Widespread long-term gene transfer to mouse skeletal muscles and heart

The road toward AAV-mediated gene therapy of Duchenne muscular dystrophy

Forty years after the dystrophin gene was cloned, significant progress has been made in developing gene therapy approaches for Duchenne muscular dystrophy (DMD). The disorder has presented numerous challenges, including the enormous size of the gene (2.2 MB), the need to target muscles body wide, and immunogenic issues against both vectors and dystrophin. Among human genetic disorders, DMD is relatively common, and the genetics are complicated since one-third of all cases arise from a spontaneous new mutation, resulting in thousands of independent lesions throughout the locus. Many approaches have been pursued in the goal of finding an effective therapy, including exon skipping, nonsense codon suppression, upregulation of surrogate genes, gene replacement, and gene editing. Here, we focus specifically on methods using AAV vectors, as these approaches have been tested in numerous clinical trials and are able to target muscles systemically. We discuss early advances to understand the structure of dystrophin, which are crucial for the design of effective DMD gene therapies. Included is a summary of efforts to deliver micro-, mini-, and full-length dystrophins to muscles. Finally, we review current approaches to adapt gene editing to the enormous DMD gene with prospects for improved therapies using all these methods.

MicroRNAs and therapeutic potentials in acute and chronic cardiac disease

microRNAs (miRNAs) are small regulatory RNAs implicated in various cardiac disorders. In this review, the role of miRNAs is discussed in relation to acute myocardial infarction and chronic heart failure. In both settings, miRNAs are altered, contributing to injury and adverse remodeling. Notably, miRNA profiles differ between acute ischemic injury and progressive heart failure. Owing to miRNA variabilities between disease stages and delivery difficulties, translation of animal studies to the clinic remains challenging. The identification of distinct miRNA signatures could lead to the development of miRNA therapies tailored to different disease stages. Here, we summarize the current understanding of miRNAs in acute and chronic cardiac diseases, identify knowledge gaps and discuss progress in developing miRNA-based treatment strategies.

The emerging role of miRNAs in myocardial infarction: From molecular signatures to therapeutic targets

Globally, myocardial infarction (MI) and other cardiovascular illnesses have long been considered the top killers. Heart failure and mortality are the results of myocardial apoptosis, cardiomyocyte fibrosis, and cardiomyocyte hypertrophy, all of which are caused by MI. MicroRNAs (miRNAs) play a crucial regulatory function in the progression and advancement of heart disease following an MI. By consolidating the existing data on miRNAs, our aim is to gain a more comprehensive understanding of their role in the pathological progression of myocardial injury after MI and to identify potential crucial target pathways. Also included are the primary treatment modalities and their most recent developments. miRNAs have the ability to regulate both normal and pathological activity, including the key signaling pathways. As a result, they may exert medicinal benefits. This review presents a comprehensive analysis of the role of miRNAs in MI with a specific emphasis on their impact on the regeneration of cardiomyocytes and other forms of cell death, such as apoptosis, necrosis, and autophagy. Furthermore, the targets of pro- and anti-MI miRNAs are comparatively elucidated.

Cardiac-Targeting Peptide: From Discovery to Applications

Despite significant strides in prevention, diagnosis, and treatment, cardiovascular diseases remain the number one cause of mortality in the United States, with rates climbing at an alarming rate in the developing world. Targeted delivery of therapeutics to the heart has been a lofty goal to achieve with strategies ranging from direct intra-cardiac or intra-pericardial delivery, intra-coronary infusion, to adenoviral, lentiviral, and adeno-associated viral vectors which have preference, if not complete cardio-selectivity, for cardiac tissue. Cell-penetrating peptides (CPP) are 5-30-amino-acid-long peptides that are able to breach cell membrane barriers while carrying cargoes up to several times their size, in an intact functional form. Identified nearly three decades ago, the first of these CPPs came from the HIV coat protein transactivator of transcription. Although a highly efficient CPP, its clinical utility is limited by its robust ability to cross any cell membrane barrier, including crossing the blood-brain barrier and transducing neuronal tissue non-specifically. Several strategies have been utilized to identify cell- or tissue-specific CPPs, one of which is phage display. Using this latter technique, we identified a cardiomyocyte-targeting peptide (CTP) more than a decade ago, a finding that has been corroborated by several independent labs across the world that have utilized CTP for a myriad of different purposes in pre-clinical animal models. The goal of this publication is to provide a comprehensive review of the identification, validation, and application of CTP, and outline its potential in diagnostic and therapeutic applications especially in the field of targeted RNA interference.

The potential role of miRNAs in the pathogenesis of cardiovascular diseases - A focus on signaling pathways interplay

For the past two decades since their discovery, scientists have linked microRNAs (miRNAs) to posttranscriptional regulation of gene expression in critical cardiac physiological and pathological processes. Multiple non-coding RNA species regulate cardiac muscle phenotypes to stabilize cardiac homeostasis. Different cardiac pathological conditions, including arrhythmia, myocardial infarction, and hypertrophy, are modulated by non-coding RNAs in response to stress or other pathological conditions. Besides, miRNAs are implicated in several modulatory signaling pathways of cardiovascular disorders including mitogen-activated protein kinase, nuclear factor kappa beta, protein kinase B (AKT), NOD-like receptor family pyrin domain-containing 3 (NLRP3), Jun N-terminal kinases (JNKs), Toll-like receptors (TLRs) and apoptotic protease-activating factor 1 (Apaf-1)/caspases. This review highlights the potential role of miRNAs as therapeutic targets and updates our understanding of their roles in the processes underlying pathogenic phenotypes of cardiac muscle.

Cancer immunotherapies: A hope for the uncurable?

The use of cancer immunotherapies is not novel but has been used over the decades in the clinic. Only recently have we found the true potential of stimulating an anti-tumor response after the breakthrough of checkpoint inhibitors. Cancer immunotherapies have become the first line treatment for many malignancies at various stages. Nevertheless, the clinical results in terms of overall survival and progression free survival were not as anticipated. Majority of cancer patients do not respond to immunotherapies and the reasons differ. Hence, further improvements for cancer immunotherapies are crucially needed. In the review, we will discuss various forms of cancer immunotherapies that are being tested or already in the clinic. Moreover, we also highlight future directions to improve such therapies.

mRNA therapy for myocardial infarction: A review of targets and delivery vehicles

Cardiovascular diseases are the leading cause of death in the world. This is partly due to the low regenerative capacity of adult hearts. mRNA therapy is a promising approach under development for cardiac diseases. In mRNA therapy, expression of the target protein is modulated by delivering synthetic mRNA. mRNA therapy benefits cardiac regeneration by increasing cardiomyocyte proliferation, reducing fibrosis, and promoting angiogenesis. Because mRNA is translated in the cytoplasm, the delivery efficiency of mRNA into the cytoplasm and nucleus significantly affects its therapeutic efficacy. To improve delivery efficiency, non-viral vehicles such as lipid nanoparticles have been developed. Non-viral vehicles can protect mRNA from enzymatic degradation and facilitate the cellular internalization of mRNA. In addition to non-viral vehicles, viral vectors have been designed to deliver mRNA templates into cardiac cells. This article reviews lipid nanoparticles, polymer nanoparticles, and viral vectors that have been utilized to deliver mRNA into the heart. Because of the growing interest in lipid nanoparticles, recent advances in lipid nanoparticles designed for cardiac mRNA delivery are discussed. Besides, potential targets of mRNA therapy for myocardial infarction are discussed. Gene therapies that have been investigated in patients with cardiac diseases are analyzed. Reviewing mRNA therapy from a clinically relevant perspective can reveal needs for future investigations.

DNA-PK phosphorylation at Ser2056 during adenovirus E4 mutant infection is promoted by viral DNA replication and independent of the MRN complex

Adenovirus (Ad) early region 4 (E4) mutants activate cellular DNA damage responses (DDRs) that include non-homologous end joining (NHEJ) pathways mediated by the DNA repair kinase DNA-PK and its associated factors Ku70/Ku86. NHEJ results in concatenation of the viral linear double-stranded DNA genome and inhibits a productive infection. E4 proteins normally prevent activation of cellular DDRs in wild-type Ad type 5 (Ad5) infections, thereby promoting efficient viral growth. The purpose of this study was to evaluate the factors that govern DNA-PK activation during adenovirus infection. Our data indicate that viral DNA replication promotes DNA-PK activation, which is required for genome concatenation by NHEJ. Although the Mre11/Rad50/Nbs1 (MRN) DDR sensor complex is not required for DNA-PK activation, Mre11 is important for recruitment of the NHEJ factor Ku86 to viral replication centers. Our study addresses the interplay between the DNA-PK and MRN complexes during viral genome concatenation by NHEJ.

MicroRNA-Related Strategies to Improve Cardiac Function in Heart Failure

Heart failure (HF) describes a group of manifestations caused by the failure of heart function as a pump that supports blood flow through the body. MicroRNAs (miRNAs), as one type of non-coding RNA molecule, have crucial roles in the etiology of HF. Accordingly, miRNAs related to HF may represent potential novel therapeutic targets. In this review, we first discuss the different roles of miRNAs in the development and diseases of the heart. We then outline commonly used miRNA chemical modifications and delivery systems. Further, we summarize the opportunities and challenges for HF-related miRNA therapeutics targets, and discuss the first clinical trial of an antisense drug (CDR132L) in patients with HF. Finally, we outline current and future challenges and potential new directions for miRNA-based therapeutics for HF.

Targeted delivery of therapeutic agents to the heart

For therapeutic materials to be successfully delivered to the heart, several barriers need to be overcome, including the anatomical challenges of access, the mechanical force of the blood flow, the endothelial barrier, the cellular barrier and the immune response. Various vectors and delivery methods have been proposed to improve the cardiac-specific uptake of materials to modify gene expression. Viral and non-viral vectors are widely used to deliver genetic materials, but each has its respective advantages and shortcomings. Adeno-associated viruses have emerged as one of the best tools for heart-targeted gene delivery. In addition, extracellular vesicles, including exosomes, which are secreted by most cell types, have gained popularity for drug delivery to several organs, including the heart. Accumulating evidence suggests that extracellular vesicles can carry and transfer functional proteins and genetic materials into target cells and might be an attractive option for heart-targeted delivery. Extracellular vesicles or artificial carriers of non-viral and viral vectors can be bioengineered with immune-evasive and cardiotropic properties. In this Review, we discuss the latest strategies for targeting and delivering therapeutic materials to the heart and how the knowledge of different vectors and delivery methods could successfully translate cardiac gene therapy into the clinical setting.

Systemic delivery of adeno-associated viral vectors

For diseases like muscular dystrophy, an effective gene therapy requires bodywide correction. Systemic viral vector delivery has been attempted since early 1990s. Yet a true success was not achieved until mid-2000 when adeno-associated virus (AAV) serotype-6, 8 and 9 were found to result in global muscle transduction in rodents following intravenous injection. The simplicity of the technique immediately attracts attention. Marvelous whole body amelioration has been achieved in rodent models of many diseases. Scale-up in large mammals also shows promising results. Importantly, the first systemic AAV-9 therapy was initiated in patients in April 2014. Recent studies have now begun to reveal molecular underpinnings of systemic AAV delivery and to engineer new AAV capsids with superior properties for systemic gene therapy.

Spacial and Temporal Patterns of Gene Expression After Cardiac MEK1 Gene Transfer Improve Post-Infarction Remodeling Without Inducing Global Hypertrophy

Alteration of mitogen activated protein (MAP) kinase signaling in transgenic mice can ameliorate post-myocardial infarction (MI) remodeling. However, pre-existing changes in transgenic hearts and clinically unrealistic transgene expression likely affect the response to injury; it is unknown whether clinically relevant induction of transgene expression in an otherwise normal heart can yield similar benefits. Constitutively active MEK1 (aMEK1) or LacZ adeno-associated virus 9 (AAV9) vectors were injected into the left ventricular (LV) chambers of mice either just before or after coronary ligation. Hearts were evaluated via Western blot, quantitative polymerase chain reaction, histology, and echocardiography. AAV9-mediated aMEK1 delivery altered ERK1/2 expression/activation as in transgenic mice. Transgene expression was not immediately detectable but plateaued at 17 days, and therefore did not likely impact acute ischemia as it would in transgenics. With AAV9-aMEK1 injection just prior to MI, robust expression in the infarct border zone during post-MI remodeling increased border zone wall thickness and reduced infarct size versus controls at 4 weeks, but did not induce global hypertrophy. Significant improvements in local and global LV function were observed, as were trends toward a preservation of LV volume. Delivery after ligation significantly lowered transgene expression in the infarct border zone and did not yield structural or functional benefits. The primary benefits observed in transgenic mice, ameliorated remodeling, and reduced chronic infarct size, were achievable via clinically relevant gene transfer of aMEK1, supporting ongoing translational efforts. Important differences, however, were observed, and consideration must be given to the timing and distribution of transgene delivery and expression. J. Cell. Biochem. 118: 775-784, 2017. © 2016 Wiley Periodicals, Inc.

CRISPR-Cas9 as a Powerful Tool for Efficient Creation of Oncolytic Viruses

The development of oncolytic viruses has led to an emerging new class of cancer therapeutics. Although the safety profile has been encouraging, the transition of oncolytic viruses to the clinical setting has been a slow process due to modifications. Therefore, a new generation of more potent oncolytic viruses needs to be exploited, following our better understanding of the complex interactions between the tumor, its microenvironment, the virus, and the host immune response. The conventional method for creation of tumor-targeted oncolytic viruses is based on homologous recombination. However, the creation of new mutant oncolytic viruses with large genomes remains a challenge due to the multi-step process and low efficiency of homologous recombination. The CRISPR-associated endonuclease Cas9 has hugely advanced the potential to edit the genomes of various organisms due to the ability of Cas9 to target a specific genomic site by a single guide RNA. In this review, we discuss the CRISPR-Cas9 system as an efficient viral editing method for the creation of new oncolytic viruses, as well as its potential future applications in the development of oncolytic viruses. Further, this review discusses the potential of off-target effects as well as CRISPR-Cas9 as a tool for basic research into viral biology.

Surmounting limited gene delivery into primary immune cell populations: Efficient cell type-specific adenoviral transduction by CAR

Ectopic gene expression studies in primary immune cells have been notoriously difficult to perform due to the limitations in conventional transfection and viral transduction methods. Although replication-defective adenoviruses provide an attractive alternative for gene delivery, their use has been hampered by the limited susceptibility of murine leukocytes to adenoviral infection, due to insufficient expression of the human coxsackie/adenovirus receptor (CAR). In this issue of the European Journal of Immunology, Heger et al. [Eur. J. Immunol. 2015. 45: XXXX-XXXX] report the generation of transgenic mice that enable conditional Cre/loxP-mediated expression of human CAR. The authors demonstrate that this R26/CAG-CAR∆1(StopF) mouse strain facilitates the faithful monitoring of Cre activity in situ as well as the specific and efficient adenoviral transduction of primary immune cell populations in vitro. Further tweaking of the system towards more efficient gene transfer in vivo remains a future challenge.

Gene therapy delivery systems for enhancing viral and nonviral vectors for cardiac diseases: current concepts and future applications

Gene therapy is one of the most promising fields for developing new treatments for the advanced stages of ischemic and monogenetic, particularly autosomal or X-linked recessive, cardiomyopathies. The remarkable ongoing efforts in advancing various targets have largely been inspired by the results that have been achieved in several notable gene therapy trials, such as the hemophilia B and Leber's congenital amaurosis. Rate-limiting problems preventing successful clinical application in the cardiac disease area, however, are primarily attributable to inefficient gene transfer, host responses, and the lack of sustainable therapeutic transgene expression. It is arguable that these problems are directly correlated with the choice of vector, dose level, and associated cardiac delivery approach as a whole treatment system. Essentially, a delicate balance exists in maximizing gene transfer required for efficacy while remaining within safety limits. Therefore, the development of safe, effective, and clinically applicable gene delivery techniques for selected nonviral and viral vectors will certainly be invaluable in obtaining future regulatory approvals. The choice of gene transfer vector, dose level, and the delivery system are likely to be critical determinants of therapeutic efficacy. It is here that the interactions between vector uptake and trafficking, delivery route means, and the host's physical limits must be considered synergistically for a successful treatment course.

Therapeutic potential of genes in cardiac repair

Cardiovascular diseases remain the primary reason of premature death and contribute to a major percentage of global patient morbidity. Recent knowledge in the molecular mechanisms of myocardial complications have identified novel therapeutic targets along with the availability of vectors that offer the chance for designing gene therapy technique for protection and revival of the diseased heart functions. Gene transfer procedure into the myocardium is demonstrated through direct injection of plasmid DNA or through the coronary vasculature using the direct or indirect delivery of viral vectors. Direct DNA injection to the myocardium is reported to be of immense value in research studies that aims at understanding the activities of various elements in myocardium. It is also deemed vital for investigating the effect of the myocardial pathophysiology on expression of the foreign genes that are transferred. Gene therapies have been reported to heal cardiac pathologies such as myocardial ischemia, heart failure and inherited myopathies in several animal models. The results obtained from these animal studies have also encouraged a flurry of early clinical trials. This translational research has been triggered by an enhanced understanding of the biological mechanisms involved in tissue repair after ischemic injury. While safety concerns take utmost priority in these trials, several combinational therapies, various routes and dose of delivery are being tested before concrete optimization and complete potential of gene therapy is convincingly understood.

Differential activation of cellular DNA damage responses by replication-defective and replication-competent adenovirus mutants

Adenovirus (Ad) mutants that lack early region 4 (E4) activate the phosphorylation of cellular DNA damage response proteins. In wild-type Ad type 5 (Ad5) infections, E1b and E4 proteins target the cellular DNA repair protein Mre11 for redistribution and degradation, thereby interfering with its ability to activate phosphorylation cascades important during DNA repair. The characteristics of Ad infection that activate cellular DNA repair processes are not yet well understood. We investigated the activation of DNA damage responses by a replication-defective Ad vector (AdRSVβgal) that lacks E1 and fails to produce the immediate-early E1a protein. E1a is important for activating early gene expression from the other viral early transcription units, including E4. AdRSVβgal can deliver its genome to the cell, but it is subsequently deficient for viral early gene expression and DNA replication. We studied the ability of AdRSVβgal-infected cells to induce cellular DNA damage responses. AdRSVβgal infection does activate formation of foci containing the Mdc1 protein. However, AdRSVβgal fails to activate phosphorylation of the damage response proteins Nbs1 and Chk1. We found that viral DNA replication is important for Nbs1 phosphorylation, suggesting that this step in the viral life cycle may provide an important trigger for activating at least some DNA repair proteins.

The evolution of heart gene delivery vectors

Gene therapy holds promise for treating numerous heart diseases. A key premise for the success of cardiac gene therapy is the development of powerful gene transfer vehicles that can achieve highly efficient and persistent gene transfer specifically in the heart. Other features of an ideal vector include negligible toxicity, minimal immunogenicity and easy manufacturing. Rapid progress in the fields of molecular biology and virology has offered great opportunities to engineer various genetic materials for heart gene delivery. Several nonviral vectors (e.g. naked plasmids, plasmid lipid/polymer complexes and oligonucleotides) have been tested. Commonly used viral vectors include lentivirus, adenovirus and adeno-associated virus. Among these, adeno-associated virus has shown many attractive features for pre-clinical experimentation in animal models of heart diseases. We review the history and evolution of these vectors for heart gene transfer.

Duchenne muscular dystrophy gene therapy: Lost in translation?

A milestone of molecular medicine is the identification of dystrophin gene mutation as the cause of Duchenne muscular dystrophy (DMD). Over the last 2 decades, major advances in dystrophin biology and gene delivery technology have created an opportunity to treat DMD with gene therapy. Remarkable success has been achieved in treating dystrophic mice. Several gene therapy strategies, including plasmid transfer, exon skipping, and adeno-associated virus-mediated microdystrophin therapy, have entered clinical trials. However, therapeutic benefit has not been realized in DMD patients. Bridging the gap between mice and humans is no doubt the most pressing issue facing DMD gene therapy now. In contrast to mice, dystrophin-deficient dogs are genetically and phenotypically similar to human patients. Preliminary gene therapy studies in the canine model may offer critical insights that cannot be obtained from murine studies. It is clear that the canine DMD model may represent an important link between mice and humans. Unfortunately, our current knowledge of dystrophic dogs is limited, and the full picture of disease progression remains to be clearly defined. We also lack rigorous outcome measures (such as in situ force measurement) to monitor therapeutic efficacy in dystrophic dogs. Undoubtedly, maintaining a dystrophic dog colony is technically demanding, and the cost of dog studies cannot be underestimated. A carefully coordinated effort from the entire DMD community is needed to make the best use of the precious dog resource. Successful DMD gene therapy may depend on valid translational studies in dystrophin-deficient dogs.

Noninvasive imaging of lipid nanoparticle-mediated systemic delivery of small-interfering RNA to the liver

Mouse models with liver-specific expression of firefly luciferase were developed that enable a noninvasive and longitudinal assessment of small-interfering RNA (siRNA)-mediated gene silencing in hepatocytes of live animals via bioluminescence imaging. Using these models, a set of lipid nanoparticles (LNPs) with different compositions of cationic lipids, polyethylene glycol (PEG), and cholesterol, were tested for their abilities in delivering a luciferase siRNA to the liver via systemic administration. A dose-dependent luciferase knockdown by LNP/siRNA assemblies was measured by in vivo bioluminescence imaging, which correlated well with the results from parallel ex vivo analyses of luciferase mRNA and protein levels in the liver. RNA interference (RNAi)-mediated target silencing was further confirmed by the detection of RNAi-specific target mRNA cleavage. A single dose of LNP02L at 3 mg/kg (siRNA) caused 90% reduction of luciferase expression and the target repression lasted for at least 10 days. With identical components, LNPs containing 2% PEG are more potent than those with 5.4% PEG. Our results demonstrate that these liver-luciferase mouse models provide a powerful tool for a high-throughput evaluation of hepatic delivery platforms by noninvasive imaging and that the molar ratio of PEG lipid can affect the efficacy of LNPs in silencing liver targets via systemic administration.

A simple technique to establish a long-term adenovirus mediated gene transfer to the heart of newborn mice

Previous studies using different techniques have shown that adenoviral-mediated gene transfer to different tissues, including the kidney, is more efficient in neonatal mice. In this study, we report a simple technique that allows an efficient and long term expression of beta-galactosidase (beta-gal) in the heart of newborn mice. Newborn and adult C57BL6/J mice were subjected to a single retro-orbital venous plexus injection of recombinant adenoviral vectors (rAd) (2 x 10(9) particles/g body weight) carrying the lac Z gene. Seven days after the injection, positive beta-gal staining was systematically observed in the heart, lung, intestine, liver, kidney and spleen of newborn mice. However, only the heart showed persistent expression of beta-gal one year after the initial injection. In contrast, adult mice showed only significant but transient beta-gal expression mainly in the liver. In summary, we have found that a single retro-orbital intravenous injection can be used to establish a long-term adenoviral-mediated gene transfer to cardiac cells of newborn mice.

Wnt signaling inhibits Forkhead box O3a-induced transcription and apoptosis through up-regulation of serum- and glucocorticoid-inducible kinase 1

In human cancers, mutations in components of the Wnt signaling pathway lead to beta-catenin stabilization and result in augmented gene transcription. HCT116 colon cancer cells carry stabilizing mutations in beta-catenin and exhibit an elevated activation of Wnt signaling. To clarify the role of an overactive Wnt signaling, we used DNA microarray analysis to search for genes whose expression is up-regulated after knockdown of the wild type adenomatous polyposis coli (APC) tumor suppressor in HCT116 cells, which further enhances Wnt signaling activation. Serum and glucocorticoid-inducible kinase 1 (SGK1) was among the most up-regulated genes following APC knockdown through small interfering RNA. Up-regulation of SGK1 in response to small interfering RNA against APC was inhibited by concomitant knockdown of beta-catenin. Quantitative real time reverse transcription-PCR, Western blot, and chromatin immunoprecipitation analyses confirmed that SGK1 is a direct beta-catenin target gene. SGK1 negatively regulates the pro-apoptotic transcription factor Forkhead box O3a (FoxO3a) via phosphorylation and exclusion from the nucleus. We show that Wnt signaling activation results in FoxO3a exclusion from the nucleus and inhibits expression of FoxO3a target genes. Importantly, FoxO3a mutants that fail to be phosphorylated and therefore are regulated by SGK1 are not influenced by activation of Wnt signaling. In line, knockdown of SGK1 relieves the effects of Wnt signaling on FoxO3a localization and FoxO3a-dependent transcription. Finally, we show that induction of Wnt signaling inhibits FoxO3a-induced apoptosis. Collectively our results indicate that evasion of apoptosis is another feature employed by an overactive Wnt signaling.

Different modulation of cellular transcription by adenovirus 5, DeltaE1/E3 adenovirus and helper-dependent vectors

One problem encountered in the use of adenoviral vectors for gene therapy is their toxicity. Although many studies have analyzed this question in vivo, few researches have investigated adenovirus vector effects at the cellular level using a large-scale approach. In particular, no such data are available for helper-dependent adenovirus vectors (HD), which are promising adenovirus vectors for clinical applications since they are devoid of all viral genes and can host large transgene cassettes. The present study used gene chips to examine (Affymetrix HG-U95Av2 interrogating 12,626 unique human transcripts) the effect on liver cells of HD vectors versus that of DeltaE1/E3 adenovirus vector and wild type Adenovirus (Ad5). The effects of the DeltaE1/E3 adenovirus and of HD vectors were comparable, and significantly milder than that of Ad5. Interestingly the expression signatures of DeltaE1/E3 adenovirus and HD vectors were non-overlapping both at the single gene and the pathway level, suggesting specific and different interactions between the host cell and the two gene therapy vectors.

β-Dystroglycan as a Target for MMP-9, in Response to Enhanced Neuronal Activity

Matrix metalloproteinase-9 has recently emerged as an important molecule in control of extracellular proteolysis in the synaptic plasticity. However, no synaptic targets for its enzymatic activity had been identified before. In this report, we show that beta-dystroglycan comprises such a neuronal activity-driven target for matrix metalloproteinase-9. This notion is based on the following observations. (i) Recombinant, autoactivating matrix metalloproteinase-9 produces limited proteolytic cleavage of beta-dystroglycan. (ii) In neuronal cultures, beta-dystroglycan proteolysis occurs in response to stimulation with either glutamate or bicuculline and is blocked by tissue inhibitor of metalloproteinases-1, a metalloproteinase inhibitor. (iii) Beta-dystroglycan degradation is also observed in the hippocampus in vivo in response to seizures but not in the matrix metalloproteinase-9 knock-out mice. (iv) Beta-dystroglycan cleavage correlates in time with increased matrix metalloproteinase-9 activity. (v) Finally, beta-dystroglycan and matrix metalloproteinase-9 colocalize in postsynaptic elements in the hippocampus. In conclusion, our data identify the beta-dystroglycan as a first matrix metalloproteinase-9 substrate digested in response to enhanced synaptic activity. This demonstration may help to understand the possible role of both proteins in neuronal functions, especially in synaptic plasticity, learning, and memory.

Phosphorylation of APP695 at Thr668 decreases gamma-cleavage and extracellular Abeta

Phosphorylation of human APP695 at Thr668 seems to be specific to neuronal tissue and could affect Abeta production. Metabolism of APP mutated at Thr668 residue was analyzed in CHO cell line and primary cultures of rat cortical neurons. By site-directed mutagenesis, T668A or T668D substitutions were introduced in wild-type APP695. In CHO cells, wild-type APP695 was very slightly phosphorylated at Thr668 and produced similar levels of extracellular Abeta40 as compared to APPT668A. On the contrary, APPT668D was more efficiently cleaved by beta-secretase. However, accumulated betaCTF were less cleaved by gamma-secretase and less extracellular Abeta40 was produced. Decreased susceptibility to cleavage by gamma-secretase was confirmed upon expression of C99T668D. In neurons, part of APP695 was phosphorylated at Thr668. Following neuronal expression of APPT668A, extracellular Abeta40 production was increased. In conclusion, phosphorylation of human APP695 at Thr668 increases APP beta-cleavage but decreases its gamma-cleavage and extracellular Abeta40 production.

Isolation of targeted AAV2 vectors from novel virus display libraries

Random peptide ligands displayed on viral capsids are emerging tools for selection of targeted gene transfer vectors even without prior knowledge of the potential target cell receptor. We have previously introduced adeno-associated viral (AAV)-displayed peptide libraries that ensure encoding of displayed peptides by the packaged AAV genome. A major limitation of these libraries is their contamination with wild-type (wt) AAV. Here we describe a novel and improved library production system that reliably avoids generation of wt AAV by use of a synthetic cap gene. Selection of targeted AAV vectors from wt-containing and the novel wt-free libraries on cell types with different permissivity for wt AAV2 replication suggested the superiority of the wt-free library. However, from both libraries highly specific peptide sequence motifs were selected which improved transduction of cells with moderate or low permissivity for AAV2 replication. Strong reduction of HeLa cell transduction compared to wt AAV2 and only low level transduction of non-target cells by some selected clones showed that not only the efficiency but also the specificity of gene transfer was improved. In conclusion, our study validates and improves the unique potential of virus display libraries for the development of targeted gene transfer vectors.

Adenovirus type 5 E1A gene therapy for ovarian clear cell carcinoma: a potential treatment strategy

Resistance of ovarian clear cell carcinoma (CCC) to platinum-based chemotherapy is associated with poor prognosis, and an effective treatment for advanced disease is urgently needed. HER2/neu is up-regulated more often in CCC than in other histologic types of epithelial ovarian cancer. The purpose of this study was to assess possible treatment for ovarian CCC with the anti-HER2 antibody trastuzumab or human adenovirus type 5 E1A. We treated 10 CCC cell lines with trastuzumab or E1A and assessed cell viability, proliferation, and colony formation and the expression of HER2 and wild-type p53 proteins and molecules downstream of those signaling pathways. HER2 protein was detected at various levels in all 10 cell lines by Western blotting and in 5 CCC cell lines by immunohistochemical staining; HER2 gene amplification was detected (by fluorescence in situ hybridization) in only one cell line (RMG-I). Trastuzumab did not inhibit proliferation in any of the four CCC cell lines tested (RMG-I, SKOV-2, OVTOKO, and OVSAYO). However, transfection with E1A (as compared with control vectors) reduced colony formation in all 10 CCC cell lines regardless of HER2 expression level. Infection of RMG-I and SMOV-2 cells with an adenoviral vector encoding E1A led to significant (P < 0.05) suppression of proliferation and enhancement of cell death; this effect required stabilization of p53 (but not p73) protein and was associated with the up-regulation of Bax and the cleavage of caspase-9. Other mechanisms, such as p53-independent apoptosis, may also be involved in E1A-mediated cell death in CCC. Finally, treatment with E1A prolonged survival in a CCC xenograft model (P < 0.001). E1A gene therapy, because of its ability to stabilize wild-type p53, is worth exploring as a treatment modality for women with ovarian CCC, which typically expresses wild-type p53.

Inducible cAMP early repressor (ICER)-evoked delayed neuronal death in the organotypic hippocampal culture

Programmed cell death involving gene regulation and de novo protein synthesis is a major component of both normal development and a number of disease conditions. Hence, knowledge of its mechanisms, especially transcription factors, that regulate expression of the genes involved in neurodegenerative disorders is of great importance. cAMP-responsive element-binding protein (CREB) has repeatedly been implicated in the neuronal survival. In the present study we showed that inducible cAMP early repressor (ICER), an endogenous CREB antagonist, is expressed during both excitotoxic and spontaneous neuronal cell death in organotypic hippocampal slice cultures in vitro. Furthermore, overexpression of ICER via an adenoviral vector evoked neuronal cell loss in such cultures. The time course of ICER-dependent cell death was hippocampal subdivision specific, with dentate gyrus neurons dying mostly 3-7 days after the adenovector infection, followed by CA3, where neuronal death peaked after 7 days, and then CA1, where most neuronal death occurred after 7-14 days. These results underscore the usefulness of the organotypic cultures for studies of neurodegeneration and point to neuronal loss having a multifaceted nature in a complex cellular environment.

Clinically applicable procedure for gene delivery to fetal gut by ultrasound-guided gastric injection: toward prenatal prevention of early-onset intestinal diseases

Targeting gene therapy vectors to the fetal intestinal tract could provide a novel means toward prevention of the early postnatal intestinal pathology of cystic fibrosis and other conditions, such as congenital enteropathy, that cause intestinal failure. Among these conditions, cystic fibrosis is by far the most common lethal genetic disease. It is caused by a functional absence or deficiency of the cystic fibrosis transmembrane conductance regulator and manifests in the gut as meconium ileus. Prenatal treatment of genetic disease may avoid early-onset tissue damage and immune sensitization, and may target cells that are less accessible in the adult. We investigated gene transfer to the fetal gut, using a minimally invasive injection technique. First-generation replication-deficient adenoviral vectors encoding the beta-galactosidase gene and transduction-enhancing agents were injected into the stomach of early-gestation fetal sheep (n = 8, 60 days of gestation; term, 145 days) under ultrasound guidance. Reporter gene expression was observed 2 days after injection in the villi of the gastrointestinal epithelia after 5-bromo-4-chloro-3-indolyl-beta-D-galactopyranoside staining and beta-galactosidase immunohistochemistry of fetal tissues. Expression of beta-galactosidase, as measured by enzyme-linked immunosorbent assay, was enhanced after pretreatment of the fetal gut with sodium caprate, which opens tight junctions, and after adenovirus complexation with DEAE-dextran, which confers a positive charge to the virus. Instillation of the fluorocarbon perflubron after virus delivery resulted in tissue transduction from the fetal stomach to the colon. Using a clinically relevant technique, we have demonstrated widespread gene transfer to the fetal gastrointestinal epithelia.

Efficacy of Therapeutic Angiogenesis by Intramyocardial Injection of pCK-VEGF165 in Pigs

BACKGROUND

Intramyocardial injection of vascular endothelial growth factor (VEGF) plasmid DNA was studied to demonstrate improvement of regional myocardial function.

METHODS

Twenty-one pigs that had undergone ligation of the left anterior descending coronary artery were randomly allocated to one of two treatments: intramyocardial injection of pCK-VEGF165 (VEGF group) or pCK-Null (control group) into the ischemic border zone. Electrocardiogram-gated single-photon emission computed tomography was performed 30 and 60 days after the coronary ligation. Segmental variables of perfusion and function were automatically quantified using a 20-segment model. In the segmental analysis, 119 segments were selected for analysis (71 segments in the VEGF group; 48 segments in the control group). Histologic analysis was also performed in the myocardial tissue of the ischemic border zone.

RESULTS

At day 30, there were no significant differences in segmental perfusion, wall thickening, and wall motion between the two groups. In the VEGF group, all variables of perfusion, wall thickening, and wall motion were significantly improved at day 60 compared with those at day 30 (p < 0.05), while there were no differences in the control group. At day 60, perfusion (p = 0.018), wall motion (p = 0.004), and wall thickening (p = 0.068) of the VEGF group were improved compared with those of the control group. Histologic analysis showed that microcapillary density was significantly higher in the VEGF group than the control group (p < 0.001).

CONCLUSIONS

Intramyocardial injection of pCK-VEGF165 significantly augmented neoangiogenesis in the ischemic area and improved regional myocardial function as well as myocardial perfusion.

1-methyl-4-phenylpyridinium neurotoxicity is attenuated by adenoviral gene transfer of human Cu/Zn superoxide dismutase

Oxidative stress has been suggested to be an important mediator of dopaminergic cell death in Parkinson's disease (PD). We investigated the neuroprotective potential of Cu/Zn superoxide dismutase (SOD1) overexpression in the rat substantia nigra (SN) following adenovirus-mediated gene transfer. Human dopaminergic SK-N-SH cells were transduced with adenoviral vectors expressing either human SOD1 (Ad-SOD1) or beta-galactosidase (Ad-betagal) before exposure to 1 mM of the 1-methyl-4-phenylpyridinium ion (MPP+). A strong neuroprotective effect of SOD1 gene transfer was observed in the SK-N-SH cells exposed to MPP+ compared with controls. Adult rats were then given unilateral injections of either Ad-SOD1 or Ad-betagal into the striatum, and MPP+ was administered 8 days later at the same location. Strong transgene expression was detected in the SN dopaminergic neurons, a consequence of retrograde axonal transport of the adenoviral particles. The amphetamine-induced rotational behavior of the rats was markedly lower in Ad-SOD1-injected rats than in control animals. Also, behavioral recovery significantly correlated with the number of tyrosine hydrolase-expressing neurons in the SN of the treated rats. These results are consistent with oxidative stress contributing to the MPP+ -induced neurodegenerative process. They also indicate that SOD1 gene transfer into the nigrostriatal system may be a potential neuroprotective strategy for treating PD.

Amino-terminal fragment of urokinase inhibits tumor cell invasion in vitro and in vivo: respective contribution of the urokinase plasminogen activator receptor-dependent or -independent pathway

The urokinase plasminogen activator (uPA) is implicated in both cancer cell invasion and angiogenesis. It can interact with a specific receptor (uPAR) via the epidermal growth factor (EGF)-like domain in the urokinase amino-terminal fragment (ATF) in a species-specific manner. Our previous studies showed that adenovirusmediated delivery of murine ATF (AdmATF) suppressed human tumor growth in mouse models, by inhibiting murine angiogenesis. However, we cannot exclude its putative inhibitory action on human cancer cell invasion through a uPAR-independent pathway. To further investigate the mechanisms of ATF, we constructed another adenovirus, AdhmATF, expressing humanized murine ATF (hmATF). hmATF binds to human uPAR but not to murine uPAR. We compared the antagonist effect of both AdmATF and AdhmATF on human and murine cancer cells. In vitro, the supernatant from AdhmATF-infected cells repressed 79% of membrane-associated uPA activity on human MDA-MB-231 cells, whereas that from AdmATF-infected cells repressed 35% of membrane-associated uPA activity. On murine LLC cells, the supernatant from AdhmATF-infected cells inhibited 29% of cell surface uPA activity, whereas that from AdmATF-infected cells inhibited 74% of cell surface uPA activity. Similar results were obtained in a cell invasion assay. In vivo, intratumoral injection of the adenoviruses into LLC tumors on day 24 postinjection induced lower but significant tumor growth suppression by AdhmATF (tumor volume was 1185 +/- 128 mm3), whereas suppression by AdmATF was greater (407 +/- 147 mm3). In the MDA-MB-231 tumor model, on day 52 postinjection, tumor size was 187 +/- 47 mm3 in the AdhmATF-treated group and 468 +/- 65 mm3 in the AdmATF-treated group. The LLC and MDA-MB- 231 cell lines transfected by mATF or hmATF genes showed growth inhibition In vivo equivalent to the results obtained by adenovirus treatment. These results demonstrate the strong anticancer activity of ATF even when its uPAR-binding affinity has been suppressed, and indicate that ATF exerts an antitumor effect via dual mechanisms: essentially through targeting the uPA-uPAR system via the EGF-like domain and partially through targeting a uPAR-independent interaction via the kringle domain.

Lactacystin decreases amyloid-β peptide production by inhibiting β-secretase activity

The human amyloid precursor protein (APP) is processed by the nonamyloidogenic and the amyloidogenic catabolic pathways. The sequential cleavage of APP by the beta- and gamma-secretase activities, known as the amyloidogenic processing of APP, leads to the formation of the amyloid-beta peptide (Abeta). Abeta is the main constituent of the amyloid core of senile plaques, a typical hallmark of Alzheimer's disease. In addition to secretases, other cellular proteolytic activities, like the proteasome, might participate in the metabolism of APP. We investigated the consequence of proteasome inhibition on the amyloidogenic processing of human APP. CHO cells and primary cultures of rat cortical neurons expressing human APP or a protein corresponding to its beta-cleaved C-terminal fragment (C99) were treated with lactacystin, an irreversible inhibitor of the chymotrypsin-like activity of the proteasome. Lactacystin significantly decreased the level of Abeta produced from APP in both cellular models, whereas the production of Abeta from C99 was not affected. Lactacystin did not inhibit gamma-secretase activity but was found to inhibit the beta-cleavage of APP, leading to a proportional decrease in Abeta production. Although lactacystin did not inhibit the catalytic activity of recombinant BACE1, a decrease in neuronal beta-secretase activity was measured after treatment with lactacystin.

Enhanced brain angiogenesis in chronic cerebral hypoperfusion after administration of plasmid human vascular endothelial growth factor in combination with indirect vasoreconstructive surgery

OBJECT

Vascular endothelial growth factor (VEGF) is a secreted mitogen associated with angiogenesis. The conceptual basis for therapeutic angiogenesis after plasmid human VEGF gene (phVEGF) transfer has been established in patients presenting with limb ischemia and myocardial infarction. The authors hypothesized that overexpression of VEGF using a gene transfer method combined with indirect vasoreconstruction might induce effective brain angiogenesis in chronic cerebral hypoperfusion, leading to prevention of ischemic attacks.

METHODS

A chronic cerebral hypoperfusion model induced by permanent ligation of both common carotid arteries in rats was used in this investigation. Seven days after induction of cerebral hypoperfusion, encephalomyosynangiosis (EMS) and phVEGF administration in the temporal muscle were performed. Fourteen days after treatment, the VEGF gene therapy group displayed numbers and areas of capillary vessels in temporal muscles that were 2.2 and 2.5 times greater, respectively, in comparison with the control group. In the brain, the number and area of capillary vessels in the group treated with the VEGF gene were 1.5 and 1.8 times greater, respectively, relative to the control group.

CONCLUSIONS

In rat models of chronic cerebral hypoperfusion, administration of phVEGF combined with indirect vasoreconstructive surgery significantly increased capillary density in the brain. The authors' results indicate that administration of phVEGF may be an effective therapy in patients with chronic cerebral hypoperfusion, such as those with moyamoya disease.

Factors influencing adenovirus-mediated airway transduction in fetal mice

Intra-amniotic injection of adenovirus allows transduction of the fetal airways following natural fetal breathing movements. This administration method is promising for use in gene therapy for cystic fibrosis and other diseases for which the main target for exogenous gene expression is the lung. Here we have investigated factors that may affect the efficacy of gene transfer to the murine fetal lung. We examined marker compound distribution and transgene expression (from a first-generation adenoviral vector) at different stages of development. This demonstrated that fetal breathing movements at 15-16 days of gestation are of sufficient intensity to carry marker/vector into the fetal lungs. These movements can be significantly stimulated by the combination of intra-amniotic theophylline administration and postoperative exposure of the dam to elevated CO(2) levels. However, the most important factor for efficient and consistent pulmonary transgene delivery is the dose of adenoviral vector used, as both the degree of transduction and the percentage of lungs transduced increases with escalating viral dose.

Comparative Efficacy of Intratracheal Adeno-Associated Virus Administration to Newborn Rats

Transient local overexpression of genes that promote lung defense or repair may help to protect or promote alveolar development in premature neonates. We showed that the use of adenoviral vectors in neonates was limited by the induction of lung growth disorders. In the present work we compare the efficiency of gene transfer to the neonatal lung by three adeno-associated viral vectors: rAAV1, rAAV2, and rAAV5. Transduction efficiency was first measured in vitro, by infecting A549 immortalized human lung epithelial cells, and primary epithelial and mesenchymal cells isolated from human fetal lung. AAV vectors yielded similar low levels of luciferase gene expression in the different cell types. In vivo transduction efficiency was evaluated in newborn rats, with AAV-LacZ vectors being intratracheally instilled at 3 days of age. Both rAAV5 and rAAV1, but not rAAV2, induced significant lung beta-galactosidase expression, which persisted on day 35. Highest beta- galactosidase levels were measured with rAAV5, but remained far lower than those obtained with adenoviral vectors. A transient increase in alveolar macrophages was observed on day 6, but not on day 8, after rAAV5-LacZ instillation. Morphometric evaluation of lung structures was performed on day 21, and showed no altered lung growth. We conclude that rAAV1 or rAAV5 was more efficient at mediating gene transfer in the neonatal lung than was rAAV2, without adversely affecting lung development. However, in vivo transgene expression was relatively low, and needs to be improved for future therapeutic use of these adeno-associated vectors.

Optimization of gene transfer into neonatal rat cardiomyocytes and unmasking of cytomegalovirus promoter silencing

Cardiomyocytes are notoriously difficult to transfect using standard techniques unless viral vectors such as recombinant adenoviruses are used. Generation of recombinant adenoviruses is, however, a complex and time-consuming procedure and not possible for every DNA construct. We therefore optimized DNA/polylysine/adenovirus complexing for efficient gene transfer in neonatal rat cardiomyocytes determining the critical parameters for this method. Importantly, not only the concentration of the various components but also the method used for plasmid purification is critical for this transfection technique. Cesium-chloride-purified DNA is inferior to anion-exchange methods for this purpose possibly because of altered ionic properties. In the second part of this study, we could demonstrate silent gene transfer into cardiomyocytes applying this optimized technique to plasmids encoding luciferase or beta-galactosidase cDNAs under the control of the cytomegalovirus immediate-early promoter. Phorbol myristate acetate and/or forskolin increased the amount of beta-galactosidase positive cells up to fivefold. Luciferase activity could even be increased as much as ninefold. These results demonstrate that the cytomegalovirus promoter is not maximally active in neonatal rat cardiomyocytes under basal conditions. In fact, a large proportion of cells is silently transfected and seems to express (an) inhibitor(s) of transcription from the CMV promoter that can be overcome by stimulation of cAMP- or protein kinase C-dependent pathways.

Uniform scale-independent gene transfer to striated muscle after transvenular extravasation of vector

BACKGROUND

The muscular dystrophies exemplify a class of systemic disorders for which widespread protein replacement in situ is essential for treatment of the underlying genetic disorder. Somatic gene therapy will require efficient, scale-independent transport of DNA-containing macromolecular complexes too large to cross the continuous endothelia under physiological conditions. Previous studies in large-animal models have revealed a trade-off between the efficiency of gene transfer and the inherent safety of the required surgical and pharmacological interventions to achieve this.

METHODS AND RESULTS

Rats and dogs underwent limb or hemibody isolation via atraumatic tourniquet placement or myocardial isolation via heterotopic transplantation. Recombinant adenovirus (10(13) particles per kilogram) or recombinant adeno-associated virus (10(14) genome copies/kg) encoding the lacZ transgene was delivered through pressurized venous infusion without pharmacological mediators. Muscle exhibited almost 100% myofiber transduction in rats and dogs by X-galactosidase staining and significantly higher beta-galactosidase levels compared with nonpressurized delivery. No significant difference was seen in beta-galactosidase levels between 100- or 400-mm Hg groups. The <50-mm Hg group yielded inhomogeneous and significantly lower transgene expression.

CONCLUSIONS

Uniform scale- and vector-independent skeletal and cardiac myofiber transduction is facilitated by pressurized venous infusion in anatomic domains isolated from the central circulation without pharmacological interference with cardiovascular homeostasis. We provide the first demonstration of uniform gene transfer to muscle fibers of an entire extremity in the dog, providing a firm foundation for further translational studies of efficacy in canine models for human diseases.

Lithium chloride increases the production of amyloid-beta peptide independently from its inhibition of glycogen synthase kinase 3

Glycogen synthase kinase 3 (GSK3) is able to phosphorylate tau at many sites that are found to be phosphorylated in paired helical filaments in Alzheimer disease. Lithium chloride (LiCl) efficiently inhibits GSK3 and was recently reported to also decrease the production of amyloid-beta peptide (Abeta) from its precursor, the amyloid precursor protein. Therefore, lithium has been proposed as a combined therapeutic agent, inhibiting both the hyperphosphorylation of tau and the production of Abeta. Here, we demonstrate that the inhibition of GSK3 by LiCl induced the nuclear translocation of beta-catenin in Chinese hamster ovary cells and rat cultured neurons, in which a decrease in tau phosphorylation was observed. In both cellular models, a nontoxic concentration of LiCl increased the production of Abeta by increasing the beta-cleavage of amyloid precursor protein, generating more substrate for an unmodified gamma-secretase activity. SB415286, another GSK3 inhibitor, induced the nuclear translocation of beta-catenin and slightly decreased Abeta production. It is concluded that the LiCl-mediated increase in Abeta production is not related to GSK3 inhibition.

Canstatin acts on endothelial and tumor cells via mitochondrial damage initiated through interaction with alphavbeta3 and alphavbeta5 integrins

Canstatin, the noncollagenous domain of collagen type IV alpha-chains, belongs to a series of collagen-derived angiogenic inhibitors. We have elucidated the functional receptors and intracellular signaling induced by canstatin that explain its strong antitumor efficacy in vivo. For this purpose, we generated a canstatin-human serum albumin (CanHSA) fusion protein, employing the HSA moiety as an expression tag. We show that CanHSA triggers a crucial mitochondrial apoptotic mechanism through procaspase-9 cleavage in both endothelial and tumor cells, which is mediated through cross-talk between alphavbeta3- and alphavbeta5-integrin receptors. As a point of reference, we employed the first three kringle domains of angiostatin (K1-3), fused with HSA, which, in contrast to CanHSA, act only on endothelial cells through alphavbeta3-integrin receptor-mediated activation of caspase-8 alone, without ensuing mitochondrial damage. Taken together, these results provide insights into how canstatin might exert its strong anticancer effect.

Catheter-based antegrade intracoronary viral gene delivery with coronary venous blockade

The purpose of this study is to evaluate the feasibility of percutaneous antegrade myocardial gene transfer (PAMGT). A consistent and safe technique for in vivo gene transfer is required for clinical application of myocardial gene therapy. PAMGT with concomitant coronary venous blockade was performed in 12 swine. The myocardium was preconditioned with 1 min of occlusion of the left anterior descending and left circumflex arteries. The anterior interventricular vein was occluded during left anterior descending artery delivery, and the great cardiac vein at the entrance of the middle cardiac vein was occluded during left circumflex artery delivery. With arterial and venous balloons inflated (3 min) and after adenosine (25 mug) injection, PAMGT was performed by antegrade injection of an adenoviral solution (1 ml of 10(11) plaque-forming units in each coronary artery) carrying beta-galactosidase or saline through the center lumen of the angioplasty balloon. In one set of animals, PAMGT was performed with selective coronary vein blockade (n = 9); in another set of animals, PAMGT was performed without coronary vein blockade (n = 5). At 1 wk after gene delivery, the animals were killed. Quantitative beta-galactosidase analysis was performed in the left and right ventricular walls. PAMGT was successfully performed in all animals with and without concomitant occlusion of the coronary veins. Quantitative beta-galactosidase analysis showed that PAMGT with coronary blockade was superior to PAMGT without coronary blockade. beta-Galactosidase activity increased significantly in the beta-galactosidase group compared with the saline group: 1.34 +/- 0.18 vs. 0.81 +/- 0.1 ng (P </= 0.01) in the left ventricular wall and 0.91 +/- 0.1 vs. 0.66 +/- 0.07 ng (P </= 0.05) in the right ventricular wall. PAMGT with selective coronary venous blockade is feasible, reproducible, and safely achieved in a large-animal model.

A conformational change in the adeno-associated virus type 2 capsid leads to the exposure of hidden VP1 N termini

The complex infection process of parvoviruses is not well understood so far. An important role has been attributed to a phospholipase A2 domain which is located within the unique N terminus of the capsid protein VP1. Based on the structural difference between adeno-associated virus type 2 wild-type capsids and capsids lacking VP1 or VP2, we show via electron cryomicroscopy that the N termini of VP1 and VP2 are involved in forming globules inside the capsids of empty and full particles. Upon limited heat shock, VP1 and possibly VP2 become exposed on the outsides of full but not empty capsids, which is correlated with the disappearance of the globules in the inner surfaces of the capsids. Using molecular modeling, we discuss the constraints on the release of the globularly organized VP1-unique N termini through the channels at the fivefold symmetry axes outside of the capsid.