DNA encapsulation

Higher expression levels were associated with the encapsulated DNA than with the administration of naked DNA in vitro, but standard liposomal transfection yielded the highest level of gene expression. In vivo, however, the encapsulated DNA exhibited higher levels of sustained expression of a marker gene at 28 days, than that associated with naked DNA or DNA delivered with liposomes. Thus, this study indicated the potential for DNA encapsulated in degradable nanospheres to elicit sustained gene expression in vivo. 

Vosch T, Antoku Y, Hsiang J-C, Richards Cl, Gonzalez JI, Dickson RM (2007) Strongly emissive individual DNA-encapsulated Ag nanoclusters as single-molecule fluorophores. Proc Natl Acad Sci 104 12616-12621... 

Particulate systems (e.g., collagen, lactic or glycolic acids, polyanhydride or polyethylene vinyl coacetate) have several potential advantages for the therapeutic delivery of DNA (or of drugs), such as DNA encapsulation within the polymer can protect DNA degradation until release injection or implantation of the polymer into the... 

Obata Y, Saito S, Takeda N et al (2009) Plasmid DNA-encapsulating liposomes effect of a spacer between the cationic head group and hydrophobic moieties of the lipids on gene expression efficiency. Biochim Biophys Acta-Biomembranes 1788 1148-1158... 

CL-DNA complexes form spontaneously when solutions of cationic liposomes (typically containing both a cationic lipid and a neutral helper lipid) are combined. We have discovered several distinct nanoscale structures of CL-DNA complexes by synchrotron X-ray diffraction, three of which are schematically shown in Fig. 1. These are the prevalent lamellar phase with DNA sandwiched between cationic membranes (Lo,c) [22], the inverted hexagonal phase with DNA encapsulated within inverse lipid tubes (Hnc) [23], and the more recently discovered Hj0 phase with hexagonally arranged rod-like micelles surrounded by DNA chains forming a continuous substructure with honeycomb symmetry [24]. Both the neutral lipid and the cationic lipid can drive the formation of specific structures of CL-DNA complexes. The inverse cone shape of DOPE favors formation of the... 

V. Kousaev, S. Sosnowski, S. Slomkowski, and G. Golomb. 2000. Sustained delivery and expression of DNA encapsulated in polymeric nanoparticles. Gene Ther. 7 1896-1905. 

Pfeifer, B. A., Burdick, J. A., Little, S. R., and Langer, R. (2005), Poly(ester-anhydride) poly(beta-amino ester) micro- and nanospheres DNA encapsulation and cellular transfection, Int. I. Pharm., 304(1-2), 210-219. 

In vivo gene expression in animals has been obtained after introduction of DNA encapsulated in liposomes, which are lipid vesicles that entrap the DNA. Further, tissue and cell type specificity has been conferred on the liposomes by coupling to cell-type specific antibodies, resulting in immunoliposom es°. In some cases a combination of liposomes and red blood cell membranes has been used for delivery (Feigner and Rhodes, 1991). 

Eguchi, A., Furusawa, H., Yamamoto, A., Akuta, T., Hasegawa, M., Okahata, Y. and Nakanishi, M. (2005) Optimization of nuclear localization signal for nuclear transport of DNA-encapsulating particle. Journal of Controlled Release, 104, 507-519. 

Although the evidence was not fully compelling, it was suggested that DNA-lipid interactions involved DNA encapsulation within a cylindrical inverted micelle, included in the lipid membrane (Figure 16.13). 

Lomas H, Canton I, MacNeU S, Du J, Armes SP, Ryan AJ, Lewis AL, Battaglia G (2007) Biomimetic pH sensitive polymersomes for efficient DNA encapsulation and delivery. Adv Mater 19 4238- 243... 

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