Cell Specific Gene Delivery Systems with DNA Complexes Coated by Sugar-bearing Polyanions

各种阳离子聚合物已被探索作为合成的非病毒载体。然而，DNA/多阳离子复合物的表面通常带正电荷，与血清蛋白的聚集一直是一个问题，特别是在体内基因治疗中。我们开发了一种新的聚乙二醇衍生物，其羧酸侧链（PEG-C）作为DNA/多阳离子复合物的自组装保护层，减少了与血细胞或血清蛋白的非特异性相互作用。将糖侧链作为配体引入PEG-C中，探讨其对转染效率的影响。含糖PEG-C可在靶细胞上实现细胞特异性高转基因表达。证实了受体介导的糖- peg -c包被DNA复合物的高效内化。此外，peg -c包被增强了质粒/PEI复合物的转录活性，这可能是由于对紧密压缩的DNA/PEI有松动作用，这有利于转录因子的接近。摘要合成了具有氨基侧链和羧基侧链的两性聚乙二醇衍生物（PEG- ac），模拟了天然转录激活蛋白HMG的结构。它比PEG-C具有更高的转录增强活性，不仅可以作为DNA复合物的多功能保护涂层，而且可以作为HMG蛋白的模型聚合物。

A variety of cationic polymers have been explored as synthetic non-viral vectors. However, the surface of the DNA/polycation complex is usually positively charged, and aggregation with serum protein has been a problem especially for in vivo gene therapy. We have developed a novel poly (ethylene glycol) derivative with carboxylic acid side chain (PEG-C) as a self-assembling protecting coat of the DNA/polycation complexes, which reduces the nonspecific interactions with blood cells or serum proteins. The sugar side chain was introduced to PEG-C as ligand, and its effect on the transfection efficiency was explored. Sugar-bearing PEG-C allowed the cell-specific high transgene expression on the target cells. The receptor-mediated highly effective internalization of sugar-PEG-C-coated DNA complex was confirmed. Moreover, PEG-C-coating enhanced the transcriptional activity of the plasmid/PEI complex, probably due to the loosening effect on the tightly compacted DNA/PEI, which would facilitate the approach of transcription factors. Amphoteric PEG derivative having both amino- and carboxyl-side chains (PEG-AC) was synthesized mimicking the structure of HMG protein, a natural transcriptional activating protein. It showed higher transcription-enhancing activity than PEG-C, and is expected as not only a multifunctional protective coating for the DNA complexes, but a model polymer for the HMG proteins.