Glioblastomas are lethal cancers defined by angiogenesis and pseudopalisading necrosis. Here, we demonstrate that these histological features are associated with distinct transcriptional programs, with vascular regions showing a proneural profile and hypoxic regions a mesenchymal pattern. As these regions harbor glioma stem cells (GSCs), we investigated the epigenetic regulation of these two niches. Proneural, perivascular GSCs activated EZH2, whereas mesenchymal GSCs in hypoxic regions expressed BMI1 protein, which promoted cellular survival under stress, due to downregulation of the E3 ligase, RNF144A. Using both genetic and pharmacologic inhibition, we found that proneural GSCs are preferentially sensitive to EZH2 disruption, whereas mesenchymal GSCs are preferentially sensitive to BMI1 inhibition. Given that glioblastomas contain both proneural and mesenchymal GSCs, combined EZH2 and BMI1 targeting proved more effective than either agent alone both in culture and in vivo, suggesting that strategies that simultaneously target multiple epigenetic regulators within glioblastomas may be necessary to overcome resistance to therapies caused by intratumoral heterogeneity.

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Osteoporosis, or bone loss, is a progressive, systemic skeletal disease that affects millions of people worldwide. Osteoporosis is generally age related, and it is underdiagnosed because it remains asymptomatic for several years until the development of fractures that confine daily life activities, particularly in elderly people. Most patients with osteoporotic fractures become bedridden and are in a life-threatening state. The consequences of fracture can be devastating, leading to substantial morbidity and mortality of the patients. The normal physiologic process of bone remodeling involves a balance between bone resorption and bone formation during early adulthood. In osteoporosis, this process becomes imbalanced, resulting in gradual losses of bone mass and density due to enhanced bone resorption and/or inadequate bone formation. Several growth factors underlying age-related osteoporosis and their signaling pathways have been identified, such as osteoprotegerin (OPG)/receptor activator of nuclear factor B (RANK)/RANK ligand (RANKL), bone morphogenetic protein (BMP), wingless-type MMTV integration site family (Wnt) proteins and signaling through parathyroid hormone receptors. In addition, the pathogenesis of osteoporosis has been connected to genetics. The current treatment of osteoporosis predominantly consists of antiresorptive and anabolic agents; however, the serious adverse effects of using these drugs are of concern. Cell-based replacement therapy via the use of mesenchymal stem cells (MSCs) may become one of the strategies for osteoporosis treatment in the future.

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Glioblastoma (GBM) is an aggressive malignant brain tumor that still lacks effective therapy. Glioblastoma stem cells (GBM-SCs) were identified to contribute to aggressive phenotypes and poor clinical outcomes for GBM. Netrin-1, an axon guidance molecule, has been found in several tumors in adults. However, the role of Netrin-1 in GBM-SCs remains largely unknown. In this study, CD133-positive U251 GBM cells were used as a putative GBM-SC population to identify the functions of Netrin-1. Using lentiviral transduction, Netrin-1 miR RNAi vectors were transduced into CD133-positive U251 cells. We demonstrated that cell proliferation and survival were decreased following targeted deletion of Netrin-1. Cell invasion was dramatically diminished in Netrin-1 knockdown GBM-SCs. Moreover, Netrin-1 knockdown GBM-SCs exhibited less proangiogenic activity. In conclusion, Netrin-1 may represent a therapeutic target in glioblastoma.

Mesenchymal stem cells (MSCs) are a type of adult stem cell that contains multi-differentiation and proliferative properties and that shows high treatment implications for many clinical problems. The outcome of stem cell transplantation is still limited due to many factors, especially their survival and their interaction with the microenvironment after transplantation. Molecular imaging is a challenging technique that has been used to overcome this limitation and is based on the concept of labeling cells with tractable, visible, and non-toxic materials to track the cells after transplantation. In this study, magnetic polymeric nanoparticles (MPNPs) were used to directly label Wharton's jelly-derived MSCs (WJ-MSCs). After labeling, the growth rate and the viability of the MSCs as well as the time of exposure were determined. The 3D images of WJ-MSCs labeled with MPNPs for 24 h were created using confocal microscopy. The results showed that, after incubation with fluorescent MPNPs for over 8 h, the growth rate and cell viability of the WJ-MSCs was similar to those of the control. Three-dimensional imaging revealed that the fluorescent MPNPs could infiltrate into the cells and spread into the cytoplasm, which suggests that the synthesized fluorescent MPNPs could possibly label MSCs for cell tracking study and be further developed for in vivo applications.

NEURO-ONCOLOGY • NOVEMBER 2017 blood and ECF samples (using intracerebral microdialysis) were collected and letrozole was quantitated employing an HPLC method. Marked gender-dependent difference in letrozole PK were observed with both plasma and brain ECF levels being markedly higher in female rats relative to those in male rats. For instance, the steady state peak plasma and ECF letrozole levels in female rats were 4.8 µg/ml and 2.3 µg/ml, respectively. For male rats, the corresponding values were 1.0 and 0.5 µg/ml. Likewise, the steady state plasma and brain ECF area under the curve (AUC) values were 4-5 fold higher in female rats. The steady state terminal half-life (t 1/2) in female rats was markedly higher (36 ± 2 h), relative to that in male rats (13 ± 3 h). A preliminary assessment of the letrozole levels in C6 tumors excised 25 days post implantation indicated that the steady state tumor levels were in the range of 4-10 µg/g of tumor tissue. These results are facilitating dose optimization for further pre-clinical pharmacology and toxicology assessments. In addition, PK-modeling based projections will aid initial dose determination in future clinical studies.

INTRODUCTION:Pre-clinical interventions to the CNS require direct cranial administration of drugs for relevant therapeutic concentrations since the efficacy of systemic administration is hindered by the blood-brain barrier (BBB). We used MR-guided Focused Ultrasound (MRgFUS) to deliver primary-patient derived mesenchymal stem cells (hMSCs) for the first time, with sub-millimeter precision, in preselected areas. This method is a revolutionary way to deliver cellular therapy to delicate or inoperable regions obviating the need for invasive surgical intervention. METHOD: MRgFUS mediates BBB opening when low intensity FUS is applied to brain vasculature containing circulating microbubbles. This causes high intensity oscillation leading to a pore formation in BBB. hMSCs were injected intracardially in mice as a proof-of-principal delivery system. Under guidance of MRI, 0.4-1MPa in situpressures at 1 MHz, 1ms bursts and 1Hz pulse repetition frequency for 120 seconds were administered on the left hemisphere. Each animal's contralateral brain served as its own control RESULTS: We demonstrate that MRgFUS augments permeability of BBB. Each animal (n=3) received 3 cavitation parameters ranging from .4-1MPa in situ pressures at time points 2, 6 and 24hrs. Immunohistochemistry identified hMSC localization on sonicated points. Further analysis showed blood cell extravasation and capillary damage due to higher pressures and increased shear force from microbubble stream. The consequence is a cavitation pore larger than intended, necessitating further optimization. There were no observed behavioral complications after sonication and no hMSCs localization in non-pulsed regions demonstrating precise localization and no off-target delivery. CONCLUSION: The global hurdle of systemic therapy due to the BBB makes access of cellular therapy to the brain parenchyma, nearly impossible. This study investigates for the first time the utility of FUS to non-destructively permeabilize the BBB by creating a transient pore big enough for hMSC access.