Optimal vaccine scheduling in cancer immunotherapy

Cancer immunotherapy aims at stimulating the immune system to react against cancer stealth capabilities. It consists of repeatedly injecting small doses of a tumor-associated molecule one wants the immune system to recognize, until a consistent immune response directed against the tumor cells is observed.

We have applied the theory of optimal control to the problem of finding the optimal schedule of injections of an immunotherapeutic agent against cancer. The method employed works for a general ODE system and can be applied to find the optimal protocol in a variety of clinical problems where the kinetics of the drug or treatment and its influence on the normal physiologic functions have been described by a mathematical model.

We show that the choice of the cost function has dramatic effects on the kind of solution the optimization algorithm is able to find. This provides evidence that a careful ODE model and optimization schema must be designed by mathematicians and clinicians using their proper different perspectives.     

Polyethylenimine （PEI）-g-comb-poly（ethylene glycol）-transferrin（Ⅰ）： Tumor-targeted Vector for Gene Delivery In.vitro

The work described the synthesis and evaluation of PEI-g-comb-PEG-transferrin as a potential system for gene therapy in vitro. The MW of PEG was 10KDa, and PEI was 2KDa. Its structure was identified by NMR, FT-IR and TGA spectroscopy. MTT assay found that at concentration up to 4000 n mol/L of the polymer, cell viability was over 85%. The bio-character of polymer/DNA complex was characterized by agarose gel electrophoresis, ethidium bromide exclusion and zeta-potential assay. The polymer could retardate DNA at N/P ratio 3.0-3.5 （mol/mol）. The particle size of the polymer/DNA complex was less than 300 nm. Transfection efficiency of the complex was studied in COS7 and NT2 cell lines.     

Studies of poly-<Emphasis Type="Italic">L</Emphasis>-lysine-starch nanoparticle preparation and its application as gene carrier

Anion starch nanoparticle (StNP) with a diameter of 50 nm was prepared in water-in-oil microemulsion, with soluble starch as raw materials and POCl₃ as crosslinking agent. PLL-StNP was prepared by linking poly-L-lysine (PLL) on the surface of StNP. At the same time, the size of PLL-StNP and its stability in aqueous solution were checked by AFM. The analysis of plasmid DNA binding, DNase I enzymatic degradation, toxicity and transfection were done. We discovered that PLL-StNP may be used as non-virus nanoparticle gene carrier. And we developed the method of preparing PLL-StNP gene carrier and used it in cell transfection. As non-virus gene carrier, PLL-StNP has some advantages, such as large load of DNA, high transfection efficiency, low cell toxicity and biodegradability.     

人钠/碘转运体基因转染结肠癌SW480细胞及相关蛋白表达的检测

目的以重组人钠/碘转运体（hNIS）基因转染结肠癌SW480细胞并检测hNIS mRNA及蛋白的表达，为放射性碘治疗非甲状腺肿瘤提供新思路。方法将构建好的重组质粒（pcDNA3.1+-hNIS）进行酶切、测序鉴定并扩增、提取。SW480细胞分为重组质粒（pcDNA3.1+-hNIS）转染组、空白质粒（pcDNA3.1+）转染组、空白对照组，转染后以RT-PCR和Western blot检测各组细胞hNIS mRNA和蛋白的表达。结果酶切和测序结果显示插入的hNIS基因大小和方向均正确。RT-PCR和Western blot显示重组质粒转染组SW480细胞可见hNIS mRNA和蛋白的表达，而空白对照组和空白质粒转染组均未检测到hNIS mRNA和蛋白的表达。结论脂质体法可有效地将hNIS基因转染至SW480细胞并成功表达hNIS蛋白。     

Transfection of Mammalian Cells Using Block Copolypeptide Vesicles

An arginine‐leucine block copolypeptide (R₆₀L₂₀) is synthesized, which is capable of forming vesicles with controllable sizes, able to transport hydrophilic cargo across the cell membrane, and exhibit relatively low cytotoxicity. The R₆₀L₂₀ vesicles also possess the ability to deliver DNA into mammalian cells for transfection. Although the transfection efficiency is lower than that of the commercially available transfection agent Lipofectamine 2000, the R₆₀L₂₀ vesicles are able to achieve transfection with significantly lower cytotoxicity and immunogenicity. This behavior is potentially due to its stronger interaction with DNA which subsequently provides better protection against anionic heparin.

     

Significance of Branching for Transfection: Synthesis of Highly Branched Degradable Functional Poly(dimethylaminoethyl methacrylate) by Vinyl Oligomer Combination

A series of degradable branched PDMAEMA copolymers were investigated with the linear PDMAEMA counterpart as gene‐delivery vectors. The branched PDMAEMA copolymers were synthesized by controlled radical cross‐linking copolymerization based on the “vinyl oligomer combination” approach. Efficient degradation properties were observed for all of the copolymers. The degree of branching was found to have a big impact on performance in transfection when tested on different cell types. The product with the highest degree of branching and highest degree of functionality had a superior transfection profile in terms of both transfection capability and the preservation of cell viability. These branched PDMAEMA copolymers show high potential for gene‐delivery applications through a combination of the simplicity of their synthesis, their low toxicity, and their high performance.     

DNA体外缩合的研究进展

DNA缩合不仅是自然界常见的生理现象,也是非病毒载体介导基因转染的关键步骤。了解DNA体外缩合的性质与特征,将有助于设计出高效的非病毒转基因载体。本文综述了近十几年来以多价阳离子为缩合剂诱发的DNA体外缩合的研究进展,着重介绍了缩合的机理、过程、影响缩合的因素以及应用于转基因的最新成果。     

基质刚性影响声孔效应介导的单细胞基因转染

实验研究了基质刚性对单细胞质粒DNA转染效果的影响。实验采用高声压短脉冲(0.45MPa,10μs)条件的超声对培养在不同硬度凝胶基质(软的凝胶基质：0.2kPa,硬的凝胶基质：40kPa)上的力学敏感细胞NIH 3T3进行质粒DNA转染实验。实验结果表明,培养在硬的凝胶基质上的细胞,质粒DNA转染效率明显高于培养在软的凝胶基质上的细胞。进一步对质粒DNA进行荧光示踪可知培养在不同刚性基质上的细胞导入质粒DNA的方式不同。当细胞被培养在硬的凝胶基质上时,通过声致穿孔产生的小孔进入细胞内的质粒DNA更多,而培养在软的凝胶基质上的细胞,更多的质粒DNA可以通过非声致穿孔作用,例如内吞方式导入细胞。 细胞骨架蛋白分布规律表明,硬的凝胶基质上培养的细胞内有更多的F肌动蛋白微丝,可以更好地支撑起细胞的铺展形态,相对不容易发生内吞作用。而软的凝胶基质上培养的细胞内F肌动蛋白则更多以球形状态存在,细胞形貌骗向圆形,此时更容易发生胞吞作用。     

聚谷氨酸接枝聚乙二醇@碳酸钙遮蔽体系用于提高聚乙烯亚胺基因转染效率

设计并合成了聚谷氨酸-聚乙二醇@碳酸钙(PPG@CaCO₃)纳米遮蔽体系, 用于遮蔽聚乙烯亚胺(PEI). 一方面, 聚谷氨酸-聚乙二醇(PPG)可以降低PEI引起的细胞毒性, 更有利于体内应用; 另一方面, CaCO₃可有效改善PPG导致的转染效率下降, 并在一定程度上提高PEI的细胞转染效率. 对比遮蔽体系PPG@CaCO₃和聚谷氨酸-聚乙二醇@磷酸钙[PPG@Ca₃(PO₄)₂]发现, PPG@CaCO₃在微酸性环境中释放二氧化碳气体是提高细胞转染效率的关键因素. 小鼠体内循环实验表明, PPG@CaCO₃遮蔽体系可以增加载体在血液中的循环时间. 因此, PPG@CaCO₃遮蔽体系对于改善阳离子类基因载体的体内应用起到重要作用.