Current Issue : April - June Volume : 2016 Issue Number : 2 Articles : 5 Articles
Background: Hematologic toxicity represents a major side effect of cytotoxic chemotherapy frequently preventing\nadequately dosed chemotherapy application and impeding therapeutic success. Transgenic (over)expression of\nchemotherapy resistance (CTX-R) genes in hematopoietic stem- and progenitor cells represents a potential strategy\nto overcome this problem. To apply this concept in the context of acute myeloid leukemia and myelodysplasia, we\nhave investigated the overexpression of the multidrug resistance 1 (MDR1) and the cytidine deaminase (CDD) gene\nconferring resistance to anthracyclines and cytarabine (Ara-C), the two most important drugs in the treatment of\nthese diseases.\nMethods: State-of-the-art, third generation, self-inactivating (SIN) lentiviral vectors were utilized to overexpress a\nhuman CDD-cDNA and a codon-optimized human MDR1-cDNA corrected for cryptic splice sites from a spleen\nfocus forming virus derived internal promoter. Studies were performed in myeloid 32D cells as well as primary\nlineage marker negative (linâË?â??) murine bone marrow cells and flow cytometric analysis of suspension cultures and\nclonogenic analysis of vector transduced cells following cytotoxic drug challenge were utilized as read outs.\nResults: Efficient chemoprotection of CDD and MDR1 transduced hematopoietic 32D as well as primary linâË?â?? cells\nwas proven in the context of Ara-C and anthracycline application. Both, CTX-R transduced 32D as well as primary\nhematopoietic cells displayed marked resistance at concentrations 5ââ?¬â??20 times the LD50 of non-transduced control\ncells. Moreover, simultaneous CDD/MDR1 gene transfer resulted in similar protection levels even when combined\nAra-C anthracycline treatment was applied. Furthermore, significant enrichment of transduced cells was observed\nupon cytotoxic drug administration.\nConclusions: Our data demonstrate efficient chemoprotection as well as enrichment of transduced cells in\nhematopoietic cell lines as well as primary murine hematopoietic progenitor cells following Ara-C and/or anthracycline\napplication, arguing for the efficacy as well as feasibility of our approach and warranting further evaluation of\nthis concept....
Non-viral gene delivery system with many advantages has a great potential for the future of\ngene therapy. One inherent obstacle of such approach is the uptake by endocytosis into\nvesicular compartments. Receptor-mediated gene delivery method holds promise to overcome\nthis obstacle. In this study, we developed a receptor-mediated gene delivery system\nbased on a combination of the Pseudomonas exotoxin A (PE), which has a receptor binding\nand membrane translocation domain, and the hyperthermophilic archaeal histone (HPhA),\nwhich has the DNA binding ability. First, we constructed and expressed the rPE-HPhA\nfusion protein. We then examined the cytotoxicity and the DNA binding ability of rPE-HPhA.\nWe further assessed the efficiency of transfection of the pEGF-C1 plasmid DNA to CHO\ncells by the rPE-HPhA system, in comparison to the cationic liposome method. The results\nshowed that the transfection efficiency of rPE-HPhA was higher than that of cationic liposomes.\nIn addition, the rPE-HPhA gene delivery system is non-specific to DNA sequence,\ntopology or targeted cell type. Thus, the rPE-HPhA system can be used for delivering genes\nof interest into mammalian cells and has great potential to be applied for gene therapy....
Radiation-gene therapy, a dual anticancer strategy of radiation therapy and gene therapy through connecting radiation-inducible\nregulatory sequence to therapeutic gene, leading to the gene being induced to express by radiation while radiotherapy is performed\nand finally resulting in a double synergistic antitumor effect of radiation and gene, has become one of hotspots in the field of cancer\ntreatment in recent years. But under routine dose of radiation, especially in the hypoxia environment of solid tumor, it is difficult\nfor this therapy to achieve desired effect because of low activity of radiation-inducible regulatory elements, low level and transient\nexpression of target gene induced by radiation, inferior target specificity and poor biosecurity, and so on. Based on the problems\nexisting in radiation-gene therapy, many efforts have been devoted to the curative effect improvement of radiation-gene therapy\nby various means to increase radiation sensitivity or enhance target gene expression and the expression�s controllability. Among\nthese synergistic techniques, gene circuit, hypoxic sensitization, and optimization of radiation-induced sequence exhibit a good\napplication potential. This review provides the main influential factors to radiation-gene therapy on cancer and the synergistic\ntechniques to improve the anticancer effect of radiation-gene therapy....
Retroviral vector gene therapy is a promising approach to treating HIV-1. However,\nintegrated vectors are mutagens with the potential to dysregulate nearby genes and cause severe\nadverse side effects. Leukemia has already been a documented severe adverse event in gene therapy\nclinical trials for the treatment of primary immunodeficiencies. These side effects will need to be\nreduced or avoided if retroviral vectors are to be used clinically for HIV-1 treatment. The addition\nof chromatin insulators to retroviral vectors is a potential strategy for reducing adverse side effects.\nInsulators have already been effectively used in retroviral vectors to reduce genotoxicity in pre-clinical\nstudies. Here, we will review how insulators function, genotoxicity in gene therapy clinical trials, the\ndesign of insulated retroviral vectors, promising results from insulated retroviral vector studies, and\nconsiderations for the development of insulated retroviral treatment vectors for HIV-1 gene therapy...
Mucopolysaccharidoses (MPSs) are a group of lysosomal\nstorage disorders (LSDs). The increasing interest in\nnewborn screening procedures for LSDs underlines the need\nfor alternative cellular and gene therapy approaches to be developed\nduring the perinatal period, supporting the treatment\nof MPS patients before the onset of clinical signs and symptoms.\nThe rationale for considering these early therapies results\nfromthe clinical experience in the treatment ofMPSs and\nother genetic disorders. The normal or gene-corrected hematopoiesis\ntransplanted in patients can produce the missing protein\nat levels sufficient to improve and/or halt the diseaserelated\nabnormalities. However, these current therapies are\nonly partially successful, probably due to the limited efficacy\nof the protein provided through the hematopoiesis. An alternative\nexplanation is that the time at which the cellular or gene\ntherapy procedures are performed could be too late to prevent\npre-existing or progressive organ damage. Considering these\naspects, in the last several years, novel cellular and gene therapy\napproaches have been tested in different animal models at\nbirth, a highly early stage, showing that precocious treatment\nis critical to prevent long-term pathological consequences.\nThis review provides insights into the state-of-art accomplishments\nmade with neonatal cellular and gene-based therapies\nand the major barriers that need to be overcome before they\ncan be implemented in the medical community....
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