Liposome complexation

Figure 7 Pharmacokinetic properties and in vivo gene expression of stabilized plasmid-lipid particles (SPLP). (A) The levels of intact plasmid DNA (pDNA) in the circulation resulting from IV injection of naked plamid pDNA ( ), lipoplexes (O), and SPLP ( ) were determined by Southern blot analysis of plasma samples (100 pg pDNA/mouse). (B) Transgene expression at a distal tumor site resulting from rv injection of naked plamid pDNA ( ), plamid pDNA-cationic liposome complexes (O), and SPLP ( ).

Nabel GJ, Nabel EG, Yang ZY, et al. Direct gene transfer with DNA-liposome complexes in melanoma expression, biologic activity, and lack of toxicity in humans. Proc Natl Acad Sci USA 1993 90(23) 11307-11311. 

Gershon H, Ghirlando R, Guttman SB, Minsky A. Mode of formation and structural features of DNA-cationic liposome complexes used for transfection. Biochemistry 1993 32(28) 7143-7151. 

Radler JO, Koltover I, Salditt T, Safinya CR. Structure of DNA-cationic liposome complexes DNA intercalation in multilamellar membranes in distinct interhelical packing regimes. Science 1997 275(5301) 810-814. 

Integrin receptor-binding peptides have been used to enhance liposome binding, uptake, and expression (25,47 9). The inclusion of an 0(5pi integrin-targeted peptide into a liposomal complex enhanced transfection efficiency four- to five-fold in Jurkat cells and 10- to 13-fold in TF-1 cells (48). Confocal and electron microscopy revealed that the mechanism of cell entry conferred by RGD peptides on liposomes is predominantly by clathrin-coated endocytosis rather than by phagocytosis (50). 

Zhu, J., Zhang, L., Hanisch, U. K., Feigner, P. L., and Reszka, R. (1996b). In vivo gene therapy of experimental brain tumors by continuous administration of DNA-liposome complexes. Gene Therapy, 3,472-6. 

Similarly comb-like copolymers of vinyl pyrollidone and vinyl alkyl amines were shown [446] to influence the permeability of negatively charged phospholipid liposomes containing encapsulated carboxyfluorescein. At a pH of approximately 7, the copolymers allowed permeability and solute release due to polymer/liposome complex formation and disruption of the phospholipid membrane. 

Successful gene delivery by use of cationic liposomes requires the following conditions (134) (1) condensation of DNA into the complex and its protection from degradation by intracellular nucleases (2) adhesion of DNA-lipid complex onto the cellular surface (3) complex internalization (4) fusion of an internalized DNA-cationic liposome complex with the endosome membrane (5) escape of DNA from the endosome (6) entry of DNA into the nucleus followed by gene expression. 

Spermine has been found to enhance the transfection efficiency of DNA-cationic liposome complexes in cell culture and in animal studies this biogenic polyamine at high concentrations caused liposome fusion most likely promoted by the simultaneous interaction of one molecule of spermine (four positively charged amino groups) with the polar head groups of two or more molecules of lipids. At low concentrations (0.03-0.1 mM) it promoted anchorage of the liposome-DNA complex to the surface of cells and enhanced significantly transfection efficiency. 

A number of factors for DOTAP-cholesterol/DNA complex preparation including the DNA/liposome ratio, mild sonication, heating, and extrusion were found to be crucial for improved systemic delivery maximal gene expression was obtained when a homogeneous population of DNA/liposome complexes (200-450 nm) was used. Cryoelectron microscopy showed that the DNA was condensed on the interior of liposomes between two lipid bilayers in these formulations, a factor that was thought to be responsible for the high transfection efficiency in vivo and for the broad tissue distribution (150). 

Nomura, T., Yasuda, K., Yamada, T., et al. (1999). Gene expression and antitumor effects following direct interferon (IFN)-gamma gene transfer with naked plasmid DNA and DC-chol liposome complexes in mice. Gene Ther., 6(1), 121-129. 

G.N. (1997). Improved DNA Liposome complexes for increased systemic delivery and gene expression. Nat. Biotechnol., 15, 647-652. 

In many cases in drug development, the solubility of some leads is extremely low. Fast dissolution rate of many drug delivery systems, for example, particle size reduction, may not be translated into good Gl absorption. The oral absorption of these molecules is usually limited by solubility (VWIImann et al., 2004). In the case of solubility limited absorption, creating supersaturation in the Gl Luids for this type of insoluble drugs is very critical as supersaturation may provide great improvement of oral absorption (Tanno et al., 2004 Shanker, 2005). The techniques to create the so-called supersaturation in the Gl Luids may include microemulsions, emulsions, liposomes, complexations, polymeric micelles, and conventional micelles, which can be found in some chapters in the book. 

Koltover, I., Salditt, T., Raedler, J.O. and Safinya, C.R. (1998) An inverted hexagonal phase of DNA-cationic liposome complexes related to DNA release and delivery. Science, 281, 78-81. 

Nomura, T., Nakajima, S., Kawabata, K., Yamashita, F., Takakura, Y. and Hashida, M. (1997) Intratumoral pharmacokinetics and in vivo gene expression of naked plasmid DNA and its cationic liposome complexes after direct gene transfer. Cancer Res., 57, 2681-2686. 

Laitinen, M., Pakkanen, T., Donetti, E., Baetta, R., Luoma, J., Lehtolainen, P. et al. (1997a) Gene transfer into the carotid artery using an adventitial collar comparison of the effectiveness of the plasmid-liposome complexes, retroviruses, pseudotyped retroviruses, and adenoviruses. Hum. Gene Then, 8, 1645-1650. 

Pakkanen, T.M., Laitinen, M., Hippelainen, M., Hiltunen, M.O., Alhava, E. and Yla-Herttuala, S. (2000) Periadventitial lacZ gene transfer to pig carotid arteries using a biodegradable collagen collar or a wrap of collagen sheet with adenoviruses and plasmid-liposome complexes. J. Gene Med. 2, 52-60. 

Subramanian M, Holopainen JM, Paukku T et al (2000) Characterisation of three novel cationic lipids as liposomal complexes with DNA. Biochim Biophys Acta-Biomembranes 1466 289-305... 

Thalidasine (i.p., mice) Thalidasine liposome complexes were more effec- 526,527... 

The surface characteristics of net anionic DNA-liposome complexes are distinctly different from classic cationic liposome-DNA complexes and, therefore, their interaction with biological fluids and membranes is different. In Figure 3, the transfection efficacy of both types of complexes in the presence of serum... 

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