Preparation of dendritic graft copolymer consisting of poly-(L-lysine) and arabinogalactan as a hepatocyte specific DNA carrier

Effect of laminin, polylysine and cell medium components on the attachment of human hepatocellular carcinoma cells to cellulose nanofibrils analyzed by surface plasmon resonance

The development of in vitro cell models that mimic cell behavior in organs and tissues is an approach that may have remarkable impact on drug testing and tissue engineering applications in the future. Plant-based, chemically unmodified cellulose nanofibrils (CNF) hydrogel is a natural, abundant, and biocompatible material that has attracted great attention for biomedical applications, in particular for three-dimensional cell cultures. However, the mechanisms of cell-CNF interactions and factors that affect these interactions are not yet fully understood. In this work, multi-parametric surface plasmon resonance (SPR) was used to study how the adsorption of human hepatocellular carcinoma (HepG2) cells on CNF films is affected by the different proteins and components of the cell medium. Both human recombinant laminin-521 (LN-521, a natural protein of the extracellular matrix) and poly-l-lysine (PLL) adsorbed on CNF films and enhanced the attachment of HepG2 cells. Cell medium components (glucose and amino acids) and serum proteins (fetal bovine serum, FBS) also adsorbed on both bare CNF and on protein-coated CNF substrates. However, the adsorption of FBS hindered the attachment of HepG2 cells to LN-521- and PLL-coated CNF substrates, suggesting that serum proteins blocked the formation of laminin-integrin bonds and decreased favorable PLL-cell electrostatic interactions. This work sheds light on the effect of different factors on cell attachment to CNF, paving the way for the utilization and optimization of CNF-based materials for different tissue engineering applications.

Micelle-like nanoparticles as carriers for DNA and siRNA

Gene therapy represents a potential efficient approach of disease prevention and therapy. However, due to their poor in vivo stability, gene molecules need to be associated with delivery systems to overcome extracellular and intracellular barriers and allow access to the site of action. Cationic polymeric nanoparticles are popular carriers for small interfering RNA (siRNA) and DNA-based therapeutics for which efficient and safe delivery are important factors that need to be optimized. Micelle-like nanoparticles (MNP) (half micelles, half polymeric nanoparticles) can overcome some of the disadvantages of such cationic carriers by unifying in one single carrier the best of both delivery systems. In this review, we will discuss how the unique properties of MNP including self-assembly, condensation and protection of nucleic acids, improved cell association and gene transfection, and low toxicity may contribute to the successful application of siRNA- and DNA-based therapeutics into the clinic. Recent developments of MNP involving the addition of stimulus-sensitive functions to respond specifically to pathological or externally applied "triggers" (e.g., temperature, pH or enzymatic catalysis, light, or magnetic fields) will be discussed. Finally, we will overview the use of MNP as two-in-one carriers for the simultaneous delivery of different agents (small molecules, imaging agents) and nucleic acid combinations.

Development of biodegradable nanoparticles for liver-specific ribavirin delivery

Ribavirin is an antiviral drug used for the treatment of chronic hepatitis C. However, ribavirin induces severe side effects such as hemolytic anemia. In this study, we prepared biodegradable nanoparticles as ribavirin carriers to modulate the pharmacokinetics of the drug. The nanoparticles encapsulating ribavirin monophosphate (RMP) were prepared from the blend of poly(d,l-lactic acid) homopolymer and arabinogalactan (AG)-poly(l-lysine) conjugate by using the solvent diffusion method in the presence of iron (III). RMP was efficiently and stably embedded in the nanoparticles and gradually released for 37 days in phosphate-buffered saline at 37°C. The coating of AG on the nanoparticles surfaces was verified by measuring the zeta potentials and performing an aggregation test of the nanoparticles using galactose-binding lectin. Moreover, the nanoparticles were efficiently internalized in cultured HepG2 cells. Ribavirin was drastically accumulated to the liver of mice after intravenous administration of the RMP-loaded nanoparticles, after which the ribavirin content gradually decreased for at least 7 days. Our results indicated successful development of nanoparticles with dual functions, targeting to the liver and sustained release of ribavirin, and suggested that the present strategy could help to advance the clinical application of ribavirin as a therapeutic agent for chronic hepatitis C.

Design of polymer materials enhancing nucleotide hybridization for anti-gene technology

Stabilization of nucleotide hybridization is considered important for improving gene therapy using oligonucleotides. We have designed comb-type copolymer consisting of polycation backbone (polylysine) and hydrophilic side chains as a stabilizer for double and triple helical DNAs. The copolymer considerably increased the thermal stability of triple helical structure but did not affect the reversible transition between triple helical and single-stranded DNA. An in vitro electrophoretic mobility shift assay revealed that the copolymer remarkably increased association constants of both Hoogsteen and reverse Hoogsteen-type triple helix formation. Moreover the triple helix-stabilizing efficiency of the copolymer was significantly higher than that of other oligocations like spermine and spermidine. Not only being good DNA triple helix stabilizer, it has also been shown to accelerate DNA strand exchange reactions between double helical DNA and its complementary oligonucleotides. From these, we conclude that this copolymer is capable of either 'stabilizing' or 'activating' DNA hybrids, and may useful for gene targeting employing oligonucleotides.

Liver cell specific targeting of peptide nucleic acid oligomers

Chimeric molecules consisting of peptide nucleic acid (PNA) and lactose have been synthesized to test the hypothesis that lactose moieties can promote cell-specific uptake of PNAs. We find that lactose modified PNAs rapidly enter liver-derived HepG2 cells while unmodified PNAs do not and that lactose modified PNAs can inhibit cellular telomerase.

Recent progress in gene delivery using non-viral transfer complexes

The delivery of genetic material into cells is a field that is expanding very rapidly. Non-viral delivery methods, especially ones that focus on the use of chemical agents complexed with genetic material, are the focus of this mini-review. More-recent uses of known transfection agents such as poly(ethylenimine), poly(L-lysine), and various liposomes are discussed, and some novel approaches (both chemical and methodical) are reviewed as well. A very brief look at how non-viral gene delivery research is being aimed at the clinic is also included.