Verbaan F J, Oussoren C, Snel C J, Crommelin D J A, Hennink W E, Storm G
Department of Pharmaceutics, Utrecht Institute for Pharmaceutical Sciences (UIPS), Utrecht University, P.O. Box 80082, 3508 TB Utrecht, The Netherlands.
J Gene Med. 2004 Jan;6(1):64-75. doi: 10.1002/jgm.475.
Efficient tumor targeting of polymeric gene transfer systems (polyplexes) represents a major challenge. To establish tumor targeting after intravenous (IV) administration, the circulation lifetime of these systems should be sufficiently long. Since naked polyplexes are rapidly eliminated from the circulation after IV adminstration, strategies have to be developed to improve their pharmacokinetics.
Complexes of plasmid DNA and poly(2-(dimethylamino)ethyl methacrylate) (pDMAEMA)-graft-PEG or AB di-block copolymers of pDMAEMA and PEG, as well as PEGylated complexes prepared via PEGylation of preformed complexes (postPEGylation), were evaluated for their physicochemical properties (size and charge) their interactions with blood constituents and transfection activity in vitro. The pharmacokinetics and biodistribution of PEG-polyplexes were studied in mice after IV administration. The degree of accumulation in two subcutaneous (SC) mouse tumors after IV administration was evaluated for the system with the longest circulation time.
It is shown that the surface charge of the pDMAEMA-polyplexes was effectively shielded by two PEGylation methods (i.e. the use of pDMAEMA-graft-PEG polymers and postPEGylation). The shielding effect was the highest for the postPEGylation method with PEG(20000), yielding polyplexes that hardly show interactions with blood components (i.e. albumin and erythrocytes) and show substantially prolonged circulation time in mice after IV administration. The superior colloidal stability and circulation kinetics of the postPEGylated polyplexes translated into tumor accumulation which amounted to about 3.5% of the injected dose per gram tumor tissue in a SC Neuro2A tumor model and to about 4.2% of the injected dose per gram tumor tissue in a SC C26 tumor model.
This study shows that postPEGylation of pDMAEMA-based polyplexes is the most attractive method to prepare polyplexes with long circulating properties. Tumor targeting capacity after intravenous administration was demonstrated in two subcutaneous tumor models.
聚合物基因传递系统（多聚体）实现高效肿瘤靶向是一项重大挑战。为了在静脉注射后实现肿瘤靶向，这些系统的循环寿命应足够长。由于裸多聚体在静脉注射后会迅速从循环中清除，因此必须制定策略来改善其药代动力学。
评估了质粒DNA与聚（甲基丙烯酸2-（二甲氨基）乙酯）（pDMAEMA）-接枝-PEG或pDMAEMA与PEG的AB二嵌段共聚物形成的复合物，以及通过对预先形成的复合物进行聚乙二醇化（后聚乙二醇化）制备的聚乙二醇化复合物的物理化学性质（大小和电荷）、它们与血液成分的相互作用以及体外转染活性。在小鼠静脉注射后研究了聚乙二醇化多聚体的药代动力学和生物分布。对循环时间最长的系统，评估了静脉注射后在两个皮下（SC）小鼠肿瘤中的积累程度。
结果表明，通过两种聚乙二醇化方法（即使用pDMAEMA-接枝-PEG聚合物和后聚乙二醇化）可有效屏蔽pDMAEMA-多聚体的表面电荷。对于使用PEG（20000）的后聚乙二醇化方法，屏蔽效果最高，产生的多聚体几乎不与血液成分（即白蛋白和红细胞）相互作用，并且在静脉注射后在小鼠体内显示出显著延长的循环时间。后聚乙二醇化多聚体优异的胶体稳定性和循环动力学转化为肿瘤积累，在SC Neuro2A肿瘤模型中，每克肿瘤组织的积累量约为注射剂量的3.5%，在SC C26肿瘤模型中，每克肿瘤组织的积累量约为注射剂量的4.2%。
本研究表明，基于pDMAEMA的多聚体进行后聚乙二醇化是制备具有长循环特性的多聚体最具吸引力的方法。在两个皮下肿瘤模型中证明了静脉注射后的肿瘤靶向能力。
