载体与基因转染的研究进展

基因载体是指将基因或其它核酸物质运载到细胞中的工具.其化学本质可以是蛋白质或多肽、核酸、脂类、糖类、其它有机分子或它们的复合物.基因传递系统是基因治疗的重要组成部分,也是目前基因治疗的瓶颈.现有的基因载体包括两类.即病毒载体和非病毒载体.病毒载体转染效率高,但由于其转染具有免疫原性和致突变性限制了它的应用;非病毒载体系统具有低毒、低免疫原性和相对靶向性等优点,是新兴发展起来的基因转移系统.就各种载体的最新研究进展作一综述.     

非病毒型纳米载体在基因治疗中的研究现状及展望

近 10年来 ,新型非病毒载体在基因治疗中日益受到欢迎。其主要代表为纳米载体 ,具有无毒性及免疫原性的优势 ,已作为高效阳离子载体用于基因转移。体外基因转移实验表明 ,纳米载体的基因转移率高于普通脂质体及其它阳离子多聚体 ,如多聚氮丙啶及聚赖氨酸。本文对纳米载体的结构特点、性能、基因转移机制进行综述 ,并将其在体内外基因转移效率与其它非病毒载体作以比较     

非病毒型纳米载体在基因治疗中的研究现状及展望

近10年来，新型非病毒载体在基因治疗中日益受到欢迎。其主要代表为纳米载体，具有无毒性及免疫原性的优势，已作为高效阳离子载体用于基因转移。体外基因转移实验表明，纳米载体的基因转移率高于普通脂质体及其它阳离子多聚体，如多聚氮丙及聚赖氨酸。本对纳米载体的结构特点，性能，基因转移机制进行综述，并将其在体内外基因转移效率与其它非病毒载体作以比较。     

非病毒转基因载体的研究进展

高效的转基因载体是基因释放系统的核心。非病毒转基因载体具有低免疫原性和易制备等特性。本就近年来非病毒转基因载体的发展作一综述。     

单基因遗传病基因治疗中病毒型载体的应用

摘要：在单基因遗传病的基因治疗中,病毒型载体是较为常用的将目的基因导入靶细胞的有效运载工具之一,分为腺病毒载体、腺相关病毒载体、逆转录病毒载体及慢病毒载体等。在本文中,我们拟就单基因遗传病基因治疗中病毒型载体的应用现状和研究进展做较为系统地阐述。     

非病毒转基因载体的研究进展

高效的转基因载体是基因释放系统的核心。非病毒转基因载体具有低免疫原性和易制备等特性。本文就近年来非病毒转基因载体的发展作一综述     

病毒载体介导的基因转移研究进展

实现基因治疗的关键在于目的基因的高效转移并适度表达 ,这将直接影响其治疗效率和安全性。因此探索理想的基因转移技术是基因治疗的一项重要内容 ,目前人们的注意力更多地集中于病毒载体 ,传统的逆转录病毒载体不能转染非分裂细胞 ,且载导容量有限 ,促使人们在寻找改进措施的同时积极研制其它类型的病毒载体 ,本文将阐述这些病毒载体的特性、应用情况及研究进展。     

痘苗病毒载体与肿瘤基因治疗（上）——重组痘苗病毒载体构建及特性

应用重组痘苗病毒载体进行肿瘤基因治疗取得了很大的进展。与其它病毒载体比较，痘苗病毒载体有较大的外源基因容量，可达２５￣４０ｋｂ，宿主范围广泛，可感染非分裂细胞，并且仅在细胞质中复制，无致癌性的报道。目前，随着重组载体构建、减毒、选择标记及外源基因表达调控方面的进展，可望作为一种较理想的载体介导肿瘤的基因治疗。     

基因转移的DNA病毒方法

在基因治疗中,作为基因转移的载体,迄今几乎都用逆转录病毒,但是在某些情况下(例如将外源基因导入非分裂状态的细胞),DNA病毒作为载体具有明显的优越性。本文对腺相关病毒、腺病毒和疱疹病毒作为外源基因载体进行了简要的讨论。     

HIV-Ⅰ慢病毒载体的研究进展与应用

基因治疗是治疗肿瘤、遗传病等难治性疾病的最有效手段之一,但目前的基因转移方法存在一定的局限性,成为基因治疗和广泛应用的障碍.以1型人类免疫缺陷病毒(HIV-1)为基础构建的慢病毒载体(LV)具有感染分裂及非分裂细胞、使目的 基因产物表达稳定、表达时间长、载体自身免疫原性小等优点,尤其是LV能有效诱导免疫应答,抑制肿瘤生长,诱导移植免疫耐受等,是很有发展潜力的体内基因治疗新载体.     

Biosafety of herpesvirus vectors

Herpesviruses are large DNA viruses, which possess a number of advantages as gene delivery vectors. These relate to an ability to package large DNA insertions and establish lifelong latent infections in which the viral genome exists as a stable episome in the nucleus. For gene therapy to become a potential future treatment option, biosafe therapeutically efficient gene transfer is a central, but more and more stringent requirement. This review highlights the progress in development of herpesvirus based vectors, describes their properties as wall as discusses the biosafety concerns that are associated with their use in gene therapy. Thought was also given to biosafety issues pertaining to design and production of herpesvirus vector systems in therapeutic gene delivery.     

Adeno-associated viral vectors for retinal gene transfer and treatment of retinal diseases

Retinal gene transfer holds big promises for the treatment of inherited and non-inherited blinding diseases, such as retinitis pigmentosa or age-related macular degeneration. Key to the development of successful gene-based therapies for the eye are efficient tools for retinal gene transfer. Vectors based on adeno-associated viruses (AAV) are able to transduce robustly and persistently different retinal cell types of animal models after a single intraocular administration. Recombinant AAV (rAAV) vectors are versatile gene transfer tools in that capsid proteins from dozens of AAV serotypes can be easily interchanged, resulting in the creation of recombinant vectors with unique transduction properties. This has allowed successful proof-of-principle studies using rAAV-mediated gene transfer to restore retinal morphology and function in small and large animal models of retinal diseases. In addition, gene delivery using rAAV vectors in the eye seems to have appropriate biosafety characteristics to rapidly move it from bench to bedside. All the above aspects will be reviewed and discussed in detail below.     

Arginine functionalized peptide dendrimers as potential gene delivery vehicles

The quest for highly efficient and safe gene delivery systems has become the key factor for successful application of gene therapy. Peptide dendrimers are currently investigated as excellent candidates for non-viral gene delivery vectors. In this study, we report the synthesis and characterization of arginine functionalized peptide dendrimer-based vectors ranging from 5th generation (G5A) to 6th generation (G6A) via click chemistry, and their use for gene transfection in vitro and in vivo. The dendrimers can condense plasmid DNA (pDNA) and protect pDNAs from nuclease digestion. Both atomic force microscopy (AFM) and dynamic light scattering (DLS) revealed that the sizes of dendrimer/DNA particles were within 180-250 nm range. In vitro studies showed that the functionalized peptide dendrimers provided serum independent and high transfection efficiency on all studied cells, as over 2 fold higher than that of branched polyetherimide (PEI) in the presence of serum. Dendrimer G5A with molecular weight of 17 kDa demonstrated 6-fold transfection activity than PEI in breast tumor models, as well as good biosafety proved by in vitro and in vivo toxicity evaluation. However, G6A with molecular weight of 46 kDa showed much higher cytotoxicity. The functionalized dendrimer G5A with optimal generation may be therefore a potential candidate for gene delivery vehicle.     

Optimization of lentiviral vectors generation for biomedical and clinical research purposes: contemporary trends in technology development and applications

Classical non-viral methods of gene transfer, such as chemical transfection, have met with limited success of instillation of genetic material into non-proliferating cells in vitro. Among the different kinds of viral vectors, Lentiviral vectors (LVs) have emerged as robust and versatile tool for ex vivo and in vivo gene delivery into multiple cell types including non-dividing cells such as neurons. The capacity of LVs to maintain stable, long-term transgene expression and the substantial flexibility in the design of the expression cassettes account for their increasing use in various pre-clinical and clinical applications. Additionally, LVs have been hugely successful in reprogramming induced pluripotent stem cells (iPSCs). Recent development using LVs in conjunction with a Cre-Lox based reversible system has opened up many new possibilities towards therapeutic application of iPSC technology in various clinical settings. Moreover, improvements in term of biosafety and efficacy, achieved either by modifying the vector design or by involving integration-deficient LVs (IDLVs), have important implications for adoption of LV as the vector of choice for clinical trials. Several human gene therapy clinical trials evaluating the use of LVs for treatment: of human diseases such as Parkinson's disease, β-thalassemia, X-linked adrenoleukodystrophy (ALD), and AIDS are currently ongoing. This review will describe the state of the art achieved by LV technology, its impact on biomedical research, and implications to human clinical trials as therapeutic gene delivery vehicle for a wide range of infectious and genetic diseases.     

非病毒基因载体材料的研究进展

非病毒材料可成为基因治疗中的基因载体,使目的基因持续有效地表达。非病毒基因载体主要有脂质体、人工合成聚合物载体、天然聚合物载体、局部基因释放载体等。其中壳聚糖及其衍生物是一种优良的基因释放载体,局部基因释放载体技术将基因治疗与组织工程结合起来,在组织修复与重建方面将发挥重要作用。     

Retroviral Vector Biosafety: Lessons from Sheep

The safety of retroviral-based systems and the possible transmission of replication-competent virus to patients is a major concern associated with using retroviral vectors for gene therapy. While much effort has been put into the design of safe retroviral production methods and effective in vitro monitoring assays, there is little data evaluating the risks resulting from retroviral vector instability at post-transduction stages especially following in vivo gene delivery. Here, we briefly describe and discuss our observations in an in vivo experimental model based on the inoculation of retroviral vector-transduced tumor cells in sheep. Our data indicates that the in vivo generation of mosaic viruses is a dynamic process and that virus variants, generated by retroviral vector-mediated recombination,may be stored and persist in infected individuals prior to selection at the level of replication. Recombination may not only restore essential viral functions or provide selective advantages in a changing environment but also reestablish or enhance the pathogenic potential of the particular virus undergoing recombination. These observations in sheep break new ground in our understanding of how retroviral vectors may have an impact on the course of a preestablished disease or reactivate dormant or endogenous viruses. The in vivo aspects of vector stability raise important biosafety issues for the future development of safe retroviral vector-based gene therapy.     

Biosafety of lentiviral vectors

The characteristics of lentiviral vectors (stable integration in non-dividing and dividing cells, long-term expression of the transgene, absence of immune response) make them ideal gene transfer vehicula for future gene therapy. However, the most potent lentiviral vectors are derived from highly pathogenic human viruses, such as HIV. We describe how the field has engineered lentivectors with increasing biosafety both for the lab worker and for the patient. The risk associated with state-of-the-art lentivectors is therefore minimal, although a psychological barrier to use these vectors in the clinic may still have to be overcome. Due to their increased performance, care should be taken to avoid accidental transduction of the lab worker with potential hazardous genes. The precautions which have to be taken are described in detail.     

Complementation of a defective human adenovirus by an otherwise incompatible ovine adenovirus recombinant carrying a functional E1A gene

All known human adenoviruses are classified as mastadenoviruses, while the ovine adenovirus (OAdV) serotype 7 is the prototype of the atadenoviruses, a proposed new genus. OAdV replicates abortively in human cell types and has potential as a gene transfer vector. However, the function of OAdV nonstructural genes is poorly understood and it is unclear whether OAdV replication might be complemented by a replicating human AdV in coinfected cells. To investigate possible interactions three human cell lines were singly infected with OAdV or human AdV5 or doubly infected. The development of a cytopathic effect and genome replication was monitored over three passages in each cell type. No significant OAdV replication occurred in any of the cell types examined either in the presence or in the absence of replicating AdV5. No aberrant AdV5 genome products were detected in coinfected cells. In contrast, in coinfected cells an OAdV recombinant that expressed the AdV5 E1A gene was able to promote the replication of an AdV5 E1A-deficient mutant, demonstrating trans-complementation between appropriate viruses. These findings have implications for the biosafety of OAdV vectors and their possible utility for enhancing gene delivery.     

Antibiotic-free plasmid stabilization by operator-repressor titration for vaccine delivery by using live Salmonella enterica Serovar typhimurium

Live, attenuated bacteria are effective vectors for heterologous antigen delivery. However, loss of heterologous gene-bearing plasmids is problematic, and antibiotics and their resistance genes are not desirable for in vivo DNA vaccine delivery due to biosafety and regulatory concerns. To solve this problem, we engineered the first vaccine delivery strain that has no requirement for antibiotics or other selectable marker genes to maintain the recombinant plasmid. This model strain of Salmonella enterica serovar Typhimurium, SLDAPD, uses operator-repressor titration (ORT) technology, which requires only the short, nonexpressed lacO sequence for selection and maintenance. SLDAPD, recovered from the spleens and Peyer's patches of mice following oral inoculation, was shown to maintain a plasmid that, in contrast, was lost from parental strain SL3261. We also demonstrated successful application of this technology to vaccine development, since SLDAPD carrying a plasmid without an antibiotic resistance gene that expressed the Yersinia pestis F1 antigen was as efficacious in protecting vaccinated mice against plague as the parental SL3261 strain carrying an antibiotic-selected version of this plasmid. Protection of mice against plague by immunization with Salmonella expressing F1 has previously required two or more doses; here we demonstrated for the first time protective immunity after a single oral immunization. This technology can easily be used to convert any suitable attenuated strain to an antibiotic-free ORT strain for recombinant protein vaccine delivery in humans.