Natural lipid extracts and biomembrane-mimicking lipid compositions are disposed to form nonlamellar phases, and they release DNA from lipoplexes most efficiently
Natural lipid extracts and biomembrane-mimicking lipid compositions are disposed to form nonlamellar phases, and they release DNA from lipoplexes most efficiently
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DOI：
10.1016/j.bbamem.2007.04.026
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发表时间：
2007-10-01
影响因子：
3.4
通讯作者：
MacDonald, Robert C.
中科院分区：
文献类型：
--
作者：
Koynova, Rumiana;MacDonald, Robert C.
现在出现的观点是，脂质介导的转染（脂质转染）中的关键因素是脂质复合物在与细胞脂质相互作用和混合时的结构演变。在这里，我们报告了我们的发现，模拟生物膜脂质组合物的脂质混合物在从lipoplex（阳离子脂质/DNA复合物）释放DNA的能力方面上级纯阴离子脂质体，即使它们具有低得多的负电荷密度（因此中和lipoplex脂质的正电荷的能力较低）。流式荧光测定法显示，与阴离子磷脂酰丝氨酸或磷脂酰甘油的阳离子O-乙基磷脂酰胆碱脂质复合物孵育30分钟后释放的DNA部分分别为19%和37%，而模拟生物膜的混合物（MM：磷脂酰胆碱/磷脂酰乙醇胺/磷脂酰丝氨酸/胆固醇45：20：20：15 w/w）和牛肝极性脂质提取物分别释放62%和74%的DNA含量。天然脂质混合物释放DNA的这种上级能力的一个可能原因是由结构实验提出的：虽然纯阴离子脂质通常形成层状相，但天然脂质混合物表现出令人惊讶的形成非层状相的偏好。因此，MM混合物在生理温度下排列成层状阵列，但在稍高的温度下开始转化为六方相，类似于40-45摄氏度。在接近生理温度下形成非层状相（六方，立方，胶束）的倾向也被发现与天然组织（牛肝，脑，心脏）的脂质提取物。这一结果表明，静电相互作用只是脂质介导的DNA递送中涉及的因素之一。脂质双层形成非层状相的趋势已经被描述为双层“挫折”，这对两个相对的单层施加了非零的固有曲率。由于在“受抑”双层中储存的曲率弹性能似乎与阳离子脂质和DNA之间的结合能相当，因此这两种能量之间的平衡可能在脂质复合物-膜相互作用和DNA释放能量学中起重要作用。(C)2007 Elsevier B. V.保留所有权利。
A viewpoint now emerging is that a critical factor in lipid-mediated transfection (lipofection) is the structural evolution of lipoplexes upon interacting and mixing with cellular lipids. Here we report our finding that lipid mixtures mimicking biomembrane lipid compositions are superior to pure anionic liposomes in their ability to release DNA from lipoplexes (cationic lipid/DNA complexes), even though they have a much lower negative charge density (and thus lower capacity to neutralize the positive charge of the lipoplex lipids). Flow fluorometry revealed that the portion of DNA released after a 30-min incubation of the cationic O-ethylphosphatidylcholine lipoplexes with the anionic phosphatidylserine or phosphatidylglycerol was 19% and 37%, respectively, whereas a mixture mimicking biomembranes (MM: phosphatidylcholine/phosphatidylethanolamine/phosphatidylserine /cholesterol 45:20:20:15 w/w) and polar lipid extract from bovine liver released 62% and 74%, respectively, of the DNA content. A possible reason for this superior power in releasing DNA by the natural lipid mixtures was suggested by structural experiments: while pure anionic lipids typically form lamellae, the natural lipid mixtures exhibited a surprising predilection to form nonlamellar phases. Thus, the MM mixture arranged into lamellar arrays at physiological temperature, but began to convert to the hexagonal phase at a slightly higher temperature, similar to 40-45 degrees C. A propensity to form nonlamellar phases (hexagonal, cubic, micellar) at close to physiological temperatures was also found with the lipid extracts from natural tissues (from bovine liver, brain, and heart). This result reveals that electrostatic interactions are only one of the factors involved in lipid-mediated DNA delivery. The tendency of lipid bilayers to form nonlamellar phases has been described in terms of bilayer "frustration" which imposes a nonzero intrinsic curvature of the two opposing monolayers. Because the stored curvature elastic energy in a "frustrated" bilayer seems to be comparable to the binding energy between cationic lipid and DNA, the balance between these two energies could play a significant role in the lipoplex-membrane interactions and DNA release energetics. (C) 2007 Elsevier B.V. All rights reserved.