Anterior interhemispheric vs. pterional approach in the microsurgical management of anterior communicating artery aneurysms: a comparative analysis employing a novel multidimensional matching-tool.

The surgical management of anterior communicating artery aneurysms (AcomA) is challenging due to their deep midline position and proximity to complex skull base anatomy. This study compares the pterional craniotomy with the interhemispheric approach based on the specific aneurysm angulation. A total of 129 AcomA cases were analyzed, with 50 undergoing microsurgical clipping via either the pterional or interhemispheric approach. All selected cases had computed tomography-angiography with sagittal imaging slices and 2D-angiography. Using an interactive tool, 14 cases treated via the interhemispheric approach were matched with 14 cases approached pterionally based on clinical and morphological parameters, emphasizing intracranial aneurysm (IA) dome angulation relative to the frontal skull base. Outcomes included IA occlusion, temporary clipping incidence, intraoperative rupture, postoperative strokes, hemorrhages, hydrocephalus, vasospasm, and patient functionality. Matched cohorts had consistent demographics. Both approaches resulted in similar IA occlusion rates, but the interhemispheric approach led to improved clinical outcomes, measured by the modified Rankin Scale. It also had a lower incidence of hydrocephalus and reduced need for permanent ventriculoperitoneal shunt placement. Vasospasms and postoperative infarction rates were comparable between the groups. Our findings suggest potential advantages of the interhemispheric approach in managing AcomA, depending on aneurysm angulation. Despite a small sample size, the results highlight the importance of customized surgical decision-making based on the unique traits of each aneurysm and the surgeon's expertise.

The prognostic significance of clinicopathological features in meningiomas: Microscopic brain invasion can predict patient outcome in otherwise benign meningiomas.

AIMS: Brain invasion (BI) was firstly defined as a single criterion of atypia in otherwise benign meningiomas in the revised fourth edition of 2016 WHO classification of brain tumours after being previously inconsistently addressed. However, recent studies have raised doubts about the prognostic significance of BI in otherwise benign meningiomas. In our study, we investigate the reproducibility of such a prognostic effect. METHODS: We identified two cohorts one consisting of 483 patients with meningioma WHO grade I (M°I) or atypical meningioma WHO grade II (M°II) from Hannover Medical School and the other including atypical meningiomas defined according to the classical WHO criteria (M°IIb) from the University Hospital Heidelberg. Follow-up data with a median observation time of 38.2 months were available from 308 cases. These included 243 M°I and 65 M°II patients with the latter group consisting of 25 patients with otherwise benign meningiomas with BI (M°IIa) and 40 with M°IIb. RESULTS: A significant difference of progression-free interval (PFI) was found between patients with M°I and M°II, M°I and M°IIa and those with M°I and M°IIb of both cohorts and each separately. However, PFI of M°IIa and M°IIb patients showed no significant difference. In the multivariate regression analysis adjusted for M°I/M°IIa versus M°IIb, sex, age, extent of resection and tumour location, BI exhibited the strongest risk of relapse (Hazard ratio: 4.95) serving as an independent predictor of PFI (p = 0.002). CONCLUSIONS: Our results clearly support the definition of BI as a single criterion of atypia in WHO classification of 2016.

Rare ADAR and RNASEH2B variants and a type I interferon signature in glioma and prostate carcinoma risk and tumorigenesis.

In search of novel germline alterations predisposing to tumors, in particular to gliomas, we studied a family with two brothers affected by anaplastic gliomas, and their father and paternal great-uncle diagnosed with prostate carcinoma. In this family, whole-exome sequencing yielded rare, simultaneously heterozygous variants in the Aicardi-Goutières syndrome (AGS) genes ADAR and RNASEH2B co-segregating with the tumor phenotype. AGS is a genetically induced inflammatory disease particularly of the brain, which has not been associated with a consistently increased cancer risk to date. By targeted sequencing, we identified novel ADAR and RNASEH2B variants, and a 3- to 17-fold frequency increase of the AGS mutations ADAR,c.577C>G;p.(P193A) and RNASEH2B,c.529G>A;p.(A177T) in the germline of familial glioma patients as well as in test and validation cohorts of glioblastomas and prostate carcinomas versus ethnicity-matched controls, whereby rare RNASEH2B variants were significantly more frequent in familial glioma patients. Tumors with ADAR or RNASEH2B variants recapitulated features of AGS, such as calcification and increased type I interferon expression. Patients carrying ADAR or RNASEH2B variants showed upregulation of interferon-stimulated gene (ISG) transcripts in peripheral blood as seen in AGS. An increased ISG expression was also induced by ADAR and RNASEH2B variants in tumor cells and was blocked by the JAK inhibitor Ruxolitinib. Our data implicate rare variants in the AGS genes ADAR and RNASEH2B and a type I interferon signature in glioma and prostate carcinoma risk and tumorigenesis, consistent with a genetic basis underlying inflammation-driven malignant transformation in glioma and prostate carcinoma development.

Brain arteriovenous malformations: implications of CEACAM1-positive inflammatory cells and sex on hemorrhage.

Brain arteriovenous malformations (bAVMs) are severe conditions which, upon rupture, cause debilitating neurological deficits and even death. The exact cellular and molecular mechanisms associated with bAVM rupture are currently unclear. The objective of this study was to explore the potential role of CEA-related cell adhesion molecule-1 (CEACAM1) in bAVM pathophysiology. Expression and localization of CEACAM1 were assessed immunohistochemically in tissue microarrays from bAVM patients (n = 60). The association of CEACAM1 with clinical parameters was analyzed with Spearman's rank correlation coefficient and chi-square test. The predictive value of CEACAM1 was tested using logistic regression analysis. CEACAM1 was highly expressed in tissue-infiltrating neutrophil granulocytes. High levels of CEACAM1-positive cells were associated with bAVM rupture (hemorrhage), but not with arteriovenous malformation (AVM) size, preoperative embolization, or seizure. This association was significant (p = 0.029, chi-square) in male but not in female patients, and high CEACAM1-positive immune infiltration showed predictive significance for hemorrhage in male bAVM patients only (OR = 6.50, 95 % CI 1.09-38.63, p = 0.040). Within the ruptured bAVM group, patients with a short hemorrhage to surgery (HTS) time interval had higher levels of CEACAM1 immune infiltration than patients with long HTS. This decrease in the levels of CEACAM1 immune infiltration between the HTS short and HTS long groups was, however, significant only in female patients (p = 0.022, chi-square). Our findings substantiate the role of inflammation in the pathophysiology of bAVM and suggest the presence of sexual dimorphism in this disease.

Stimulation of mesenchymal stromal cells (MSCs) via TLR3 reveals a novel mechanism of autocrine priming.

Mesenchymal stem/stromal cells (MSCs) are emerging as important regulators of innate and adaptive immunity. In this context, both proinflammatory and anti-inflammatory effects have been described for MSCs. The mechanisms mediating this functional plasticity are poorly characterized at present. Here, we investigated the inflammatory responses of MSCs isolated from human nasal mucosa (nmMSCs) upon challenge with different Toll-like receptor (TLR) ligands. We found that TLR3 ligands induced the strongest release of both proinflammatory cytokines [interleukin (IL)-6 and IL-8] and type I interferon by nmMSCs compared with other TLR ligands. Notably, TLR3 ligands triggered a biphasic cytokine response, with an early peak of type I interferon at 4 h poststimulation and a late release of proinflammatory cytokines at 24 h poststimulation. While the early interferon response was subject to direct stimulation, the proinflammatory response was regulated by factors released during the early cytokine response, which subsequently enhanced sensitivity to TLR3 ligation and amplified the production of IL-6 and IL-8 but not that of interferon. Taken together, our findings indicate that TLR3 ligands polarize the inflammatory phenotype of MSCs in a time-dependent manner. Thus, our study proposes a novel model that helps to explain the strikingly dichotomous functionality of MSCs in inflammation and immunoregulation.

Modulation of neutrophil granulocytes in the tumor microenvironment: mechanisms and consequences for tumor progression.

Accumulating evidence indicates a critical role of myeloid cells in the pathophysiology of human cancers. In contrast to the well-characterized tumor-associated macrophages (TAMs), the significance of granulocytes in cancer has only recently begun to emerge. Increased numbers of neutrophil granulocytes have been observed both in the peripheral blood and in the tumor tissues of patients with different types of cancer. Importantly, these studies linked neutrophils to poor clinical outcome in cancer patients which suggests that these cells might have important tumor-promoting activities. Indeed, a number of functional in vitro and in vivo studies demonstrated that tumors stimulated neutrophils to promote angiogenesis and immunosuppression, as well as migration, invasion and metastasis of the tumor cells. Therefore, it became necessary to understand the mechanisms modulating the changes in the biology and functions of neutrophils in the context of the tumor microenvironment. In this review we will discuss several functions of neutrophils that might contribute to tumor progression. Furthermore, we will address in detail the cellular and molecular mechanisms that control modulation of neutrophils in the tumor microenvironment, such as recruitment to the tumor site (chemotaxis), prolonged survival and enhanced release of protumoral mediators.

Is an Elevated Preoperative CRP Level a Predictive Factor for Wound Healing Disorders following Lumbar Spine Surgery?

Postoperative wound infections are a prevalent concern among the hospital-associated infections in Europe, leading to prolonged hospital stays, increased morbidity and mortality, and substantial patient burdens. Addressing the root causes of this complication is crucial, especially given the rising number of spine surgeries due to aging populations. METHODS: A retrospective analysis was conducted on a cohort of 3019 patients who underwent lumbar spine surgery over a decade in our department. The study aimed to assess the predictors of wound healing disorders, focusing on laboratory values, particularly inflammatory parameters. RESULTS: Of the 3019 patients, 2.5% (N = 74) experienced deep or superficial wound healing disorders, showing the significant correlation between C-reactive protein (CRP) levels and these disorders (p = 0.004). A multivariate analysis identified several factors, including age, sex, hypertension, diabetes, cardiac comorbidity, surgical duration, dural injury, and blood loss, as being correlated with wound healing disorders. CONCLUSION: Demographic factors, pre-existing conditions, and perioperative variables play a role in the occurrence of adverse effects related to wound healing disorders. Elevated CRP levels serve as an indicator of increased infection risk, though they are not a definitive diagnostic tool for wound healing disorders.

Impact of Perioperative Acetylsalicylic Acid (ASA) Administration on Postoperative Intracranial Hemorrhage (pICH) and Thromboembolic Events in Patients with Intracranial Meningiomas.

Background: In routine medical practice, patients are increasingly using ASA for primary and secondary prevention. Although many of these patients discontinue ASA prior to elective intracranial surgery, there are limited data to support whether perioperative ASA use raises the risk of postoperative hemorrhage. This study aimed to investigate the implications of continuing or stopping ASA around the time of surgery in patients with intracranial meningiomas, focusing on postoperative hemorrhage and thromboembolic events. Methods: For this purpose, medical records and radiological images of 1862 patients who underwent cranial neurosurgical procedures for brain tumors over a decade at our neurosurgical institute were retrospectively analyzed. The risk of postoperative hemorrhage was evaluated by comparing meningioma patients who received ASA treatment with those who did not. Furthermore, we investigated other factors that influence postoperative hemorrhage and thromboembolic events, particularly in patients receiving ASA treatment. Results: A total of 422 patients diagnosed with meningiomas underwent surgical intervention. Among the patients who received ASA preoperatively, 4 out of 46 (8.69%) experienced postoperative hemorrhage requiring surgical intervention, whereas the same complication occurred in only 4 out of 376 patients (1.06%) in the non-ASA group (p = 0.007). There was no significant difference in the incidence of thromboembolic events between the two groups. Conclusions: Our analysis revealed an increased risk of postoperative hemorrhage in patients using ASA.

Extravascular optical coherence tomography of cerebral vessel walls in vivo.

PURPOSE: Evaluation of extravascular, microscope integrated OCT (iOCT) as an in vivo imaging modality of cerebral blood vessels and as an intraoperative imaging method. METHODS: Microscope integrated optical coherence tomography of major cerebral arteries (n = 13) and superficial sylvian veins (n = 5) and one incidental cerebral vasospasm (n = 1) in (n = 10) patients. Post procedural analysis of OCT volume scans, microscopic images and videos during the time of scan as well as measurements of the diameter of vessel walls and its layers with an accuracy of 7.5 µm. RESULTS: iOCT was feasible during vascular microsurgical procedures. In all scanned arteries a clear delineation of the physiological three layered vessel wall composition could be achieved. Pathological arteriosclerotic alterations of cerebral artery walls could precisely be demonstrated. Major superficial cortical veins conversely presented a mono layered composition. First in vivo measurements of vascular mean diameters were possible. Cerebral artery walls showed a diameter of 296 µm, tunica externa 78 µm, media 134 µm and interna 84 µm. CONCLUSION: For the first time the microstructural composition of cerebral blood vessels could be illustrated in vivo. Due to an outstanding spatial resolution a clear definition of physiological and pathological characteristics was possible. Therefore, microscope integrated optical coherence tomography holds promise for basic research in the field of cerebrovascular arteriosclerotic diseases and for intraoperative guidance during microvascular surgery.

Neutrophils and granulocytic myeloid-derived suppressor cells: immunophenotyping, cell biology and clinical relevance in human oncology.

Accumulating evidence indicates that myeloid cells are critically involved in the pathophysiology of human cancers. In contrast to the well-characterized tumor-associated macrophages, the significance of granulocytes in cancer has only recently begun to emerge. A number of studies found increased numbers of neutrophil granulocytes and granulocytic myeloid-derived suppressor cells (GrMDSCs) both in the peripheral blood and in the tumor tissues of patients with different types of cancer. Most importantly, granulocytes have been linked to poor clinical outcome in cancer patients which suggests that these cells might have important tumor-promoting effects. In this review, we will address in detail the following major topics: (1) neutrophils and GrMDSCs in the peripheral blood of cancer patients-phenotype and functional changes; (2) neutrophils and GrMDSCs in the tumor tissue-potential mechanisms of tumor progression and (3) relevance of neutrophils and GrMDSCs for the clinical outcome of cancer patients. Furthermore, we will discuss the advantages and disadvantages of the current strategies used for identification and monitoring of human MDSCs. We propose a six-color immunophenotyping protocol that discriminates between monocytic MDSCs (MoMDSCs), two subsets of GrMDSCs and two subsets of immature myeloid cells in human cancer patients, thus, allowing for an improved characterization and understanding of these multifaceted cells.

Overcoming Barriers in Neurosurgical Education: A Novel Approach to Practical Ventriculostomy Simulation.

BACKGROUND: In the high-risk, high-stakes specialty of neurosurgery, traditional teaching methods often fail to provide young residents with the proficiency needed to perform complex procedures in stressful situations, with direct effects on patient outcomes. Physical simulators provide the freedom of focused, hands-on training in a more controlled environment. However, the adoption of simulators in neurosurgical training remains a challenge because of high acquisition costs, complex production processes, and lack of realism. OBJECTIVE: To introduce an easily reproducible, cost-effective simulator for external ventricular drain placements through various ventriculostomy approaches with life-like tactile brain characteristics based on real patients' data. METHODS: Whole brain and skull reconstruction from patient's computed tomography and MRI data were achieved using freeware and a desktop 3-dimensional printer. Subsequently, a negative brain silicone mold was created. Based on neurosurgical expertise and rheological measurements of brain tissue, gelatin in various concentrations was tested to cast tactilely realistic brain simulants. A sample group of 16 neurosurgeons and medical students tested and evaluated the simulator in respect to realism, haptics, and general usage, scored on a 5-point Likert scale. RESULTS: We saw a rapid and significant improvement of accuracy among novice medical students. All participants deemed the simulator as highly realistic, effective, and superior to conventional training methods. CONCLUSION: We were able to demonstrate that building and implementing a high-fidelity simulator for one of the most important neurosurgical procedures as an effective educational and training tool is achievable in a timely manner and without extensive investments.

Canonical WNT pathway inhibition reduces ATP synthesis rates in glioblastoma stem cells.

BACKGROUND: The conserved stem cell signaling network canonical Wingless (WNT) plays important roles in development and disease. Aberrant activation of this pathway has been linked to tumor progression and resistance to therapy. Industry and academia have substantially invested in developing substances, which can efficiently and specifically block the WNT signaling pathway. However, a clear clinical proof of the efficacy of this approach is still missing. Studies on the metabolomics dysregulation of cancer cells have led to innovations in oncological diagnostics. In addition, modulation of cancer cell metabolome is at the base of promising clinical oncology trials currently underway. While onco-protein activation can have profound metabolic outcomes, the involvement of stem cell signals, such as the WNT pathway, in tumor cell metabolomics is yet insufficiently characterized. MATERIAL AND METHODS: We determined live cell metabolism and bioenergetics in pathophysiological relevant, WNT-dependent glioblastoma stem cell (GSC) models. We quantified those parameters in cells with canonical WNT activity and in isogenic cells where WNT activity had been inhibited by short hairpin RNA against ß-catenin. Furthermore, we applied computational analysis of RNA sequencing to verify our functional findings in independent GSCs cohorts. RESULTS: The investigated collection of disease models allows the separation in tumors with low, moderate and high base line metabolic activity. Suppression of canonical WNT signaling led to significant reduction of total, mitochondrial, and glycolytic ATP production rates. Elevated canonical WNT transcription signature in GSCs positively correlated with transcription levels of mitochondrial ATP synthesis, whereas non-canonical WNT gene expression signature did not. CONCLUSION: The applied disease modeling technology allows the recapitulation of inter-tumoral heterogeneous metabolic properties of glioblastoma. Our data show for the first time that inhibition of canonical WNT signaling in alive GSCs functionally correlates with energy inhibition and glucose homeostasis. As this correlation occurs in GSCs from different transcriptional or epigenetic transcriptional subtypes, our results suggest that developing therapies directed against glycolysis/ATP-synthesis may be a promising strategy to overcome therapy resistance due to inter-tumoral heterogeneity and offers starting point to impair downstream signal WNT.

Tumor-derived macrophage migration inhibitory factor modulates the biology of head and neck cancer cells via neutrophil activation.

Macrophage migration inhibitory factor (MIF) is an inflammatory cytokine that has been reported to enhance the aggressiveness and metastatic potential of tumor cells. However, the mechanisms through which MIF influences tumor development and progression are not understood. The objectives of our study were to assess the effects of tumor-derived MIF on neutrophils in head and neck cancer (HNC) and to identify possible feedback effects on tumor cells. To this end, we used an in vitro system to model the interaction between human HNC cells and neutrophils. In addition, we analyzed expression of MIF in tissues from HNC patients in relation to neutrophilic infiltration and clinical parameters. Our results show that human HNC is infiltrated by neutrophils proportional to the levels of tumoral MIF. Strong MIF expression by the tumor is associated with higher lymph node metastasis and reduced survival in HNC patients. In vitro, MIF modulated functions of human neutrophils by inducing chemokine CXC motif receptor 2(CXCR2)-dependent chemotaxis, enhancing neutrophil survival and promoting release of chemokine C-C Motif Ligand 4 (CCL4) and matrix metalloprotease 9(MMP9). Further, neutrophils activated with tumor-derived MIF enhanced migratory properties of HNC cells. In conclusion, our data indicate that the effects of tumor-derived MIF on neutrophils represent an additional mechanism by which MIF might contribute to tumor progression.

Polymorphonuclear granulocytes in human head and neck cancer: enhanced inflammatory activity, modulation by cancer cells and expansion in advanced disease.

The progression of epithelial cancer is associated with an intense immunological interaction between the tumor cells and immune cells of the host. However, little is known about the interaction between tumor cells and polymorphonuclear granulocytes (PMNs) in patients with head and neck squamous cell carcinoma (HNSCC). In our study, we investigated systemic PMN-related alterations in HNSCC, the role of tumor-infiltrating PMNs and their modulation by the tumor microenvironment. We assessed the infiltration of HNSCC tissue by PMNs (retrospectively) and systemic PMN-related alterations in blood values (prospectively) in HNSCC patients (n = 99 and 114, respectively) and control subjects (n = 41). PMN recruitment, apoptosis and inflammatory activity were investigated in an in vitro system of peripheral blood PMNs and a human HNSCC cell line (FaDu). HNSCC tissue exhibited considerable infiltration by PMNs, and strong infiltration was associated with poorer survival in advanced disease. PMN count, neutrophil-to-lymphocyte ratio and serum concentrations of CXCL8 (interleukin-8), CCL4 (MIP-1ß) and CCL5 (RANTES) were significantly higher in the peripheral blood of HNSCC patients than in that of controls. In vitro, HNSCC-conditioned medium inhibited apoptosis of PMNs, increased chemokinesis and chemotaxis of PMNs, induced release of lactoferrin and matrix metalloproteinase 9 by PMNs and enhanced the secretion of CCL4 by PMN. Our findings demonstrate alterations in PMN biology in HNSCC patients. In vitro, tumor-derived factors modulate cellular functions of PMNs and increase their inflammatory activity. Thus, the interaction between HNSCC and PMNs may contribute to host-mediated changes in the tumor microenvironment.

EGFR-specific T cell frequencies correlate with EGFR expression in head and neck squamous cell carcinoma.

BACKGROUND: In head and neck squamous cell carcinoma (HNSCC), expression levels of the epidermal growth factor receptor (EGFR) correlate with poor prognosis and decreased survival rates. As the mechanisms responsible for cellular immune response to EGFR in vivo remain unclear, the frequency and function of EGFR-specific cytotoxic T cells (CTL) was determined in HNSCC patients. METHODS: The frequency of CTL specific for the HLA-A2.1-restricted EGFR-derived YLN peptide (YLNTVQPTCV) and KLF peptide (KLFGTSGQKT) was determined in 16 HLA-A2.1+ HNSCC patients and 16 healthy HLA-A2.1+ individuals (NC) by multicolor flow cytometry. Patients' results were correlated to EGFR expression obtained by immunohistochemistry in corresponding tumor sections. Proliferation and anti-tumor activity of peptide-specific CTL was demonstrated by in vitro stimulation with dendritic cells pulsed with the peptides. RESULTS: Frequency of EGFR-specific CTL correlated significantly with EGFR expression in tumor sections (p = 0.02, r2 = 0.6). Patients with elevated EGFR scores (> 7) had a significantly higher frequency of EGFR-specific CTL than NC and patients with low EGFR scores (< 7). EGFR-specific CTL from cancer patients were expanded ex vivo and produced IFN-γ upon recognition of EGFR+ target cells. CONCLUSION: EGFR expressed on HNSCC cells induces a specific immune response in vivo. Strategies for expansion of EGFR-specific CTL may be important for future immunotherapy of HNSCC patients.

Proliferation activity is significantly elevated in partially embolized cerebral arteriovenous malformations.

BACKGROUND: The natural history of cerebral arteriovenous malformations (AVMs) is yet to be determined. It has been shown that angiogenic factors are involved in the pathogenesis of AVMs, in particular in partially embolized lesions. This study was conducted to investigate the expression of angiogenic and proliferative factors in relation to different clinical conditions and treatment modalities. METHODS: Immunohistochemistry was performed for 145 consecutive cases of cerebral AVMs. The specimens were stained with antibodies against VEGF, bFGF, Ki 67, CD 34 and CD 31. Expression was correlated with clinical presentation (haemorrhage, seizures or other symptoms), AVM localization, size, eloquence and venous drainage, as well as with preoperative AVM embolization. RESULTS: Whereas no correlation was found between the expression of angiogenic factors and different clinical conditions, we observed a significantly increased proliferation activity as shown by Ki 67 expression in patients with intracerebral haemorrhage (p = 0.02) and in patients with preoperative embolization (p = 0.02). CONCLUSIONS: Increased proliferation activity in partially embolized AVMs supports a 'no-touch' strategy and clinical observation in high-risk AVMs and demands complete AVM elimination in treatable lesions.

Age-dependent changes of collagen alpha-2(IV) expression in the extracellular matrix of brain arteriovenous malformations.

OBJECTIVES: Brain arteriovenous malformations (bAVM) are rare vascular lesions. Recent observations challenge the congenital nature of these lesions. The underlying cellular and molecular mechanisms associated with dynamic changes of bAVM still remain unclear. The objective of this study was to explore the potential role of COL4A2 (Collagen alpha-2(IV)) in the pathophysiology of bAVM. PATIENTS AND METHODS: Expression and localization of COL4A2 were analyzed on tissue microarrays from bAVM patients (n = 60) by immunohistochemistry. Correlations between COL4A2 levels and clinical parameters were examined with Pearson's test for normally- distibuted or Spearman's Rho for not normally distributed data. Comparison between different clinical parameters was performed using t-test, non-parametric Mann-Whitney U test or Kruskal- Wallis test. Fisher's exact test was used for categorical data. RESULTS: COL4A2 was mainly expressed beneath the endothelium of vessels in the tunica media of bAVM. This pattern of expression indicates the basement membrane of the vessel walls. High levels of COL4A2 expression correlated with the age at surgery of patients (p = 0.005; R = 0.393; Spearman's Rho). The age at surgery in young (17-25 years) and old patients (55-76 years) showed a linear correlation; a greater variance of COL4A2 expression was observed in the age group between 26-54 years. CONCLUSION: This study reports for the first time the expression of COL4A2 in bAVM and suggests a potential role of COL4A2 in bAVM pathophysiology. These findings contribute to a better understanding of the microenvironment of bAVM and may foster the development of improved therapeutic strategies for this disease.

Cannabinoids in Glioblastoma Therapy: New Applications for Old Drugs.

Glioblastoma (GBM) is the most malignant brain tumor and one of the deadliest types of solid cancer overall. Despite aggressive therapeutic approaches consisting of maximum safe surgical resection and radio-chemotherapy, more than 95% of GBM patients die within 5 years after diagnosis. Thus, there is still an urgent need to develop novel therapeutic strategies against this disease. Accumulating evidence indicates that cannabinoids have potent anti-tumor functions and might be used successfully in the treatment of GBM. This review article summarizes the latest findings on the molecular effects of cannabinoids on GBM, both in vitro and in (pre-) clinical studies in animal models and patients. The therapeutic effect of cannabinoids is based on reduction of tumor growth via inhibition of tumor proliferation and angiogenesis but also via induction of tumor cell death. Additionally, cannabinoids were shown to inhibit the invasiveness and the stem cell-like properties of GBM tumors. Recent phase II clinical trials indicated positive results regarding the survival of GBM patients upon cannabinoid treatment. Taken together these findings underline the importance of elucidating the full pharmacological effectiveness and the molecular mechanisms of the cannabinoid system in GBM pathophysiology.

Procollagen-Lysine, 2-Oxoglutarate 5-Dioxygenase 2 Expression in Brain Arteriovenous Malformations and its Association with Brain Arteriovenous Malformation Size.

BACKGROUND AND OBJECTIVE: Brain arteriovenous malformations (bAVM) are severe conditions that can cause severe neurologic deficits and mortality. The underlying cellular and molecular mechanisms associated with bAVM growth and rupture remain unclear. The objective of this study was to explore the potential role of PLOD2 (procollagen-lysine, 2-oxoglutarate 5-dioxygenase 2) in the pathophysiology of bAVM. METHODS: Expression and localization of PLOD2 were analyzed on tissue microarrays from patients with bAVM (n = 60) by immunohistochemistry. Correlations between PLOD2 levels and clinical parameters were examined with a Pearson test or Spearman rank correlation coefficient. Comparison between different clinical parameters was performed using a t test or nonparametric Mann-Whitney U test. A Fisher exact test was used for categorical data. RESULTS: PLOD2 was mainly expressed within the tunica media of the blood vessels. High levels of PLOD2 expression correlated with bAVM size (linear regression, P = 0.0083, R2=0.158). Small bAVM showed a higher frequency of hemorrhage compared with large ones (P = 0.001). Although PLOD2 was not directly associated with bAVM hemorrhage, high PLOD2-expressing bAVM had a lower frequency of hemorrhage compared with low or medium PLOD2-expressing bAVM (25% vs. 63% and 75%, respectively). CONCLUSIONS: This study reports for the first time the expression of PLOD2 in bAVM and suggests a potential role of PLOD2 in bAVM pathophysiology. These findings contribute to an better understanding of the microenvironment of bAVM and may foster the development of improved therapeutic strategies for this disease.

Adenosine metabolism of human mesenchymal stromal cells isolated from patients with head and neck squamous cell carcinoma.

BACKGROUND: Mesenchymal stromal cells (MSC) are a major component of the tumor microenvironment in patients with head and neck squamous cell carcinoma (HNSCC). MSC display innate and regulatory immunologic functions, very similar to many hematopoietic 'classical' immune cells. Conversion of ATP to immunosuppressive adenosine is an immunosuppressive mechanism utilized by other hematopoietic immune cells. The present study explores the adenosine metabolism of tumor derived MSC in comparison to autologous MSC from non-malignant tissue. METHODS: From HNSCC patients (n=10), paired MSC were generated from tumor tissue (tMSC) and autologous healthy control tissue (cMSC). Differentiation properties and phenotype (CD105, CD73, CD39, CD90, CD26, CD29) were compared by flow cytometry. Production of immunosuppressive adenosine (ADO) by functionally active ectonucleotidases, CD39 and CD73, was determined by luminescence and mass spectrometry. Suppressive activity of ADO was tested in CFSE proliferation assays of isolated T-cells. Plasticity of cMSC was explored after incubation with tumor-cell conditioned media. RESULTS: Differentiation into osteogenic, chondrogenic and adipogenic directions was comparable in tMSC and cMSC. Expression of ectonucleotidases, CD39 and CD73, was decreased in tMSC as compared to corresponding cMSC, which correlated with decreased ATP metabolism in mass spectrometry. Proliferation of CD4+ T-cells was significantly suppressed by exogenous ADO. Tumor-conditioned medium was unable to down-regulate ADO production in cMSC. CONCLUSION: We identified MSC of the oropharyngeal mucosa as an important producer of exogenous ADO. In patients with HNSCC, reduced expression of ADO may contribute to excessive inflammation and tumor growth.