The delivery of antisense therapeutics

Synthesis of oligonucleotide glycoconjugates using sequential click and oximation ligations

Oligodeoxyribonucleotide glycoconjugates bearing two trivalent glycoclusters have been synthesized by two alternative methods based on solid-supported oximation of aminooxy functionalized oligonucleotides with glycoclusters constructed by click chemistry. In more detail, the trivalent glycoclusters (5 and 6) bearing three sugar pendants were first assembled by treating a 4-[tri-O-propargylpentaerythrityloxy]benzaldehyde scaffold with methyl 6-azido-6-deoxyglycopyranoside under the click reaction conditions. Two phosphoramidite reagents containing a phthaloyl protected aminooxy function, viz., 2-cyanoethyl N,N-diisopropylphosphoramidites derived from 3-[3,5-bis(phthalimidoxymethyl)phenoxy]propanol (12) and 5-(4,4'-dimethoxytrityl)-1,2-dideoxy-1-C-(2-phthalimidoxyethyl)-beta-d-erythro-pentofuranose (16), were synthesized and incorporated as branching units in appropriate places of the oligonucleotide chains. On using 12, the phthaloyl protections of the branching unit were removed and two identical glycoclusters were attached via oxime linkage to the 5'-terminus of the support-bound oligonucleotide chain. With branching unit 16, the phosphoramidite coupling and the oximation were carried out alternately, allowing introduction of two dissimilar trivalent glycoclusters close to the 3'-end of the oligonucleotide chain. The products (20, 26) were released and deprotected by ammonolysis and purified by HPLC chromatography.

Carbonate apatite-facilitated intracellularly delivered siRNA for efficient knockdown of functional genes

Gene therapy through intracellular delivery of a functional gene or a gene-silencing element is a promising approach to treat critical diseases. Elucidation of the genetic basis of human diseases with complete sequencing of human genome revealed many vital genes as possible targets in gene therapy programs. RNA interference (RNAi), a powerful tool in functional genomics to selectively silence messenger RNA (mRNA) expression, can be harnessed to rapidly develop novel drugs against any disease target. The ability of synthetic small interfering RNA (siRNA) to effectively silence genes in vitro and in vivo, has made them particularly well suited as a drug therapeutic. However, since naked siRNA is unable to passively diffuse through cellular membranes, delivery of siRNA remains the major hurdle to fully exploit the potential of siRNA technology. Here pH-sensitive carbonate apatite has been developed to efficiently deliver siRNA into the mammalian cells by virtue of its high affinity interactions with the siRNA and the desirable size of the resulting siRNA/apatite complex for effective cellular endocytosis. Moreover, following internalization by cells, siRNA was found to be escaped from the endosomes in a time-dependent manner and finally, more efficiently silenced reporter genes at a low dose than commercially available lipofectamine. Knockdown of cyclin B1 gene with only 10nM of siRNA delivered by carbonate apatite resulted in the significant death of cancer cells, suggesting that the new method of siRNA delivery is highly promising for pre-clinical and clinical cancer therapy.

Topical and intravitreous administration of cationic nanoemulsions to deliver antisense oligonucleotides directed towards VEGF KDR receptors to the eye

Antisense oligonucleotides (ODNs) specific for VEGFR-2-(17 MER) and inhibiting HUVEC proliferation in-vitro were screened. One efficient sequence was selected and incorporated in different types of nanoemulsions the potential toxicity of which was evaluated on HUVEC and ARPE19 cells. Our results showed that below 10 microl/ml, a 2.5% mid-chain triglycerides cationic DOTAP nanoemulsion was non-toxic on HUVEC and retinal cells. This formulation was therefore chosen for further experiments. In-vitro transfection of FITC ODNs in ARPE cells using DOTAP nanoemulsions showed that nanodroplets do penetrate into the cells. Furthermore, ODNs are released from the nanoemulsion after 48 h and accumulate into the cell nuclei. In both ex-vivo and in-vivo ODN stability experiments in rabbit vitreous, it was noted that the nanoemulsion protected at least partially the ODN from degradation over 72 h. The kinetic results of fluorescent ODN (Hex) distribution in DOTAP nanoemulsion following intravitreal injection in the rat showed that the nanoemulsion penetrates all retinal cells. Pharmacokinetic and ocular tissue distribution of radioactive ODN following intravitreal injection in rabbits showed that the DOTAP nanoemulsion apparently enhanced the intraretinal penetration of the ODNs up to the inner nuclear layer (INL) and might yield potential therapeutic levels of ODN in the retina over 72 h post injection.

[Antisense oligonucleotides for therapy of cystic fibrosis. Inhibition of sodium absorption mediated by ENaC in nasal epithelial cells]

BACKGROUND

The genetic disease cystic fibrosis (CF) is characterised by reduced chloride secretion mediated by the cystic fibrosis transmembrane conductance regulator (CFTR) and Na(+) hyperabsorption through amiloride-sensitive epithelial sodium channels (ENaC). Mutations in CFTR cause the accumulation of thick mucus and dysfunction of mucociliary clearance in the respiratory tract.

MATERIAL AND METHODS

In this project it was investigated whether Na(+) hyperabsorption is inhibited by the use of antisense oligonucleotides (AON). For functional analyses monolayers of human non-CF and CF nasal epithelial cells were measured in modified Ussing chambers. To analyse the AON effects on the protein level Western blotting analyses were carried out.

RESULTS

AON transfection significantly inhibits Na(+) absorption via ENaC in non-CF and CF cells. Furthermore, Western blot analyses demonstrate a suppression of the ENaC protein in AON transfected human non-CF cells.

CONCLUSION

The inhibition of ENaC associated Na(+) absorption by specific AON could offer a new perspective for the regulation of the Na(+) hyperabsorption in CF patients.

Stepwise synthesis of oligonucleotide-peptide conjugates containing guanidinium and lipophilic groups in their 3'-termini

Two different series of oligonucleotide-peptide conjugates have been efficiently synthesized by stepwise solid-phase synthesis. First, oligonucleotides and oligonucleotide phosphorothioates containing polar groups at the 3'-termini, such as amine and guanidinium groups were prepared. ODNs conjugates carrying several lysine residues were obtained directly from Fmoc deprotection whereas ODN conjugates with guanidinium groups were obtained by post-synthetic guanidinylation. The second family contains different urea moieties that were achieved by standard protocols. All products were fully characterized by reversed phase HPLC and MALDI-TOF mass spectrometry yielding satisfactory results. Oligonucleotide-phosphorothioate conjugates were evaluated as potential antisense oligonucleotides in the inhibition of the luciferase gene.

Development of pH-responsive nanocarriers using trimethylchitosans and methacrylic acid copolymer for siRNA delivery

RNA interference-based therapies are dependent on intracellular delivery of siRNA. The release of siRNA from the endosomal compartment may be a rate limiting step in the transfection process. The purpose of this study was to produce pH-responsive nanocarriers made of trimethylchitosan (TMC). To this end, pH-sensitive methacrylic acid (MAA) copolymer was added to TMC-siRNA formulations. Four different TMCs associated or not with MAA were evaluated as siRNA carriers. Nanoparticles were characterized in terms of size, surface charge, morphology and interaction with siRNA. A swelling behaviour due to a decrease in pH was observed and was found to be dependent on MAA content in the complexes. In vitro experiments aimed at evaluating how the capacity of the nanocarriers to transfect siRNA in L929 cells was affected by MAA content. Confocal microscopy experiments showed that fluorescent MAA-containing particles exhibit a different distribution pattern inside the cells comparing to their counterpart without this pH-sensitive polymer. Transfection efficiency was investigated by RhoA mRNA expression inhibition. MAA-TMC-siRNA complexes were able to transfect L929 cells with greater efficiency than corresponding TMC-siRNA complexes. This study gives an insight into the opportunity of pH-sensitive nanocarriers for siRNA delivery. Such formulations may represent an attractive strategy to improve endosomal escape of siRNA.

Specific inhibition of epithelial Na+ channels by antisense oligonucleotides for the treatment of Na+ hyperabsorption in cystic fibrosis

BACKGROUND

Cystic fibrosis (CF) respiratory epithelia are characterized by a defect Cl(-) secretion and an increased Na(+) absorption through epithelial Na(+) channels (ENaC). The present study aimed to find an effective inhibitor of human ENaC with respect to replacing amiloride therapy for CF patients. Therefore, we developed specific antisense oligonucleotides (AON) that efficiently suppress Na(+) hyperabsorption by inhibiting the expression of the alpha-ENaC subunit.

METHODS

We heterologously expressed ENaC in oocytes of Xenopus laevis for mass screening of AON. Additionally, primary cultures of human nasal epithelia were transfected with AON and were used for Ussing chamber experiments, as well as biochemical and fluorescence optical analyses.

RESULTS

Screening of several AON by co-injection or sequential microinjection of AON and ENaC mRNA in X. laevis oocytes led to a sustained decrease in amiloride-sensitive current and conductance. Using primary cultures of human nasal epithelia, we show that AON effectively suppress amiloride-sensitive Na(+) absorption mediated by ENaC in CF and non-CF tissues. In western blot experiments, it could be shown that the amount of ENaC protein is effectively reduced after AON transfection.

CONCLUSIONS

Our data comprise an initial step towards a preclinical test with AON to reduce Na(+) hyperabsorption in CF epithelia.

Oral delivery of siRNA and antisense oligonucleotides

Inhibition of gene expression with antisense oligonucleotides or RNA interference (RNAi) mediated gene silencing by small interfering RNA (siRNA) has tremendous potential to silence the expression of disease-causing genes in the clinic. A major hurdle to their widespread clinical use is the safe and efficient delivery to target cells in vivo. Delivery via the oral route is considered the holy grail for small molecule and macromolecular drug delivery as it has the advantages of ease of administration, increased patient compliance, and cost-effectiveness. However, the harsh biological milieu of the acidic stomach and enzyme-rich gastrointestinal tract make efficient delivery of oligonucleotides and siRNA via the oral route difficult. Nonetheless, the first studies on the oral delivery of siRNA in animals and antisense oligonucleotides in humans suggest that significant oral delivery of these nucleic acids can be achieved across the gut wall. This can occur either by encapsulating siRNA within biodegradable particles that protect them from degradation and target them to M cells in intestinal Peyer's patches or by using chemically stabilized antisense oligonucleotides together with a penetration enhancer. This article reviews these studies as they mark important advances in the delivery of gene silencing nucleic acids and have heralded a new wave of enthusiasm that might lead to a significant expansion of the therapeutic options available for gene silencing drugs in the clinic.

DNA as therapeutics; an update

Human gene therapy is the introduction of new genetic material into the cells of an individual with the intention of producing a therapeutic benefit for the patient. Deoxyribonucleic acid and ribonucleic acid are used in gene therapy. Over time and with proper oversight, human gene therapy might become an effective weapon in modern medicine's arsenal to help fight diseases such as cancer, acquired immunodeficiency syndrome, diabetes, high blood pressure, coronary heart disease, peripheral vascular disease, neurodegenerative diseases, cystic fibrosis, hemophilia and other genetic disorders. Gene therapy trials in humans are of two types, somatic and germ line gene therapy. There are many ethical, social, and commercial issues raised by the prospects of treating patients whose consent is impossible to obtain. This review summarizes deoxyribonucleic acid-based therapeutics and gene transfer technologies for the diseases that are known to be genetic in origin. Deoxyribonucleic acid-based therapeutics includes plasmids, oligonucleotides for antisense and antigene applications, deoxyribonucleic acid aptamers and deoxyribonucleic acidzymes. This review also includes current status of gene therapy and recent developments in gene therapy research.

Solid-phase synthesis of oligonucleotide conjugates useful for delivery and targeting of potential nucleic acid therapeutics

Olignucleotide-based drugs show promise as a novel form of chemotherapy. Among the hurdles that have to be overcome on the way of applicable nucleic acid therapeutics, inefficient cellular uptake and subsequent release from endosomes to cytoplasm appear to be the most severe ones. Covalent conjugation of oligonucleotides to molecules that expectedly facilitate the internalization, targets the conjugate to a specific cell-type or improves the parmacokinetics offers a possible way to combat against these shortcomings. Since workable chemistry is a prerequisite for biological studies, development of efficient and reproducible methods for preparation of various types of oligonucleotide conjugates has become a subject of considerable importance. The present review summarizes the advances made in the solid-supported synthesis of oligonucleotide conjugates aimed at facilitating the delivery and targeting of nucleic acid drugs.

Synthesis and characterization of mannosylated oligoribonucleotides

Oligoribonucleotide (RNA)-carbohydrate conjugates bearing mono- and divalent mannosides were readily obtained using 3,4-diethoxy-3-cyclobutene-1,2-dione as the linking agent in the presence of trace amount of triethylamine. The glycoconjugates were purified by HPLC and characterized by electrospray mass spectroscopy.

Suppression of matrix metalloproteinase-9 expression by RNA interference inhibits SGC7901 gastric adenocarcinoma cell growth and invasion in vitro and in vivo

Matrix metalloproteinase-9 (MMP-9) is considered the key enzyme that degrades extracellular matrix (ECM) via breaking down type IV collagens. Up-regulated MMP-9 promotes growth and invasion of gastric adenocarcinomas. The present study is to block MMP-9 expression in gastric adenocarcinoma cells in order to inhibit tumor growth and invasion. The association between MMP-9 expression and tumor pathology was reconfirmed by applying immunohistochemistry on tissue arrays. Small interference RNAs (siRNA) targeted on human MMP-9 were used to suppress gene expression in SGC7901 human gastric adenocarcinoma cells. Cell growth and invasion were significantly inhibited in specific siRNA-targeted cells. In addition, we generate a SGC7901-subcutaneous mice model to observe anti-tumor effects from RNA interference (RNAi). Data showed tumor masses in MMP-9 siRNA-treated mice were significantly smaller than those in control mice. The expression of vascular endothelial growth factor and proliferating cell nuclear antigen were down-regulated in MMP-9 siRNA treated cells. Our results demonstrate that MMP-9 targeted RNAi is able to successfully suppress MMP-9 gene expression and inhibit cell growth and invasion of SGC7901 gastric adenocarcinoma in vitro and in vivo. MMP-9 is a potential therapeutic target for gastric adenocarcinomas.

Antitumor activity of G3139 lipid nanoparticles (LNPs)

G3139, an antisense oligodeoxyribonucleotide (ODN) against Bcl-2, contains two CpG dinucleotides and has shown immunostimulatory activities in preclinical studies. It has been suggested that immunoactivation, rather than antisense activity, is primarily responsible for the therapeutic efficacy of G3139. Nanoparticle formulations naturally target phagocytic antigen presenting cells and therefore might enhance the immunological effects of G3139. In this study, a novel formulation of lipid nanoparticles (LNPs) encapsulating G3139 was synthesized and evaluated in mice bearing L1210 subcutaneous tumors. Intravenous injection of G3139-LNPs into mice led to increased serum levels of IL-6 and IFN-gamma, promoted proliferation of natural killer (NK) cells and dendritic cells (DCs), and triggered a strong antitumor immune response in mice. The observed effects were much greater than those induced by free G3139. Correspondingly, the G3139-LNPs more effectively inhibited tumor growth and induced complete tumor regression in some mice. In contrast, free G3139 was ineffective in tumor growth inhibition and did not prolong survival of the tumor-bearing mice. These results suggest that G3139-LNPs are a potential immunomodulatory agent and may have applications in cancer therapy.

Studies on the hydrolytic stability of 2'-fluoroarabinonucleic acid (2'F-ANA)

The stability of 2'-deoxy-2'-fluoroarabinonucleic acid (2'F-ANA) to hydrolysis under acidic and basic conditions was compared to that of DNA, RNA and 2'F-RNA. In enzyme-free simulated gastric fluid (pH approximately 1.2), 2'F-ANA was found to have dramatically increased stability (virtually no cleavage observed after 2 days) with respect to both DNA (t(1/2) approximately 2 min) and RNA (t(1/2) approximately 3 h (PO) or 3 days (PS)). These results were observed for both phosphodiester and phosphorothioate backbones and with multiple mixed-base sequences. Under basic conditions, 2'F-ANA also showed good stability. In 1 M NaOH at 65 degrees C, 2'F-ANA had a t(1/2) of approximately 20 h, while RNA was entirely degraded in a few minutes. Furthermore, the nuclease cleavage of phosphorothioate 2'F-ANA and DNA by snake venom phosphodiesterase was studied in detail. One diastereomer of the PS-2'F-ANA linkage was found to be much more vulnerable to enzymatic cleavage than the other, which is parallel to the properties observed for PS-DNA. Additional studies of 2'F-ANA-containing oligonucleotides are warranted based on the excellent stability properties described here.

Topical delivery of interleukin-13 antisense oligonucleotides with cationic elastic liposome for the treatment of atopic dermatitis

BACKGROUND

Interleukin (IL)-13, overproduced in the skin of atopic dermatitis (AD), has been shown to play an essential role in the pathogenesis of the disease. Thus, inhibition of IL-13 production should provide a key step to alleviate disease conditions of the atopic skin. In the present study, IL-13 antisense oligonucleotide (ASO) was designed and formulated with cationic elastic liposome (cEL) to improve transdermal delivery.

METHODS

ASOs were generated against murine IL-13 mRNA (+4 to + 23) and complexed with cEL. Physicochemical properties of IL-13 ASO/cEL complex were examined by DNA retardation and DNase I protection assay. An in vitro inhibition study was performed in T-helper 2 (Th2) cells and cytotoxicity was tested by the XTT assay. The in vivo effect of IL-13 ASO/cEL complex was tested in a murine model of AD.

RESULTS

In vitro, the IL-13 ASO/cEL complex showed dose- and ratio-dependent inhibition of IL-13 secretion in Th2 cells. At the IL-13 ASO/cEL ratio of 6, maximum inhibition of IL-13 secretion was observed. When applied to the ovalbumin-sensitized murine model of AD, topically administered IL-13 ASO/cEL complex dramatically suppressed IL-13 production (by up to 70% of the control) in the affected skin region. In addition, the levels of IL-4 and IL-5 were also significantly reduced. Moreover, IL-13 ASO/cEL-treated AD mice showed reduced infiltration of inflammatory cells into the epidermal and dermal areas, with concomitant reduction of skin thickness.

CONCLUSIONS

These data suggests that IL-13 ASO/cEL complex can provide a potential therapeutic tool for the treatment of AD and also be applied to other immune diseases associated with the production of Il-13.

In vitro and in vivo tumor suppressive activity induced by human telomerase transcriptase-targeting antisense oligonucleotides mediated by cationic liposomes

The objective of this study was to investigate the in vitro and in vivo influence of cationic liposomes on the tumor suppressive effect of antisense telomerase oligodeoxynucleotides to human cervical adenocarcinoma cells (HeLa). Antisense oligodeoxynucleotides (ASODN) against the human telomerase transcriptase (hTERT) served as telomerase inhibitors. The cholesterol derivative, 3beta [N-(N',N'-dimethylaminoethane)-carbamoyl] cholesterol (DC-Chol), was synthesized, and cationic liposomes (CL) were prepared using DC-Chol and dioleoylphosphatidylethanolamine (DOPE). The in vitro IC50 of the CL-ASODN complex was 1.88 mumol/l, while the IC50 of the cells treated with free ASODNs or CL alone was 25.24 mumol/l and 55.18 mumol/l, respectively. The CL-ASODN complex inhibited HeLa cell growth for at least 120 h. In vivo, the CL-ASODN complex inhibited the tumor growth rate by 55.11%, which increased to 89.47% when CL-ASODN was combined with 5-fluorouracil treatment. ASODNs alone failed to induce tumor-suppressive activity, suggesting that CL prepared from DOPE and DC-Chol can significantly enhance the growth inhibitory effect of ASODN on tumor cells both in vitro and in vivo.

Efficient siRNA delivery with non-viral polymeric vehicles

Sequence-specific gene silencing using small interfering RNA (siRNA) provides a potent and specific method for gene expression, thus is now being evaluated in clinical trials as a novel therapeutic strategy. As a results, there has been a significant surge of interest in the application of siRNA in therapeutics as a means of silencing the specific gene function. However, for siRNA technology to be valuable and effective, the development of efficient siRNA delivery strategy is essential for improving biological activities such as stability, cellular uptake, sequence-specificity, devoid of nonspecific knockdown and toxic side effects. Accordingly, a number of delivery systems, both viral and nonviral, have been reported and some of them successfully used for the introduction of siRNA into cells both in vitro and in vivo. Here, we discuss the current understanding of synthetic siRNA delivery mechanism and strategies of siRNA delivery by non-viral polymeric vehicles which are currently used in vitro and in vivo.

Polypropylenimine dendrimer-induced gene expression changes: The effect of complexation with DNA, dendrimer generation and cell type

Polypropylenimine (PPI) dendrimers appear attractive non-viral vectors for the delivery of genes, antisense oligonucleotides, and small interfering RNA (siRNA). However, the effects of these synthetic gene delivery vectors on global gene expression are poorly understood. Here we have examined the toxicogenomics of generation 2 (DAB-8) and generation 3 (DAB-16) PPI dendrimers in two human cell lines. At concentrations and treatment protocols routinely used for gene and oligonucleotide transfection, PPI dendrimers alone elicited marked changes in endogenous gene expression in A431 epithelial cells. The extent of PPI-induced gene changes appeared to be dependent on the dendrimer generation as the number of genes affected was greater with G3 compared to G2 PPI dendrimers in A431 cells. The signature of DAB16-induced gene changes in A549 cells was different to those elicited in A431 cells implying a strong dependence on cell type. The DAB-16 polymer complexed with DNA (dendriplexes) also elicited marked gene expression changes in A549 cells but with a signature that was different from the polymer alone implying that dendriplexes are "recognised" by cells as chemical entities that are distinct from the polymer alone. Alterations in expression of a variety of gene ontologies were observed including those involved in defence responses, cell proliferation and apoptosis. Although there was a tendency for increased DNA damage in cells treated with DAB16 alone or its DNA dendriplexes as detected by the COMET assay, these differences were not statistically significant. These data show for the first time that PPI-dendrimers, separate from their capability as transfection reagents, can intrinsically alter the expression of many endogenous genes that could potentially lead to them exerting multiple biological effects in cells. The impact and consequences of polymer-induced gene changes should guide their rational use as delivery systems for gene-based therapeutics.

Tumour Angiogenesis, Vascular Biology and Enhanced Drug Delivery

It is now common knowledge that for a solid tumour to become life-threatening clinically, an adequate blood supply to the neoplasm has to be established. Although neovascularisation via angiogenesis leads to a subsequent rapid growth of the tumour mass, it provides the most reliable route by which neoplastic cells may be reached by cytotoxics. In addition, for a majority of tumours, the lesion's vasculature is more permeable and tortuous than that of the surrounding healthy host tissue. Such deviation potentiates selective delivery of drugs to be achieved. This review examines, from various viewpoints, the area of tumour angiogenesis and vascularisation, currently one of the most fertile and active fields of cancer research.

Advances in antisense oligonucleotide development for target identification, validation, and as novel therapeutics

Antisense oligonucleotides (As-ODNs) are single stranded, synthetically prepared strands of deoxynucleotide sequences, usually 18–21 nucleotides in length, complementary to the mRNA sequence of the target gene. As-ODNs are able to selectively bind cognate mRNA sequences by sequence-specific hybridization. This results in cleavage or disablement of the mRNA and, thus, inhibits the expression of the target gene. The specificity of the As approach is based on the probability that, in the human genome, any sequence longer than a minimal number of nucleotides (nt), 13 for RNA and 17 for DNA, normally occurs only once. The potential applications of As-ODNs are numerous because mRNA is ubiquitous and is more accessible to manipulation than DNA. With the publication of the human genome sequence, it has become theoretically possible to inhibit mRNA of almost any gene by As-ODNs, in order to get a better understanding of gene function, investigate its role in disease pathology and to study novel therapeutic targets for the diseases caused by dysregulated gene expression. The conceptual simplicity, the availability of gene sequence information from the human genome, the inexpensive availability of synthetic oligonucleotides and the possibility of rational drug design makes As-ODNs powerful tools for target identification, validation and therapeutic intervention. In this review we discuss the latest developments in antisense oligonucleotide design, delivery, pharmacokinetics and potential side effects, as well as its uses in target identification and validation, and finally focus on the current developments of antisense oligonucleotides in therapeutic intervention in various diseases.

Time-resolved microspectrofluorometry and fluorescence imaging techniques: study of porphyrin-mediated cellular uptake of oligonucleotides

Time-resolved confocal microspectrofluorometry and fluorescence microscopy imaging were applied to monitor the cellular uptake of fluorescent-labeled oligonucleotides (ONs) delivered by a porphyrin molecule. The fate of porphyrin-ON complexes inside living cells has also been monitored. Due to intrinsic fluorescence of the porphyrin and sensitivity of its characteristics to microenvironment, multicomponent analysis of time-resolved fluorescence provides unique information about stability of the porphyrin-ON complexes, ON interactions with their target sequences, and ON and porphyrin distributions after delivery inside the cells. Time-resolved confocal microspectrofluorometry indeed delivers additional information compared with fluorescence confocal microscopy imaging widely employed to study ON uptake.

Design and synthesis of novel galactosylated polymers for liposomes as gene drug carriers targeting the hepatic asialoglycoprotein receptor

The 18-mer oligodeoxynucleotides (ODNs) that can inhibit survivin gene expression were selected as a model gene drug to study hepatic-targeting drug delivery system. Novel galactosylated polymers (cholesteryloxycarbonylamino) ethylamine-alpha,beta-polyasparthydrazied (CHE-PAHy-Lacs), which target asialoglycoprotein receptor on hepatic parenchymal cells (PC), were designed and synthesized as non-toxic, non-antigenic and non-teratogenic ligands for liposomes. The liposomes incorporating different CHE-PAHy-Lacs were prepared and characterized by zeta potential and particle size analyzer. The drug encapsulation efficiency was measured by gel filtration method. 1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate was used as a marker for all the liposome preparations in the in vivo experiments. The CHE-PAHy-Lac liposomes produced a significant improvement in the encapsulation efficiency of ODNs (28.73-51.37%) compared with conventional liposomes (9.88%). The in vivo results showed that the liposomes incorporating CHE-PAHy-Lac, which contained about 30% (w/w) galactosyl residues, exhibited marked accumulation in the liver and hepatic PC. These results suggest that the novel galactosylated polymers used for liposomes have a great potential as a gene delivery system for hepatic targeting.

Nonviral delivery of synthetic siRNAs in vivo

Sequence-specific gene silencing using small interfering RNA (siRNA) is a Nobel prize-winning technology that is now being evaluated in clinical trials as a potentially novel therapeutic strategy. This article provides an overview of the major pharmaceutical challenges facing siRNA therapeutics, focusing on the delivery strategies for synthetic siRNA duplexes in vivo, as this remains one of the most important issues to be resolved. This article also highlights the importance of understanding the genocompatibility/toxicogenomics of siRNA delivery reagents in terms of their impact on gene-silencing activity and specificity. Collectively, this information is essential for the selection of optimally acting siRNA delivery system combinations for the many proposed applications of RNA interference.

MicroRNAs as targets for antisense-based therapeutics

MicroRNAs (miRNAs) are a novel class of endogenous non-coding single-stranded RNAs, which regulate gene expression post-transcriptionally by base pairing with their target mRNAs. So far > 5000 miRNA entries have been registered and miRNAs have been implicated in most, if not all, central cellular processes and several diseases. As the mechanism of action for miRNA regulation of target mRNAs is mediated by Watson-Crick base pairing, antisense oligonucleotides targeting the miRNAs appear as an obvious choice to specifically inhibit miRNA function. Indeed, miRNAs can be antagonized in vivo by oligonucleotides composed of high-affinity nucleotide mimics. Lessons learned from traditional antisense strategies and small-interfering RNA approaches, that is from potent nucleotide mimics, design rules, pharmacokinetics, administration and safety issues, are likely to pave the way for future clinical trials of miRNA-antagonizing oligonucleotides.

Gene modulation for treating liver fibrosis

Despite tremendous progress in our understanding of fibrogenesis, injury stimuli process, inflammation, and hepatic stellate cell (HSC) activation, there is still no standard treatment for liver fibrosis. Delivery of small molecular weight drugs, proteins, and nucleic acids to specific liver cell types remains a challenge due to the overexpression of extracellular matrix (ECM) and consequent closure of sinusoidal gaps. In addition, activation of HSCs and subsequent release of inflammatory cytokines and infiltration of immune cells are other major obstacles to the treatment of liver fibrosis. To overcome these barriers, different therapeutic approaches are being investigated. Among them, the modulation of certain aberrant protein production is quite promising for treating liver fibrosis. In this review, we describe the mechanism of antisense, antigene, and RNA interference (RNAi) therapies and discuss how the backbone modification of oligonucleotides affects their in vivo stability, biodistribution, and bioactivity. Strategies for delivering these nucleic acids to specific cell types are discussed. This review critically addresses various insights developed with each individual strategy and for multipronged approaches, which will be helpful in achieving more effective outcomes.

Delivery of large biopharmaceuticals from cardiovascular stents: a review

This review focuses on new and emerging large-molecule bioactive agents delivered from stent surfaces in drug-eluting stents (DESs) to inhibit vascular restenosis in the context of interventional cardiology. New therapeutic agents representing proteins, nucleic acids (small interfering RNAs and large DNA plasmids), viral delivery vectors, and even engineered cell therapies require specific delivery designs distinct from traditional smaller-molecule approaches on DESs. While small molecules are currently the clinical standard for coronary stenting, extension of the DESs to other lesion types, peripheral vasculature, and nonvasculature therapies will seek to deliver an increasingly sophisticated armada of drug types. This review describes many of the larger-molecule and biopharmaceutical approaches reported recently for stent-based delivery with the challenges associated with formulating and delivering these drug classes compared to the current small-molecule drugs. It also includes perspectives on possible future applications that may improve safety and efficacy and facilitate diversification of the DESs to other clinical applications.

Water-soluble chitosan-based antisense oligodeoxynucleotide of interleukin-5 for treatment of allergic rhinitis

Interleukin (IL)-5 produced by allergen specific T cells is a major cytokine in the allergic inflammation such as allergic rhinitis (AR). To inhibit the production of IL-5, water-soluble chitosan (WSC)-based IL-5 antisense oligodeoxynucleotide (AS-ODN) complex was generated. WSC, a biocompatible cationic polymer, was used as a non-viral vector for the improvement of stability and transfection efficiency. After condensation IL-5 AS-ODN with WSC, the size, morphology and zeta potential analysis of IL-5 AS-ODN/WSC complexes were performed. The protective effect of complex was also observed against the enzymatic degradation. In vitro transfection efficiency into H1299 epithelial cells was investigated by flow cytometer and inhibition effect of IL-5 levels was also evaluated in D10.G4.1 cells. In the murine model with AR, the IL-5 and IgE levels closely related to the allergic inflammation were significantly reduced after the intranasal administration of IL-5 AS-ODN/WSC complexes. Based on these results, the condensation with WSC improved the physicochemical stability and transfection efficiency of IL-5 AS-ODN/WSC complex. Our results suggest that AS therapy using IL-5 AS-ODN/WSC complex can be an effective strategy in regulating IL-5 and may be applied to the treatment of allergic disorder related to IL-5.

Effects of vascular endothelial growth factor antisense oligodeoxynucleotide on the mRNA expression of vascular endothelial growth factor, fms-like tyrosine kinase-1 and kinase insert domain-containing receptor and vascular endothelial growth factor protein excretion of gallbladder carcinoma GBC-SD cells in vitro

AIM: To investigate the effect of oligofectamine-mediated vascular endothelial growth factor (VEGF) antisense oligodeoxynucleotide (ASODN) transfection on the mRNA expression of VEGF, fms-like tyrosine kinase-1 (Flt-1) and kinase insert domain-containing receptor (KDR) as well as VEGF protein excretion of gallbladder carcinoma GBC-SD cells in vitro.

METHODS: Gallbladder carcinoma GBC-SD cells were transfected with VEGF ASODN and scrambled oligodeoxynucleotide (SODN) by Oligofectamine mediation. The mRNA expression of VEGF, Flt-1 and KDR in GBC-SD cells of each group were detected by semi-quantitive reverse transcription-polymerase chain reaction (RT-PCR) and the excretion of VEGF protein was measured by enzyme-linked immunosorbent assay (ELISA).

RESULTS: Semi-quantitive RT-PCR revealed that VEGF, Flt-1 and KDR mRNA expression in groups of ASODN (VEGF165: 0.686 ± 0.033, 0.569 ± 0.049, 0.489 ± 0.036, 0.716 ± 0.017; VEGF165: 0.462 ± 0.046, 0.338 ± 0.034, 0.219 ± 0.022, 0.471 ± 0.038; Flt-1: 0.694 ± 0.019, 0.562 ± 0.045, 0.435 ± 0.042, 0.724 ± 0.026; KDR: 0.667 ± 0.063, 0.490 ± 0.033, 0.301 ± 0.029, 0.665 ± 0.068) and ASODN + Oligofectamine (VEGF165: 0.601 ± 0.021, 0.465 ± 0.042, 0.416 ± 0.023, 0.662 ± 0.035; VEGF121: 0.408 ± 0.014, 0.286 ± 0.019, 0.157 ± 0.021, 0.418 ± 0.037; Flt-1: 0.609 ± 0.018, 0.442 ± 0.049, 0.314 ± 0.015, 0.614 ± 0.029; KDR: 0.523 ± 0.048, 0.432 ± 0.027, 0.218 ± 0.036, 0.524 ± 0.037) were significantly inhibited 24, 48, 72 and 96 h after transfection in comparison with those in the control group (P < 0.05), and the inhibitory effect of ASODN + Oligofectamine was stronger (P > 0.05). ELISA results discovered that VEGF protein excretion was markedly decreased in the culture media of ASODN (281.26 ± 18.62, 526.44 ± 34.95, 791.13 ± 20.99) and ASODN + Oligofectamine (250.7 ± 14.57, 506.09 ± 19.14, 711.79 ± 19.91) group (P < 0.05) as compared with that in the control group, and ASODN + Oligofectamine was more efficient (P > 0.05).

CONCLUSION: VEGF ASODN can inhibit VEGF, Flt-1 and KDR mRNA expression and VEGF protein excretion of GBC-SD cells, and the effect may be strengthened by Oligofectamine mediation.

Toxicogenomics of non-viral drug delivery systems for RNAi: potential impact on siRNA-mediated gene silencing activity and specificity

RNA interference (RNAi) is an evolutionary conserved cellular process for the regulation of gene expression. In mammalian cells, RNAi is induced via short (21-23 nt) duplexes of RNA, termed small interfering RNA (siRNA), that can elicit highly sequence-specific gene silencing. However, synthetic siRNA duplexes are polyanionic macromolecules that do not readily enter cells and typically require the use of a delivery vector for effective gene silencing in vitro and in vivo. Choice of delivery system is usually made on its ability to enhance cellular uptake of siRNA. However, recent gene expression profiling (toxicogenomics) studies have shown that separate from their effects on cellular uptake, delivery systems can also elicit wide ranging gene changes in target cells that may impact on the 'off-target' effects of siRNA. Furthermore, if delivery systems also alter the expression of genes targeted for silencing, then siRNA activity may be compromised or enhanced depending on whether the target gene is up-regulated or down-regulated respectively. Citing recent examples from the literature, this article therefore reviews the toxicogenomics of non-viral delivery systems and highlights the importance of understanding the genomic signature of siRNA delivery reagents in terms of their impact on gene silencing activity and specificity. Such information will be essential in the selection of optimally acting siRNA-delivery system combinations for the many applications of RNA interference.

Novel cationic lipophilic peptides for oligodeoxynucleotide delivery

In search of new oligodeoxynucleotide (ODN) delivery agents, we evaluated novel peptides derived from core peptide H-GLRILLLKV-OH (CP). CP is a fragment designed from the T-cell antigen receptor (TCR) alpha-chain transmembrane sequence. CP was able to enter cells including T-cells and inhibited interleukin-2 (IL-2) production. To examine the effect of increased lipophilicity on cellular uptake and activity of CP, a lipoamino acid (2-aminododecanoic acid) was incorporated into peptide CP resulting in 2-aminodecanoyl-CP (LP). The toxicity of CP and LP was assessed by measuring the haemolytic activity. Neither compound caused any haemolysis of red blood cells. We have also compared the biological activities of the CP and LP. Using a T-cell antigen presentation assay, the more lipophilic LP caused greater inhibition of IL-2 production than the parent CP in the antigen stimulated T-cells. The LP also showed increased permeability than CP in the Caco-2 cell assay. We utilised the enhanced cell permeability property of LP in oligodeoxynucleotide ODN1 delivery. Isothermal titration calorimetry (ITC) suggested that CP and LP complex with ODN1 in a 12:1 (CP:ODN1) and 15:1 (LP:ODN1) ratio. These complexes were then transfected into human retinal pigment epithelial cells. The level of transfection was measured by the decreased production of the protein human vascular endothelial growth factor (hVEGF). The results revealed greater transfection efficiency for both CP and LP (47%, 55% more inhibition) compared to commercially available transfection agent cytofectin GSV. These results suggested that the CP and particularly its lipophilic analogue LP have the potential to be used as oligodeoxynucleotide delivery systems.

Delivery of antisense oligonucleotides to leukemia cells by RNA bacteriophage capsids

BACKGROUND

Acute myelogenous leukemia (AML) is the most common type of acute leukemia in adults. Because conventional treatments are associated with substantial side effects, novel therapeutic strategies are required. Antisense oligodeoxynucleotides (ODNs) have shown promise as the basis of emerging therapies for fighting cancer, although in vivo application is hampered by high sensitivity to cellular nuclease degradation. Encapsidation of ODNs in a drug-delivery capsule would reduce such degradation, thereby increasing the potency of therapy. MS2 bacteriophage capsid proteins may be used as novel virus-like particles (VLPs) to deliver ODNs. Here we report an analysis of the uptake mechanism of this VLP system and preliminary examples of its use to deliver a number of ODNs, including some targeting p120 messenger RNAs, a biomarker overexpressed in myelogenous leukemia cells.

METHODS

The ODNs were synthesized as covalent extensions to the translational repressor/assembly initiation signal (TR), a 19 nt stem-loop, of the RNA phage MS2. The VLPs were constructed by soaking ODN-TR directly into recombinant RNA-free capsid shells. Targeting of the encapsidated ODNs into cells was achieved by a receptor-mediated endocytosis pathway identified by immunofluorescence microscopy or by transmission electron microscopy with gold-labeled antibodies.

RESULTS

After covalent decoration with transferrin on their surface, the VLPs containing ODNs demonstrated increased effectiveness in killing target leukemia cells expressing transferrin receptors, suggesting that this system is worthy of more extensive analysis.

CONCLUSIONS

The findings suggest that RNA phage VLPs may be useful as a new nanomaterial for targeted delivery of antisense ODNs, or other macromolecular drug candidates.

Synthesis and applications of oligonucleotide-carbohydrate conjugates

Nowadays, oligonucleotide-carbohydrate conjugates are used in antisense biotechnology and in the study of glycosylated DNA functioning in vitro. The application of mono- and disaccharide phosphoramidites, solid-phase supports with immobilized carbohydrates, glycosylated nucleoside phosphoramidites, and postsynthetic conjugation of reactive sugar derivatives with oligonucleotides for preparation of oligonucleotide-carbohydrate conjugates have been systematically studied. The advantages and disadvantages of these approaches are considered. Possible strategies for synthesis of glycoclusters with different topologies conjugated to DNA are discussed. Applications of oligonucleotide-carbohydrate conjugates are highlighted. Studies of interactions of glycosylated oligonucleotides with proteins and effective cell-specific delivery of oligonucleotide-carbohydrate conjugates are discussed.

Glycotargeting to improve cellular delivery efficiency of nucleic acids

Nucleic acids bearing glycans of various structures have been under vigorous investigation in the past decade. The carbohydrate moieties of such complexes can serve as recognition sites for carbohydrate-binding proteins-lectins-and initiate receptor-mediated endocytosis. Therefore, carbohydrates can enhance cell targeting and internalization of nucleic acids that are associated with them and thus improve the bioavailability of nucleic acids as therapeutic agents. This review summarizes nucleic acid glycosylation in nature and approaches for the preparation of both non-covalently associated and covalently-linked carbohydrate-nucleic acid complexes.

Modeling cytoplasmic release of encapsulated oligonucleotides from cationic liposomes

Transfection activity of antisense oligodeoxynucleotides (ODN)-loaded cationic liposomes is mainly restricted by uptake and ODN release into cytoplasm, which is difficult to evaluate in cell culture studies. Well-designed models of cellular membranes, aim of the present study, might facilitate investigation of such processes. In this investigation, a phosphorothioate ODN was actively encapsulated in a DODAP-containing cationic liposome by ethanol injection with 73% efficiency. ODN release was determined by fluorescence dequenching of FITC-ODN upon incubation of liposomes with early endosomal (EE), late endosomal (LE) and plasma membranes (PM) models. LE provided the highest release (up to 76%) in a temperature-dependent manner. Release by EE (<16%), total PM (<11%) and PM external layer ( approximately 0) were not temperature sensitive. These differences are attributed to lipid charge, chain mobility, critical packing parameter and cholesterol content of the models. Intracellular distribution of FITC-ODN, determined by fluorescence microscopy and flowcytometry in the presence and absence of sodium azide, confirmed that liposomes were internalized mainly via endocytosis; hence inability of our PL models to simulate such active processes. Instead, release of ODN from endosomes into cytoplasm was pH-sensitive and in good agreement with model membrane studies in terms of amount and mechanism.

Mechanisms of co-modified liver-targeting liposomes as gene delivery carriers based on cellular uptake and antigens inhibition effect

In order to deliver antisense oligonucleotides (asODN) into hepatocytes orientedly in the treatment of hepatitis B virus (HBV) infection, the liver-targeting cationic liposomes was developed as a gene carrier, which was co-modified with the ligand of the asialoglycoprotein receptor (ASGPR), beta-sitosterol-beta-d-glucoside (sito-G) and the nonionic surfactant, Brij 35. Flow cytometry (FCM) analysis and enzyme-linked immunosorbent assay (ELISA) showed that the asODN-encapsulating cationic liposomes exhibited high transfection efficiency and strong antigens inhibition effect in primary rat hepatocytes and HepG2.2.15 cells, respectively. With the help of several inhibitors acting on different steps during the targeting lipofection, the cellular uptake mechanisms of the co-modified liver-targeting cationic liposomes were investigated through antigens inhibition effect assay and confocal laser scanning microscopy (CLSM) analysis. The cellular uptake with high transfection efficiency seemed to involve both endocytosis and membrane fusion. The ligand sito-G was confirmed to be able to enhance ASGPR-mediated endocytosis, the nonionic surfactant Brij 35 seemed to be able to facilitate membrane fusion, and the co-modification resulted in the most efficient transfection but no enhanced cytotoxicity. These results suggested that the co-modified liver-targeting cationic liposomes would be a specific and effective carrier to transfer asODN into hepatocytes infected with HBV orientedly.

In vivo disposition and stability of DNA frayed wires in mice

DNA frayed wires (DNA(FW)) are an alternate form of DNA organization formed by the self-association of several strands of guanine-rich oligonucleotides. The purpose of this study was to define for the first time the blood clearance kinetics, tissue distribution, and stability of DNA(FW) in vivo in mice. Single bolus doses (1200 pmol/mouse) of (32)P-DNA(FW) and (32)P-random DNA were administered intravenously (IV) and intraperitoneally (IP) followed by scheduled blood, urine, fecal and tissue samplings. Blood clearance kinetics was described well by a first order two-compartment open model. The overall half-lives of elimination from the central compartment (T(1/2))(K10) were 3.57+/-0.1h for IV and 2.38+/-0.11 h for IP. In contrast, random DNA was completely degraded after 15 min regardless of the route of administration. Tissue distribution results demonstrated that DNA(FW) were primarily distributed and retained in the liver, intestines, kidneys, and heart. Low levels could also be detected in brain. Autoradiographs of blood, tissues, feces and urine extracts established that DNA(FW) remained intact after administration as no measurable levels of metabolites or degradation products were found after 24h. (32)P-DNA(FW) was primarily eliminated via hepato-biliary excretion into feces after either IV or IP administration (51.8+/-4.53% and 36.2+/-3.4%, respectively). The improved stability and longer half-life of DNA(FW), previously shown in vitro, is also seen in vivo, indicating that DNA(FW) may provide a stable delivery system for DNA gene therapies. In conclusion, this is the first study demonstrating the in vivo stability, pharmacokinetics, and disposition of DNA superstructures.

Liposomal nanocapsules in food science and agriculture

Liposomes, spherical bilayer vesicles from dispersion of polar lipids in aqueous solvents, have been widely studied for their ability to act as drug delivery vehicles by shielding reactive or sensitive compounds prior to release. Liposome entrapment has been shown to stabilize encapsulated, bioactive materials against a range of environmental and chemical changes, including enzymatic and chemical modification, as well as buffering against extreme pH, temperature, and ionic strength changes. Liposomes have been especially useful to researchers in studies of various physiological processes as models of biological membranes in both eukaryotes and prokaryotes. Industrial applications include encapsulation of pharmaceuticals and therapeutics, cosmetics, anti-cancer and gene therapy drugs. In the food industry, liposomes have been used to deliver food flavors and nutrients and more recently have been investigated for their ability to incorporate food antimicrobials that could aid in the protection of food products against growth of spoilage and pathogenic microorganisms. In this review we briefly introduce key physicochemical properties of liposomes and review competing methods for liposome production. A survey of non-agricultural and food applications of liposomes are given. Finally, a detailed up-to-date summary of the emerging usage of liposomes in the food industry as delivery vehicles of nutrients, nutraceuticals, food additives, and food antimicrobials is provided.

Polyethylenimine-based antisense oligodeoxynucleotides of IL-4 suppress the production of IL-4 in a murine model of airway inflammation

BACKGROUND

Interleukin-4 (IL-4) plays a crucial role as an inflammatory mediator in allergic asthma via inducing Th2 inflammation and IgE synthesis. To develop an effective therapeutic agent which specifically inhibits production of IL-4, antisense oligodeoxynucleotides (AS-ODNs) against murine IL-4 mRNA were generated and complexed with polyethylenimine (PEI) to improve intracellular delivery.

METHODS

AS-ODNs were generated against the translation initiation region of murine IL-4 mRNA, and complexed with linear PEI. In vitro efficacy of AS-ODNs/PEI complexes was tested by measuring IL-4 production in the D10.G4.1 cell line, and cytotoxicity was tested by XTT assay. Physicochemical properties of polyplexes were examined using atomic force microscopy (AFM) and DNase I protection assay. In vivo effects of IL-4 AS-ODNs/PEI complexes were tested in a murine model of airway inflammation. IL-4 concentrations in the bronchoalveolar lavage (BAL) fluid and circulating IgE levels were measured by ELISA, and histological analysis of lung tissues was performed.

RESULTS

IL-4 AS-ODNs/PEI complexes were spheres with an average diameter of 98 nm and resistant to DNase I-mediated degradation. IL-4 AS-ODNs/PEI complexes showed up to 35% inhibition of IL-4 production in D10.G4.1 cells without causing any toxicity, while naked ODNs gave less than 1% reduction. Furthermore, IL-4 AS-ODNs/PEI complexes were effective in suppressing secretion of IL-4 (up to 30% reduction) in the BAL fluid in an ovalbumin-sensitized murine model of airway inflammation. Circulating IgE levels were decreased, and airway inflammation was alleviated by treatment with IL-4 AS-ODNs polyplexes.

CONCLUSIONS

These data demonstrate that complexation of IL-4 AS-ODNs with PEI provides a potential therapeutic tool in controlling inflammation associated with allergic asthma, and further presents an opportunity to the development of clinical therapy based on combination of multiple AS-ODNs of cytokines and/or signaling effectors involved in Th2 inflammation and eosinophilia.

Enhanced cellular binding of concatemeric oligonucleotide complexes

Interaction of oligonucleotides condensed into long concatemeric complexes with cancer cells was investigated. Pairs of 24- and 25-mer oligodeoxyribonucleotides were designed so that they could hybridize and form concatemeric structures. Pre-assembling of the oligonucleotides into concatemers considerably enhanced their ability to bind to human embryo kidney 293 cells and neuroblastoma IMR-32 cells as compared to free oligonucleotides. Efficiency of concatemers binding to the cells is improved with increase of the length and concentration of concatemeric complexes. The obtained results suggest incorporation of pharmacologically active oligonucleotides into concatemeric complexes as an approach to improvement of their cellular interaction.

Enhanced Hepatic Uptake and Bioactivity of Type α1(I) Collagen Gene Promoter-Specific Triplex-Forming Oligonucleotides after Conjugation with Cholesterol

A triplex-forming oligonucleotide (TFO) specific for type alpha1(I) collagen promoter is a promising candidate for treating liver fibrosis. Earlier, we determined the pharmacokinetics and biodistribution of TFO after systemic administration into normal and fibrotic rats. In this study, we conjugated cholesterol to the 3' end of the TFO via a disulfide bond and determined its cellular and nuclear uptake and bioactivity using HSC-T6 cell lines in vitro, followed by biodistribution at whole-body, organ (liver), and subcellular levels. Conjugation with cholesterol had little effect on the triplex-forming ability of the TFO with target duplex DNA, and the cellular uptake of (33)P-TFO-cholesterol (Chol) increased by 2- to approximately 4-fold. Real-time reverse transcriptase-polymerase chain reaction analysis after transfection of HSC-T6 cells with TFO-Chol or TFO indicated that TFO-Chol had higher inhibition on type alpha1(I) collagen primary transcript than naked TFO at low concentration (200 nM) but showed similar inhibition at higher concentration (500 and 1000 nM). There was increase in the inhibition on primary transcript with transfection time. The hepatic uptake of (33)P-TFO-Chol after systemic administration was 72.22% of the dose compared with 45.8% of (33)P-TFO. There was significant increase in the uptake of (33)P-TFO-Chol by hepatic stellate cells and hepatocytes. More importantly, the nuclear uptake of TFO-Chol was higher than TFO in cell culture system and in vivo studies. In conclusion, TFO-Chol is a potential antifibrotic agent.

Protection of oligonucleotides against nucleases by pegylated and non-pegylated liposomes as studied by fluorescence correlation spectroscopy

Antisense phosphodiester oligonucleotides (ONs), complexed to carriers such as cationic liposomes, inhibit the production of proteins. The biochemical and biophysical phenomena that govern the extent of this inhibition are still not fully understood. Major biological barriers limiting a pronounced antisense effect are the cellular entry and endosomal escape of the ONs containing liposomes, the release of the ONs from the liposomes and the extra- and intracellular degradation of the ONs. In this paper we focus on the latter barrier and evaluate, by fluorescence correlation spectroscopy (FCS), to what extent phosphodiester ONs complexed to DOTAP/DOPE liposomes, are protected against degradation by nucleases. Liposomes studied were either with or without a polyethyleneglycol (PEG) moiety at the surface. Using non-pegylated liposomes the phosphodiester ONs were initially adequately protected when exposed to DNase I. Indeed, in the mechanism for lipoplex formation as suggested by others, the ONs become trapped between lipid bilayers and are therefore shielded from the environment. However, after a few hours the phosphodiester ONs no longer stayed intact. This was explained by a gradual fusion of the lipoplexes in time thereby spontaneously releasing phosphodiester ONs. Using pegylated liposomes, a substantial fraction of the phosphodiester ONs degraded immediately after exposing the complexes to DNase I. Based on experimental evidence we suggest that the presence of the PEG-chains influences lipoplex formation so that the ONs are not trapped between lipid bilayers and therefore remain accessible by the DNase I enzyme.

Locked nucleic acid: a potent nucleic acid analog in therapeutics and biotechnology

Locked nucleic acid (LNA) is a class of nucleic acid analogs possessing very high affinity and excellent specificity toward complementary DNA and RNA, and LNA oligonucleotides have been applied as antisense molecules both in vitro and in vivo. In this review, we briefly describe the basic physiochemical properties of LNA and some of the difficulties that may be encountered when applying LNA technology. The central part of the review focuses on the use of LNA molecules in regulation of gene expression, including delivery to cells, stability, unspecific effects, toxicity, pharmacokinetics, and design of LNA oligonucleotides. The last part evaluates LNA as a diagnostic tool in genotyping.

Transfection protocol for antisense oligonucleotides affects uniformity of transfection in cell culture and efficiency of mRNA target reduction

In an effort to optimize the transfection of cell lines with antisense oligonucleotides, we examined cellular accumulation of a labeled oligonucleotide by flow cytometry. We were surprised to observe that a routinely used transfection protocol, a fixed lipid/oligonucleotide ratio, resulted in variable transfection efficiency depending on the concentration of oligonucleotide used. A significant population of cells, especially at lower doses of oligonucleotide and cationic lipid, were untransfected. We investigated lipid/oligonucleotide ratios, different lipid preparations, and different cell types and found that these variables did not alter the percentage of cells transfected at these lower doses of oligonucleotide. However, when lipid-oligonucleotide complexes were formed at the high dose and then diluted into a solution of lipid or a complex of lipid and unlabeled, negative control oligonucleotide, a constant percentage of cells was transfected. Under these conditions, mRNA target reduction dose-response curves were also shifted to lower doses. We hypothesize that poor transfection observed at a low concentration of lipid-oligonucleotide complex when diluted in medium is due to loss of active complexes, either by adsorption to the substrate or by changes in physical characteristics of complexes. By maintaining a constant lipid concentration, more consistent transfection was achieved.