Turek J, Dubertret C, Jaslin G, Antonakis K, Scherman D, Pitard B
UMR7001, Vectorologie Moléculaire et Cellulaire, Ecole Nationale Supérieure de Chimie de Paris, France.
J Gene Med. 2000 Jan-Feb;2(1):32-40. doi: 10.1002/(SICI)1521-2254(200001/02)2:1<32::AID-JGM78>3.0.CO;2-U.
Cationic lipids are the most widely used nonviral vectors for gene delivery. Upon complexation to DNA, they offer a nonimmunogenic alternative to viral gene transfer. Unfortunately, their in vivo application has been limited due to a serum-associated inhibition of transfection. As a result, significant research effort has focused on overcoming this deleterious effect of serum.
To better understand this phenomenon, we investigated the influence of lipoplex colloidal stability on gene transfection in the presence of serum. In addition, conditions of the reaction medium were modulated and their effects on collidal stability and subsequent in vitro transfection efficiency were studied.
The colloidal stability of the cationic lipid-DNA complexes, which depended on the charge ratio, determined the efficiency of in vitro transfection in the presence of serum. In particular, large-sized, colloidally unstable complexes of over 700 nm mean diameter induced efficient transfection in the presence or absence of serum. Conversely, colloidally stable complexes of less than 250 nm in size resulted in efficient transfection only in the absence of serum. Furthermore, for the same charge ratio, both colloidally stable and unstable lipoplexes could be obtained depending on the degree to which various solution parameters (NaCl concentration, cationic lipid acyl chain length, pH and DNA concentration) were altered. In each case, only those complexes lacking colloidal stability resulted in high levels of in vitro transfection in the presence of serum. This phenomenon was shown to be independent of both the percent DNA internalized and of the lamellar organization of the cationic lipid/DNA lipoplexes.
Through the modulation of various mixture conditions, large-sized lipoplexes can be formed which are resistant to the transfection-inhibiting effect of serum.
阳离子脂质是基因传递中应用最广泛的非病毒载体。与DNA复合后，它们为病毒基因转移提供了一种非免疫原性替代方法。不幸的是，由于血清对转染的抑制作用，其体内应用受到了限制。因此，大量研究工作集中在克服血清的这种有害影响上。
为了更好地理解这一现象，我们研究了脂质体胶体稳定性对血清存在下基因转染的影响。此外，对反应介质的条件进行了调节，并研究了它们对胶体稳定性及随后体外转染效率的影响。
阳离子脂质-DNA复合物的胶体稳定性取决于电荷比，它决定了血清存在下的体外转染效率。特别是，平均直径超过700 nm的大尺寸、胶体不稳定的复合物在有无血清的情况下都能诱导高效转染。相反，尺寸小于250 nm的胶体稳定复合物仅在无血清时才导致高效转染。此外，对于相同的电荷比，根据各种溶液参数（NaCl浓度、阳离子脂质酰基链长度、pH和DNA浓度）改变的程度，可以得到胶体稳定和不稳定的脂质体。在每种情况下，只有那些缺乏胶体稳定性的复合物在血清存在下导致高水平的体外转染。这一现象表明与内化的DNA百分比和阳离子脂质/DNA脂质体的层状结构均无关。
通过调节各种混合条件，可以形成对血清转染抑制作用具有抗性的大尺寸脂质体。
