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Lentiviral-mediated integration of a CFTR transgene cassette into airway basal cells is a strategy being considered for cystic fibrosis (CF) cell-based therapies. However,CFTR expression is highly regulated in differentiated airway cell types and a subset of intermediate basal cells destined to differentiate. Since basal stem cells typically do not express CFTR,suppressing the CFTR expression from the lentiviral vector in airway basal cells may be beneficial for maintaining their proliferative capacity and multipotency. We identified miR-106b as highly expressed in proliferating airway basal cells and extinguished in differentiated columnar cells. Herein,we developed lentiviral vectors with the miR-106b-target sequence (miRT) to both study miR-106b regulation during basal cell differentiation and detarget CFTR expression in basal cells. Given that miR-106b is expressed in the 293T cells used for viral production,obstacles of viral genome integrity and titers were overcome by creating a 293T-B2 cell line that inducibly expresses the RNAi suppressor B2 protein from flock house virus. While miR-106b vectors effectively detargeted reporter gene expression in proliferating basal cells and following differentiation in the air-liquid interface and organoid cultures,the CFTR-miRT vector produced significantly less CFTR-mediated current than the non-miR-targeted CFTR vector following transduction and differentiation of CF basal cells. These findings suggest that miR-106b is expressed in certain airway cell types that contribute to the majority of CFTR anion transport in airway epithelium. View Publication

Brain tumors can arise following deregulation of signaling pathways normally activated during brain development and may derive from neural stem cells. Given the requirement for Hedgehog in non-neoplastic stem cells,we investigated whether Hedgehog blockade could target the stem-like population in glioblastoma multiforme (GBM). We found that Gli1,a key Hedgehog pathway target,was highly expressed in 5 of 19 primary GBM and in 4 of 7 GBM cell lines. Shh ligand was expressed in some primary tumors,and in GBM-derived neurospheres,suggesting a potential mechanism for pathway activation. Hedgehog pathway blockade by cyclopamine caused a 40%-60% reduction in growth of adherent glioma lines highly expressing Gli1 but not in those lacking evidence of pathway activity. When GBM-derived neurospheres were treated with cyclopamine and then dissociated and seeded in media lacking the inhibitor,no new neurospheres formed,suggesting that the clonogenic cancer stem cells had been depleted. Consistent with this hypothesis,the stem-like fraction in gliomas marked by both aldehyde dehydrogenase activity and Hoechst dye excretion (side population) was significantly reduced or eliminated by cyclopamine. In contrast,we found that radiation treatment of our GBM neurospheres increased the percentage of these stem-like cells,suggesting that this standard therapy preferentially targets better-differentiated neoplastic cells. Most importantly,viable GBM cells injected intracranially following Hedgehog blockade were no longer able to form tumors in athymic mice,indicating that a cancer stem cell population critical for ongoing growth had been removed. Disclosure of potential conflicts of interest is found at the end of this article. View Publication

Genetic reprogramming of somatic cells to a pluripotent state (induced pluripotent stem cells or iPSCs) by over-expression of specific genes has been accomplished using mouse and human cells. However,it is still unclear how similar human iPSCs are to human Embryonic Stem Cells (hESCs). Here,we describe the transcriptional profile of human iPSCs generated without viral vectors or genomic insertions,revealing that these cells are in general similar to hESCs but with significant differences. For the generation of human iPSCs without viral vectors or genomic insertions,pluripotent factors Oct4 and Nanog were cloned in episomal vectors and transfected into human fetal neural progenitor cells. The transient expression of these two factors,or from Oct4 alone,resulted in efficient generation of human iPSCs. The reprogramming strategy described here revealed a potential transcriptional signature for human iPSCs yet retaining the gene expression of donor cells in human reprogrammed cells free of viral and transgene interference. Moreover,the episomal reprogramming strategy represents a safe way to generate human iPSCs for clinical purposes and basic research. View Publication

OBJECTIVE: To test the graft-promoting effects of mesenchymal stem cells (MSCs) in a cynomolgus monkey model of islet/bone marrow transplantation. RESEARCH DESIGN AND METHODS: Cynomolgus MSCs were obtained from iliac crest aspirate and characterized through passage 11 for phenotype,gene expression,differentiation potential,and karyotype. Allogeneic donor MSCs were cotransplanted intraportally with islets on postoperative day (POD) 0 and intravenously with donor marrow on PODs 5 and 11. Recipients were followed for stabilization of blood glucose levels,reduction of exogenous insulin requirement (EIR),C-peptide levels,changes in peripheral blood T regulatory cells,and chimerism. Destabilization of glycemia and increases in EIR were used as signs of rejection; additional intravenous MSCs were administered to test the effect on reversal of rejection. RESULTS: MSC phenotype and a normal karyotype were observed through passage 11. IL-6,IL-10,vascular endothelial growth factor,TGF-β,hepatocyte growth factor,and galectin-1 gene expression levels varied among donors. MSC treatment significantly enhanced islet engraftment and function at 1 month posttransplant (n = 8),as compared with animals that received islets without MSCs (n = 3). Additional infusions of donor or third-party MSCs resulted in reversal of rejection episodes and prolongation of islet function in two animals. Stable islet allograft function was associated with increased numbers of regulatory T-cells in peripheral blood. CONCLUSIONS: MSCs may provide an important approach for enhancement of islet engraftment,thereby decreasing the numbers of islets needed to achieve insulin independence. Furthermore,MSCs may serve as a new,safe,and effective antirejection therapy. View Publication

Receptor activator of nuclear factor kappa-B ligand (RANKL) is a critical osteoclastogenic factor expressed in bone marrow stromal/osteoblast lineage cells. Tumor necrosis factor (TNF) related apoptosis-inducing ligand (TRAIL) levels are elevated in pathologic conditions such as multiple myeloma and inflammatory arthritis,and have been positively correlated with osteolytic markers. Osteoprotegerin (OPG) which inhibits osteoclastogenesis is a decoy receptor for RANKL and also known to interact with TRAIL. Herein,we show that TRAIL increases DR5 and DcR1 receptors but no change in the levels of DR4 and DcR2 expression in human bone marrow derived stromal/preosteoblast (SAKA-T) cell line. We further demonstrated that TRAIL treatment significantly decreased OPG mRNA expression. Interestingly,TRAIL treatment induced RANKL mRNA expression in these cells. In addition,TRAIL significantly increased NF-kB and c-Jun N-terminal kinase (JNK) activity. Human transcription factor array screening by real-time RT-PCR identified TRAIL up-regulation of the signal transducers and activators of the transcription (STAT)-6 expression in SAKA-T cells. TRAIL stimulation induced p-STAT-6 expression in human bone marrow derived primary stromal/preosteoblast cells. Confocal microscopy analysis further revealed p-STAT-6 nuclear localization in SAKA-T cells. Chromatin immunoprecipitation (ChIP) assay confirmed p-STAT-6 binding to the hRANKL gene distal promoter region. In addition,siRNA suppression of STAT-6 expression inhibits TRAIL increased hRANKL gene promoter activity. Thus,our results suggest that TRAIL induces RANKL expression through a STAT-6 dependent transcriptional regulatory mechanism in bone marrow stromal/preosteoblast cells. View Publication

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Histoplasma capsulatum (Hc) is a facultative intracellular fungus that modulates the intraphagosomal environment to survive within macrophages (Mphi). In the present study,we sought to quantify the intraphagosomal pH under conditions in which Hc yeasts replicated or were killed. Human Mphi that had ingested both viable and heat-killed or fixed yeasts maintained an intraphagosomal pH of approximately 6.4-6.5 over a period of several hours. These results were obtained using a fluorescent ratio technique and by electron microscopy using the 3-(2,4-dinitroanilo)-3'-amino-N-methyldipropylamine reagent. Mphi that had ingested Saccharomyces cerevisae,a nonpathogenic yeast that is rapidly killed and degraded by Mphi,also maintained an intraphagosomal pH of approximately 6.5 over a period of several hours. Stimulation of human Mphi fungicidal activity by coculture with chloroquine or by adherence to type 1 collagen matrices was not reversed by bafilomycin,an inhibitor of the vacuolar ATPase. Human Mphi cultured in the presence of bafilomycin also completely degraded heat-killed Hc yeasts,whereas mouse peritoneal Mphi digestion of yeasts was completely reversed in the presence of bafilomycin. However,bafilomycin did not inhibit mouse Mphi fungistatic activity induced by IFN-gamma. Thus,human Mphi do not require phagosomal acidification to kill and degrade Hc yeasts,whereas mouse Mphi do require acidification for fungicidal but not fungistatic activity. View Publication

BackgroundX-chromosome inactivation silences one X chromosome in females to achieve dosage compensation with the single X chromosome in males. While most genes are silenced on the inactive X chromosome,the gene for the long non-coding RNA XIST is silenced on the active X chromosome and expressed from the inactive X chromosome with which the XIST RNA associates,triggering silencing of the chromosome. In mouse,an alternative Xist promoter,P2 is also the site of YY1 binding,which has been shown to serve as a tether between the Xist RNA and the DNA of the chromosome. In humans there are many differences from the initial events of mouse Xist activation,including absence of a functional antisense regulator Tsix,and absence of strictly paternal inactivation in extraembryonic tissues,prompting us to examine regulatory regions for the human XIST gene.ResultsWe demonstrate that the female-specific DNase hypersensitivity site within XIST is specific to the inactive X chromosome and correlates with transcription from an internal P2 promoter. P2 is located within a CpG island that is differentially methylated between males and females and overlaps conserved YY1 binding sites that are only bound on the inactive X chromosome where the sites are unmethylated. However,YY1 binding is insufficient to drive P2 expression or establish the DHS,which may require a development-specific factor. Furthermore,reduction of YY1 reduces XIST transcription in addition to causing delocalization of XIST.ConclusionsThe differentially methylated DNase hypersensitive site within XIST marks the location of an alternative promoter,P2,that generates a transcript of unknown function as it lacks the A repeats that are critical for silencing. In addition,this region binds YY1 on the unmethylated inactive X chromosome,and depletion of YY1 untethers the XIST RNA as well as decreasing transcription of XIST. View Publication

Frontotemporal dementia (FTD) and other tauopathies characterized by focal brain neurodegeneration and pathological accumulation of proteins are commonly associated with tau mutations. However,the mechanism of neuronal loss is not fully understood. To identify molecular events associated with tauopathy,we studied induced pluripotent stem cell (iPSC)-derived neurons from individuals carrying the tau-A152T variant. We highlight the potential of in-depth phenotyping of human neuronal cell models for pre-clinical studies and identification of modulators of endogenous tau toxicity. Through a panel of biochemical and cellular assays,A152T neurons showed accumulation,redistribution,and decreased solubility of tau. Upregulation of tau was coupled to enhanced stress-inducible markers and cell vulnerability to proteotoxic,excitotoxic,and mitochondrial stressors,which was rescued upon CRISPR/Cas9-mediated targeting of tau or by pharmacological activation of autophagy. Our findings unmask tau-mediated perturbations of specific pathways associated with neuronal vulnerability,revealing potential early disease biomarkers and therapeutic targets for FTD and other tauopathies. View Publication

BACKGROUND: Virus-specific T-cells (VSTs) proliferate exponentially after adoptive transfer into hematopoietic stem cell transplant (HSCT) recipients,eliminate virus infections,then persist and provide long-term protection from viral disease. If VSTs behaved similarly when modified with tumor-specific chimeric antigen receptors (CARs),they should have potent anti-tumor activity. This theory was evaluated by Cruz et al. in a previous clinical trial with CD19.CAR-modified VSTs,but there was little apparent expansion of these cells in patients. In that study,VSTs were gene-modified on day 19 of culture and we hypothesized that by this time,sufficient T-cell differentiation may have occurred to limit the subsequent proliferative capacity of the transduced T-cells. To facilitate the clinical testing of this hypothesis in a project supported by the NHLBI-PACT mechanism,we developed and optimized a good manufacturing practices (GMP) compliant method for the early transduction of VSTs directed to Epstein-Barr virus (EBV),Adenovirus (AdV) and cytomegalovirus (CMV) using a CAR directed to the tumor-associated antigen disialoganglioside (GD2). RESULTS: Ad-CMVpp65-transduced EBV-LCLs effectively stimulated VSTs directed to all three viruses (triVSTs). Transduction efficiency on day three was increased in the presence of cytokines and high-speed centrifugation of retroviral supernatant onto retronectin-coated plates,so that under optimal conditions up to 88% of tetramer-positive VSTs expressed the GD2.CAR. The average transduction efficiency of early-and late transduced VSTs was 55 ± 4% and 22 ± 5% respectively,and early-transduced VSTs maintained higher frequencies of T cells with central memory or intermediate memory phenotypes. Early-transduced VSTs also had higher proliferative capacity and produced higher levels of TH1 cytokines IL-2,TNF-α,IFN-γ,MIP-1α,MIP-1β and other cytokines in vitro. CONCLUSIONS: We developed a rapid and GMP compliant method for the early transduction of multivirus-specific T-cells that allowed stable expression of high levels of a tumor directed CAR. Since a proportion of early-transduced CAR-VSTs had a central memory phenotype,they should expand and persist in vivo,simultaneously protecting against infection and targeting residual malignancy. This manufacturing strategy is currently under clinical investigation in patients receiving allogeneic HSCT for relapsed neuroblastoma and B-cell malignancies (NCT01460901 using a GD2.CAR and NCT00840853 using a CD19.CAR). View Publication

Clinical implications of induced pluripotent stem (iPS) cell technology are enormous for personalized medicine. However,extensive use of viral approach for ectopic expression of reprogramming factors is a major hurdle in realization of its true potential. Non-viral methods for making iPS cells,although plausible,are impractical because of high cost. MicroRNAs are important cellular modulators that have been shown to rival transcription factors and are important players in embryonic development. We have generated distinct microRNA-omes" signature of iPS cells that remain in a near embryonic stem (ES) cell state and distinct from differentiated cells. Recent advances in the microRNA field and experimentally validated microRNAs warrant a review in experimental protocols for microRNA expression profile." View Publication

In this report,we sought to optimize gene transfer into primitive human umbilical cord blood (UCB) cells. Initially,we found that fresh UCB isolated with the CD34brCD38 CD33 phenotype were highly enriched for hematopoietic progenitors detected in extended long-term cultures (8-week LTCs). In addition,following ex vivo gene transfer,this population possessed virtually all the 8-week LTC activity of the cultured cells. A multiparameter FACS assay was developed to efficiently screen the effects of alternative retroviral vector gene transfer procedures on the transduction efficiency and maintenance of CD34brCD38 CD33 cells. Proliferation of the CD34brCD38 CD33 cells was found to be a prerequisite for efficient transduction. However,in all conditions tested,proliferation of the CD34brCD38 CD33 cells was associated with a progressive loss of primitive cell properties including a reduction in CD34 expression,an increase in CD38/CD33 expression,and a decline in the ability to sustain 8-week LTCs. These observations indicate that it will be necessary to define conditions that more effectively support the self-renewal capacity of CD34brCD38 CD33 cells to optimize retroviral vector gene transfer in these cells. Evaluating these conditions and reagents will be facilitated by the multiparameter FACS assay described in this report. View Publication