Skeletal muscle regeneration after insulin-like growth factor I gene transfer by recombinant Sendai virus vector

Advances in RNA Viral Vector Technology to Reprogram Somatic Cells: The Paramyxovirus Wave

Ethical issues are a significant barrier to the use of embryonic stem cells in patients due to their origin: human embryos. To further the development of stem cells in a patient application, alternative sources of cells were sought. A process referred to as reprogramming was established to create induced pluripotent stem cells from somatic cells, resolving the ethical issues, and vectors were developed to deliver the reprogramming factors to generate induced pluripotent stem cells. Early viral vectors used integrating retroviruses and lentiviruses as delivery vehicles for the transcription factors required to initiate reprogramming. However, because of the inherent risk associated with vectors that integrate into the host genome, non-integrating approaches were explored. The development of non-integrating viral vectors offers a safer alternative, and these modern vectors are reliable, efficient, and easy to use to achieve induced pluripotent stem cells suitable for direct patient application in the growing field of individualized medicine. This review summarizes all the RNA viral vectors in the field of reprogramming with a special focus on the emerging delivery vectors based on non-integrating  Paramyxoviruses, Sendai and measles viruses. We discuss their design and evolution towards being safe and efficient reprogramming vectors in generating induced pluripotent stem cells from somatic cells.

PHD3 mediates denervation skeletal muscle atrophy through Nf-κB signal pathway

Skeletal muscle is the largest organ of the body, the development of skeletal muscle is very important for the health of the animal body. Prolyl hydroxylases (PHDs) are the classical regulator of the hypoxia inducible factor (HIF) signal pathway, many researchers found that PHDs are involved in the muscle fiber type transformation, muscle regeneration, and myocyte differentiation. However, whether PHDs can impact the protein turnover of skeletal muscle is poorly understood. In this study, we constructed denervated muscle atrophy mouse model and found PHD3 was highly expressed in the atrophic muscles and there was a significant correlation between the expression level of PHD3 and skeletal muscle weight which was distinct from PHD1 and PHD2. Then, the similar results were getting from the different weight muscles of normal mice. To further verify the relationship between PHD3 and skeletal muscle protein turnover, we established a PHD3 interference model by injecting PHD3 sgRNA virus into tibialis anterior muscle (TA) muscle of MCK-Cre-cas9 mice and transfecting PHD3 shRNA lentivirus into primary satellite cells. It was found that the Knock-out of PHD3 in vivo led to a significant increase in muscle weight and muscle fiber area (P < .05). Besides, the activity of protein synthesis signal pathway increased significantly, while the protein degradation pathway was inhibited evidently (P < .05). In vitro, the results of 5-ethynyl-2'-deoxyuridine (EdU) and tetramethylrhodamine ethyl ester (TMRE) fluorescence detection showed that PHD3 interference could lead to a decrease in cell proliferation and an increase of cell apoptosis. After the differentiation of satellite cells, the production of puromycin in the interference group was higher than that in the control group, and the content of 3-methylhistidine in the interference group was lower than that in the control group (P < .05) which is consistent with the change of protein turnover signal pathway in the cell. Mechanistically, there is an interaction between PHD3, NF-κB, and IKBα which was detected by immunoprecipitation. With the interfering of PHD3, the expression of the inflammatory signal pathway also significantly decreased (P < .05). These results suggest that PHD3 may affect protein turnover in muscle tissue by mediating inflammatory signal pathway. Finally, we knocked out PHD3 in denervated muscle atrophy mice and LPS-induced myotubes atrophy model. Then, we found that the decrease of PHD3 protein level could alleviate the muscle weight and muscle fiber reduction induced by denervation in mice. Meanwhile, the protein level of the inflammatory signal pathway and the content of 3-methylhistidine in denervated atrophic muscle were also significantly reduced (P < .05). In vitro, PHD3 knock-out could alleviate the decrease of myotube diameter induced by LPS, and the expression of protein synthesis pathway was also significantly increased (P < .05). On the contrary, the expression level of protein degradation and inflammatory signal pathway was significantly decreased (P < .05). Through these series of studies, we found that the increased expression of PHD3 in denervated muscle might be an important regulator in inducing muscle atrophy, and this process is likely to be mediated by the inflammatory NF-κB signal pathway.

Gene Therapy for Recurrent Laryngeal Nerve Injury

Recurrent laryngeal nerve (RLN) injury has considerable clinical implications, including voice and swallowing dysfunction, which may considerably impair the patient’s quality of life. Recovery of vocal fold movement is an essential novel treatment option for RLN injury. The potential of gene therapy for addressing this issue is highly promising. The target sites for RLN gene therapy are the central nervous system, nerve fibers, laryngeal muscles, and vocal cord mucosa. Gene transduction has been reported in each site using viral or non-viral methods. The major issues ensuing after RLN injury are loss of motoneurons in the nucleus ambiguus, degeneration and poor regeneration of nerve fibers and motor end plates, and laryngeal muscle atrophy. Gene therapy using neurotrophic factors has been assessed for most of these issues, and its efficacy has been reported. Another important matter for functional vocal fold movement recovery is misdirected regeneration, in which the wrong neurons may innervate other laryngeal muscles, where even if innervation is reestablished, proper motor function is not restored. Novel strategies involving gene therapy bear promise for overcoming this issue and further investigations are underway.

Sendai virus-mediated gene transfer of the c-myc suppressor far-upstream element-binding protein-interacting repressor suppresses head and neck cancer

Far-upstream element-binding protein-interacting repressor (FIR) is a transcription factor that inhibits c-Myc expression and has been shown to have antitumor effects in some malignancies. Here, we evaluated the antitumor effects of FIR using fusion gene-deleted Sendai virus (SeV/ΔF) as a nontransmissible vector against head and neck squamous cell carcinoma (HNSCC). Using in vitro and in vivo xenograft mouse models, we observed efficient expression of green fluorescent protein (GFP) following transduction with the SeV/ΔF vector encoding GFP (GFP-SeV/ΔF) into HNSCC cells. In vitro and in vivo studies revealed that administration of the FIR-encoded SeV/ΔF (FIR-SeV/ΔF) vector exerted significant antitumor effects, suppressed c-Myc expression and induced apoptosis in HNSCC. Additionally, the antitumor effects of FIR or the expression of GFP following administration of the FIR- or GFP-SeV/ΔF vector, respectively, were dependent on the multiplicity of infection or titer. Furthermore, the SeV/ΔF vector itself had no cytotoxic effects. Therefore, the SeV/ΔF vector may be safe and useful for the treatment of HNSCC, allowing for high-titer SeV/ΔF vector administration for anticancer gene therapy. In addition, SeV/ΔF vector-mediated FIR gene therapy demonstrated effective tumor suppression in HNSCC, suggesting that this therapy may have the potential for clinical use as a novel strategy for HNSCC treatment.

Cellular unfolded protein response against viruses used in gene therapy

Viruses are excellent vehicles for gene therapy due to their natural ability to infect and deliver the cargo to specific tissues with high efficiency. Although such vectors are usually "gutted" and are replication defective, they are subjected to clearance by the host cells by immune recognition and destruction. Unfolded protein response (UPR) is a naturally evolved cyto-protective signaling pathway which is triggered due to endoplasmic reticulum (ER) stress caused by accumulation of unfolded/misfolded proteins in its lumen. The UPR signaling consists of three signaling pathways, namely PKR-like ER kinase, activating transcription factor 6, and inositol-requiring protein-1. Once activated, UPR triggers the production of ER molecular chaperones and stress response proteins to help reduce the protein load within the ER. This occurs by degradation of the misfolded proteins and ensues in the arrest of protein translation machinery. If the burden of protein load in ER is beyond its processing capacity, UPR can activate pro-apoptotic pathways or autophagy leading to cell death. Viruses are naturally evolved in hijacking the host cellular translation machinery to generate a large amount of proteins. This phenomenon disrupts ER homeostasis and leads to ER stress. Alternatively, in the case of gutted vectors used in gene therapy, the excess load of recombinant vectors administered and encountered by the cell can trigger UPR. Thus, in the context of gene therapy, UPR becomes a major roadblock that can potentially trigger inflammatory responses against the vectors and reduce the efficiency of gene transfer.

Efficient transfection of sendai virus vector to mouse pancreatic stem cells in the floating state

Sendai virus (SeV) vectors can efficiently introduce foreign genes without toxicity into various organs and are expected to be clinically applicable. We previously compared the transfectional efficiency of SeV and adenovirus (AdV) vectors by assessing the transfer of the green fluorescent protein (GFP) gene to pancreatic stem cells. Although the gene transfer efficiency was similar between these vectors, SeV vector had a lower toxicity in comparison to the AdV vector. In this study, we assessed the gene transfer efficiency of SeV vector in the floating state to pancreatic stem cells. The efficiency of gene transfer was much higher at all time points and at all concentrations in the floating state versus in the adhesion state. In addition, the pancreatic stem cells transfected with SeV in the floating state maintained their differentiation ability. These data suggest that SeV transfection to pancreatic stem cells in the floating state may be useful in gene transfer technology.

RECOMBINANT SENDAI VIRUS FOR EFFICIENT GENE TRANSFER TO HUMAN AIRWAY EPITHELIUM

Recombinant Sendai virus (rSeV) infects respiratory epithelial cells in animal models and cultures of undifferentiated human nasal cells. It was the aim of this study to investigate the capability of rSeV to express a transgene in human airway epithelium. Differentiated human airway epithelial cells were generated using air-liquid interface culture techniques. Application of rSeV coding for green fluorescence protein (GFP) onto the apical surface (using a multiplicity of infection of 3) resulted in expression of the transgene in more than 90% of the cells followed by decreasing numbers of positive cells during the observation time of 3 weeks. The infection of human respiratory epithelial cells is mediated by sialic acid residues at the apical surface. Despite the secretion of interleukin (IL)-8 and the replication of rSeV in the epithelial cells, the authors could not detect any cytopathic effect after the infection. In conclusion, rSeV infects differentiated human airway epithelial cells with high efficiency. Transgene expression is transient and accompanied by the secretion of an inflammatory cytokine.

Comparison of Sendai Virus-Mediated Gene Transfer Efficiency to Adhesive and Floating Adipose Tissue-Derived Stem Cells

Sendai virus (SeV) vectors have potential clinical applications because they can efficiently introduce foreign genes without toxicity into various organs. A recent study reported the green fluorescent protein (GFP) gene transfer to adipose tissue-derived stem cells (ASCs) with SeV vectors results in more efficient expression of GFP than AdV and identified the preservation of the multilineage potential of ASCs transfected with SeV vectors. This study assessed the gene transfer efficiency to floating ASCs with SeV vectors. Although a slight cytotoxicity was observed, the efficiency of gene transfer to cells in the floating state was much higher at all times and all concentrations at MOIs of 2, 10, and 20 than in the adhesion state. Moreover, ASCs transfected with SeV vectors in floating state have the same potential for their differentiation into specific tissues, such as adipocytes and osteocytes, as untransfected ASCs. These data suggest that SeV transfection to ASCs in the floating state could therefore be useful for gene transfer technology.

Recombinant Sendai Virus-Mediated Gene Transfer to Mouse Pancreatic Stem Cells

Efficient gene transfer into stem cells is essential for the basic research and for therapeutic applications in gene-modified regenerative medicine. Adenovirus (AdV) vectors, one of the most commonly used types of vectors, can mediate high, albeit transient, levels of expression of the transgene in pancreatic stem/progenitor cells. However, high multiplicity of infection (MOI) with AdV vectors can result in cellular toxicity. Therefore, AdV vectors have been of limited usefulness in clinical applications. In this study, we investigated the in vitro gene transfer efficiency of Sendai virus (SeV) vectors, a paramyxovirus vector that can efficiently introduce foreign genes without toxicity into several cell types, including pancreatic stem cells. The dose-dependent GFP expression of pancreatic stem cells transfected with SeV vectors after 48 h of culture at 37°C was observed. The transfection of pancreatic stem cells with SeV vectors and AdV vectors results in equal expression of the transgene (GFP expression) in the cells after 48 h of culture at 37°C. Although the transfection of pancreatic stem cells with AdV vectors at high MOIs was cytotoxic, transfection with SeV vectors at high MOIs was rarely cytotoxic. In addition, pancreatic stem cells transfected with SeV maintained their differentiation ability. These data suggest that SeV could provide advantages with respect to safety issues in gene-modified regenerative medicine.

Potent specific immune responses induced by prime-boost-boost strategies based on DNA, adenovirus, and Sendai virus vectors expressing gag gene of Chinese HIV-1 subtype B

To study the immune responses elicited by multiple vectors and develop vaccines strategies against prevalent HIV-1 strains in China, we have examined the potency of vaccine regimens of plasmid DNA, adenovirus, and Sendai virus vectors expressing HIV-1 gag consensus sequence of HIV-1 isolates from China for inducing specific immune responses. In BALB/c mice, combination of these vectors induced higher Gag-specific cellular immune response than any regimen using single vector alone. The prime-boost-boost regimen consisting of the triple heterologous vectors induced Gag-specific T-cell responses the most efficiently. In rhesus macaques, the prime-boost-boost regimen induced potent Gag-specific cellular immune responses as well as long lasting humoral immune response, and each booster resulted in rapid and efficient expansion of Gag-specific T cells. These results indicate that this prime-boost-boost regimen using triple heterologous vectors is a promising AIDS vaccine candidate for efficiently inducing HIV-1-specific cellular and humoral immune responses. Its further studies as a promising scheme for therapeutic and/or prophylactic HIV-1 vaccines should be grounded.

Recombinant Sendai Virus-Mediated Gene Transfer to Adipose Tissue-Derived Stem Cells (ASCs)

Adipose tissue-derived stem cells (ASCs) are expected to have clinical applications as well as other stem cells, because ASCs can be obtained safely from adult donors and used in autologous therapies without concern about rejection and the need for immunosuppression. However, the use of gene transfer with Sendai virus (SeV) vectors, which can efficiently introduce foreign genes without toxicity into several cells, with ASCs has not yet been investigated. This study documents on the use of SeV vectors for gene transfer to ASCs. The dose-dependent GFP expression of ASCs transfected with SeV vectors after 48 h of culture at 37°C was first evaluated. Next, the cellular toxicity of ASCs transfected with SeV vectors was verified. In addition, SeV vectors were compared with adenovirus (AdV) vectors. Finally, the time-dependent GFP expression of ASCs transfected with SeV vectors was evaluated. The results showed that transfection of ASCs with SeV vectors results in more efficient expression of transgene (GFP expression) in the ASCs than with AdV vectors after 48 h of culture at 37°C. Moreover, while the transfection of ASCs with AdV vectors at high MOIs was cytotoxic (a lot of transfected cells died) that of ASCs with SeV vectors at high MOIs was not necessarily cytotoxic. In addition, the preservation of multilineage ASCs transfected with SeV was observed. In conclusion, this is the first report describing the successful use of SeV-mediated gene transfer in ASCs, and the results indicate that SeV may thus provide advantages with respect to safety issues in gene therapy.

CFTR gene transfer to human cystic fibrosis pancreatic duct cells using a Sendai virus vector

Cystic fibrosis (CF) is a fatal inherited disease caused by the absence or dysfunction of the CF transmembrane conductance regulator (CFTR) Cl- channel. About 70% of CF patients are exocrine pancreatic insufficient due to failure of the pancreatic ducts to secrete a HCO3- -rich fluid. Our aim in this study was to investigate the potential of a recombinant Sendai virus (SeV) vector to introduce normal CFTR into human CF pancreatic duct (CFPAC-1) cells, and to assess the effect of CFTR gene transfer on the key transporters involved in HCO3- transport. Using polarized cultures of homozygous F508del CFPAC-1 cells as a model for the human CF pancreatic ductal epithelium we showed that SeV was an efficient gene transfer agent when applied to the apical membrane. The presence of functional CFTR was confirmed using iodide efflux assay. CFTR expression had no effect on cell growth, monolayer integrity, and mRNA levels for key transporters in the duct cell (pNBC, AE2, NHE2, NHE3, DRA, and PAT-1), but did upregulate the activity of apical Cl-/HCO3- and Na+/H+ exchangers (NHEs). In CFTR-corrected cells, apical Cl-/HCO3- exchange activity was further enhanced by cAMP, a key feature exhibited by normal pancreatic duct cells. The cAMP stimulated Cl-/HCO3- exchange was inhibited by dihydro-4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (H2-DIDS), but not by a specific CFTR inhibitor, CFTR(inh)-172. Our data show that SeV vector is a potential CFTR gene transfer agent for human pancreatic duct cells and that expression of CFTR in CF cells is associated with a restoration of Cl- and HCO3- transport at the apical membrane.

Novel treatments for cancer cachexia

Cancer cachexia is a debilitating and life-threatening syndrome characterised by anorexia, body weight loss, loss of adipose tissue and skeletal muscle, and accounts for > or = 20% of deaths in neoplastic patients. Cancer cachexia significantly impairs quality of life and response to antineoplastic therapies, increasing the morbidity and mortality of cancer patients. Muscle wasting is the most important phenotypic feature of cancer cachexia and the principle cause of function impairment, fatigue and respiratory complications, and is mainly related to a hyperactivation of muscle proteolytic pathways. Existing therapeutic strategies have proven to be only partially effective. In the last decade, the correction of anorexia, the inhibition of catabolic processes and the stimulation of anabolic pathways in muscle has been attempted pharmacologically, giving encouraging results in animal models and through preliminary clinical trials.

Gene therapy for laryngeal paralysis

OBJECTIVES

The surgical options for laryngeal paralysis only achieve static changes of vocal fold position. Laryngeal reinnervation procedures have had little impact on the return of dynamic laryngeal function. The development of a new treatment for laryngeal paralysis, aimed at the return of dynamic function and neurologic restoration and regeneration, is necessary.

METHODS

To assess the possibility of gene therapy for laryngeal paralysis aiming for the return of dynamic laryngeal function, we investigated the therapeutic effects of gene therapy using rat laryngeal paralysis models.

RESULTS

In a rat vagal nerve avulsion model, we transferred glial cell line-derived neurotrophic factor (GDNF) gene into the nucleus ambiguus using an adenovirus vector. Two and 4 weeks after the GDNF gene transfer, a significantly larger number of surviving motoneurons was observed. These neuroprotective effects of GDNF gene transfer were enhanced by simultaneous brain-derived neurotrophic factor gene transfer. In a rat recurrent laryngeal nerve crush model, we transferred GDNF gene into recurrent laryngeal nerve fibers after crush injury. Two and 4 weeks after GDNF gene transfer, we observed significantly faster nerve conduction velocity and better vocal fold motion recovery.

CONCLUSIONS

These results indicate that gene therapy could be a future treatment strategy for laryngeal paralysis. Further studies will be necessary to demonstrate the safety of the vector before clinical application.

Sendai Virus Vector-Mediated Transgene Expression in the Cochlea in vivo

We injected a recombinant Sendai virus (SeV) vector into the guinea pig cochlea using two different approaches--the scala media and scala tympani--and investigated which cell types took up the vector. The hearing threshold shift and distribution of transfected cells in animals using the scala media approach were different compared to those using the scala tympani approach. SeV can transfect very different types of cells, including stria vascularis, spiral ganglion neurons, and sensory epithelia of the organ of Corti, and fibrocytes of the scala tympani. Because SeV vectors can potentially deliver stimuli to the cochlea to induce hair cell regeneration, it may be a powerful tool for repairing the organ of Corti.

Sendai virus-mediated gene delivery into hepatocytes via isolated hepatic perfusion

The recombinant Sendai virus vector is a promising tool for human gene therapy, capable of inducing high-level expression of therapeutic genes in tissue cells in situ. The target tissues include airway epithelium, blood vessels, skeletal muscle, retina and the central nervous system, but application to hepatic tissues has not yet been achieved, because direct intraportal injection of the vector is not feasible. We report an efficient and harmless procedure of gene delivery by recombinant Sendai virus into rat parenchymal hepatocytes, based on isolated hepatic perfusion with controlled inflow. Critical parameters for successful hepatic gene delivery are a brief preperfusion period (25 degrees C, 5 min); appropriate vector concentration in the perfusate (10(7) pfu/ml); moderate portal vein pressure (12 mmHg) and a brief hyperthermic postperfusion period (42 degrees C, 5 min). Under these optimized conditions, marker genes were expressed in most parenchymal hepatocytes without significant damage to hepatic tissues. Furthermore, expression of the marker genes was undetectable in nonhepatic tissues, including the gonads, indicating that this approach strictly targets hepatic tissues and thus offers good clinical potential for human gene therapy.

Sendai virus, the mouse parainfluenza type 1: a longstanding pathogen that remains up-to-date

Biologically speaking, Sendai virus (SeV), the murine parainfluenza virus type 1, is perceived as a common respiratory pathogen that is endemic in many rodent colonies throughout the world. Currently it is believed that SeV is the leading cause of pneumonia in mice and together with the mouse hepatitis viruses, is the most prevalent and important of the naturally occurring infections of mice. The scientific community also considers SeV as the archetype organism of the Paramyxoviridae family because most of the basic biochemical, molecular and biologic properties of the whole family were derived from its own characteristics. Recently, scientific interest for this old pathogen has re-emerged, this time because of its potential value as a vector for gene transfer. This review aimed at drawing an exhaustive picture of this multifaceted pathogen.

Gene therapy with anabolic growth factors to prevent muscle atrophy

PURPOSE OF REVIEW

Many situations cause muscle atrophy. When severe, muscle atrophy is associated with an increase in morbidity and mortality. This loss of muscle mass is thought to be due to an imbalance between catabolic and anabolic pathways, resulting in an increase of muscle protein proteolysis and in a decrease in protein synthesis. Changes in muscle levels of muscle growth factors are thought to play a major role in this imbalance. Despite recent better understanding of the metabolic and molecular derangements leading to muscle wasting, therapy of muscle atrophy still has a poor success rate.

RECENT FINDINGS

The recent demonstration that changes in local growth factors, such as insulin-like growth factor-I and myostatin, occur during muscle atrophy has stimulated research interest to prevent muscle mass loss by delivering these growth factors or their inhibitors into the muscle. During the last few years, several advances in the field of muscle gene transfer, using electroporation or recombinant adeno-associated viral vectors, have opened novel therapeutic ways to deliver growth factors able to counteract the loss of muscle mass.

SUMMARY

Preventing decrease of insulin-like growth factor-I muscle, or inhibiting myostatin action by local genes over-expression, may provide a clinically relevant avenue for the preservation, attenuation or reversal of disease-related muscle loss.

Laryngeal muscle surface receptors identified using random phage library

OBJECTIVES

The ultimate goal of this study is to improve the efficiency of gene transfer in mammalian muscle by developing targeted adenoviral vectors. Altering the tropism of viral vectors to recognize tissue specific antigens is one method to achieve this goal. This approach requires identification of cell-surface receptors and the insertion of target peptide sequences into the adenoviral fiber protein. In this study, phage biopanning was performed on cultured rat skeletal and laryngeal muscle to identify cell-surface receptors.

STUDY DESIGN

In vitro cell culture and in vivo animal model.

METHODS

M-13 Phage biopanning was used for muscle cell-surface receptor analysis on cultured rat skeletal and laryngeal muscle. Nonbinding and binding phage to cultured skeletal and laryngeal muscle were screened for muscle specific surface peptides. In vivo studies were then performed using muscle specific phage.

RESULTS

Skeletal muscle specific binding by the YASTNPM phage was observed by in vivo immunostaining. Phage titering demonstrated a 10(9)-fold increase in skeletal muscle binding compared with nontarget tissue. A peptide sequence (NPSQVKH) specific for laryngeal muscle yielded a 10(7)-fold increase in laryngeal muscle phage titer compared with nontarget tissue.

CONCLUSIONS

These results identify muscle cell-surface receptors that may be used as potential targets for genetic modification of adenovirus tropism. Moreover, phage specificity for skeletal and laryngeal muscle indicates specific muscle groups may be targeted.

Prevention and treatment of cancer cachexia: new insights into an old problem

Cancer cachexia (CC) is a multifactorial paraneoplastic syndrome characterized by anorexia, body weight loss, loss of adipose tissue and skeletal muscle, accounting for at least 20% of deaths in neoplastic patients. CC significantly impairs quality of life and response to anti-neoplastic therapies, increasing morbidity and mortality of cancer patients. Muscle wasting is the most important phenotypic feature of CC and the principal cause of function impairment, fatigue and respiratory complications, mainly related to a hyperactivation of muscle proteolytic pathways. Most therapeutic strategies to CC have proven to be only partially effective . The inhibition of catabolic processes in muscle has been attempted pharmacologically with encouraging results in animal models. However, data in the clinical setting are still scanty and contradictory. Stimulation of muscle anabolism could represent a promising and valid therapeutic alternative for cancer-related muscle wasting. This goal may be currently achieved with the conventional, short-acting and adverse side effect-rich anabolic steroids. Insulin-like growth factor-1 (IGF-1) plays a critical role in muscle homeostasis, hypertrophy and regeneration. IGF-1 overexpression at the muscular level by gene therapy reverses muscle hypotrophy secondary to catabolic conditions and induces muscle hypertrophy increasing muscle mass and strength. This allows the speculation that this approach could also prove effective in modulating cancer-induced muscle wasting, while avoiding the potentially hazardous side effects of systemic IGF-1 administration. The present review will focus on the potential biochemical and molecular targets of CC therapy, and will define the rationale for a novel, gene therapy-based approach.

Recombinant Sendai virus vector induces complete remission of established brain tumors through efficient interleukin-2 gene transfer in vaccinated rats

PURPOSE

Sendai virus (SeV), a murine parainfluenza virus type I, replicates independent of cellular genome and directs high-level gene expressions when used as a viral vector. We constructed a nontransmissible recombinant SeV vector by deleting the matrix (M) and fusion (F) genes from its genome (SeV/DeltaMDeltaF) to enhance its safety. We also estimated the therapeutic efficacy of the novel vector system against a rat glioblastoma model.

EXPERIMENTAL DESIGN

We administered the recombinant SeV vector carrying the lacZ gene or the human interleukin-2 (hIL-2) gene into established 9L brain tumors in vivo simultaneous with peripheral vaccination using irradiated 9L cells. Sequential monitoring with magnetic resonance imaging was used to evaluate the therapeutic efficacy.

RESULTS

We found extensive transduction of the lacZ gene into the brain tumors and confirmed sufficient amounts of interleukin 2 (IL-2) production by hIL2-SeV/DeltaMDeltaF both in vitro and in vivo. The magnetic resonance imaging study showed that the intracerebral injection of hIL2-SeV/DeltaMDeltaF brought about significant reduction of the tumor growth, including complete elimination of the established brain tumors. The (51)Cr release assay showed that significant amounts of 9L-specific cytotoxic T cells were induced by the peripheral vaccination. Immunohistochemical analysis revealed that CD4(+) T cells and CD8(+) T cells were abundantly infiltrated in the target tumors.

CONCLUSION

The present results show that the recombinant nontransmissible SeV vector provides efficient in vivo gene transfer that induces significant regression of the established brain tumors and suggest that it will be a safe and useful viral vector for the clinical practice of glioma gene therapy.

Recombinant Sendai virus vectors deleted in both the matrix and the fusion genes: efficient gene transfer with preferable properties

BACKGROUND

Sendai virus (SeV) is a new type of cytoplasmic RNA vector, which infects and replicates in most mammalian cells, directs high-level expression of the genes on its genome and is free from genotoxicity. In order to improve this vector, both the matrix (M) and fusion (F) genes were deleted from its genome.

METHODS

For the recovery of the M and F genes-deleted SeV (SeV/DeltaMDeltaF), the packaging cell line was established by using a Cre/loxP induction system. SeV/DeltaMDeltaF was characterized and compared with wild-type and F or M gene-deleted SeV vectors in terms of transduction ability, particle formation, transmissible property and cytotoxicity.

RESULTS

SeV/DeltaMDeltaF was propagated in high titers from the packaging cell line. When this vector was administered into the lateral ventricle and the respiratory tissue, many of the ependymal and epithelial cells were transduced, respectively, as in the case of wild-type SeV. F gene-deletion made the SeV vector non-transmissible, and M gene-deletion worked well to inhibit formation of the particles from infected cells. Simultaneous deletions of these two genes in the same genome resulted in combining both advantages. That is, both virus maturation into particles and transmissible property were almost completely abolished in cells infected with SeV/DeltaMDeltaF. Further, the cytopathic effect of SeV/DeltaMDeltaF was significantly attenuated rather than that of wild type in vitro and in vivo.

CONCLUSIONS

SeV/DeltaMDeltaF is an advanced type of cytoplasmic RNA vector, which retains efficient gene transfer, gains non-transmissible properties and loses particle formation with less cytopathic effect.

Efficient and stable Sendai virus-mediated gene transfer into primate embryonic stem cells with pluripotency preserved

Efficient gene transfer and regulated transgene expression in primate embryonic stem (ES) cells are highly desirable for future applications of the cells. In the present study, we have examined using the nonintegrating Sendai virus (SeV) vector to introduce the green fluorescent protein (GFP) gene into non-human primate cynomolgus ES cells. The GFP gene was vigorously and stably expressed in the cynomolgus ES cells for a year. The cells were able to form fluorescent teratomas when transplanted into immunodeficient mice. They were also able to differentiate into fluorescent embryoid bodies, neurons, and mature blood cells. In addition, the GFP expression levels were reduced dose-dependently by the addition of an anti-RNA virus drug, ribavirin, to the culture. Thus, SeV vector will be a useful tool for efficient gene transfer into primate ES cells and the method of using antiviral drugs should allow further investigation for regulated SeV-mediated gene expression.

Generation of a recombinant Sendai virus that is selectively activated and lyses human tumor cells expressing matrix metalloproteinases

Malignant tumor cells often express matrix metalloproteinases (MMPs) at a high level to enable their dissemination and metastasis. Sendai virus (SeV), a nonsegmented negative strand RNA virus, spreads in the target tissues in vivo via cleavage activation of the viral fusion glycoprotein by a tissue-specific, trypsin-like enzyme. By deleting the viral matrix protein, we previously generated a recombinant SeV that does not bud to mature virions, but is highly fusogenic and spreads extensively from cell to cell in a trypsin-dependent manner. Here, we changed the tryptic cleavage site of the fusion glycoprotein of this virus to a site susceptible to MMPs. The resulting recombinant virus was no longer activated by trypsin but spread efficiently in cultured cells supplemented with MMP2 or MMP9 and in human tumor cell lines expressing these MMPs. Furthermore, the virus spread extensively in tumor cells xenotrasplanted to nude mice without disseminating to the surrounding normal cells, leading to the inhibition of the tumor growth in the mice. These results demonstrate the selective targeting and killing of human tumor cells by recombinant SeV technology and greatly advance the reemerging concept of oncolytic virotherapy, which currently appears to rely largely upon a natural preference of certain viruses for cancer cells.

Postischemic administration of Sendai virus vector carrying neurotrophic factor genes prevents delayed neuronal death in gerbils

Sendai virus (SeV) vector-mediated gene delivery of glial cell line-derived neurotrophic factor (GDNF) and nerve growth factor (NGF) prevented the delayed neuronal death induced by transient global ischemia in gerbils, even when the vector was administered several hours after ischemia. Intraventricular administration of SeV vector directed high-level expression of the vector-encoded neurotrophic factor genes, which are potent candidates for the treatment of neurodegenerative diseases. After occlusion of the bilateral carotid arteries of gerbils, SeV vector carrying GDNF (SeV/GDNF), NGF (SeV/NGF), brain-derived neurotrophic factor (SeV/BDNF), insulin-like growth factor-1 (SeV/IGF-1) or vascular endothelial growth factor (SeV/VEGF) was injected into the lateral ventricle. Administration of SeV/GDNF, SeV/NGF or SeV/BDNF 30 min after the ischemic insult effectively prevented the delayed neuronal death of the hippocampal CA1 pyramidal neurons. Furthermore, the administration of SeV/GDNF or SeV/NGF as late as 4 or 6 h after the ischemic insult also prevented the death of these neurons. These results indicate that SeV vector-mediated gene transfer of neurotrophic factors has high therapeutic potency for preventing the delayed neuronal death induced by transient global ischemia, and provides an approach for gene therapy of stroke.

Efficient propagation of single gene deleted recombinant Sendai virus vectors

Recombinant Sendai virus vectors (SeVV) have become an attractive tool for basic virological as well as for gene transfer studies. However, to (i) reduce the cellular injury induced by basic recombinant SeV vectors (encoding all six SeV genes as being present in SeV wild-type (wt) genomes) and to (ii) improve SeV vector safety, deletions of viral genes are necessary for the construction of superior SeVV generations. As a strong expression system recombinant replication-incompetent adenoviruses, coding for SeV proteins hemagglutinin-neuraminidase (HN), fusion (F), or matrix (M), were generated and successfully employed for the propagation of single gene deleted (DeltaHN, DeltaF, DeltaM) recombinant SeVV. Further investigations of the propagation procedures required for single gene deleted recombinant SeVV demonstrated (i) modifications of the cell culture medium composition as well as (ii) incubation with vitamin E as crucial steps for the enhancement of SeVV-DeltaHN, -DeltaF, or -DeltaM viral particle yield. Such optimized propagation procedures even led to a successful propagation of HN-deleted viral particles (SeVV-DeltaHN), which has not been reported before.

Reduced toxicity of F-deficient Sendai virus vector in the mouse fetus

Current concerns over insertional mutagenesis by retroviral vectors mitigate investigations into alternative, potentially persistent gene therapy vector systems not dependent on genomic integration, such as Sendai virus vectors (SeVV). Prenatal gene therapy requires efficient gene delivery to several tissues, which may not be achievable by somatic gene transfer to the adult. Initially, to test the potential and tropism of the SeVV for gene delivery to fetal tissues, first-generation (replication- and propagation-competent) recombinant SeVV, expressing beta-galactosidase was introduced into late gestation immunocompetent mice via the amniotic and peritoneal cavities and the yolk sac vessels. At 2 days, this resulted in very high levels of expression particularly in the airway epithelium, mesothelium and vascular endothelium, respectively. However, as expected, substantial vector toxicity was observed. The efficiency of gene transfer and the level of gene expression were then examined using a second-generation SeVV. The second generation was developed to be still capable of cytoplasmic RNA replication and therefore high-level gene expression, but incapable of vector spread due to lack of the gene for viral F-protein. Vector was introduced into the fetal amniotic and peritoneal cavities, intravascularly, intramuscularly and intraspinally; at 2 days, expression was observed in the airway epithelia, peritoneal mesothelia, unidentified cells in the gut wall, locally at the site of muscle injection and in the dorsal root ganglia, respectively. Mortality was dramatically diminished compared with the first-generation vector.

Toward novel vaccines and therapies based on negative-strand RNA viruses

The study of negative-strand RNA viruses has suggested new strategies to produce more attenuated viruses. Reverse genetics has allowed the implementation of the strategies, and new or improved monovalent vaccines are being developed. In addition, recombinant viruses expressing foreign proteins or epitopes have been produced with the aim of developing multivalent vaccines capable of stimulating humoral and cellular immune responses against more than one pathogen. Finally, recombinant viruses that selectively enter cells expressing tumor markers or the HIV envelope protein have been engineered and shown to lyse target cells. Preclinical and clinical trials of improved and multivalent vaccines and therapeutic (oncolytic) viruses are ongoing.

Recombinant Sendai virus vectors for activated T lymphocytes

T-lymphocyte-directed gene therapy has potential as a treatment of subjects with immunological disorders. One current limitation of this therapeutic strategy is low gene transfer efficiency, even when complex procedures are used. We report herein that a recombinant Sendai virus vector (SeV) was able to overcome this issue. Using jellyfish enhanced green fluorescent protein gene (EGFP), we found that SeV was able to transduce and express a foreign gene specifically and efficiently in activated murine and human T cells, but not in naive T cells, without centrifugation or reagents including polybrene and protamine sulfate; the present findings were in clear contrast to those demonstrated with the use of retroviruses. The transduction was selective in antigen-activated T cells, while antigen-irrelevant T cells were not transduced, even under bystander activation from specific T-cell responses by antigens ex vivo. Receptor saturation studies suggested a possible mechanism of activated T-cell-specific gene transfer, ie, SeV might attach to naive T cells but might be unable to enter their cytoplasm. We therefore propose that the SeV vector system may prove to be a potentially important alternative in the area of T-cell-directed gene therapy used in the clinical setting.

Sendai virus vectors as an emerging negative-strand RNA viral vector system

The power to manipulate the genome of negative-strand RNA viruses, including the insertion of additional non-viral genes, has led to the development of a new class of viral vectors for gene transfer approaches. The murine parainfluenza virus type I, or Sendai virus (SeV), has emerged as a prototype virus of this vector group, being employed in numerous in vitro as well as animal studies over the last few years. Extraordinary features of SeV are the remarkably brief contact time that is necessary for cellular uptake, a strong but adjustable expression of foreign genes, efficient infection in the respiratory tract despite a mucus layer, transduction of target cells being independent of the cell cycle, and an exclusively cytoplasmic replication cycle without any risk of chromosomal integration. In this review we describe the current knowledge of Sendai virus vector (SeVV) development as well as the results of first-generation vector applications under both in vitro and in vivo conditions. So far, Sendai virus vectors have been identified to be a highly efficient transduction tool for a broad range of different tissues and applications. Future directions in vector design and development are discussed.

A new Sendai virus vector deficient in the matrix gene does not form virus particles and shows extensive cell-to-cell spreading

A new recombinant Sendai virus vector (SeV/DeltaM), in which the gene encoding matrix (M) protein was deleted, was recovered from cDNA and propagated in a packaging cell line expressing M protein by using a Cre/loxP induction system. The titer of SeV/DeltaM carrying the enhanced green fluorescent protein gene in place of the M gene was 7 x 10(7) cell infectious units/ml or more. The new vector showed high levels of infectivity and gene expression, similar to those of wild-type SeV vector, in vitro and in vivo. Virus maturation into a particle was almost completely abolished in cells infected with SeV/DeltaM. Instead, SeV/DeltaM infection brought about a significant increase of syncytium formation under conditions in which the fusion protein was proteolytically cleaved and activated by trypsin-like protease. This shows that SeV/DeltaM spreads markedly to neighboring cells in a cell-to-cell manner, because both hemagglutinin-neuraminidase and active fusion proteins are present at very high levels on the surface of cells infected with SeV/DeltaM. Thus, SeV/DeltaM is a novel type of vector with the characteristic features of loss of virus particle formation and gain of cell-to-cell spreading via a mechanism dependent on the activation of the fusion protein.

Sendai virus vector-mediated gene transfer of glial cell line-derived neurotrophic factor prevents delayed neuronal death after transient global ischemia in gerbils

We have developed a cytoplasmic replicating virus vector of Sendai virus (SeV) that infects and replicates in most mammalian cells, including neurons, and directs high-level gene expression. To investigate the protective effect of SeV vector-mediated gene transfer of glial cell line-derived neurotrophic factor (GDNF) on the delayed neuronal death caused by transient global ischemia in gerbils, SeV vectors carrying either GDNF (SeV/GDNF) or enhanced green fluorescent protein gene (SeV/GFP) were stereotaxically microinjected into the lateral ventricle. Four days after injection, occlusion of the bilateral common carotid arteries for 5 min produced transient global forebrain ischemia. Treatment with SeV/GDNF significantly decreased the delayed neuronal death of the hippocampal CA1 pyramidal neurons observed 6 days after the operation. TUNEL staining demonstrated that SeV/GDNF treatment markedly reduced the number of apoptotic cells in the hippocampal CA1 neurons, indicating that SeV/GDNF treatment prevented apoptosis. Furthermore, delayed neuronal death on the contralateral side of the hippocampal CA1 was also prevented to a similar extent as that on the ipsilateral side. These results suggest that SeV/GDNF prevents the delayed neuronal death induced by ischemia and is potentially useful for gene therapy for stroke.

Adenoviral gene transfer of GDNF, BDNF and TGF beta 2, but not CNTF, cardiotrophin-1 or IGF1, protects injured adult motoneurons after facial nerve avulsion

We examined neuroprotective effects of recombinant adenoviral vectors encoding glial cell line-derived neurotrophic factor (GDNF), brain-derived neurotrophic factor (BDNF), ciliary neurotrophic factor (CNTF), cardiotrophin-1 (CT1), insulin-like growth factor-1 (IGF1), and transforming growth factor-beta2 (TGFbeta2) on lesioned adult rat facial motoneurons. The right facial nerves of adult Fischer 344 male rats were avulsed and removed from the stylomastoid foramen, and adenoviral vectors were injected into the facial canal. Animals avulsed and treated with adenovirus encoding GDNF, BDNF, CNTF, CT1, IGF1 and TGFbeta2 showed intense immunolabeling for these factors in lesioned facial motoneurons, respectively, indicating adenoviral induction of the neurotrophic factors in these neurons. The treatment with adenovirus encoding GDNF, BDNF, or TGFbeta2 after avulsion significantly prevented the loss of lesioned facial motoneurons, improved choline acetyltransferase immunoreactivity and prevented the induction of nitric oxide synthase activity in these neurons. The treatment with adenovirus encoding CNTF, CT1 or IGF1, however, failed to protect these neurons after avulsion. These results indicate that the gene transfer of GDNF and BDNF and TGFbeta2 but not CNTF, CT1 or IGF1 may prevent the degeneration of motoneurons in adult humans with motoneuron injury and motor neuron diseases.

Nontransmissible virus-like particle formation by F-deficient sendai virus is temperature sensitive and reduced by mutations in M and HN proteins

The formation of nontransmissible virus-like particles (NTVLP) by cells infected with F-deficient Sendai virus (SeV/deltaF) was found to be temperature sensitive. Analysis by hemagglutination assays and Western blotting demonstrated that the formation of NTVLP at 38 degrees C was about 1/100 of that at 32 degrees C, whereas this temperature-sensitive difference was only moderate in the case of F-possessing wild-type SeV. In order to reduce the NTVLP formation with the aim of improving SeV for use as a vector for gene therapy, amino acid substitutions found in temperature-sensitive mutant SeVs were introduced into the M (G69E, T116A, and A183S) and HN (A262T, G264R, and K461G) proteins of SeV/deltaF to generate SeV/M(ts)HN(ts)deltaF. The use of these mutations allows vector production at low temperature (32 degrees C) and therapeutic use at body temperature (37 degrees C) with diminished NTVLP formation. As expected, the formation of NTVLP by SeV/M(ts)HN(ts)deltaF at 37 degrees C was decreased to about 1/10 of that by SeV/deltaF, whereas the suppression of NTVLP formation did not cause either enhanced cytotoxicity or reduced gene expression of the vector. The vectors showed differences with respect to the subcellular distribution of M protein in the infected cells. Clear and accumulated immunocytochemical signals of M protein on the cell surface were not observed in cells infected by SeV/deltaF at an incompatible temperature, 38 degrees C, or in those infected by SeV/M(ts)HN(ts)deltaF at 37 or 38 degrees C. The absence of F protein in SeV/deltaF and the additional mutations in M and HN in SeV/M(ts)HN(ts)deltaF probably weaken the ability to transport M protein to the plasma membrane, leading to the diminished formation of NTVLP.

Cell cycle independent infection and gene transfer by recombinant Sendai viruses

A common problem for viral vectors in the field of somatic gene therapy is the dependence of an efficient cellular transduction on the cell cycle phase of target cells. An optimized viral vector system should therefore transduce cells in different cell cycle phases equally to improve transduction efficiencies. Recent observations that recombinant Sendai viruses (SeV) can infect a broad range of different tissues suggested SeV to be a good candidate for future gene therapeutic strategies in which dividing and non-dividing cells have to be reached. However, detailed data on the influence of distinct cell cycle phases on the infection of SeV or related viruses are missing. We report that synchronization of NIH 3T3 cells as well as contact inhibition of human fibroblast cells did not exhibit any negative influence on SeV infection rates. Furthermore, different attractive target tissues like human umbilical cord derived cells or primary human hepatocytes can be reached by SeV efficiently. As an important information for further cell cycle studies of paramyxoviruses we discovered surprisingly that the DNA polymerase inhibitor aphidicolin (induces a G(1)/M arrest) functions as an inhibitor of SeV but not of an adenoviral expression vector. In conclusion, the results demonstrate SeV based vector particles to be an ideal tool to reach equally cells coexisting in different cell cycle phases.

Recombinant Sendai virus provides a highly efficient gene transfer into human cord blood-derived hematopoietic stem cells

Hematopoietic stem cells (HSCs) are a promising target for gene therapy, however, the low efficiencies of gene transfer using currently available vectors face practical limitations. We have recently developed a novel and efficient gene transfer agent, namely recombinant Sendai virus (SeV), and we have here characterized SeV-mediated gene transfer to human cord blood (CB) HSCs and primitive progenitor cells (PPC) using the jelly fish green fluorescent protein (GFP) gene. Even at a relatively low titer (10 multiplicity of infections), SeV achieved highly efficient GFP expression in CB CD34(+) cells (85.5+/-5.8%), as well as more immature CB progenitor cells, CD34(+)AC133(+) (88.2+/-3.7%) and CD34(+)CD38(-) (84.6+/-5.7%) cells, without cytokines prestimulation, that was a clear contrast to the features of gene transfer using retroviruses. SeV-mediated gene transfer was not seriously affected by the cell cycle status. In vitro cell differentiation studies revealed that gene transfer occurred in progenitor cells of all lineages (GM-CFU, 73.0+/-11.1%; BFU-E, 24.7+/-4.0%; Mix-CFU, 59+/-4.0%; and total, 50.0+/-7.0%). These findings show that SeV could prove to be a promising vector for efficient gene transfer to CB HSCs, while preserving their ability to reconstitute the entire hematopoietic series.

Negative-strand RNA viral vectors: intravenous application of Sendai virus vectors for the systemic delivery of therapeutic genes

Treatment by gene replacement is critical in the field of gene therapy. Suitable vectors for the delivery of therapeutic genes have to be generated and tested in preclinical settings. Recently, extraordinary features for a local gene delivery by Sendai virus vectors (SeVV) have been reported for different tissues. Here we show that direct intravenous application of SeVV in mice is not only feasible and safe, but it results in the secretion of therapeutic proteins to the circulation, for example, human clotting Factor IX (hFIX). In vitro characterization of first-generation SeVV demonstrated that secreted amounts of hFIX were at least comparable to published results for retroviral or adeno-associated viral vectors. Furthermore, as a consideration for application in humans, SeVV transduction led to efficient hFIX synthesis in primary human hepatocytes, and SeVV-encoded hFIX proteins could be shown to be functionally active in the human clotting cascade. In conclusion, our investigations demonstrate for the first time that intravenous administration of negative-strand RNA viral vectors may become a useful tool for the wide area of gene replacement requirements.

Recombinant Sendai viruses expressing different levels of a foreign reporter gene

Sendai virus (SeV) is an enveloped virus with a nonsegmented negative strand RNA genome. The recovery of infectious virus from cDNA and generation of recombinant SeV carrying a foreign gene at the promoter proximal position has been demonstrated. In this study, we constructed a series of recombinant SeVs carrying a reporter human secreted alkaline phosphatase (SEAP) gene at each viral gene junction or the 5' distal end in order to measure the expression level of the foreign gene. We demonstrated that there was a gradient in the reporter gene expression level that depended on location, due to the polarity of transcription. In contrast, the growth and final titers of these recombinant viruses showed an opposite gradient to the foreign gene expression level. This suggests the potential for matching therapeutic gene expression level to individual therapy programs by changing the position of the foreign gene when SeVs are used as vectors for human gene therapy.