Alphaviruses in Gene Therapy

Alphavirus vectors present an attractive approach for gene therapy applications due to the rapid and simple recombinant virus particle production and their broad range of mammalian host cell transduction. Mainly three types of alphavirus vectors, namely naked RNA, recombinant particles and DNA/RNA layered vectors, have been subjected to preclinical studies with the goal of achieving prophylactic or therapeutic efficacy, particularly in oncology. In this context, immunization with alphavirus vectors has provided protection against challenges with tumor cells. Moreover, alphavirus intratumoral and systemic delivery has demonstrated substantial tumor regression and significant prolonged survival rates in various animal tumor models. Recent discoveries of the strong association of RNA interference and disease have accelerated gene therapy based approaches, where alphavirus-based gene delivery can play an important role.     

Progress in Chimeric Vector and Chimeric Gene Based Cardiovascular Gene Therapy

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Harnessing the Natural Biology of Adeno-Associated Virus to Enhance the Efficacy of Cancer Gene Therapy

Adeno-associated virus (AAV) was first characterized as small “defective” contaminant particles in a simian adenovirus preparation in 1965. Since then, a recombinant platform of AAV (rAAV) has become one of the leading candidates for gene therapy applications resulting in two FDA-approved treatments for rare monogenic diseases and many more currently in various phases of the pharmaceutical development pipeline. Herein, we summarize rAAV approaches for the treatment of diverse types of cancers and highlight the natural anti-oncogenic effects of wild-type AAV (wtAAV), including interactions with the cellular host machinery, that are of relevance to enhance current treatment strategies for cancer.     

Foamy Virus Vectors for HIV Gene Therapy

Highly active antiretroviral therapy (HAART) has vastly improved outcomes for patients infected with HIV, yet it is a lifelong regimen that is expensive and has significant side effects. Retroviral gene therapy is a promising alternative treatment for HIV/AIDS; however, inefficient gene delivery to hematopoietic stem cells (HSCs) has so far limited the efficacy of this approach. Foamy virus (FV) vectors are derived from non-pathogenic viruses that are not endemic to the human population. FV vectors have been used to deliver HIV-inhibiting transgenes to human HSCs, and they have several advantages relative to other retroviral vectors. These include an attractive safety profile, broad tropism, a large transgene capacity, and the ability to persist in quiescent cells. In addition, the titers of FV vectors are not reduced by anti-HIV transgenes that affect the production of lentivirus (LV) vectors. Thus FV vectors are very promising for anti-HIV gene therapy. This review covers the advantages of FV vectors and describes their preclinical development for anti-HIV gene therapy.     

Alpharetroviral Vectors: From a Cancer-Causing Agent to a Useful Tool for Human Gene Therapy

Gene therapy using integrating retroviral vectors has proven its effectiveness in several clinical trials for the treatment of inherited diseases and cancer. However, vector-mediated adverse events related to insertional mutagenesis were also observed, emphasizing the need for safer therapeutic vectors. Paradoxically, alpharetroviruses, originally discovered as cancer-causing agents, have a more random and potentially safer integration pattern compared to gammaretro- and lentiviruses. In this review, we provide a short overview of the history of alpharetroviruses and explain how they can be converted into state-of-the-art gene delivery tools with improved safety features. We discuss development of alpharetroviral vectors in compliance with regulatory requirements for clinical translation, and provide an outlook on possible future gene therapy applications. Taken together, this review is a broad overview of alpharetroviral vectors spanning the bridge from their parental virus discovery to their potential applicability in clinical settings.     

逆转录病毒介导HSV-TK基因治疗胰腺癌——实验研究

目的:探讨应用逆转录病毒载体介导HSV-TK基因治疗实验性人胰腺癌细胞系8988的价值。方法:HSV-TK被定向克隆入逆转录病毒载体pMNSM的SV_(40) 下游。重组逆转录病毒载体pMNS-TK-M转染至逆转录病毒包装细胞PA317细胞,产生的重组病毒将HSV-TK转入人胰腺癌细胞系8988细胞内。结果:Southern-blot试验及药敏试验均证实HSV-TK基因已整合至细胞DNA中并完全表达。体外试验证实,HSV-TK阳性8988细胞对ACV的敏感性较母细胞明显为高;裸鼠移植瘤试验证实,腹腔注射ACV有明显阻止移植瘤的形成以及对移植瘤的治疗作用。结论:HSV-TK/ACV有体内治疗胰腺癌的作用,可作为胰腺癌基因治疗的潜在方法之一。     

Integration Site and Clonal Expansion in Human Chronic Retroviral Infection and Gene Therapy

Retroviral vectors have been successfully used therapeutically to restore expression of genes in a range of single-gene diseases, including several primary immunodeficiency disorders. Although clinical trials have shown remarkable results, there have also been a number of severe adverse events involving malignant outgrowth of a transformed clonal population. This clonal expansion is influenced by the integration site profile of the viral integrase, the transgene expressed, and the effect of the viral promoters on the neighbouring host genome. Infection with the pathogenic human retrovirus HTLV-1 also causes clonal expansion of cells containing an integrated HTLV-1 provirus. Although the majority of HTLV-1-infected people remain asymptomatic, up to 5% develop an aggressive T cell malignancy. In this review we discuss recent findings on the role of the genomic integration site in determining the clonality and the potential for malignant transformation of cells carrying integrated HTLV-1 or gene therapy vectors, and how these results have contributed to the understanding of HTLV-1 pathogenesis and to improvements in gene therapy vector safety.     

Gene Therapy Strategies for HIV/AIDS: Preclinical Modeling in Humanized Mice

In the absence of an effective vaccine and lack of a complete cure, gene therapy approaches to control HIV infection offer feasible alternatives. Due to the chronic nature of infection, a wide window of opportunity exists to gene modify the HIV susceptible cells that continuously arise from the bone marrow source. To evaluate promising gene therapy approaches that employ various anti-HIV therapeutic molecules, an ideal animal model is necessary to generate important efficacy and preclinical data. In this regard, the humanized mouse models that harbor human hematopoietic cells susceptible to HIV infection provide a suitable in vivo system. This review summarizes the currently used humanized mouse models and different anti-HIV molecules utilized for conferring HIV resistance. Humanized mouse models are compared for their utility in this context and provide perspectives for new directions.     

Ultrasound Gene Therapy: On the Road from Concept to Reality

The promise of gene therapy lies in the potential to ameliorate or cure conditions that are resistant to conventional therapeutic approaches. Progress in vascular and all other fields of gene therapy has been hampered by concerns over the safety and practicality of recombinant viral vectors and the inefficiency of current nonviral transfection techniques. This review summarizes the increasing evidence that exposure of eukaryotic cells to relatively modest intensity ultrasound, within the range emitted by diagnostic transducers, either alone or in combination with other nonviral techniques, can enhance transgene expression by up to several orders of magnitude over naked DNA alone. In combination with the flexibility and excellent clinical safety profile of therapeutic and diagnostic ultrasound, these data suggest that ultrasound-assisted gene delivery has great promise as a novel approach to improve the efficiency of many forms of nonviral gene delivery.     

心力衰竭的基因治疗研究进展

心力衰竭是多种机制参与的复杂的临床综合征,患病率呈上升趋势,预后严重。基因治疗是较有希望治愈心力衰竭的方法之一。随着基因载体、基因转移方法的进步以及对心力衰竭机制认识的深入,目前研究的靶基因主要集中在5个方面,现将就其进展作一综述。     

经血管途径转基因治疗中枢神经系统疾病

基因治疗为许多无法用小分子药物治疗或小分子药物长期疗效不佳的神经系统疾病提供了希望。但血脑屏障的存在却使外源性基因难以进入脑内，是中枢神经系统转基因治疗的主要障碍。从最初人为地开放血脑屏障，到现在利用分子生物学方法开发出高效的新型非病毒载体，探索经血管途径转基因治疗和增强目的基因的靶向性已成为中枢神经系统疾病转基因治疗研究的热点。     

巨噬细胞在脑梗死基因治疗中的应用

通过浸润性巨噬细胞选择性侵入缺血性脑梗死灶介导基因治疗是一个值得探索的问题。文章对巨噬细胞与基因治疗、巨噬细胞应用于脑梗死基因治疗的理论基础和尚需解决的问题做了综述     

Stem-Cell-Based Gene Therapy for HIV Infection

Despite the enormous success of combined anti-retroviral therapy, HIV infection is still a lifelong disease and continues to spread rapidly worldwide. There is a pressing need to develop a treatment that will cure HIV infection. Recent progress in stem cell manipulation and advancements in humanized mouse models have allowed rapid developments of gene therapy for HIV treatment. In this review, we will discuss two aspects of HIV gene therapy using human hematopoietic stem cells. The first is to generate immune systems resistant to HIV infection while the second strategy involves enhancing anti-HIV immunity to eliminate HIV infected cells.     

Care of the Cancer Survivor: Metabolic Syndrome after Hormone-Modifying Therapy

Emerging evidence implicates metabolic syndrome as a long-term cancer risk factor but also suggests that certain cancer therapies might increase patients' risk of developing metabolic syndrome secondary to cancer therapy. In particular, breast cancer and prostate cancer are driven in part by sex hormones; thus, treatment for both diseases is often based on hormone-modifying therapy. Androgen suppression therapy in men with prostate cancer is associated with dyslipidemia, increasing risk of cardiovascular disease, and insulin resistance. Anti-estrogen therapy in women with breast cancer can affect lipid profiles, cardiovascular risk, and liver function. As the number of cancer survivors continues to grow, treating physicians must be aware of the potential risks facing patients who have been treated with either androgen suppression therapy or anti-estrogen therapy so that early diagnosis and intervention can be achieved.     

p53, Deleted in Colorectal Cancer Gene,and Thymidylate Synthase as Predictors of Histopathologic Response and Survival in Low,Locally Advanced Rectal Cancer Treated With Preoperative Adjuvant Therapy

PURPOSE: Adjuvant therapy, either preoperatively or postoperatively, and modifications of surgery have been used to try to improve outcome of surgery for rectal cancer in regard to both local recurrence and survival. Assessment of prognosis in patients after resection is currently primarily based on clinicopathologic factors. These predict the subsequent behavior of the tumor only imperfectly. The aim of this study was to evaluate three potential molecular genetic markers of prognosis (p53, deleted in colorectal cancer gene, and thymidylate synthase) in Dukes Stage B and C low rectal tumors treated with adjuvant therapy and to determine whether they correlate with survival, local recurrence, or the pathologic response to adjuvant therapy (assessed by extent of tumor regression and tumor down-staging). METHODS: Sixty locally advanced low rectal tumors resected after preoperative chemoradiotherapy or radiotherapy alone were studied by immunohistochemical staining for p53, deleted in colorectal cancer gene, and thymidylate synthase. In addition, p53 gene mutations were sought by polymerase chain reaction–single-strand conformation polymorphism analysis. These results were correlated with survival, local recurrence, and pathologic response to adjuvant therapy. RESULTS: Lack of thymidylate synthase staining by immunohistochemistry was associated with tumor down-staging after preoperative chemoradiotherapy but not after radiotherapy or for these two combined groups. There was no correlation between p53, deleted in colorectal cancer gene, or thymidylate synthase immunohistochemical staining or between p53 polymerase chain reaction–single-strand conformation polymorphism and local recurrence or survival in locally advanced low rectal cancers treated with preoperative adjuvant therapies. CONCLUSION: Prediction of prognosis in patients with locally advanced low rectal cancers treated with preoperative adjuvant therapies continues to be problematic. Thymidylate synthase immunohistochemistry appears to be the most promising factor of those assessed in predicting tumor down-staging after preoperative chemoradiotherapy for locally advanced low rectal cancers.     

Biofunctional Layered Double Hydroxide Nanohybrids for Cancer Therapy

Layered double hydroxides (LDHs) with two-dimensional nanostructure are inorganic materials that have attractive advantages such as biocompatibility, facile preparation, and high drug loading capacity for therapeutic bioapplications. Since the intercalation chemistry of DNA molecules into the LDH materials were reported, various LDH nanohybrids have been developed for biomedical drug delivery system. For these reasons, LDHs hybridized with numerous therapeutic agents have a significant role in cancer imaging and therapy with targeting functions. In this review, we summarized the recent advances in the preparation of LDH nanohybrids for cancer therapeutic strategies including gene therapy, chemotherapy, immunotherapy, and combination therapy.     

Special Issue: Gene Therapy with Emphasis on RNA Interference

Gene therapy was originally thought to cover replacement of malfunctioning genes in treatment of various diseases. Today, the field has been expanded to application of viral and non-viral vectors for delivery of recombinant proteins for the compensation of missing or insufficient proteins, anti-cancer genes and proteins for destruction of tumor cells, immunostimulatory genes and proteins for stimulation of the host defense system against viral agents and tumors. Recently, the importance of RNA interference and its application in gene therapy has become an attractive alternative for drug development.     

Large Animal Models for Foamy Virus Vector Gene Therapy

Foamy virus (FV) vectors have shown great promise for hematopoietic stem cell (HSC) gene therapy. Their ability to efficiently deliver transgenes to multi-lineage long-term repopulating cells in large animal models suggests they will be effective for several human hematopoietic diseases. Here, we review FV vector studies in large animal models, including the use of FV vectors with the mutant O⁶-methylguanine-DNA methyltransferase, MGMTP140K to increase the number of genetically modified cells after transplantation. In these studies, FV vectors have mediated efficient gene transfer to polyclonal repopulating cells using short ex vivo transduction protocols designed to minimize the negative effects of ex vivo culture on stem cell engraftment. In this regard, FV vectors appear superior to gammaretroviral vectors, which require longer ex vivo culture to effect efficient transduction. FV vectors have also compared favorably with lentiviral vectors when directly compared in the dog model. FV vectors have corrected leukocyte adhesion deficiency and pyruvate kinase deficiency in the dog large animal model. FV vectors also appear safer than gammaretroviral vectors based on a reduced frequency of integrants near promoters and also near proto-oncogenes in canine repopulating cells. Together, these studies suggest that FV vectors should be highly effective for several human hematopoietic diseases, including those that will require relatively high percentages of gene-modified cells to achieve clinical benefit.