Biomedical subjects

J S Remy

Publications and source records attributed to J S Remy.

21 records · Page 2Linked to original sources

PubMedDate not supplied

Size reduction of galactosylated PEI/DNA complexes improves lectin-mediated gene transfer into hepatocytes.

Hepatocytes are interesting targets for gene therapy applications. Several hepatocyte-directed gene delivery vectors have been described. For example, simple galactosyl residues coupled to polyethylenimine (PEI) gave an efficient vector which selectively transfected hepatocytes via the asialoglycoprotein receptor-mediated endocytosis [Zanta, M. A., et al. (1997) Bioconjugate Chem. 8, 839-844]. However, the large size of these galactosylated PEI/DNA complexes prevented their use in vivo. We have investigated the role of the saccharide length on the size of glycosylated-PEI/DNA particles. When 5% of the PEI nitrogens were grafted with a linear tetragalactose structure (lGal4), small and stable particles were formed upon complexation with plasmid DNA. These particles were essentially toroids having a size of 50-80 nm and a zeta-potential close to neutrality. Moreover, these slightly charged PEI-lGal4/DNA complexes were as selective as the previously described galactosylated-PEI vector to transfect hepatocytes, but in addition, they were more efficient. It is expected that the properties of the PEI-lGal4/DNA complexes may increase their diffusion into the liver and their efficiency to transfect hepatocytes.

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PubMedDate not supplied

Controlled template-assisted assembly of plasmid DNA into nanometric particles with high DNA concentration.

A series of novel cationic detergents that contain cleavable hydrophilic isothiuronium headgroups was synthesized, and their utility in controlled assembly of plasmid DNA into small stable particles with high DNA concentration investigated. The detergents have alkyl chains of C(8)-C(12) and contain hydrophilic isothiuronium headgroups that give relatively high critical micelle concentration (CMC) to the detergents (>10 mM). The isothiuronium group masks a sulfhydryl group on the detergent and can be cleaved in a controlled manner under basic conditions to generate a reactive thiol group. The thiol group can undergo a further reaction after the detergents have accumulated on a DNA template to form a disulfide-linked lipid containing two alkyl chains. The pH-dependent kinetics of cleavage of the isothiuronium group, the CMC of the surfactants, the formation of the complexes, and the transfection efficiency of the DNA complexes have been investigated. Using the C(12) detergent, a approximately 6 kilo-basepair plasmid DNA was compacted into a small particle with an average diameter of around 40 nm with a approximately -13 mV zeta-potential at high DNA concentration (up to 0.3 mg/mL). The compounds were well tolerated in cell culture and showed no cytotoxicity under their CMCs. Under appropriate conditions, the small particle retained transfection activity.

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PubMedDate not supplied

Gene transfer optimization with lipospermine-coated DNA.

Designed synthetic DNA carriers represent an attractive alternative to the widely used calcium phosphate gene transfer technique. In this context, we developed a class of nucleic acid binding lipids, the lipopolyamines, which spontaneously condense DNA on a cationic lipid layer. The resulting nucleolipidic particles transfect most animal cells efficiently. However, compaction depends on many experimental factors, some of which have been varied here to give optimal transfection efficiency. When plasmid condensation by the lipospermine is performed in the absence of competing polyions or serum proteins, or when the gene of interest is diluted into carrier DNA, transfection efficiency is increased by 2-3 orders of magnitude. With these improvements, chloramphenicol acetyl transferase activity resulting from transfection of as little as 25 ng could easily be detected by a nonradioactive ELISA test.

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