Manconi Maria, Isola Raffaella, Falchi Angela Maria, Sinico Chiara, Fadda Anna Maria
Dipartimento Farmaco Chimico Tecnologico, Università di Cagliari, Via Ospedale 72, Cagliari, Italy.
Colloids Surf B Biointerfaces. 2007 Jun 15;57(2):143-51. doi: 10.1016/j.colsurfb.2007.01.016. Epub 2007 Feb 6.
In order to study mechanisms involved in liposome-cell interaction, this work attempted to assess the influence of vesicle composition on the delivery of liposomal content to Hela cells. In particular, to evaluate pH-sensitive properties and cell interaction of the prepared liposomes, the lipid formulations contained cholesterol (Chol) and they were varied by using phosphatidylcholines with different purity degree: soy lecithin (SL; 80% phosphatidylcholine), a commercial mixture of soy phosphatidylcholine (P90; 90% phosphatidylcholine) or dipalmitoylphosphatidylcholine (DPPC; 99% of purity). A second series of liposomes also contained stearylamine (SA). Dehydration-rehydration vesicles (DRV) were prepared and then sonicated to decrease vesicle size. Vesicle-cell interactions and liposomal uptake were examined by fluorescence microscopy using carboxyfluorescein (CF) and phosphatidylethanolamine-dioleoyl-sulforhodamine B (Rho-PE) as fluorescent markers. Fluorescence dequenching assay was used to study the influence of pH on CF release from the liposomal formulations. Liposome adhesion on the cell surface and internalization were strongly dependent on vesicle bilayer composition. SA vesicles were not endocytosed. DPPC/Chol liposomes were endocytosed but did not release their fluorescent content into the cytosol. SL/Chol and P90/Chol formulations displayed a diffuse cytoplasmic fluorescence of liposomal marker.
为了研究脂质体与细胞相互作用的机制，本研究试图评估囊泡组成对脂质体内容物向Hela细胞递送的影响。具体而言，为了评估所制备脂质体的pH敏感特性和细胞相互作用，脂质制剂中含有胆固醇（Chol），并通过使用不同纯度的磷脂酰胆碱来改变脂质组成：大豆卵磷脂（SL；80%磷脂酰胆碱）、大豆磷脂酰胆碱的商业混合物（P90；90%磷脂酰胆碱）或二棕榈酰磷脂酰胆碱（DPPC；99%纯度）。第二组脂质体还含有硬脂胺（SA）。制备脱水再水化囊泡（DRV），然后进行超声处理以减小囊泡尺寸。使用羧基荧光素（CF）和磷脂酰乙醇胺 - 二油酰 - 磺基罗丹明B（Rho - PE）作为荧光标记，通过荧光显微镜检查囊泡与细胞的相互作用以及脂质体的摄取情况。采用荧光猝灭测定法研究pH对脂质体制剂中CF释放的影响。脂质体在细胞表面的黏附和内化强烈依赖于囊泡双层膜的组成。SA囊泡未被内吞。DPPC/Chol脂质体被内吞，但未将其荧光内容物释放到细胞质中。SL/Chol和P90/Chol制剂显示出脂质体标记物的弥漫性细胞质荧光。
