Antisense therapy for restenosis following percutaneous coronary intervention

Sustained Release of Cx43 Antisense Oligodeoxynucleotides from Coated Collagen Scaffolds Promotes Wound Healing

Antisense oligodeoxynucleotides targeting the mRNA of the gap junction protein Cx43 promote tissue repair in a variety of different wounds. Delivery of the antisense drug has most often been achieved by a thermoreversible hydrogel, Pluronic F-127, which is very effective in the short term but does not allow for sustained delivery over several days. For chronic wounds that take a long time to heal, repeated dosing with the drug may be desirable but is not always compatible with conventional treatments such as the weekly changing of compression bandages on venous leg ulcers. Here the coating of collagen scaffolds with antisense oligonucleotides is investigated and a way to provide protection of the oligodeoxynucleotide drug is found in conjunction with sustained release over a 7 d period. This approach significantly reduces the normal foreign body reaction to the scaffold, which induces an increase of Cx43 protein and an inhibition of healing. As a result of the antisense integration into the scaffold, inflammation is reduced with the rate of wound healing and contracture is significantly improved. This coated scaffold approach may be very useful for treating venous leg ulcers and also for providing a sustained release of any other types of oligonucleotide drugs that are being developed.

Novel compounds for the treatment of Duchenne muscular dystrophy: emerging therapeutic agents

The identification of dystrophin and the causative role of mutations in this gene in Duchenne and Becker muscular dystrophies (D/BMD) was expected to lead to timely development of effective therapies. Despite over 20 years of research, corticosteroids remain the only available pharmacological treatment for DMD, although significant benefits and extended life have resulted from advances in the clinical care and management of DMD individuals. Effective treatment of DMD will require dystrophin restitution in skeletal, cardiac, and smooth muscles and nonmuscle tissues; however, modulation of muscle loss and regeneration has the potential to play an important role in altering the natural history of DMD, particularly in combination with other treatments. Emerging biological, molecular, and small molecule therapeutics are showing promise in ameliorating this devastating disease, and it is anticipated that regulatory environments will need to display some flexibility in order to accommodate the new treatment paradigms.

Therapeutic Targeting of Myc

Protein-protein interactions between members of the Myc transcription factor network are potential targets of small molecule inhibitors and stabilizers. Diverse screening strategies, including fluorescence resonance energy transfer, fluorescence polarization, two hybrid and protein complementation assays have identified several lead compounds that inhibit Myc-Max dimerization and one compound that stabilizes the Max homodimer. Representative compounds interfere with Myc-induced transcriptional activation, Myc-mediated oncogenic transformation, Myc-driven cellular replication and DNA binding of Myc. For the best characterized compounds, specific binding sites have been determined, and molecular mechanisms of action have been documented. This knowledge of small molecule - protein interaction is currently applied to highly targeted approaches that seek to identify novel compounds with improved potency.

Inhibition of aortic intimal hyperplasia and cell cycle protein and extracellular matrix protein expressions by BuYang HuanWu Decoction

AIM OF THE STUDY

The inhibitive effect of BuYang HuanWu Decoction (BYHWD) and its major components on vascular intimal hyperplasia and the expressions of cell cycle protein and extracellular matrix protein.

MATERIALS AND METHODS

Sprague-Dawley rats were randomly divided into sham-operated, control, alkaloid, glycoside, BYHWD and atorvastatin groups. Rat aorta intima in all groups were injured by insesion of domestic balloon catheter into the aortae except sham-operated rats. Drugs were administrated orally from the second day after vascular injury and continued for 14 days. The injured segments of aortae were collected on the sixteenth day after operation to observe the morphological changes of vascular structure and to examine the expressions of proteins in vascular cells associated with cell cycle including proliferating cell nuclear antigen(PCNA), cyclinD(1) and cyclinE, and extracellular matrix(ECM) proteins including collagen I (Col-I) and fibronectin (FN), further to discover the involved biologically active substances and the potential mechanisms.

RESULTS

Alkaloid and glycosid isolated from BYHWD were more effective than BYHWD in the inhibition of intimal hyperplasia and the expressions of PCNA, cyclinD(1), cyclinE, Col-I and FN, suggesting that alkaloid and glycoside may be the main components of BYHWD responsible for the observed inhibition of excessive hyperplasia of vascular intima.

CONCLUSIONS

The mechanism associated with the anti-hyperplasia activity of BYHWD and its effective components may be related to the blockage of cell cycles of VSMC, and the inhibition of the ECM protein synthesis, even the increased degradation of ECM proteins.

Modulating the functional contributions of c-Myc to the human endothelial cell cyclic strain response

This study addresses whether pathological levels of cyclic strain activate the c-Myc promoter, leading to c-Myc transcription and downstream gene induction in human umbilical vein endothelial cells (HUVEC) or human aortic endothelial cells (HAEC). mRNA and protein expression of c-Myc under physiological (6-10%) and pathological cyclic strain conditions (20%) were studied. Both c-Myc mRNA and protein expression increased 2-3-fold in HUVEC cyclically strained at 20%. c-Myc protein increased 4-fold in HAEC. In HUVEC, expression of mRNA peaked at 1.5-2 h. Subsequently, the effect of modulating c-Myc on potential downstream gene targets was determined. A small molecular weight compound that binds to and stabilizes the silencer element in the c-Myc promoter attenuates cyclic strain-induced c-Myc transcription by about 50%. This compound also modulates c-Myc downstream gene targets that may be instrumental in induction of vascular disease. Cyclic strain-induced gene expression of vascular endothelial growth factor, proliferating cell nuclear antigen and heat shock protein 60 are attenuated by this compound. These results offer a possible mechanism and promising clinical treatment for vascular diseases initiated by increased cyclic strain.

Comparative analysis of antisense oligonucleotide sequences for targeted skipping of exon 51 during dystrophin pre-mRNA splicing in human muscle

Duchenne muscular dystrophy (DMD) is caused by mutations in the dystrophin gene that result in the absence of functional protein. In the majority of cases these are out-of-frame deletions that disrupt the reading frame. Several attempts have been made to restore the dystrophin mRNA reading frame by modulation of pre-mRNA splicing with antisense oligonucleotides (AOs), demonstrating success in cultured cells, muscle explants, and animal models. We are preparing for a phase I/IIa clinical trial aimed at assessing the safety and effect of locally administered AOs designed to inhibit inclusion of exon 51 into the mature mRNA by the splicing machinery, a process known as exon skipping. Here, we describe a series of systematic experiments to validate the sequence and chemistry of the exon 51 AO reagent selected to go forward into the clinical trial planned in the United Kingdom. Eight specific AO sequences targeting exon 51 were tested in two different chemical forms and in three different preclinical models: cultured human muscle cells and explants (wild type and DMD), and local in vivo administration in transgenic mice harboring the entire human DMD locus. Data have been validated independently in the different model systems used, and the studies describe a rational collaborative path for the preclinical selection of AOs for evaluation in future clinical trials.

Antisense oligonucleotide induced exon skipping and the dystrophin gene transcript: cocktails and chemistries

Background

Antisense oligonucleotides (AOs) can interfere with exon recognition and intron removal during pre-mRNA processing, and induce excision of a targeted exon from the mature gene transcript. AOs have been used in vitro and in vivo to redirect dystrophin pre-mRNA processing in human and animal cells. Targeted exon skipping of selected exons in the dystrophin gene transcript can remove nonsense or frame-shifting mutations that would otherwise have lead to Duchenne Muscular Dystrophy, the most common childhood form of muscle wasting.

Results

Although many dystrophin exons can be excised using a single AO, several exons require two motifs to be masked for efficient or specific exon skipping. Some AOs were inactive when applied individually, yet pronounced exon excision was induced in transfected cells when the AOs were used in select combinations, clearly indicating synergistic rather than cumulative effects on splicing. The necessity for AO cocktails to induce efficient exon removal was observed with 2 different chemistries, 2'-O-methyl modified bases on a phosphorothioate backbone and phosphorodiamidate morpholino oligomers. Similarly, other trends in exon skipping, as a consequence of 2'-O-methyl AO action, such as removal of additional flanking exons or variations in exon skipping efficiency with overlapping AOs, were also seen when the corresponding sequences were prepared as phosphorodiamidate morpholino oligomers.

Conclusion

The combination of 2 AOs, directed at appropriate motifs in target exons was found to induce very efficient targeted exon skipping during processing of the dystrophin pre-mRNA. This combinatorial effect is clearly synergistic and is not influenced by the chemistry of the AOs used to induce exon excision. A hierarchy in exon skipping efficiency, observed with overlapping AOs composed of 2'-O-methyl modified bases, was also observed when these same sequences were evaluated as phosphorodiamidate morpholino oligomers, indicating design parameters established with one chemistry may be applied to the other.

Alternate mRNA processing of the hepatocyte nuclear factor genes and its role in monogenic diabetes

Variation in mRNA processing has the capacity to exert fine control over gene expression in most cell types. The hepatic nuclear factor genes, like approximately 74% of the genome, produce multiple transcripts. Hepatic nuclear factor isoforms exhibit both spatial and temporal variation in expression. In this review, the known isoforms of the hepatocyte nuclear factor-1α, hepatocyte nuclear factor-1β and hepatocyte nuclear factor-4α genes are described and their properties are compared. Finally, data are discussed regarding the influence of hepatocyte nuclear factor-1α alternate mRNA processing on the clinical phenotype of maturity-onset diabetes of the young.

Controlled delivery of antisense oligodeoxynucleotide from cationically modified phosphorylcholine polymer films

Antisense strategy is a promising approach for the prevention of in-stent restenosis if therapeutic agents such as antisense oligodeoxynucleotides (AS-ODNs) can be successfully delivered to the implant site. Optimizing the routes and conditions for controlled loading and release of therapeutic agents from a biocompatible polymer coating is still required. In this study, phosphorylcholine (PC) polymer films bearing different cationic charge densities were deposited onto smooth silicon substrates. The thickness of these films was determined by spectroscopic ellipsometry (SE). Human c-myc AS-ODNs were incorporated into the PC polymer films by immersion in concentrated AS-ODN solution and eluted into PBS under physiological conditions. The elution profile was monitored by UV spectrometry and gel electrophoresis. Cellular uptake of the eluted AS-ODN into vascular smooth muscle cells (VSMCs) was evaluated by fluorescence microscopy. The results showed that ODN loading capacities increased with film thickness and were also strongly dependent on the cationic charge density. AS-ODN release was characterized by a slight initial burst in the first half hour followed by a period of sustained release up to 8 days. Gel electrophoresis demonstrated DNA integrity, and different transfection efficiencies were observed when the eluted ODNs were transfected into VSMCs. These results demonstrated that cationically modified PC polymers are capable of delivery of antisense ODNs in a controlled manner and that they are well suited for specific biomedical devices such as DNA-eluting stents.

Drug-Eluting Coronary Stents

The introduction and widespread use of coronary stents have been the most important advancement in the percutaneous treatment of coronary artery disease since the introduction of balloon angioplasty. Coronary artery stents reduce the rate of angiographic and clinical restenosis compared to balloon angioplasty. This angiographic restenosis was further reduced with the introduction of drug-eluting stents and hence further reduction in the frequency of major adverse cardiac events. Herein we present a comprehensive and up-to-date review about the use of drug-eluting stents in the treatment of coronary artery disease.

Comparison of basic peptides- and lipid-based strategies for the delivery of splice correcting oligonucleotides

Expression of alternatively spliced mRNA variants at specific stages of development or in specific cells and tissues contributes to the functional diversity of the human genome. Aberrations in alternative splicing were found as a cause or a contributing factor to the development, progression, or maintenance of numerous diseases. The use of antisense oligonucleotides (ON) to modify aberrant expression patterns of alternatively spliced mRNAs is a novel means of potentially controlling such diseases. Oligonucleotides can be designed to repair genetic mutations, to modify genomic sequences in order to compensate for gene deletions, or to modify RNA processing in order to improve the effects of the underlying gene mutation. Steric block ON approach have proven to be effective in experimental model for various diseases. Here, we describe our experience in investigating two strategies for ON delivery: ON conjugation with basic peptides and lipid-based particulate system (lipoplex). Basic peptides or Cell Penetrating Peptides (CPP) such as the TAT-derived peptide appear to circumvent many problems associated with ON and drug delivery. This strategy may represent the next paradigm in our ability to modulate cell function and offers a unique avenue for the treatment of disease. Lipoplexes result from the intimate interaction of ON with cationic lipids leading to ON carrying particles able to be taken up by cells and to release ON in the cytoplasm. We have used as an experimental model the correction of a splicing alteration of the mutated beta-globin intron causing thalassemia. Data on cell penetration and efficacy of correction of specific steric block ON delivered either by basic peptides or lipoplex are described. A comparison of the properties of both delivery systems is made respective to the use of this new class of therapeutic molecules.