Endosomal escape of polymeric gene delivery complexes is not always enhanced by polymers buffering at low pH
Endosomal escape of polymeric gene delivery complexes is not always enhanced by polymers buffering at low pH
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DOI：
10.1021/bm034041
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发表时间：
2004-01-01
影响因子：
6.2
通讯作者：
Hennink, WE
中科院分区：
文献类型：
--
作者：
Funhoff, AM;van Nostrum, CF;Hennink, WE
用阳离子聚合物进行基因递送的关键步骤之一是聚合物/DNA复合物（“聚合复合物”）从内体逃逸。增强内体逃逸的一种可能方式是使用pK（a）约为或略低于生理pH的阳离子聚合物（“质子海绵”）。我们合成了一种在每个单体单元中具有两个叔胺基团的新聚合物{聚（2-甲基-丙烯酸2-[（2（二甲氨基）-乙基）-甲基-氨基] -乙基酯），缩写为pDAMA}。单体的一个pK（a）约为9，在生理pH下提供阳离子电荷，从而提供DNA结合特性，另一个约为5，提供内体缓冲能力。使用动态光散射和zeta电位测量，表明pDAMA能够将DNA凝聚成具有表面电荷的小颗粒，这取决于聚合物/DNA比率。pDAMA具有比其他聚合物转染剂低得多的毒性，但在体外，基于pDAMA的聚合物复合物的转染活性非常低。将膜破坏性肽添加到基于pDAMA的聚合复合物中显著增加了转染效率，而不会对系统的细胞毒性产生不利影响。这表明单独的基于pDAMA的聚合复合物不能介导通过质子海绵机制从内体逃逸。我们的观察意味着，质子海绵假说是不普遍适用于聚合物在低pH值的缓冲能力，并引起重新考虑这一假设。
One of the crucial steps in gene delivery with cationic polymers is the escape of the polymer/DNA complexes ("polyplexes") from the endosome. A possible way to enhance endosomal escape is the use of cationic polymers with a pK(a) around or slightly below physiological pH ("proton sponge"). We synthesized a new polymer with two tertiary amine groups in each monomeric unit {poly(2-methyl-acrylic acid 2-[(2(dimethylamino)-ethyl)-methyl-amino] -ethyl ester), abbreviated as pDAMA}. One pK(a) of the monomer is approximately 9, providing cationic charge at physiological pH, and thus DNA binding properties, the other is approximately 5 and provides endosomal buffering capacity. Using dynamic light scattering and zeta potential measurements, it was shown that pDAMA is able to condense DNA in small particles with a surface charge depending on the polymer/DNA ratio. pDAMA has a substantial lower toxicity than other polymeric transfectants, but in vitro, the transfection activity of the pDAMA-based polyplexes was very low. The addition of a membrane disruptive peptide to pDAMA-based polyplexes considerably increased the transfection efficiency without adversely affecting the cytotoxicity of the system. This indicates that the pDAMA-based polyplexes alone are not able to mediate escape from the endosomes via the proton sponge mechanism. Our observations imply that the proton sponge hypothesis is not generally applicable for polymers with buffering capacity at low pH and gives rise to a reconsideration of this hypothesis.