Restenosis and gene therapy

Efficacy of antisense gene therapy for proliferative cholangitis

AIM: To compare the effects of short hairpin RNAs (shRNAs) targeting the proliferating cell nuclear antigen (PCNA), c-Myc and cdc2 k genes on the hyperplastic behavior and lithogenic potential of proliferative cholangitis (PC), and to select the best target for antiproliferative treatment of PC.

METHODS: A rat model of PC was developed by retrogradely inserting a nylon thread into the common bile duct. Using the nylon thread as the guide wire, an intralumenal injection of PCNA, c-Myc and cdc2 k shRNAs into the common bile duct was performed in three different groups of model rats, respectively.

RESULTS: Compared to the c-Myc and cdc2 k shRNA treatment groups, the degree of hyperplasia of biliary epithelium and collagen fibers in the bile duct wall in the PCNA shRNA treatment group were significantly decreased. In addition, the protein expression and secretion of mucin from the hyperplastic biliary epithelium and peribiliary gland were remarkably reduced in the PCNA shRNA treatment group.

CONCLUSION: PCNA shRNA possesses more strong inhibitory effects on collagen fiber hyperplasia in and mucin secretion from the bile duct wall of rats with experimental PC than c-Myc and cdc2 k shRNAs. Therefore, PCNA shRNA holds more promise for prevention of postoperative biliary restenosis and stone recurrence in PC patients.

Tubular cationized pullulan hydrogels as local reservoirs for plasmid DNA

In the present study, we measured the ability of various cationized pullulan tubular hydrogels to retain plasmid DNA, and tested the ability of retained plasmid DNA to transfect vascular smooth muscle cells (VSMCs). Cationized pullulans were obtained by grafting at different charge densities ethylamine (EA) or diethylaminoethylamine (DEAE) on the pullulan backbone. Polymers were characterized by elemental analysis, acid-base titration, size exclusion chromatography, Fourier-transform infrared spectroscopy, and proton nuclear magnetic resonance. The complexation of cationized pullulans in solution with plasmid DNA was evidenced by fluorescence quenching with PicoGreen. Cationized pullulans were then chemically crosslinked with phosphorus oxychloride to obtain tubular cationized pullulan hydrogels. Native pullulan tubes did not retain loaded plasmid DNA. In contrast, the ability of cationized pullulan tubes to retain plasmid DNA was dependent on both the amine content and the type of amine. The functional integrity of plasmid DNA in cationized pullulan tubes was demonstrated by in vitro transfection of VSMCs. Hence, cationized pullulan hydrogels can be designed as tubular structures with high affinity for plasmid DNA, which may provide new biomaterials to enhance the efficiency of local arterial gene transfer strategies.

Cationized pullulan 3D matrices as new materials for gene transfer

This study deals with the development of a novel biocompatible cationized pullulan three-dimensional matrix for gene delivery. A water-soluble cationic polysaccharide, diethylaminoethyl-pullulan (DEAE-pullulan), was first synthesized and characterized. Fluorescence quenching and gel retardation assays evidenced the complexation in solution of DNA with DEAE-pullulan, but not with neutral pullulan. On cultured smooth muscle cells (SMCs) incubated with DEAE-pullulan and a plasmid vector expressing a secreted form of alkaline phosphatase (pSEAP), SEAP activity was 150-fold higher than with pSEAP alone or pSEAP with neutral pullulan. DEAE-pullulan was then chemically crosslinked using phosphorus oxychloride. The resulting matrices were obtained in less than a minute and molded as discs of 12 mm diameter and 2 mm thickness. Such DEAE-pullulan 3D matrices were loaded with up to 50 microg of plasmid DNA, with a homogeneous plasmid loading observed with YOYO-1 fluorescence staining. Moreover, the DEAE-pullulan matrix was shown to protect pSEAP from DNase I degradation. Incubation of cultured SMCs with pSEAP-loaded DEAE-pullulan matrices resulted in significant gene transfer without cell toxicity. This study suggests that these cationized pullulan 3D matrices could be useful biomaterials for local gene transfer.

Local gene transduction of cyclooxygenase-1 increases blood flow in injured atherosclerotic rabbit arteries

BACKGROUND

Cyclooxygenase-1 (COX-1) is the rate-limiting component in the synthesis of prostacyclin (PGI2), an important vasodilator and antithrombotic molecule. In balloon-injured, atherosclerosis-free porcine arteries, COX-1 gene transduction increases PGI2 production, induces durable vasodilation, and reduces thrombus formation. We tested the effectiveness of COX-1 local gene transduction for the prevention of postangioplasty restenosis in atherosclerotic arteries in a hypercholesterolemic rabbit model.

METHODS AND RESULTS

We injured 1 carotid artery in 43 Watanabe heritable hyperlipidemic rabbits and performed local gene transduction using a viral vector containing the COX-1 gene (AdCOX-1, n=22) or no genes (Adnull, n=21). Three days later, AdCOX-1-treated arteries stimulated with arachidonic acid produced 100% more PGI2 (P<0.01), 400% more prostaglandin E2 (PGE2) (P<0.01), 400% more prostaglandin E1 (PGE1) (P<0.01), and 250% more cAMP (P<0.05) than Adnull-treated arteries. Twenty-eight days after treatment, Doppler sonography showed that blood flow velocity was preserved in AdCOX-1-treated arteries (ratio 0.92, injured compared with contralateral uninjured carotid artery) but reduced in Adnull-treated arteries (ratio 0.39), suggesting that AdCOX-1 prevented restenosis after injury. COX-1-transduced arteries also showed 80% greater lumen area 28 days after injury (P<0.01).

CONCLUSIONS

The effectiveness of COX-1 in preventing restenosis and preserving normal blood flow 28 days after injury results from increased lumen area caused by durable vasodilation. COX-1 efficacy correlates with an early increase in the production of PGI2, PGE2, PGE1 (known to cause vasodilation), and cAMP. These results demonstrate for the first time that COX-1 gene transduction is an effective treatment for the prevention of postangioplasty restenosis of atherosclerotic arteries under clinically relevant conditions.

[Gene therapy of restenosis and atherosclerosis: hopes and facts]

Stents are the main technique of coronary revascularization in France and western countries. However, a better understanding of the pathophysiology of in-stent restenosis and the well-recognized roles played by inflammation and cell proliferation led to the development of drug-eluting stents, which have nearly eliminated the risk of restenosis. In this context, the success of gene therapy will depend on our ability to simplify and optimize current protocols of arterial gene transfer. For the time being, arterial gene therapy remains a powerful tool for deciphering the complex pathophysiology of restenosis and will certainly have far-reaching implications in the fields of vascular biology and therapeutics.

Cardiovascular Gene Therapy: Angiogenesis and Beyond

Recent advances in understanding the mechanisms of disease have produced many new targets for gene therapy. However, it has been difficult to convert these new insights into clinically useful applications. In the field of cardiovascular medicine, most clinical studies of gene therapy have focused on angiogenesis as a treatment for ischemia. Initial enthusiasm was supported by small, uncontrolled, phase 1 trials. However, several large efficacy studies have recently been published that have not shown clinically significant improvement, and a few well-publicized complications of gene therapy have cast a pall over the entire field. In this review, we will summarize specific technical aspects of cardiovascular gene therapy, examine the recent series of clinical studies, and explore the direction of future work for the principal cardiovascular diseases.

Gene therapy: theoretical and bioethical concepts

Gene therapy holds great promise. Somatic gene therapy has the potential to treat a wide range of disorders, including inherited conditions, cancers, and infectious diseases. Early progress has already been made in the treatment of a range of disorders. Ethical issues surrounding somatic gene therapy are primarily those concerned with safety. Germline gene therapy is theoretically possible but raises serious ethical concerns concerning future generations.

Leucine 7 to proline 7 polymorphism of the preproneuropeptide Y gene is not associated with restenosis after coronary stenting

PURPOSE

To identify if an association exists between the leucine 7 (Leu7) to proline 7 (Pro7) polymorphism located in the signal peptide of the preproneuropeptide Y (preproNPY) gene and restenosis after coronary stenting. The Pro7 allele of the preproNPY gene affects the plasma levels of human neuropeptide Y, a potent mitogen of vascular smooth muscle cells.

METHODS

A population of 1850 consecutive patients with symptomatic coronary artery disease undergoing coronary stent implantation was enrolled in a study that featured angiography at 6 months and genotype determination. The primary endpoint was angiographically documented restenosis (> or =50% diameter stenosis) at 6 months. The secondary endpoint was the clinical outcome at 1 year (death, myocardial infarction, target vessel revascularization). Genotyping was based on the polymerase chain reaction with fluorescent allele-specific oligonucleotide probes (TaqMan method).

RESULTS

The carrier frequency of the rare Pro7 allele was 6.2%. Baseline, lesion-related, angiographic, and procedural parameters were similar in the patients with the Leu7/Leu7 genotype and carriers of the Pro7 allele (i.e., subjects with genotype Leu7/Pro7 or Pro7/Pro7). Restenosis rates at 6 months did not differ significantly between the groups (33% versus 30%, p=0.54). In addition, no relationship of the polymorphism with the clinical outcomes at 1 year was observed.

CONCLUSION

Our results suggest that the Leu7 to Pro7 polymorphism of the preproNPY gene is not associated with angiographic restenosis or adverse clinical events after stent placement in coronary arteries.