Weissig V, Lizano C, Torchilin V P
Department of Pharmaceutical Sciences, Bouve College of Health Sciences, Northeastern University, Boston, Massachusetts 02115, USA.
Drug Deliv. 2000 Jan-Mar;7(1):1-5. doi: 10.1080/107175400266722.
The number of diseases found to be associated with defects of the mitochondrial genome has grown significantly over the past decade (Wallace 1999). Despite major advances in understanding mtDNA defects at the genetic and biochemical level, there is no satisfactory treatment available for the vast majority of patients and the exploration of gene therapeutic approaches is highly warranted. However, mitochondrial gene therapy still appears only theoretical and speculative. Any possibility for gene replacement depends on the use of a yet unavailable mitochondria-specific transfection vector. Mitochondria-specific vectors must posses two properties: they have to transport DNA to the side of mitochondria; they must not release DNA during endocytosis. Amphiphile compounds with delocalized cationic charge centers such as rhodamine 123 and the bolaamphiphile dequalinium have long been known to accumulate in mitochondria. Sufficient lipophilicity combined with delocalization of the positive charge to reduce the free energy change when moving from an aqueous to a hydrophobic environment are believed to be prerequisite for mitochondrial accumulation in response to the mitochondrial membrane potential. We have recently succeeded in preparing cationic vesicles made of dequalinium that we termed DQAsomes (Weissig et al. 1998a). We have shown that DQAsomes bind and protect DNA against DNase activity (Lasch et al. 1999). Based on the intrinsic property of dequalinium to preferentially accumulate in mitochondria in response to the electrochemical gradient at the mitochondrial membrane, we believe that DQAsomes can serve as a vector to deliver DNA to mitochondria in living cells. As a first step in the development of mitochondria-specific DNA delivery systems, we report here that DQAsome/DNA complexes selectively release DNA at cardiolipin-rich liposomes mimicking both the inner and the outer mitochondrial membrane. We demonstrate that DNA remains tightly associated with DQAsomes in the presence of an excess of anionic lipids other than cardiolipin.
在过去十年中，已发现与线粒体基因组缺陷相关的疾病数量显著增加（华莱士，1999年）。尽管在遗传和生化水平上对线粒体DNA缺陷的理解取得了重大进展，但绝大多数患者仍没有令人满意的治疗方法，因此极有必要探索基因治疗方法。然而，线粒体基因治疗目前似乎仍只是理论上的和推测性的。基因替代的任何可能性都取决于使用一种尚未获得的线粒体特异性转染载体。线粒体特异性载体必须具备两个特性：它们必须将DNA转运到线粒体所在位置；它们在胞吞作用过程中不能释放DNA。长期以来，人们已知具有离域阳离子电荷中心的两亲化合物，如罗丹明123和双季铵盐去甲金霉素，会在线粒体中积累。足够的亲脂性与正电荷的离域相结合，以减少从水性环境转移到疏水环境时的自由能变化，被认为是响应线粒体膜电位而在线粒体中积累的先决条件。我们最近成功制备了由去甲金霉素制成的阳离子囊泡，我们将其称为双季铵盐脂质体（魏西格等人，1998a）。我们已经表明，双季铵盐脂质体能够结合并保护DNA免受DNase活性的影响（拉施等人，1999年）。基于去甲金霉素响应线粒体膜上的电化学梯度而优先在线粒体中积累的内在特性，我们认为双季铵盐脂质体可以作为一种载体，将DNA递送至活细胞的线粒体中。作为线粒体特异性DNA递送系统开发的第一步，我们在此报告，双季铵盐脂质体/DNA复合物在模拟线粒体内外膜的富含心磷脂的脂质体处选择性释放DNA。我们证明，在存在除心磷脂以外的过量阴离子脂质的情况下，DNA仍与双季铵盐脂质体紧密结合。
