Syntheses, Transfection Efficacy and Cell Toxicity Properties of Novel Cholesterol-based Gemini Lipids having Hydroxyethyl Head group
作者:Joydeep Biswas、Santosh K. Mishra、Paturu Kondaiah、Santanu Bhattacharya
DOI:10.1039/c0ob00940g
日期:——
We have synthesized five new cholesterol based gemini cationic lipids possessing hydroxyethyl (-CH2CH2OH) function on each head group, which differ in the length of the polymethylene spacer chain. These gemini lipids are important for gene delivery processes as they possess pre-optimized molecular features, e.g., cholesterol backbone, ether linkage and a variable spacer chain between both the headgroups of the gemini lipids. Cationic liposomes were prepared from each of these lipids individually and as a mixture of individual cationic gemini lipid and 1,2-dioleoyl phosphatidylethanolamine (DOPE). Each gemini lipid based formulation induced better transfection activity than that of their monomeric counterpart. One such gemini lipid with a -(CH2)12- spacer, HG-12, showed dramatic increase in the mean fluorescence intensity due to the expression of green-fluorescence protein (GFP) in the presence of 10% FBS compared to the conditions where there was no serum. Other gemini lipids retained their gene transfection efficiency without any marked decrease in the presence of serum. The only exception was seen with the gemini with a -(CH2)3- spacer, HG-3, which on gene transfection in the presence of 10% FBS lost ∼70% of its transfection efficiency. Overall the gemini lipid with a -(CH2)5- spacer, HG-5, showed the highest transfection activity at N/P (lipid/DNA) ratio of 0.5 and lipid : DOPE molar ratio of 2. Upon comparison of the relevant parameters, e.g., %-transfected cells, the amount of DNA transfected to each cell and %-cell viability all together against Lipofectamine 2000, one of the best commercial transfecting agents, the optimized lipid formulation based on DOPE/HG-5 was found to be comparable. In terms of its ability to induce gene-transfer in the presence of serum and shelf-life DOPE/HG-5 liposome was found to be superior to its commercial counterpart. Confocal imaging analysis confirmed that in the presence of 10% serum using a Lipid : DOPE of 1 : 4 and N/P charge ratio of 0.75 with 1.2 μg DNA per well, HG-5 is better than Lipofectamine 2000.
我们合成了五种新的胆固醇基双子季铵脂质,其头部每个基团都具有羟乙基(-CH2CH2OH)功能,这些脂质在聚亚甲基间隔链的长度上有所不同。这些双子脂质对于基因传递过程非常重要,因为它们具有预优化的分子特征,例如胆固醇骨架、醚键以及双子脂质两个头部基团之间的可变间隔链。从每种脂质单独制备了阳离子脂质体,并将其与1,2-二油酰磷脂酰乙醇胺(DOPE)混合作为单个阳离子双子脂质。每种基于双子脂质的配方诱导的转染活性均优于其单体对应物。其中一种具有-(CH2)12-间隔链的双子脂质,HG-12,在存在10%胎牛血清(FBS)的情况下,由于绿色荧光蛋白(GFP)的表达,平均荧光强度显著增加,而在无血清的条件下则没有这种增加。其他双子脂质在存在血清的情况下仍保持其基因转染效率,没有任何明显的降低。唯一的例外是具有-(CH2)3-间隔链的双子脂质,HG-3,在存在10% FBS的情况下进行基因转染时,其转染效率损失了约70%。总体而言,具有-(CH2)5-间隔链的双子脂质,HG-5,在N/P(脂质/DNA)比率为0.5和脂质:DOPE摩尔比为2时,显示出最高的转染活性。通过比较相关参数,例如转染细胞的百分比、每个细胞转染的DNA量和细胞存活率的百分比,与Lipofectamine 2000(市场上最好的商业转染试剂之一)相比,基于DOPE/HG-5的优化脂质配方被发现是可比的。就其在存在血清的情况下诱导基因转移的能力和保质期而言,DOPE/HG-5脂质体被发现优于其商业对应物。共聚焦成像分析证实,在10%血清的存在下,使用脂质:DOPE比率为1:4和N/P电荷比为0.75,每孔1.2 μg DNA,HG-5优于Lipofectamine 2000。