Together, these results demonstrate that human gliomas contain multiple populations of cells with the capacity to form tumors and specifically identify a population of tumorigenic A2B5+ cells that are phenotypically distinct from CD133+ cells.

Despite increasing evidence that anti-tumor immune control exists in the pediatric brain, these findings have yet to be exploited successfully in the clinic. A barrier to development of immunotherapeutic strategies in pediatric brain tumors is that the immunophenotype of these tumors’ microenvironment has not been defined. To address this the present study used multicolor FACS of disaggregated tumor to systematically characterize the frequency and phenotype of infiltrating immune cells in the most common pediatric brain tumor types. The initial study cohort consisted of 7 pilocytic astrocytoma (PA), 19 ependymoma (EPN), 5 glioblastoma (GBM), 6 medulloblastoma (MED) and 5 non-tumor brain (NT) control samples obtained from epilepsy surgery. Immune cell types analyzed included both myeloid and T-cell lineages and respective markers of activated or suppressed functional phenotypes. Immune parameters that distinguished each of the tumor types were identified. PA and EPN demonstrated significantly higher infiltrating myeloid and lymphoid cells compared to GBM, MED or NT. Additionally, PA and EPN conveyed a comparatively activated/M1-skewed myeloid functional phenotype denoted in particular by HLA-DR and CD64 expression. In contrast, GBM and MED contained progressively fewer infiltrating leukocytes and more muted functional phenotype similar to that of NT. These findings were recapitulated using whole tumor expression of corresponding immune marker genes in a large gene expression microarray cohort of pediatric brain tumors. The results of this cross-tumor comparative analysis demonstrate that different pediatric brain tumor types exhibit distinct immunophenotypes, implying that specific immunotherapeutic approaches may be most effective for each tumor type.

Communicating hydrocephalus is an almost universal finding in patients after hemicraniectomy. Delayed time to cranioplasty is linked with the development of persistent hydrocephalus, necessitating permanent CSF diversion in some patients. We propose that early cranioplasty, when possible, may restore normal intracranial pressure dynamics and prevent the need for permanent CSF diversion in patients after hemicraniectomy.

Purpose: The source of glioblastoma (GBM)-associated immunosuppression remains multifactorial. We sought to clarify and therapeutically target myeloid cell-derived peripheral immunosuppression in patients with GBM.Experimental Design: Direct ex vivo T-cell function, serum Arginase I (ArgI) levels, and circulating myeloid lineage populations were compared between patients with GBM and normal donors or patients with other intracranial tumors. Immunofunctional assays were conducted using bulk and sorted cell populations to explore the potential transfer of myeloid cell-mediated immunosuppression and to identify a potential mechanism for these effects. ArgI-mediated immunosuppression was therapeutically targeted in vitro through pharmacologic inhibition or arginine supplementation.Results: We identified a significantly expanded population of circulating, degranulated neutrophils associated with elevated levels of serum ArgI and decreased T-cell CD3z expression within peripheral blood from patients with GBM. Sorted CD11b þ cells from patients with GBM were found to markedly suppress normal donor T-cell function in coculture, and media harvested from mitogen-stimulated GBM peripheral blood mononuclear cell (PBMC) or GBM-associated mixed lymphoid reactions showed ArgI levels that were significantly higher than controls. Critically, T-cell suppression in both settings could be completely reversed through pharmacologic ArgI inhibition or with arginine supplementation. Conclusions: These data indicate that peripheral cellular immunosuppression in patients with GBM is associated with neutrophil degranulation and elevated levels of circulating ArgI, and that T-cell function can be restored in these individuals by targeting ArgI. These data identify a novel pathway of GBM-mediated suppression of cellular immunity and offer a potential therapeutic window for improving antitumor immunity in affected patients. Clin Cancer Res; 17(22); 6992-7002. Ó2011 AACR.

SummaryThe authors report the use of dense two-dimensional microelectrode array recordings to characterize fine resolution electrocortical activity ("μEEG") in epileptogenic human cortex. A 16-mm 2 96 microelectrode array with 400-μm interelectrode spacing was implanted in five patients undergoing invasive EEG monitoring for medically refractory epilepsy. High spatial resolution data from the array were analyzed in conjunction with simultaneously acquired data from standard intracranial electrode grids and strips. μEEG recorded from within the epileptogenic zone demonstrates discharges resembling both interictal epileptiform activity ("microdischarges") and electrographic seizures ("microseizures") but confined to cortical regions as small as 200 μm 2 . In two patients, this activity appeared to be involved in the initiation or propagation of electrographic seizures. The authors hypothesize that microdischarges and microseizures are generated by small cortical domains that form the substrate of epileptogenic cortex and play important roles in seizure initiation and propagation. KeywordsMultichannel extracellular recording; Epilepsy; Intracranial EEG; Epileptiform EEG discharges Recent findings of small (<1 mm 2 ) foci of high frequency oscillations in both human epilepsy (Bragin et al., 1999 and animal models of epilepsy (Bragin et al., 2000(Bragin et al., ,2003(Bragin et al., , 2005 suggest that seizures may be initiated in regions comparable in size with basic cortical functional units. It is not known whether epileptiform activity under 40 Hz (i.e., in the frequency range of standard clinical EEG) exhibits similar focality. Although intracranial EEG (iEEG) recordings in patients with intractable epilepsy (Engel et al., 1990;Tonini et al., 2004) afford higher spatial resolution than scalp EEG (Pacia and Ebersole, 1997;Tao et al., 2005), the electrodes used, typically 3 to 5 mm in diameter, effectively sum the electrical potentials generated in large regions of underlying cortex and so cannot register spatial signal patterns at a submillimeter scale. High resolution (∼100 μm) recordings spanning cortical layers have been obtained in epilepsy patients using linear array multielectrodes (Ulbert et al., 2004a, Copyright © 2008 (Schroeder and Seto, 1995) or even microcolumns (Lakatos et al., 2007) but only from one site at a time. High spatiotemporal resolution data from epilepsy patients have also been obtained using bundles of flexible microwires incorporated in a clinical depth electrode with a 1.5-mm tip-to-tip span (Bragin et al., 1999(Bragin et al., ,2003Worrell et al., 2008), but recording sites are not precisely constrained and spatial resolution is limited. We report results from a twodimensional, 96-microelectrode array (MEA) in epileptic patients to record neuroelectric signals at high spatial resolution. Our findings demonstrate epileptic abnormalities at a submillimeter scale, including highly focal ictal-appearing events, and provide new insights into the nature of electrophysiological disturbance...

ICE can provide high-fidelity intracranial EEG in an intensive care unit setting, can detect ictal discharges not readily apparent on scalp EEG, and can identify early changes in brain activity caused by secondary neurological complications. We predict that ICE will facilitate the development of EEG-based alarm systems and lead to prevention of secondary neuronal injury.

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Survival in the majority of high grade astrocytoma (HGA) patients is very poor, with only a rare population of long-term survivors. A better understanding of the biological factors associated with long-term survival in HGA would aid development of more effective therapy and survival prediction. Factors associated with long-term survival have not been extensively studied using unbiased genome-wide expression analyses. In the present study, gene expression microarray profiles of HGA from long-term survivors were interrogated for discovery of survival-associated biological factors. Ontology analyses revealed that increased expression of immune function-related genes was the predominant biological factor that positively correlated with longer survival. A notable T-cell signature was present within this prognostic immune gene-set. Using immune cell-specific gene classifiers, both T-cell and myeloid linage-associated genes were shown to be enriched in HGA from long versus short-term survivors. Association of immune function and cell-specific genes with survival was confirmed independently in a larger publicly available glioblastoma gene expression microarray dataset. Histology was used to validate the results of microarray analyses in a larger cohort of long-term survivors of HGA. Multivariate analyses demonstrated that increased immune cell infiltration was a significant independent variable contributing to longer survival, as was Karnofsky/Lansky performance score. These data provide evidence of a prognostic anti-tumor adaptive immune response and rationale for future development of immunotherapy in HGA.