery specimens from glioblastoma. In many cases, the expression of this ECM molecule was clearly associated with blood vessels, particularly with microvessels. Three of the new antibodies highlighted individual TN-C-expressing single cells in glioma tissues. The effect of TN-C domains on glioma cells was examined by a BrdU-proliferation assay and an adhesion assay. Short fragments of constitutively expressed TN-C-domains did not exert significant effects on the proliferation of glioma cells, whereas the intact molecule increased cell division rates. In contrast, the long fragment TNfnALL containing all of the FNIII domains of TN-C decreased proliferation. Additionally, we found strong differences between the adhesion-influencing properties of the recombinant fragments on glioma cells.

Rap1 signaling is important for both major processes of vessel formation: vasculogenesis, or de novo vessel formation, and angiogenesis, sprouting of new vessels from pre-existing ones. We provide an overview of genetic studies in mice and zebrafish and discuss some of the proposed underlying mechanisms derived from cellular models, with particular emphasis on Rap1's role in angiogenesis, maintenance of endothelial barrier and connection with cerebral cavernous malformation (CCM), a neurological deficit that leads to seizures and lethal stroke. Lastly, we provide a brief summary of studies in cardiac and smooth muscle cells, where the Epac-Rap1 signaling axis is emerging as an important regulator of contractility., (© 2013 Elsevier Inc. All rights reserved.)

Cerebral blood volume (CBV) measurement complements conventional magnetic resonance imaging (MRI) to indicate pathologies in the central nervous system (CNS). Dynamic susceptibility contrast (DSC) perfusion imaging is limited by low resolution and distortion. Steady-state (SS) imaging may provide higher resolution CBV maps but was not previously possible in patients. We tested the feasibility of clinical SS-CBV measurement using ferumoxytol, a nanoparticle blood pool contrast agent. SS-CBV measurement was analyzed at various ferumoxytol doses and compared with DSC-CBV using gadoteridol. Ninety nine two-day MRI studies were acquired in 65 patients with CNS pathologies. The SS-CBV maps showed improved contrast to noise ratios, decreased motion artifacts at increasing ferumoxytol doses. Relative CBV (rCBV) values obtained in the thalamus and tumor regions indicated good consistency between the DSC and SS techniques when the higher dose (510 mg) ferumoxytol was used. The SS-CBV maps are feasible using ferumoxytol in a clinical dose of 510 mg, providing higher resolution images with comparable rCBV values to the DSC technique. Physiologic imaging using nanoparticles will be beneficial in visualizing CNS pathologies with high vascularity that may or may not correspond with blood-brain barrier abnormalities.

Endothelial Wnt/β-catenin signaling is necessary for angiogenesis of the central nervous system and blood-brain barrier (BBB) differentiation, but its relevance for glioma vascularization is unknown. In this study, we show that doxycycline-dependent Wnt1 expression in subcutaneous and intracranial mouse glioma models induced endothelial Wnt/β-catenin signaling and led to diminished tumor growth, reduced vascular density, and normalized vessels with increased mural cell attachment. These findings were corroborated in GL261 glioma cells intracranially transplanted in mice expressing dominant-active β-catenin specifically in the endothelium. Enforced endothelial β-catenin signaling restored BBB characteristics, whereas inhibition by Dkk1 (Dickkopf-1) had opposing effects. By overactivating the Wnt pathway, we induced the Wnt/β-catenin-Dll4/Notch signaling cascade in tumor endothelia, blocking an angiogenic and favoring a quiescent vascular phenotype, indicated by induction of stalk cell genes. We show that β-catenin transcriptional activity directly regulated endothelial expression of platelet-derived growth factor B (PDGF-B), leading to mural cell recruitment thereby contributing to vascular quiescence and barrier function. We propose that reinforced Wnt/β-catenin signaling leads to inhibition of angiogenesis with normalized and less permeable vessels, which might prove to be a valuable therapeutic target for antiangiogenic and edema glioma therapy.

Introduction: Alterations of microvasculature are integral to CNS neoplasia, and a diagnostic feature of high-grade gliomas. The objectives of this study were two fold: First, to correlate morphometrically measured microvessel density (MVD), microvessel caliber (VC), and percentage of total microvessel area (%TVA) with WHO histologic grade in various types of primary CNS tumors. Second, to evaluate if such a correlation could be further refined by using mathematical derivatives of measured parameters namely coefficient of variation of VC (COofVC), microvessel cross-sectional area (VCSA), and percentage of total VCSA (%TVCSA)., Materials and Methods: Various microvessel parameters were assessed in a variety of 30 primary CNS tumors as consecutively encountered in routine surgical pathology practice including gliomas, meningiomas and others by image morphometry using CD34-immunostained sections. We introduced a novel method of effectively determining VC. Results were correlated with tumor type and grade. Appropriate statistical analysis was performed., Results: Microvessel characteristics, especially VC (p<0.0022), VCSA (p<0.0164), CVofVC (p<0.0001), %TVCSA (p<0.0002) and %TVA (p<0.0003) of tumors were significantly greater than normal tissue. MVD increased in all tumors, excepting meningiomas, and was significantly higher in gliomas (p<0.0062). MVD showed negative correlation with VC (r=-0.808) and VCSA (r=-0.848) in the normal brain but was less significant in tumors. Unlike tumors, caliber distribution of microvessels in normal brain was noted to follow a Gaussian pattern. Histological grades of tumors showed positive correlation with MVD (r=0.547), VC (r=0.606), CVofVC (r=0.623), VCSA (r=0.485), %TVCSA (r=0.783) and %TVA (r=0.603). Calculated scores, estimated from multiple regressions of vessel parameters, correlated well with histological grade, with S2 (calculated using all measured as well as mathematically derived microvessel parameters) being better than S1 (calculated using measured parameters: MVD and VC)., Conclusion: Tumor grades positively correlated with all microvessel parameters, with %TVCSA displaying the best. The correlation of %TVA with tumor grade was weaker than %TVCSA mainly due to the impact of MVD. These findings emphasize the value of VC as effectively measured using our novel method and best illustrated by its derivative %TVCSA (an indicator of blood flow), in addition to the well-recognized value of MVD in tumor prognostication. Multiple regressions of microvessel parameters provided the best correlation with grade. Morphometric analysis of microvessels in CNS tumor facilitates a better understanding of the tumor grade, tumor progression and overall prognosis., (Copyright © 2012 Elsevier Inc. All rights reserved.)

Lack of suitable mouse models for central nervous system (CNS)-associated leukemias has hindered mechanism-guided development of therapeutics. By transplanting retrovirus-transformed mouse erythroleukemia cells into syngeneic mice, we developed a new animal model of meningeal leukemia associated with rapid paralysis. Necropsy revealed massive proliferation of the leukemic cells in the bone marrow (BM) followed by pathological angiogenesis and invasion of the leukemic cells into the meninges of the CNS. Further analysis demonstrated that the erythroleukemia cells secreted high levels of VEGF and preferentially adhered in vitro to fibronectin. This unique animal model for meningeal leukemia should facilitate studies of engraftment and proliferation of leukemic cells in the BM and their invasion of the CNS as well as pre-clinical evaluation of experimental therapeutics for CNS-associated leukemias., (Published by Elsevier Ltd.)

No literature data are available concerning the expression of aquaporin-4 in primary central nervous system lymphomas and the relationship between aquaporin-4 expression and the morphological characteristics of blood vessels. Here, we have investigated this relationship in 24 human diffuse large B-cell primary central nervous system lymphomas by means of immunocytochemistry and confocal laser microscopy. Results have shown that: (i) a high aquaporin-4 expression correlated with a high Ki-67 index and aquaporin-4 marked tumour and endothelial cells in cytoplasm and plasma membranes, while aquaporin-4 expression was low in tumour areas with a low Ki-67 index where few tumour cells were positive to aquaporin-4, and endothelial cells showed aquaporin-4 expression on their abluminal side. (ii) Different type of cells participated in vessels formation: CD20(+) tumour cells and factor VIII(+) endothelial cells; aquaporin-4(+) tumour cells and CD31(+) endothelial cells; CD20(+) and aquaporin-4(+) tumour cells; glial fibrillary acidid protein(+) endothelial cells surrounded by glial fibrillary acidic protein(+) tumour cells. Overall, these data suggest the importance of aquaporin-4 in primary central nervous system lymphomas due to its involvement in cerebral oedema formation and resolution and tumour cell migratory activity, and have documented that tumour microvasculature in lymphomas is extremely heterogeneous, confirming the importance of neoangiogenesis in the pathogenesis of lymphomas., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Background: Hemangiopericytomas are rare vascular tumors of the central nervous system. Although hemangiopericytomas have been associated with other vascular malformations, there is no report of an intracranial hemangiopericytoma found in association with multiple arteriovenous malformations and dural arteriovenous fistulae., Case Description: We present the case of an otherwise healthy 25-year-old woman who presented with a large hemangiopericytoma involving the superior sagittal sinus. The highly vascular nature of the lesion, the total occlusion of the sinus anterior to the tumor, and the presence of multiple arteriovenous malformations and dural arteriovenous fistulae complicated resection of this tumor., Conclusion: To our knowledge, no prior report has described a tumor of this magnitude in association with multiple AVMs and dAVFs., (Copyright © 2011 Elsevier Inc. All rights reserved.)

Insulin-like growth factor binding protein 7 (IGFBP7) is downregulated in several solid cancers. IGFBP7 has been proposed to act as a tumor suppressor gene through mechanisms involving senescence and apoptotic pathways. The tumor suppressor effect of IGFBP7 in glioblastoma multiforme (GBM) was examined in this study using two human GBM cell lines, U87MG and T98G. Exogenously applied IGFBP7 (20 and 100 nM) significantly reduced U87MG (~70 and ~75%, respectively) and T98G (~37 and ~50%, respectively) cell growth in soft agar. IGFBP7 stimulated senescence-associated β-galactosidase in both U87MG and T98G cells without stimulating apoptosis (annexin V and propidium iodide staining, expression of SMARCB1 or BNIP3L and caspase cleavage) or affecting phosphorylation of p44/42 MAPK. The inhibitory effect of IGFBP7 on U87MG cell growth was further assessed in vivo using U87MG cells grafted on the chick chorioallantoic membrane. In this model, U87MG cells formed solid and highly vascularized tumors that were reduced in size (~40%) when treated with 500 nM IGFBP7 compared with control tumors. Vessels in IGFBP7-treated tumors were clustered, unevenly distributed and associated with higher number of α-SMA positive cells compared with those in untreated tumors. IGFBP7 induced both aortic smooth muscle cell (AoSMC) chemoattraction and endothelial cell (EC) transdifferentiation into a SM-like cell phenotype. U87MG conditioned media-induced IGFBP7 expression in ECs was significantly inhibited by the cross-talk/interaction with SMCs. This study indicates that IGFBP7 suppresses U87MG tumor cell growth, induces cell senescence and participates in tumor vessel stabilization by promoting SMC/pericyte recruitment and differentiation.

Aims: Interactions between tumour cells and extracellular matrix (ECM) are critical in the metastatic cascade. We compared effects of desmoplastic stroma versus neural tissue on central nervous system (CNS) metastasis., Methods and Results: Using integrins (ECM receptors), ECM (fibronectin, laminin and collagen IV) and CD31 and vascular endothelial growth factor (VEGF) for angiogenesis, this study examined immunohistochemically 69 consecutive cases of CNS metastases. In contrast to low-level expression in tumour-embedded neural tissue, ECM [fibronectin (71%), laminin γ-1 (79%) and collagen IV (92%)] and CD31-positive microvascular densities (33 versus 4 vessels/field) were significantly richer in desmoplastic tumour stroma, which was present in 90% (53 of 59) of carcinomas, 100% (five of five) of malignant melanomas and 100% (two of two) of sarcomas. Collagen IV expression in tumour stroma was correlated with the expression of fibronectin (P = 0.013) and laminin (P = 0.034) and with infiltrative tumour edges (P = 0.005); fibronectin-positive tumour stroma was correlated with a higher microvascular density (P = 0.015). In addition, tumour cells expressed integrins (∼75%) and laminin (84%) more frequently than VEGF (23%), and tumour expression of laminin was correlated with the presence of desmoplastic stroma (P = 0.006). Interestingly, laminin-positive tumour stroma was a worse prognosticator (P = 0.072)., Conclusions: ECM- and vascular-rich stroma is important in tumour growth, which underlies therapeutic strategies targeting tumour-associated stroma., (© 2011 Blackwell Publishing Limited.)

It remains a challenge to deliver effective concentrations of therapeutics into CNS pathologies, which is primarily due to the fact that current and investigational CNS therapeutics are suboptimally-sized to accumulate to effective concentrations in individual diseased CNS tissue cells. The blood-CNS barrier of blood capillary microvasculature within neuropathologic tissues is known to be permeable to lipid-insoluble macromolecules in a wide-spectrum of neuropathologies. In the case of CNS solid tumor tissue blood capillaries, the physiological upper limit of pore size to the transcapillary passage of spherical lipid-insoluble macromolecules is approximately 12 nanometers, and systemically administered imageable dendrimer nanoparticles within the 7 to 10 nanometer size range accumulate to therapeutic concentrations in solid tumors since this size range of particles maintain peak blood concentrations for several hours. In preliminary pre-clinical studies, it has recently been shown that one intravenous dose of small molecule chemotherapy-conjugated imageable dendrimer nanoparticles within the 7 to 10 nanometer size range, with doxorubicin bound to the particle exterior via acid-labile covalent linkages, is effective at regressing orthotopic rodent malignant gliomas. Although it is foreseeable that such drug-conjugated imageable nanoparticles within the 7 to 10 nanometer size range will be effective theranostic agents for the concurrent treatment (i.e. neutron capture therapy) and imaging (i.e. magnetic resonance) of solid tumor disease, the issue of maintaining a neutralized particle exterior following the attachment of cationic drugs will need to be addressed to eliminate cationic charge-mediated nanoparticle toxicity to blood capillary walls. In this review, the ultrastructural basis for blood capillary microvascular permeability to lipid-insoluble macromolecules is discussed, and the importance of delineating the precise physiologic upper limits of pore size in the blood capillary microvasculature of other CNS pathologies, including neurodegenerative, inflammatory and ischemic CNS diseases, is emphasized. The discussion herein will serve as guide for the future development of optimally-sized, non-toxic and non-immunogenic lipid-insoluble systemic therapies, which should be the focus of future patent applications and patents on CNS drug development.

Melanoma metastases are characterized by pronounced neo-angiogenesis and spontaneous bleeding frequently occurring within central nervous system metastases. Clinically apparent spontaneous hemorrhage within subcutaneous melanoma metastases, however, is a rare event that coincides with progression of such metastases. We report, to our knowledge the first observation, on regression of subcutaneous metastases with hemorrhage of the overlying skin in three patients with stage IV melanoma who participated in clinical trials on therapeutic vaccination. In two patients, loss of arterial flow on Doppler ultrasound imaging was documented in the metastasis at the time of hematoma formation. One patient suffered from an intracranial hemorrhage in a subcentimetric brain metastasis coincident with the hemorrhagic regression of some of his skin metastases.

Sphingosine-1-phosphate is a potent sphingolipid mediator of diverse processes important for brain tumors, including cell growth, survival, migration, invasion, and angiogenesis. Sphingosine kinase 1 (SphK1), one of the two isoenzymes that produce sphingosine-1-phosphate, is up-regulated in glioblastoma and has been linked to poor prognosis in patients with glioblastoma multiforme (GBM). In the present study, we found that a potent isotype-specific SphK1 inhibitor, SK1-I, suppressed growth of LN229 and U373 glioblastoma cell lines and nonestablished human GBM6 cells. SK1-I also enhanced GBM cell death and inhibited their migration and invasion. SK1-I rapidly reduced phosphorylation of Akt but had no significant effect on activation of extracellular signal-regulated kinase 1/2, another important survival pathway for GBM. Inhibition of the concomitant activation of the c-Jun-NH(2)-kinase pathway induced by SK1-I attenuated death of GBM cells. Importantly, SK1-I markedly reduced the tumor growth rate of glioblastoma xenografts, inducing apoptosis and reducing tumor vascularization, and enhanced the survival of mice harboring LN229 intracranial tumors. Our results support the notion that SphK1 may be an important factor in GBM and suggest that an isozyme-specific inhibitor of SphK1 deserves consideration as a new therapeutic agent for this disease.

Background: Preoperative differentiation of primary central nervous system lymphomas (PCNSLs) from other tumors is important for presurgical staging, intraoperative management, and postoperative treatment. Dynamic susceptibility contrast-enhanced perfusion magnetic resonance imaging (DSC perfusion MRI) can provide in vivo assessment of the microvasculature in intracranial mass lesions., Purpose: To determine the utility of DSC perfusion MRI in the differentiation of PCNSLs and high-grade gliomas, as well as their pathological and physiological differences., Material and Methods: Nine patients with pathologically proven PCNSLs and 11 patients with high-grade gliomas were examined using a 1.5 T MRI scanner. DSC perfusion MRI was performed by gradient-echo echo-planar imaging (GE-EPI). The maximum rCBV ratio, the signal intensity-time curves, and the percentage of signal intensity recovery were obtained. The maximum relative cerebral blood volume (rCBV) ratio and the percentage of signal intensity recovery of PCNSLs were compared with those of high-grade gliomas by using Student's t test. Microvessel density (MVD) was evaluated using immunohistochemical staining of surgical specimens with anti-CD34, and MVDs of the two tumor groups were compared by using Student's t test., Results: The maximum rCBV ratio of primary intracranial lymphomas was 1.72+/-0.59, while that of high-grade gliomas was 4.86+/-2.18. PCNSLs tended to have relatively low perfusion compared to high-grade gliomas (P=0.001), and the MVD labeled by anti-CD34 of PCNSLs was much lower than that of gliomas (P<0.001). The signal intensity-time curve of primary intracranial lymphomas was different from that of high-grade gliomas. The percentage of signal intensity recovery was significantly greater in PCNSLs compared with that of high-grade gliomas (P<0.001)., Conclusion: The difference in DSC perfusion MRI characteristics between PCNSLs and high-grade gliomas is determined by their different vascularities and different patterns of contrast agent leakage. This difference may be helpful in the diagnosis and preoperative differentiation between PCNSLs and high-grade gliomas, which sometimes may have similar conventional MR imaging appearance.

In neurosurgery, the question of the optimal transfusion "trigger" remains a controversial matter. Regarding the brain, the current data are still incomplete, justifying the continuation of experimental and clinical studies. The existing expert advices are based on these rather poor data and would probably evolve after the completion of clinical studies in progress. In spine surgery, the situation is simpler and the transfusional stakes are quite similar to those of orthopedics and traumatology. With regard to hemostasis, standardized recommendations exist depending on the laboratory test results or the anticoagulant treatments of the patient.

Background: Adults with malignant glioma, especially the most common subtype, glioblastoma multiforme, have an unacceptably poor outcome with current therapies. Malignant gliomas are amongst the most angiogenic of cancers, and VEGF is the dominant angiogenic mediator in these tumors., Objective: To summarize the clinical experience of VEGF-directed treatment for malignant glioma., Methods: We reviewed the completed, ongoing and planned clinical trials evaluating anti-VEGF strategies for malignant glioma patients., Results/conclusions: Recent studies incorporating anti-VEGF agents plus cytotoxic therapy among recurrent malignant glioma patients have achieved unprecedented improvements in radiographic response, time to progression and survival. Furthermore, acceptable toxicity was observed. Hence, a major current focus in neuro-oncology is to further develop antiangiogenic strategies for this desperate patient population.

Angiogenesis and angiogenic growth factors have a major role in the pathogenesis of malignancies. However, very little is known about the clinical and histopathological relevance of angiogenesis in primary central nervous system lymphoma (PCNSL). We investigated that expression of vascular endothelial growth factor (VEGF) of the lymphoma cells and microvessel density (MVD) were examined in 19 patients with PCNSL. Additionally, the presence of the blood-brain barrier (BBB) was examined using immunohistochemistry and the electron microscopy. MVD was significantly higher in nine cases with VEGF immunoreactivity (VEGF+) than in ten cases with negative immunoreactivity for VEGF (VEGF-) (P < 0.001). VEGF expression was significantly associated with a longer survival (P < 0.005). BBB markers were negative in angiogenic vessels of VEGF+. BBB markers were identified in vessels surrounding tumor cells and tight junctions were also preserved in the capillary endothelium surrounding tumor cells in VEGF-. Angiogenesis is associated with VEGF expression and an absent BBB in the vessels of PCNSL. The BBB may be preserved in lesions with lymphoma cell infiltration, especially in VEGF- PCNSL. VEGF may have a prognostic effect in PCNSL.

Since the advent of modern neuroimaging (MRI) cerebral cavernomas are usually diagnosed "in vivo". In this paper we describe the data which improved our knowledge of the disease: 1) nosologically, cerebral cavernomas belong to the group of cerebral vascular hamartomas which can be associated between themselves ("mixed" lesions); 2) hemodynamically, the annual risk of hemorrhage increases after a first bleeding and in deep located lesions (brainstem); 3) association between cavernomas and developmental venous anomalies may be observed; the later on must be left in place at operation; 4) immunocytochemical studies (PCNA) show that cavernomas should be considered more as a benign vascular tumor than as a malformation; 5) familial forms (20%) are characterized by multiple locations and "de novo" lesions; 6) better understanding of the natural history of cavernomas, which is a dynamic lesion, leads to broader surgical indications (no alternative treatment).

Endoglin (CD105) is predominantly expressed on the cellular lineages within the vascular system and it is overexpressed on proliferating endothelial cells that participate in neoangiogenesis, with a weak or negative expression in the vascular endothelium of normal tissues. To investigate the correlation between the CD105 expression and possible prognostic markers or progression in the primary central nervous system lymphomas (PCNSLs), the present study assessed 26 cases of PCNSL by immunostaining for CD105 and CD34. Intratumoral microvessel density (IMVD) was determined in the hotspots and interfaces at a magnification of x200. According to the mean value, the patients were classified into lower-IMVD and higher-IMVD groups. When CD34 was used as a marker of angiogenesis, the survival rates of these two groups demonstrated no significant difference. In contrast, when CD105 was used as a marker of angiogenesis, the survival rate of the lower-IMVD group was significantly higher than that for the higher-IMVD group (P < 0.01). In the group of CD34-immunostained vessels, no difference was observed in IMVD between the hotspots and interfaces (P = 0.31). In the group with CD105-immunostained vessels, a greater IMVD was observed in the hotspots than in the interfaces (P < 0.01). These results suggested that the growth of PCNSLs was dependent on angiogenesis, that IMVD as determined by anti-CD105 monoclonal antibody was a reliable prognostic marker in PCNSLs, and that PCNSLs may therefore not require sufficient neoangiogenesis at the start of PCNSLs, however, it may instead require a higher rate of neoangiogenesis as they infiltrate and destroy the brain parenchyma.

Gliomas are the most frequent primary tumors of the central nervous system in adults. Glioblastoma multiforme, the most aggressive form of astrocytic tumors, displays a rapid progression that is accompanied by particular poor prognosis of patients. Intense angiogenesis is a distinguishing pathologic characteristic of these tumors and in fact, glioblastomas are of the most highly vascularized malignant tumors. For this reason, research and therapy strategies have focused on understanding the mechanisms leading to the origin of tumor angiogenic blood vessels in order to develop new approaches that effectively block angiogenesis and cause tumor regression. We discuss here some important features of glioma angiogenesis and we present molecules and factors and their possible functions and interactions that play a role in neovascularization. In spite of the great progress that molecular biology has achieved on investigating tumor angiogenesis, many aspects remain obscure and the complexity of the angiogenic process stands for an obstacle in identifying the exact and complete molecular pathways orchestrating new blood vessels formation, which are necessary for the survival and expansion of these tumors.

Primary CNS lymphoma is an aggressive form of non-Hodgkin lymphoma whose growth is restricted to the central nervous system. We used cDNA microarray analysis to compare the gene expression signature of primary CNS lymphomas with nodal large B-cell lymphomas. Here, we show that while individual cases of primary CNS lymphomas may be classified as germinal center B-cell, activated B-cell, or type 3 large B-cell lymphoma, brain lymphomas are distinguished from nodal large B-cell lymphomas by high expression of regulators of the unfolded protein response (UPR) signaling pathway, by the oncogenes c-Myc and Pim-1, and by distinct regulators of apoptosis. We demonstrate that interleukin-4 (IL-4) is expressed by tumor vasculature as well as by tumor cells in CNS lymphomas. We also identify high expression in CNS lymphomas of several IL-4-induced genes, including X-box binding protein 1 (XBP-1), a regulator of the UPR. In addition, we demonstrate expression of the activated form of STAT6, a mediator of IL-4 signaling, by tumor cells and tumor endothelia in CNS lymphomas. High expression of activated STAT6 in tumors was associated with short survival in an independent set of patients with primary CNS lymphoma who were treated with high-dose intravenous methotrexate therapy.

Magnetic resonance (MR) imaging provides excellent soft tissue differentiation and in vivo assessment of physiologic and metabolic properties of tissue. As new and more aggressive treatment modalities and combined modalities are being investigated for brain tumor treatment, it is becoming more important to accurately define tumor volumes for treatment planning, to determine the most aggressive tumor regions for intensified radiation treatment, to identify early regional response to therapy for reoptimization of treatment, and to detect early indicators of developing normal tissue toxicity. Readily available MR techniques of physiologic and metabolic imaging can currently provide useful information regarding tumor tissue properties including chemical composition, cerebral blood volume, perfusion, vascular permeability, and water mobility. This article will focus on the potential value of MR physiologic and metabolic imaging in the clinical management of malignant gliomas.

To evaluate whether the chemosensitivity of primary central nervous system lymphomas to water-soluble drugs could result from improved drug delivery, we quantitatively assessed pharmacokinetic factors in seven patients. The capillary permeability surface product was found to be significantly increased in central nervous system lymphomas compared with glioblastoma multiforme, medulloblastomas, and metastases. Tumoral blood flow was significantly greater than in normal white matter. Our results suggest favorable pharmacokinetics to water- and lipid-soluble drugs in primary central nervous system lymphomas.

Background: In the present study apoptosis, vascularity, and proliferation were quantitatively analyzed with immunohistopathological techniques in primary central nervous system lymphomas (PCNSL). Statistical analysis of these parameters was performed to evaluate their possible relationship with the unfavorable outcome of this tumor., Methods: A series of 32 PCNSL patients for a total of 33 tumors treated from 1984 to 2000 in the Neurosurgical Department were reviewed, and their histologic specimens examined for apoptosis, vascularity, and proliferation., Results: Patients were treated with either gross total/subtotal tumor removal or stereotactic biopsy. Vascularity was studied by means of FVIII staining, proliferative index with Ki-67 staining, and apoptosis with the TUNEL technique. Most tumors could be classified as immunoblastic or centroblastic B-Cell NHL. Mean Mib-1 Labeling Index was 35.34% (5-80), blood vessel density of 40.8 per 10 high power fields. Apoptotic cells were zero or less than 8 cells per 10 high power fields., Conclusion: No statistically significant correlation between survival and histopathological parameters could be shown. However, the apoptosis index was found to be negatively correlated with proliferative index and may account for a more aggressive clinical course of PCNSL.

The binding of Lycopersicon esculentum lectin (LEA) to the vascular endothelium was studied in the central nervous system of rat, mouse and guinea pig at different developmental ages, and in a gliosarcoma model. Our observations showed that LEA consistently stained the entire vascular tree in the spinal cord and in the brain of all animal species at all developmental ages investigated. In the tumor model, the staining of the vascular network was very reproducible, enabled an easy identification of vascular profiles and displayed a higher efficiency when compared to two other commonly used vascular marker (EHS laminin and PECAM-1). Moreover, our results showed that LEA staining was comparable in both vibratome and paraffin sections and could be easily combined with other markers in double labeling experiments. These observations indicate that LEA staining may represent an effective and versatile endothelial marker for the study of the vasculature of the central nervous system in different animal species and experimental conditions.

Quantitative determination of the degree of vascularity has been shown to be independently prognostically significant in many human tumor types. In particular, tumor vascularity has known importance in astrocytomas, in which endothelial proliferation is a criterion for anaplasia in many grading schemes. This chapter summarizes the known associations of quantitated microvessel parameters obtained from histologic sections of human brain tumors with clinical outcome, or other pathobiologic factors that have been examined. Among the conclusions are 1) brain tumors have the unique feature of complex "glomeruloid" vessels, as well as heterogeneity of microvascular distribution and caliber; 2) lower-grade astrocytomas incorporate pre-existing vessels, while glioblastomas develop new vessels; 3) quantitation may have additional independent prognostic value over and above routine histologic grade in low-grade astrocytomas with low tumor cell proliferative indices. These findings have implications for the appropriateness of antiangiogenic therapies

This chapter focuses on the morphology of blood vessel formation in and around the early central nervous system (CNS, i.e., brain and spinal cord) of avian embryos. We discuss cell lineages, proliferation and interactions of endothelial cells, pericytes and smooth muscle cells, and macrophages. Due to space limitations, we can not review the molecular control of CNS angiogenesis, but refer the reader to other chapters in this book and to recent publications on the assembly of the vasculature (1,2).

Primary central nervous system tumors are infrequent lesions observed in both pediatric and adult patients that account for a disproportionate amount of cancer related morbidity and mortality. A significant number of advances in neurosurgical and radiation therapy techniques have occurred over the last few decades and yet only small improvements in long-term outcome have resulted. The major reason for this is the ability of these advances to minimize surgical or radiation morbidity on surrounding normal tissue rather than eradicating the microscopic infiltrating disease that remains after up-front standard therapy. As such, a great deal of effort has gone into adjuvant chemotherapy that might complement the standard surgical and radiation approaches. This paper will review the literature on anti-angiogenic therapies in central nervous system (CNS) tumor models and clinical disease, with a focus on anti-angiogenic chemotherapy (also referred to as metronomic or low-dose chemotherapy) and the utilization of this approach in conjunction with standard radiation and surgery. A number of excellent reviews covering related aspects of this topic are also available (1-13).

A subset of oligodendrogliomas and oligoastrocytomas has been associated with 1p/19q deletion. Subsequently, this genetic alteration was linked to chemosensitivity and classic histology of oligodendrogliomas. Tumoural progression includes deletions of 9p, 10q and alterations of CDKN2A. However, these (epi)genetic changes have not been associated with specific histological features. In a series of 45 gliomas including oligodendrogliomas, oligoastrocytomas and astrocytomas, deletions of chromosomal regions implied in these tumours (1p, 9p, 10, 17p13, 19q and 22) were looked for by microsatellite analysis. Tumours that were deleted for 1p and 19q were selected. Subsequently, presence of deletions in the other studied regions, (epi)genetic changes in p14ARF, CDKN2A and CDKN2B, as well as histological features, were associated to these tumours. 1p/19q deletion was observed in 22 tumours. Twenty-one of them presented regions of classic histology of oligodendroglioma. A deletion of 9p was found in eight of them, always in association with tumour necrosis and/or microvascular proliferation. In addition, (epi)genetic alterations of CDKN2A were observed in 71% of these tumours. Presence of regions of classic histology of oligodendroglioma in a tumour sample is predictive of 1p/19q deletions. Necrosis and/or microvascular proliferation are signs of an additional 9p deletion. Finally, as CDKN2A (epi)genetic alterations were found in 71% of the 1p/19q/9p-deleted oligodendrogliomas, CDKN2A may have a role in oligodendroglioma-associated microvascular proliferation.

Urokinase-type plasminogen activator (uPA) and its receptor (uPAR) play an important role in the invasiveness of gliomas and other infiltrative tumors. In glioma cell lines and tumors, high grade correlates with increased expression of uPAR and uPA. We report here the downregulation of uPAR and uPA by delivery of antisense sequences of uPAR and uPA in a single adenoviral vector, Ad-uPAR-uPA (Ad, adenovirus). The bicistronic construct (Ad-uPAR-uPA) infected glioblastoma cell line had significantly reduced levels of uPAR, uPA enzymatic activity and immunoreactivity for these proteins when compared to controls. The Ad-uPAR-uPA infected cells showed a markedly lower level of invasion in the Matrigel invasion assays, and their spheroids failed to invade the fetal rat brain aggregates in the coculture system. Intracranial injection of SNB19 cells with the Ad-uPAR-uPA antisense bicistronic construct showed inhibited invasiveness and tumorigenicity. Subcutaneous injections of bicistronic antisense constructs into established tumors (U87 MG) caused regression of those tumors. Our results support the therapeutic potential of targeting the individual components of the uPAR-uPA system by using a single adenovirus construct for the treatment of glioma and other invasive cancers.

Despite extensive progress in characterizing the genetic events involved in the development of gliomas, the cellular origin and the defined molecular mechanisms that lead to their occurrence are still unclear. It is known that tumours are of monoclonal origin. This is contrasted by the fact that gliomas frequently express features of different glial cell lineages. With the identification of pluripotent neural stem cells and the growth factors that control neural cell development, we are now making early inroads towards understanding glial cell migration as well as the neural cell plasticity within the adult central nervous system (CNS). Gliomas share several fetal antigens with immature brain cells. It is therefore tempting to speculate that the migration of neural precursor cells actually represents the normal counterpart of glioma cell migration. The migratory behavior of gliomas may be due to a predetermined interplay between normal brain tissue and the migrating cells, where the brain represents a permissive tissue for guiding cells with certain phenotypic traits to migrate along specific anatomical structures. Malignant progression is also accompanied by extensive angiogenesis which is especially prominent in glioblastoma multiforme (GBM). For cell proliferation to take place, several cell signaling cues mediated by specific growth factors are shared between the glioma cells and the endothelial cells while others are unique for endothelial cells. Therefore the endothelial cell compartment represents a promising target for novel therapeutic strategies including gene therapy and cell-based therapies.

The role of growth factors in tumour growth and progression has increasingly been studied over the last few years. This review summarizes the available data and discusses their limitations as well as their potential influence on future therapeutic strategies. A large body of data suggests an important role of EGF, TGF-beta, PDGF and VEGF ligands and receptors in the vascularization of several brain tumour types, including gliomas and meningiomas. Recent experimental data indicate that inhibition of the signalling pathways may represent promising therapeutic strategies. Some inhibitory agents have now entered clinical trials, mainly for recurrent gliomas. Early results are presented.

Von Hippel-Lindau (VHL) disease is an uncommon, autosomal dominant hereditary multitumor syndrome caused by germline alterations of the VHL gene, which has been cloned recently and identified as a tumor suppressor gene. The major lesions in VHL disease include hemangioblastomas in the central nervous system and retina, clear cell renal cell carcinomas, pheochromocytomas, pancreatic tumors, epididymal cystadenomas, endolymphatic sac tumors, carcinoid tumors, and multiple cysts of the kidney, pancreas, and epididymis. Compared with sporadic ones, the tumors in VHL disease develop at an earlier age and often multifocally. Histologic features of VHL tumors are characterized by their high degree of vascularization and the presence of a clear cell component. Hypervascularization is induced by overexpression of vascular endothelial growth factor (VEGF), and because the principal function of VHL protein is the negative regulation of hypoxia-inducible mRNAs including VEGF mRNA, inactivation of VHL gene plays critical roles in angiogenesis of the VHL tumors. In addition, since VHL protein is also required for the down-regulation of transcription activity of certain genes for the cell growth and cell cycle, inactivation of VHL gene may contribute to tumorigenesis of the VHL tumors. A significant difference in the frequency of types of VHL gene mutation has been noted among the affected families, known as the genotype-phenotype correlations., (Copyright 2003 Wiley-Liss, Inc.)

Since the introduction of the concept of an "angiogenic switch" driving tumor growth and malignant progression by Judah Folkman in 1971, there have been numerous scientific reports confirming the central concept that tumor growth is angiogenesis dependent. Various angiogenic genes and gene products, from both neoplastic and normal tissues, have been isolated, purified, and cloned that contribute to the 'angiogenic switch'. Of these various molecules, two have been identified that act specifically on endothelial cells. First is Vascular Endothelial Growth Factor (VEGF), the cognate receptors of which are almost specifically expressed on endothelial cells. VEGF plays a crucial role in the development of the embryonic vasculature by providing differentiation and mitogenic signals to endothelial cells and their mesodermal precursors. Second are the Angiopoietins and their cognate receptor, Tie2. Angiopoietins are primarily involved in maturation of both embryonal and adult vasculature, with Angiopoietin 1 2 being naturally occurring agonists and antagonists of Tie2 respectively, indicating a very precise level of regulation in-vivo. In this review we summarize what is known of the biological role of Angiopoietins and Tie2, their interaction with VEGF in normal and tumor related angiogenesis, with emphasis on their functional consequence in the progression and growth of malignant human astrocytomas.