多肽在药物靶向运送及疾病治疗中的研究进展

作为非病毒转基因载体骨架组件,功能性多肽在构建转基因载体、载体的核转运和靶向运送等方面发挥着重要作用。本文综述了多肽在药物靶向运送和疾病治疗中的研究进展。     

Construction of Smac gene-containing and human prostate specific antigen promoter-regulated vector and its expression

To construct an eukaryotic expression vector containing Smac gene and study the expression efficiency and specificity of prostate specific antigen（PSA） enhancer/promoter in a possible targeted gene therapy scheme for prostate cancer. Methods： PSA enhancer （PSAE） and promoter （PSAP） sequences were amplified using PCR method. CMV and T7 promoters were deleted from pcDNA3.1-Smac and replaced by the two specific fragments to generate pPSAE-PSAP-Smac. After transfection into different cell lines, the status of cells was observed. And then, we determined the relative concentration of Smac mRNA in RT-PCR. Results： The recombinant plasmid of pPSAE-PSAP-Smac was successfully constructed. And only the prostate cancer cell line PC-3 was suppressed after transfection with pPSAE-PSAP-Smac. However, other nonprostate lines were not. Moreover, the concentration of Smac mRNA regulated by PSA promoter and enhancer was higher in comparison to the CMV promoter-driven control vectors. Conclusion： An expression vector containing the Smac gene （based on elements of the PSA gene regulatory sequences） has been developed and shown to function in prostate cancer cell lines which provides a solid platform for launching clinical studies.     

Gene Transfer And Models Of Gene Therapy For The Myocardium

1. Gene transfer into the myocardium can be achieved through direct injection of plasmid DNA or through the delivery of viral vectors, either directly or through the coronary vasculature. Direct DNA injection has proven extremely valuable in studies aimed at characterizing the activities of promoter elements in cardiac tissue and for examining the influence of the pathophysiological state of the myocardium on expression of transferred foreign genes. 2. Viral vectors, in particular adenoviruses and adeno-associated virus, are capable of transfecting genetic material with high transduction efficiencies and have been applied to a range of model systems for in vivo gene transfer. Efficient gene transfer has been achieved into the coronary vessels and surrounding myocardium by intracoronary infusion of adenovirus. 3. Because the immunogenicity of viral vectors can limit transgene expression, much attention has been paid to strategies for circumventing this, including the development of new modified adenovirus and adeno-associated virus vectors that do not elicit significant inflammatory responses. While cellular transplantation may prove valuable for the repair of myocardial tissue, confirmation of its value awaits establishment of a functional improvement in the myocardium following cell grafting. 4. Because gene transfer into the myocardium can now be achieved with high efficiency in the absence of significant inflammatory responses, the ability to regulate foreign gene expression in response to an endogenous disease phenotype will enable the development of new effective viral vectors with direct clinical applicability for specified therapeutic targets.     

Role of calcium in gene delivery

The treatment of genetic diseases using therapeutic gene transfer is considered to be a significant development. This development has brought with it certain limitations, and the process of overcoming these barriers has seen a drastic change in gene delivery. Many metal ions such as Mg²⁺, Mn²⁺, Ba²⁺ and, most importantly, Ca²⁺ have been demonstrated to have significant roles in gene delivery. Recently, calcium phosphate alone, or in combination with viral and nonviral vectors, was found to exert a positive effect on gene transfer when incorporated in the colloidal particulate system, which is an advancing approach to gene delivery. This review elaborates on various successful methods of using calcium in gene delivery.     

Viral vectors in malaria vaccine development

Traditional vaccine technologies have resulted in an impressive array of efficacious vaccines against a variety of infectious agents. However, several potentially deadly pathogens, including retroviruses and parasites, have proven less amenable to the application of traditional vaccine platforms, indicating the need for new approaches. Viral vectors represent an attractive way to deliver and present vaccine antigens that may offer advantages over traditional platforms. Due to their ability to induce strong cell-mediated immunity (CMI) in addition to antibodies, viral vectors may be suitable for infectious agents, such as malaria parasites, where potent CMI is required for protection. Poxvirus-vectored malaria vaccines have been the most extensively studied in the clinic, achieving significant reductions in liver-stage parasite burden. More recently, adenovirus-vectored malaria vaccines have entered clinical testing. The most promising approach – heterologous prime-boost regimens, in which different viral vectors are sequentially paired with each other or with DNA or recombinant protein vaccines – is now being explored, and could provide high-grade protection, if findings in animal models are translatable to humans. Significant barriers remain, however, such as pre-existing immunity to the vector particle and an unexplained safety signal observed in one trial suggesting an increased risk of HIV acquisition in volunteers with pre-existing immunity to the vector.     

肝细胞移植临床前研究：大鼠肝细胞分离,培养和逆转录病毒转导

目的建立完善的肝细胞培养系统，研究逆转录病毒载体转移并表达于大鼠原代肝细胞。方法采用表皮生长因子（ＥＧＦ）刺激大鼠原代肝细胞增殖，以表达β－半乳糖苷酶的双顺反子逆转录病毒载体（ｐＧＣＥＮ／β－ｇａｌ）感染肝细胞。Ｘ－ｇａｌ原位染色方法检测肝细胞内ＬａｃＺ的表达，采用ＰＣＲ方法扩增ＮｅｏＲ基因，从ＤＮＡ水平证实逆转录病毒载体整合入肝细胞。结果ＥＧＦ在体外可刺激肝细胞增殖并维持肝细胞功能，肝细胞表达β－半乳糖苷酶基因，肝细胞中可扩增出ＮｅｏＲ基因片断。结论双顺反子逆转录病毒载体可有效介导β－ｇａｌ和ＮｅｏＲ基因表达于大鼠肝细胞，提示可用于标记原代大鼠肝细胞，有利于研究肝细胞移植后移植之肝细胞在体内的寿命、分布及功能。     

天津东疆港区医学媒介生物监测

目的掌握天津东疆港区医学媒介生物分布情况,为防治工作提供依据。方法 2009年6月到2010年5月,天津东疆局对东疆港区内医学媒介生物鼠、蚊、蝇、蜚蠊进行监测,鼠类使用夹夜法;蚊类采用人工诱捕法;蝇类采用笼诱法;蜚蠊采用药激法。结果全年共捕获鼠类228只,蚊类461只,蝇类43830只,蜚蠊177只,掌握了四种医学媒介生物的季节消长情况,并根据调查数据开展媒介生物控制。结论东疆港区四种医学媒介生物密度较高,应采取综合性防治措施,加强环境治理,确保媒介生物密度符合国家标准。     

小鼠活体内hMSCs干细胞生物发光示踪监测

目的:利用慢病毒载体转染和生物发光技术实时监测小鼠活体内人骨髓间充质干细胞(hMSCs)。方法:构建萤火虫荧光素酶(LUC)慢病毒载体,转染hMSCs后注射到小鼠皮下,(IVIS)生物发光成像系统连续检测体外hMSCs和小鼠注射部位的发光强度。结果:1.慢病毒载体对hMSCs的转染率为(29.6±1.5)%,转染后20代的hMSCs仍稳定表达LUC;2.慢病毒载体对hMSCs的生长和增值没有影响;3.小鼠活体内生物发光强度与注射细胞数量成正比(R2=0.9826);4.小鼠活体内生物发光时间持续6d。结论:可利用慢病毒载体转染LUC对小鼠活体内移植的hMSCs进行生物发光示踪监测。