Steven N. Kalkanis

The induction of autophagy by γ-radiation contributes to the radioresistance of glioma stem cells

Malignant gliomas are characterized by a short median survival which is largely impacted by the resistance of these tumors tochemo‐ and radiotherapy. Recent studies suggest that a small subpopulation of cancer stem cells, which are highly resistant to γ‐radiation, has the capacity to repopulate the tumors and contribute to their malignant progression. γ‐radiation activates the process of autophagy and inhibition of this process increases the radiosensitivity of glioma cells; however, the role of autophagy in the resistance of glioma stem cells (GSCs) to radiation has not been yet reported. In this study we examined the induction of autophagy by γ‐radiation in CD133+ GSCs. Irradiation of CD133+ cells induced autophagy within 24–48 hr and slightly decreased the viability of the cells. γ‐radiation induced a larger degree of autophagy in the CD133+ cells as compared with CD133− cells and the CD133+ cells expressed higher levels of the autophagy‐related proteins LC3, ATG5 and ATG12. The autophagy inhibitor bafilomycin A1 and silencing of ATG5 and beclin1 sensitized the CD133+ cells to γ‐radiation and significantly decreased the viability of the irradiated cells and their ability to form neurospheres. Collectively, these results indicate that the induction of autophagy contributes to the radioresistance of these cells and autophagy inhibitors may be employed to increase the sensitivity of CD133+ GSCs to γ‐radiation.

MICROVASCULAR DECOMPRESSION SURGERY IN THE UNITED STATES, 1996 TO 2000: MORTALITY RATES, MORBIDITY RATES, AND THE EFFECTS OF HOSPITAL AND SURGEON VOLUMES

OBJECTIVEMicrovascular decompression (MVD) is associated with low mortality and morbidity rates at specialized centers, but many MVD procedures are performed outside such centers. We studied short-term end points after MVD in a national hospital discharge database sample. METHODSA retrospective cohort study was performed by using the Nationwide Inpatient Sample, 1996 to 2000. RESULTSThe sample included 1326 MVD procedures for treatment of trigeminal neuralgia, 237 for treatment of hemifacial spasm, and 27 for treatment of glossopharyngeal neuralgia, performed at 305 hospitals by 277 identified surgeons. The mortality rate was 0.3%, and the rate of discharge other than to home was 3.8%. Neurological complications were coded in 1.7% of cases, hematomas in 0.5%, and facial palsies in 0.6%, with 0.4% of patients requiring ventriculostomies and 0.7% postoperative ventilation. Trigeminal nerve section was also coded for 3.4% of patients with trigeminal neuralgia, more commonly among older patients (P = 0.08), among female patients (P = 0.03), and at teaching hospitals (P = 0.02). The median annual caseloads were 5 cases per hospital (range, 1–195 cases) and 3 cases per surgeon (range, 1–107 cases). With adjustment for age, sex, race, primary insurance, diagnosis (trigeminal neuralgia versus hemifacial spasm versus glossopharyngeal neuralgia), geographic region, admission type and source, and medical comorbidities, outcomes at discharge were superior at higher-volume hospitals (P = 0.006) and with higher-volume surgeons (P = 0.02). Complications were less frequent after surgery performed at high-volume hospitals (P = 0.04) or by high-volume surgeons (P = 0.01). The rate of discharge other than to home was 5.1% for the lowest-volume-quartile hospitals, compared with 1.6% for the highest-volume-quartile hospitals. Volume and mortality rate were not significantly related, but three of the four deaths in the series followed procedures performed by surgeons who had performed only one MVD procedure that year. Length of stay (median, 3 d) and hospital volume were not significantly related. Hospital charges were slightly higher at higher-volume hospitals (P = 0.007). CONCLUSIONAlthough most MVD procedures in the United States are performed at low-volume centers, mortality rates remain low. Morbidity rates are significantly lower at high-volume hospitals and with high-volume surgeons.

Multimodal Actions of Neural Stem Cells in a Mouse Model of ALS: A Meta-Analysis

A meta-analysis reports the beneficial effects of transplanting mouse or human neural stem cells into the spinal cord of the SOD1G93A mouse, a model of ALS. Stem Cells to the Rescue Amyotrophic lateral sclerosis (ALS) or Lou Gehrig’s disease is an untreatable fatal disorder characterized by rapid and unremitting degeneration of nerve cells in the spinal cord that enable movement and respiration. Multiple processes involving these neurons and other cell types have been implicated as the cause of this disease. Neural stem cells (NSCs) normally function in the nervous system to create structures during development and to restore function to damaged systems throughout life. When these cells are isolated from the nervous system, grown and expanded in a dish, and then transplanted back into a diseased or injured part of the nervous system, they are thought to be able to perform at least some of these same tasks by producing therapeutic factors, improving the milieu, rescuing dying neurons, protecting neural connections, and reducing inflammation. Transplanted NSCs might be able to ameliorate some of the pathological processes that occur in ALS. Teng et al. now test this hypothesis by performing a meta-analysis of 11 studies that have transplanted mouse or human NSCs into the spinal cord of the transgenic mutant SOD1 ALS mouse. The authors found that disease onset and progression were slowed, such that extensive, often motor symptom-reduced, survival was predictably achievable in a subset of animals. This was particularly noticeable in those mice where transplanted NSCs covered a large part of the spinal cord including regions mediating vital functions such as respiration. The benefits of transplanted NSCs seem to be derived from a number of different actions including production of trophic factors, preservation of neuromuscular function, and a reduction in astrogliosis and inflammation. Through multiple modulatory mechanisms, NSCs may have potential for treating ALS and other untreatable degenerative diseases. Amyotrophic lateral sclerosis (ALS) is a lethal disease characterized by the unremitting degeneration of motor neurons. Multiple processes involving motor neurons and other cell types have been implicated in its pathogenesis. Neural stem cells (NSCs) perform multiple actions within the nervous system to fulfill their functions of organogenesis and homeostasis. We test the hypothesis that transplanted, undifferentiated multipotent migratory NSCs may help to ameliorate an array of pathological mechanisms in the SOD1G93A transgenic mouse model of ALS. On the basis of a meta-analysis of 11 independent studies performed by a consortium of ALS investigators, we propose that transplanted NSCs (both mouse and human) can slow both the onset and the progression of clinical signs and prolong survival in ALS mice, particularly if regions sustaining vital functions such as respiration are rendered chimeric. The beneficial effects of transplanted NSCs seem to be mediated by a number of actions including their ability to produce trophic factors, preserve neuromuscular function, and reduce astrogliosis and inflammation. We conclude that the widespread, pleiotropic, modulatory actions exerted by transplanted NSCs may represent an accessible therapeutic application of stem cells for treating ALS and other untreatable degenerative diseases.

Gliosarcoma stem cells undergo glial and mesenchymal differentiation in vivo

Cancer stem cells (CSCs) are characterized by their self‐renewing potential and by their ability to differentiate and phenocopy the original tumor in orthotopic xenografts. Long‐term propagation of glioblastoma (GBM) cells in serum‐containing medium results in loss of the CSCs and outgrowth of cells genetically and biologically divergent from the parental tumors. In contrast, the use of a neurosphere assay, a serum‐free culture for selection, and propagation of central nervous system‐derived stem cells allows the selection of a subpopulation containing CSCs. Gliosarcoma (GS), a morphological variant comprising approximately 2% of GBMs, present a biphasic growth pattern, composed of glial and metaplastic mesenchymal components. To assess whether the neurosphere assay would allow the amplification of a subpopulation of cells with “gliosarcoma stem cell” properties, capable of propagating both components of this malignancy, we have generated neurospheres and serum cultures from primary GS and GBM surgical specimens. Neurosphere cultures from GBM and GS samples expressed neural stem cell markers Sox2, Musashi1, and Nestin. In contrast to the GBM neurosphere lines, the GS neurospheres were negative for the stem cell marker CD133. All neurosphere lines generated high‐grade invasive orthotopic tumor xenografts, with histological features strikingly similar to the parental tumors, demonstrating that these cultures indeed are enriched in CSCs. Remarkably, low‐passage GS serum cultures retained the expression of stem cell markers, the ability to form neurospheres, and tumorigenicity. The GS experimental tumors phenocopied the parental tumor, exhibiting biphasic glial and mesenchymal components, constituting a clinically relevant model to investigate mesenchymal differentiation in GBMs. STEM CELLS 2010;28:181–190

Combination Therapy with Antiangiogenic Treatment and Photodynamic Therapy for the Nude Mouse Bearing U87 Glioblastoma

The objective of this study was to evaluate the effects of combination therapy with photodynamic therapy (PDT) and a novel antiangiogenic regimen using monoclonal antibodies against both vascular endothelial growth factor receptors (VEGFR)‐1 (MF1) and VEGFR‐2 (DC101) on intracranial glioblastoma xenografts in nude mice. Nude mice bearing intracerebral U87 glioblastoma were treated with PDT and the antiangiogenic regimen (MF1 and DC101) either alone or in combination, while those left untreated served as tumor controls. Tumor volume and animal survival time were analyzed to evaluate the outcome of different treatment modalities. In addition, the immunohistochemical expression of VEGF in the brain adjacent to the tumor, von Willebrand factor (vWF), apoptotic, and proliferative markers in the tumor area were examined. PDT or MF1u2003+u2003DC101 alone significantly reduced the tumor volume and prolonged the survival time of glioma‐implanted animals. Combined therapy markedly reduced tumor volume and increased survival time with significantly better outcomes than both monotherapies. Both vWF and VEGF levels significantly increased after PDT while they both significantly decreased after antiangiogenic treatment, compared with no treatment. PDT plus antiangiogenic treatment led to significant decreases in both vWF and VEGF expression, compared with PDT alone. Either PDT or antiangiogenic treatment alone significantly increased tumor cell apoptosis compared with no treatment, while combination therapy resulted in further augmentation of apoptosis. Antiangiogenic treatment with or without PDT significantly decreased tumor cell proliferation, compared with either no treatment or PDT alone. In summary, we demonstrate both significant inhibition of tumor growth and extended survival of mice treated by the combination therapy with PDT and antiangiogenic agents, compared with each single treatment, suggesting that the combination therapy may be a promising strategy to improve clinical outcomes in glioblastoma.

Odyssey of hope: a physician’s guide to communicating with brain tumor patients across the continuum of care

The optimal treatment of a patient with a malignant brain tumor requires attention to the physical and emotional well-being of the affected individual and the family. We review the concept of hope as a critical support modality throughout the continuum of care for brain tumor patients and families. We offer suggestions based on our own observations over 17xa0years as well as the lessons taught to us by our patients and their families over that time and through a structured interview process.

Low-dose photodynamic therapy increases endothelial cell proliferation and VEGF expression in nude mice brain

We tested whether low-dose photodynamic therapy (PDT) induces an angiogenic response in the normal brain of nude mice (n=20). Normal brains of nude mice were subjected to PDT at low doses (Photofrin: 2xa0mg/kg; optical: 2xa0J/cm2 and 4xa0J/cm2). BrdU (50xa0mg/kg) was injected (intraperitoneally, i.p.) daily from PDT treatment to sacrifice (1 and 2xa0weeks after PDT). Laser scanning confocal microscopy, immunohistochemistry, and immunofluorescence staining were performed to assay angiogenic response. Morphological results show no significant tissue damage induced by PDT and two- and three-dimensional image analyses revealed no significant difference in vascular structure between the areas of exposure to PDT and contralateral areas in all mice. However, the number of BrdU immunoreactive cells were significantly increased in the areas of PDT treatment compared with contralateral hemisphere in both groups, and the number of BrdU-positive cells increased in a PDT-dose-dependent manner. Furthermore, immunohistochemical data indicate that PDT at these low doses significantly induces the expression of the vascular endothelial growth factor (VEGF) in PDT-treated regions in the 1-week group, but not in the 2-week group. These data indicate that low-dose PDT results in increased VEGF expression and endothelial cell proliferation in normal brains.

Vision 20/20: The role of Raman spectroscopy in early stage cancer detection and feasibility for application in radiation therapy response assessment

Raman spectroscopy is an optical technique capable of identifying chemical constituents of a sample by their unique set of molecular vibrations. Research on the applicability of Raman spectroscopy in the differentiation of cancerous versus normal tissues has been ongoing for many years, and has yielded successful results in the context of prostate, breast, brain, skin, and head and neck cancers as well as pediatric tumors. Recently, much effort has been invested on developing noninvasive Raman probes to provide real-time diagnosis of potentially cancerous tumors. In this regard, it is feasible that the Raman technique might one day be used to provide rapid, minimally invasive real-time diagnosis of tumors in patients. Raman spectroscopy is relatively new to the field of radiation therapy. Recent work involving cell lines has shown that the Raman technique is able to identify proteins and other markers affected by radiation therapy. Although this work is preliminary, one could ask whether or not the Raman technique might be used to identify molecular markers that predict radiation response. This paper provides a brief review of Raman spectroscopic investigations in cancer detection, benefits and limitations of this method, advances in instrument development, and also preliminary studies related to the application of this technology in radiation therapy response assessment.

Intracellular free calcium mediates glioma cell detachment and cytotoxicity after photodynamic therapy

Photofrin photodynamic therapy (PDT) caused a dose-dependent decrease of enzymatic cell detachment by trypsin/ethylenediamine tetra-acetic acid (EDTA) in human glioma U251n and U87 cells. This happened coincidently with the increase of intracellular free calcium ([Ca2+]i). Thapsigargin, which increased [Ca2+]i, induced further decrease in enzymatic cell detachment and increased cytotoxicity. Opposite effects were observed when 1,2-bis(2-aminophenoxy) ethane-N,N,N′,N′-tetra-acetic acid tetrakis, an intracellular Ca2+ chelator, was used. PDT-induced changes in [Ca2+]i and cell detachment were not blocked by calcium channel antagonists nickel (Ni2+) or nimodipine, nor were they altered when cells were irradiated in a buffer free from Ca2+ and magnesium (Mg2+), suggesting that [Ca2+]i is derived from the internal calcium stores. Decreased cell migration was observed after PDT, as assessed by chemotactic and wound-healing assays. Our findings indicated that internal calcium store-derived [Ca2+]i plays an important role in PDT-induced enzymatic cell detachment decrease and cytotoxicity. Cell migration may be affected by these changes.

Prophylactic antiepileptic drug administration following brain tumor resection: results of a recent AANS/CNS Section on Tumors survey

OBJECTIVE Antiepileptic drugs (AEDs) are often administered prophylactically following brain tumor resection. With conflicting evidence and unestablished guidelines, however, the nature of this practice among tumor surgeons is unknown. METHODS On November 24, 2015, a REDCap (Research Electronic Database Capture) survey was sent to members of the AANS/CNS Section on Tumors to query practice patterns. RESULTS Responses were received from 144 individuals, including 18.8% of board-certified neurosurgeons surveyed (across 86 institutions, 16 countries, and 5 continents). The majority reported practicing in an academic setting (85%) as a tumor specialist (71%). Sixty-three percent reported always or almost always prescribing AED prophylaxis postoperatively in patients with a supratentorial brain tumor without a prior seizure history. Meanwhile, 9% prescribed occasionally and 28% rarely prescribed AED prophylaxis. The most common agent was levetiracetam (85%). The duration of seizure prophylaxis varied widely: 25% of surgeons administered prophylaxis for 7 days, 16% for 2 weeks, 21% for 2 to 6 weeks, and 13% for longer than 6 weeks. Most surgeons (61%) believed that tumor pathology influences epileptogenicity, with high-grade glioma (39%), low-grade glioma (31%), and metastases (24%) carrying the greatest seizure risk. While the majority used prophylaxis, 62% did not believe or were unsure if prophylactic AEDs reduced seizures postoperatively. The vast majority (82%) stated that a well-designed randomized trial would help guide their future clinical decision making. CONCLUSIONS Wide knowledge and practice gaps exist regarding the frequency, duration, and setting of AED prophylaxis for seizure-naive patients undergoing brain tumor resection. Acceptance of universal practice guidelines on this topic is unlikely until higher-level evidence supporting or refuting the value of modern seizure prophylaxis is demonstrated.