External irradiation models for intracranial 9L glioma studies

<p>Abstract</p> <p>Purpose</p> <p>Radiotherapy has been shown to be an effective for the treatment human glioma and consists of 30 fractions of 2 Gy each for 6-7 weeks in the tumor volume with margins. However. in preclinical studies, many different radiation schedules are used. The main purpose of this work was to review the relevant literature and to propose an external whole-brain irradiation (WBI) protocol for a rat 9L glioma model.</p> <p>Materials and methods</p> <p>9L cells were implanted in the striatum of twenty 344-Fisher rats to induce a brain tumor. On day 8, animals were randomized in two groups: an untreated group and an irradiated group with three fractions of 6 Gy at day 8, 11 and 14. Survival and toxicity were assessed.</p> <p>Results</p> <p>Irradiated rats had significantly a longer survival (p = 0.01). No deaths occurred due to the treatment. Toxicities of reduced weight and alopecia were increased during the radiation period but no serious morbidity or mortality was observed. Moreover, abnormalities disappeared the week following the end of the therapeutic schedule.</p> <p>Conclusions</p> <p>Delivering 18 Gy in 3 fractions of 6 Gy every 3 days, with mild anaesthesia, is safe, easy to reproduce and allows for standardisation in preclinical studies of different treatment regimens glioma rat model.</p

In vitro expansion of human glioblastoma cells at non-physiological oxygen tension irreversibly alters subsequent in vivo aggresiveness and AC 133 expression

Among markers of glioblastoma initiating cells, AC133 has been shown to be associated with glioblastoma resistance and malignancy. Recently, it was demonstrated that increasing oxygen tension (pO(2)) down-regulated AC133 expression in glioblastoma cells in vitro. In order to better understand extrinsic factor regulation of AC133, this work aimed to investigate the relationship between cell culture pO(2), AC133 expression, and tumor development and phenotype. Using treatments with CoCl(2) and HIF-1α shRNA knockdowns on non-sorted human primary glioblastoma cells cultured at low (3%) versus high (21%) oxygen tension, we established a responsibility for low pO(2) in the maintenance of high levels of AC133 expression, with a major but non-exclusive role for HIF-1α. We also demonstrated that human glioblastoma cells previously cultured under high oxygen tension can lose part of their aggressiveness when orthotopically engrafted in SCID mice or lead to tumors with distinct phenotypes and no re-expression of AC133. These observations showed that the specific pO(2) microenvironment irreversibly impacts glioblastoma cell phenotypes, highlighting the pertinence of culture conditions when extrapolating data from xenogenic models to human cells in their source environment. They also raised AC133 as a marker of non-exposure to oxygenated areas rather than a marker of aggressiveness or low pO(2) niches

DGKI Methylation Status Modulates the Prognostic Value of MGMT in Glioblastoma Patients Treated with Combined Radio-Chemotherapy with Temozolomide

International audienceBackgroundConsistently reported prognostic factors for glioblastoma (GBM) are age, extent of surgery, performance status, IDH1 mutational status, and MGMT promoter methylation status. We aimed to integrate biological and clinical prognostic factors into a nomogram intended to predict the survival time of an individual GBM patient treated with a standard regimen. In a previous study we showed that the methylation status of the DGKI promoter identified patients with MGMT-methylated tumors that responded poorly to the standard regimen. We further evaluated the potential prognostic value of DGKI methylation status.Methods399 patients with newly diagnosed GBM and treated with a standard regimen were retrospectively included in this study. Survival modelling was performed on two patient populations: intention-to-treat population of all included patients (population 1) and MGMT-methylated patients (population 2). Cox proportional hazard models were fitted to identify the main prognostic factors. A nomogram was developed for population 1. The prognostic value of DGKI promoter methylation status was evaluated on population 1 and population 2.ResultsThe nomogram-based stratification of the cohort identified two risk groups (high/low) with significantly different median survival. We validated the prognostic value of DGKI methylation status for MGMT-methylated patients. We also demonstrated that the DGKI methylation status identified 22% of poorly responding patients in the low-risk group defined by the nomogram.ConclusionsOur results improve the conventional MGMT stratification of GBM patients receiving standard treatment. These results could help the interpretation of published or ongoing clinical trial outcomes and refine patient recruitment in the future

DNA methylation in glioblastoma: impact on gene expression and clinical outcome

International audienceBACKGROUND: Changes in promoter DNA methylation pattern of genes involved in key biological pathways have been reported in glioblastoma. Genome-wide assessments of DNA methylation levels are now required to decipher the epigenetic events involved in the aggressive phenotype of glioblastoma, and to guide new treatment strategies. RESULTS: We performed a whole-genome integrative analysis of methylation and gene expression profiles in 40 newly diagnosed glioblastoma patients. We also screened for associations between the level of methylation of CpG sites and overall survival in a cohort of 50 patients uniformly treated by surgery, radiotherapy and chemotherapy with concomitant and adjuvant temozolomide (STUPP protocol). The methylation analysis identified 616 CpG sites differentially methylated between glioblastoma and control brain, a quarter of which was differentially expressed in a concordant way. Thirteen of the genes with concordant CpG sites displayed an inverse correlation between promoter methylation and expression level in glioblastomas: B3GNT5, FABP7, ZNF217, BST2, OAS1, SLC13A5, GSTM5, ME1, UBXD3, TSPYL5, FAAH, C7orf13, and C3orf14. Survival analysis identified six CpG sites associated with overall survival. SOX10 promoter methylation status (two CpG sites) stratified patients similarly to MGMT status, but with a higher Area Under the Curve (0.78 vs. 0.71, p-value < 5e-04). The methylation status of the FNDC3B, TBX3, DGKI, and FSD1 promoters identified patients with MGMT-methylated tumors that did not respond to STUPP treatment (p-value < 1e-04). CONCLUSIONS: This study provides the first genome-wide integrative analysis of DNA methylation and gene expression profiles obtained from the same GBM cohort. We also present a methylome-based survival analysis for one of the largest uniformly treated GBM cohort ever studied, for more than 27,000 CpG sites. We have identified genes whose expression may be tightly regulated by epigenetic mechanisms and markers that may guide treatment decisions

MYELOPATHIES TARDIVES CHEZ LES BLESSES MEDULLAIRES (ETUDE RETROSPECTIVE ET REVUE DE LA LITTERATURE (DES MEDECINE PHYSIQUE ET READAPTATION))

ANGERS-BU Médecine-Pharmacie (490072105) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

Cellules stromales mésenchymateuses comme vecteurs cellulaires de nanoparticules (un nouvel outil thérapeutique des tumeurs cérébrales)

Ce travail de thèse a pour objectif le développement d un nouvel outil thérapeutique des tumeurs cérébrales en utilisant le tropisme tumoral des cellules stromales mésenchymateuses (CSMs) pour véhiculer et distribuer des nanoparticules (NPs) chargées en principe actif. Une sous-population de CSMs humaines extraites à partir de la moelle osseuse de la crête iliaque de patients, les cellules MIAMI (" Marrow-Isolated Adult Multilineage Inducible") et deux types de NPs [NPs polymériques et nanocapsules lipides (NCLs)] ont été utilisés pour montrer la preuve de concept de cet outil thérapeutique. Nous avons montré que les cellules MIAMI incorporent efficacement ces deux types de NPs sans modification de leur potentiel souche. De plus, ces cellules sont capables de véhiculer et de distribuer les NPs in vivo au sein d une tumeur cérébrale. La toxicité de ce nouvel outil a été validée in vitro et in vivo dans le modèle du gliome humain U87MG en utilisant des cellules MIAMI chargées en NCLs de ferrociphenol. La sureté de l utilisation des cellules MIAMI, en tant que vecteurs cellulaires, a également été étudiée. Nous avons montré que les cellules MIAMI n étaient pas capables de se transformer in vitro et in vivo. Cependant, l interaction des cellules MIAMI avec les cellules gliales tumorales semble être gliome dépendant suggérant que des investigations supplémentaires doivent être réalisées pour s assurer de la sureté des cellules MIAMI. L ensemble de ce travail de thèse a montré que les cellules MIAMI combinées à des NPs pour délivrer spécifiquement un principe actif au sein d une tumeur cérébrale constituent un outil prometteur dans la thérapie du gliome.The aim of this study is to develop a new therapeutic tool for brain tumors using the migratory capacity of mesenchymal stromal cells (MSCs) towards tumor to vehicle and distribute therapeutic nanoparticles (NPs). A subpopulation of human MSCs extracted from patient iliac crest bone marrow, MIAMI cells ("Marrow-Isolated Adult Multilineage Inducible"), and two types of NPs [polymer NPs and lipid nanocapsules (LNCs)] were used to show the proof of concept of this therapeutic tool. We have shown that MIAMI cells efficiently incorporate these NPs, without modification of their stemness properties. Moreover, MIAMI cells were able to vehicle and distribute NPs in vivo within the brain tumor. The toxicity of this new tool has been validated in vitro and in vivo in the human U87MG glioma model with MIAMI cells loaded with ferrociphenol-LNCs. The safety of the use of MIAMI cells, as cellular vectors, was also studied. We have shown that MIAMI cells were not able of transformation in vitro and in vivo. However, the interaction between MIAMI cells and glioma cells seemed glioma dependant suggesting that supplementary studies may be done to ensure the safety of MIAMI cells. Taken together, this work demonstrates that MIAMI cells combined with NPs to deliver specifically a drug within a brain tumor constitute a new promising tool in glioma therapy.ANGERS-BU Médecine-Pharmacie (490072105) / SudocSudocFranceF

Immunothérapie des gliomes (Evaluation préclinique et clinique d'une vaccination contre les gliomes malins par cellules tumorales autologues irradiées et microperfusion de GM-CSF [Granulocyte Macrophage Colony Stimulating Factor])

ANGERS-BU Médecine-Pharmacie (490072105) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

Stratégies interventionnelles dans le traitement de la maladie de Parkinson idiopathique (réalités et perspectives )

ANGERS-BU Médecine-Pharmacie (490072105) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

Mesenchymal Stromal-Like Cells in the Glioma Microenvironment: What Are These Cells?

International audienceThe glioma microenvironment is a critical regulator of tumor progression. It contains different cellular components such as blood vessels, immune cells, and neuroglial cells. It also contains non-cellular components, such as the extracellular matrix, extracellular vesicles, and cytokines, and has certain physicochemical properties, such as low pH, hypoxia, elevated interstitial pressure, and impaired perfusion. This review focuses on a particular type of cells recently identified in the glioma microenvironment: glioma-associated stromal cells (GASCs). This is just one of a number of names given to these mesenchymal stromal-like cells, which have phenotypic and functional properties similar to those of mesenchymal stem cells and cancer-associated fibroblasts. Their close proximity to blood vessels may provide a permissive environment, facilitating angiogenesis, invasion, and tumor growth. Additional studies are required to characterize these cells further and to analyze their role in tumor resistance and recurrence