Expression of hepatitis B virus surface antigen in adult rat liver. Co-introduction of DNA and nuclear protein by a simplified liposome method

Emerging micro- and nanotechnology based synthetic approaches for insulin delivery

Insulin is essential for type 1 and advanced type 2 diabetics to maintain blood glucose levels and prolong lives. The traditional administration requires frequent subcutaneous insulin injections that are associated with poor patient compliance, including pain, local tissue necrosis, infection, and nerve damage. Taking advantage of emerging micro- and nanotechnologies, numerous alternative strategies integrated with chemical approaches for insulin delivery have been investigated. This review outlines recent developments in the controlled delivery of insulin, including oral, nasal, pulmonary, transdermal, subcutaneous and closed-loop insulin delivery. Perspectives from new materials, formulations and devices at the micro- or nano-scales are specifically surveyed. Advantages and limitations of current delivery methods, as well as future opportunities and challenges are also discussed.

Therapeutic effects of hepatocyte growth factor-overexpressing human umbilical cord blood-derived mesenchymal stem cells on liver fibrosis in rats

Fibrosis is a common end stage for a variety of liver diseases, including most chronic liver diseases, and results from an imbalance between collagen deposition and degradation. Mesenchymal stem cells (MSCs) have the ability to migrate into fibrotic livers and differentiate into hepatocytes. Hepatocyte growth factor (HGF) has potent anti-apoptotic and mitogenic effects on hepatocytes during liver injury and plays an essential role in the development and regeneration of the liver. In this study, human HGF-overexpressing human umbilical cord blood-derived MSCs (hHGF-HUCB-MSCs) were prepared using the pMEX Expression System, and the upregulation of hHGF expression was confirmed by RT-PCR and ELISA. HGF expressed by hHGF-HUCB-MSCs exerted a stimulatory effect on hepatocyte proliferation in vitro. hHGF-HUCB-MSCs were transplanted to investigate the therapeutic effects of these cells on carbon tetrachloride (CCL4)-induced liver fibrosis in a rat model. After 4 weeks of cell treatment once per week with 2 × 10(6) cells, biochemical analysis of the serum and histopathological analysis of the liver tissue were performed. The results of the biochemical analysis of the serum show that the hHGF-HUCB-MSC-treated group had higher levels of alanine aminotransferase, aspartate aminotransferase and alkaline phosphatase, indicating the improvement of liver function. Histopathology showed that the hHGF-HUCB-MSC-treated group had reduction in the density of collagen fibres. Thus hHGF-HUCB-MSCs can enhance liver regeneration and could be useful for the treatment of patients with liver fibrosis or cirrhosis.

Polyethylenimine-based amphiphilic core-shell nanoparticles: study of gene delivery and intracellular trafficking

Amphiphilic core-shell nanoparticle, which is composed of a hydrophobic core and a branched polyethylenimine (PEI) shell, has been designed and synthesized as a novel gene delivery nanocarrier. In our previous study, we demonstrated that the core-shell nanoparticle was not only able to efficiently complex with plasmid DNA (pDNA) and protect it against enzymatic degradation, but also three times less cytotoxic, and threefold more efficient in gene transfection than branched 25 kDa PEI. This paper reports our further studies in the following three aspects: (1) the ability of the PEI-based nanoparticles to deliver gene in various mammalian cell lines; (2) intracellular distributions of the nanoparticles and their pDNA complexes in HeLa cells; and (3) incorporation of nuclear targeting agent into the nanoparticle/pDNA complexes to enhance the nuclear targeting ability. The PEI-based nanoparticles were able to transfect both human and non-human cell lines and their transfection efficiencies were cell-dependent. Within our four tested cell lines (MCF-7, BEL 7404, C6 and CHO-K1), gene transfer using PEI-based core-shell nanoparticles displayed gene expression levels comparable to, or even better than, the commercial Lipofectamine™ 2000. Confocal laser scanning microscopy showed that the nanoparticles and their pDNA complexes were effectively internalized into the HeLa cells. The in vitro time series experiments illustrated that both the nanoparticle/pDNA complexes and PEI-based nanoparticles were distributed in the cytoplasmic region after transfection for 10 and 60 min, respectively. Nuclear localization was also observed in both samples after transfection for 20 and 60 min, respectively. Incorporation of the high mobility group box 1 (HMGB1) protein for nuclear targeting has also been demonstrated with a simple approach: electrostatic complexation between the PEI-based nanoparticles and HMGB1. In the in vitro transfection study in MCF-7 cells, the expression level of the firefly luciferase gene encoded by the pDNA increased remarkably by up to eightfold when the HMGB1 protein was incorporated into the nanoparticle/pDNA complexes. Our results demonstrate that the PEI-based core-shell nanoparticles are promising nanocarriers for gene delivery.

Gemcitabine-loaded innovative nanocarriers vs GEMZAR: biodistribution, pharmacokinetic features and in vivo antitumor activity

INTRODUCTION

Gemcitabine, an anticancer drug, is a nucleoside analog deoxycytidine antimetabolite, which acts against a wide range of solid tumors. The limitation of gemcitabine is its rapid inactivation by the deoxycytidine deaminase enzyme following its in vivo administration.

AREAS COVERED

One of the most promising new approaches for improving the biopharmaceutical properties of gemcitabine is the use of innovative drug delivery devices. This review explains the current status of gemcitabine drug delivery, which has been under development over the past 5 years, with particular emphasis on liposomal delivery. In addition, the use of novel supramolecular vesicular aggregates (SVAs), polymeric nanoparticles and squalenoylation were treated as interesting innovative approaches for the administration of the nucleoside analog.

EXPERT OPINION

Different colloidal systems containing gemcitabine have been realized, with the aim of providing important potential advancements through traditional ways of therapy. A possible future commercialization of modified gemcitabine is desirable, as was true in the case of liposomal doxorubicin (Doxil(®), Caely(®)).

HVJ liposomes and HVJ envelope vectors

This protocol describes techniques for construction of fusion-mediated vectors based on inactivated HVJ (hemagglutinating virus of Japan; Sendai virus). HVJ liposomes are constructed by fusing liposomes containing DNA with inactivated HVJ. The HVJ envelope vector, a more simplified vector, incorporates DNA into inactivated HVJ particles without liposomes. Both vectors have many advantages. They can be used to introduce proteins, peptides, oligonucleotides (including antisense oligonucleotides, decoy oligonucleotides, and ribozymes), and short interfering RNA (siRNA), as well as plasmid DNA, into cultured cells in vitro and into organs in vivo. Fusion-mediated delivery avoids the degradation of therapeutic molecules before reaching the cytoplasm. Finally, repeated injection of the vector in vivo is not inhibited and even enhances the effects of the delivered molecules. These vectors have been used in many gene therapy experiments in animal models to address problems such as liver cirrhosis, hearing impairment, ischemic brain damage, peripheral arterial diseases, and cancers. This protocol describes methods for the preparation of HVJ liposomes and of HVJ envelope vectors and their use in delivery of plasmid DNA into various cells and tissues.

Functional lipids and lipoplexes for improved gene delivery

Cationic lipids are the most common non-viral vectors used in gene delivery with a few currently being investigated in clinical trials. However, like most other synthetic vectors, these vectors suffer from low transfection efficiencies. Among the various approaches to address this challenge, functional lipids (i.e., lipids responding to a stimuli) offer a myriad of opportunities for basic studies of nucleic acid-lipid interactions and for in vitro and in vivo delivery of nucleic acid for a specific biological/medical application. This manuscript reviews recent advances in pH, redox, and charge-reversal sensitive lipids.

Adsorption of lecithin liposomes to acid clay

The interaction between lecithin liposomes and acid clay was investigated to clarify the mechanism for liposome adsorption to the clay. It was found that the multilamellar vesicular structure of the liposomes was broken as a result of primary adsorption. The acid clay particles aggregated and were eventually covered by the lecithin layer structure. In the case of kaolin, on the other hand, the liposomes were weakly adsorbed to the clay and maintained the vesicular structure. The amount of primary adsorption to the clay surface, which was estimated from the adsorption isotherm, was more for acid clay than for kaolin, and the total amount adsorbed to the acid clay was also more than to kaolin. This result can be explained by the much higher density of the negative charge on the acid clay surface than that for kaolin. The liposomes are therefore considered to be adsorbed to the acid clay mainly by the choline positive charge residing at the end of the lecithin molecule, although this is of no net charge as a whole.

Targeting antibodies to the cytoplasm

A growing number of research consortia are now focused on generating antibodies and recombinant antibody fragments that target the human proteome. A particularly valuable application for these binding molecules would be their use inside a living cell, e.g., for imaging or functional intervention. Animal-derived antibodies must be brought into the cell through the membrane, whereas the availability of the antibody genes from phage display systems allows intracellular expression. Here, the various technologies to target intracellular proteins with antibodies are reviewed.

The biological routes of gene delivery mediated by lipid-based non-viral vectors

Cationic lipid/DNA complexes (lipoplexes) represent an attractive alternative to viral vectors for cell transfection in vitro and in vivo but still suffer from relatively low efficiency. Comprehension of the interactions between vectors and DNA as well as cellular pathways and mechanisms in DNA entry into cells and ultimately nuclei will lead to the design of better adapted non-viral vectors for gene therapy applications. Here, some recent developments in the field on the pathways and mechanisms involved in lipoplex-mediated transfection are discussed. The techniques that are widely used to study the mechanism of gene delivery are also discussed.

Liposome-mediated Gene Therapy in the Kidney

Gene therapy directed to the kidney has been attempted to improve renal disorders such as inherited kidney diseases and common renal diseases that cause interstitial fibrosis, tubular atrophy, and glomerulosclerosis. Viral and non-viral vectors have been tried and been modulated to obtain sufficient transgene expression. However, gene delivery to the kidney is usually difficult because of characteristics of renal cell biology. Among non-viral vectors, the liposome system is a promising procedure for kidney-targeted gene therapy. Using cationic liposome, tubular cells were effectively transduced by retrograde injection of liposome/cDNA complex. Although transgene expression was reportedly modest using cationic liposomes, this method improved renal disease models such as carbonic anhydrase II deficiency and unilateral ureteral obstruction. In contrast, HVJ-liposome system is an effective transfection method to glomerular cells using intra-renal arterial infusion and improved glomerular disease models such as glomerulonephritis and glomerulosclerosis. In addition, intra-renal pelvic injection of DNA by HVJ-liposome system showed transgene expression in interstitial fibroblasts. In kidney-targeted gene therapy, liposome-mediated gene transfer is an attractive method because of its simplicity and reduced toxicity. In spite of modest transgene expression, several renal disease models were successfully modulated by liposome system. Although one limitation of liposome-mediated gene delivery is the duration of transgene expression, the liposome/cDNA complex can be repeatedly administered due to the absence of an immune response.

[Sendai virus vector: vector development and its application to health care and biotechnology]

Sendai virus (SeV) is an enveloped virus with a nonsegmented negative-strand RNA genome and a member of the paramyxovirus family. We have developed SeV vector which has shown a high efficiently of gene transfer and expression of foreign genes to a wide range of dividing and non-dividing mammalian cells and tissues. One of the characteristics of the vector is that the genome is located exclusively in the cytoplasm of infected cells and does not go through a DNA phase; thus there is no concern about unwanted integration of foreign sequences into chromosomal DNA. Therefore, this new class of "cytoplasmic RNA vector", an RNA vector with cytoplasmic expression, is expected to be a safer and more efficient viral vector than existing vectors for application to human therapy in various fields including gene therapy and vaccination. In this review, I describe development of Sendai virus vector, its application in the field of biotechnology and clinical application aiming to treat for a large number of diseases including cancer, cardiovascular disease, infectious diseases and neurologic disorders.

Bio-nanocapsule conjugated with liposomes for in vivo pinpoint delivery of various materials

Bio-nanocapsules (BNCs) consisting of hepatitis B virus (HBV) surface antigen (HBsAg) are approximately 50-nm hollow particles displaying a human hepatocyte-recognizing molecule (pre-S1 peptide). They have been used as an HB vaccine for the last two decades. Original BNC can incorporate various payloads (e.g., drugs, genes) by electroporation and deliver them to human hepatocytes specifically by utilizing the HBV infection mechanism. Here, we developed a new BNC conjugated with liposomes and succeeded in incorporating large materials (100-nm fluorescence-labeled polystyrene beads and >30 kbp plasmids) into the BNC-liposome complex. The complex delivered these large materials to human hepatocytes specifically ex vivo and in vivo. The transfection efficiency of the BNC-liposome complex was significantly higher than that of the original BNC. These results indicated that BNC confers the tissue- and cell-specificity on the conventional liposomes and raises new possibilities for drug delivery systems, gene delivery systems, and bio-imaging systems in vivo.

Nucleocytoplasmic transport of DNA: enhancing non-viral gene transfer

Gene therapy, the correction of dysfunctional or deleted genes by supplying the lacking component, has long been awaited as a means to permanently treat or reverse many genetic disorders. To achieve this, therapeutic DNA must be delivered to the nucleus of cells using a safe and efficient delivery vector. Although viral-based vectors have been utilized extensively due to their innate ability to deliver DNA to intact cells, safety considerations, such as pathogenicity, oncogenicity and the stimulation of an immunological response in the host, remain problematical. There has, however, been much progress in the development of safe non-viral gene-delivery vectors, although they remain less efficient than the viral counterparts. The major limitations of non-viral gene transfer reside in the fact that it must be tailored to overcome the intracellular barriers to DNA delivery that viruses already master, including the cellular and nuclear membranes. In particular, nuclear transport of the therapeutic DNA is known to be the rate-limiting step in the gene-delivery process. Despite this, much progress had been made in recent years in developing novel means to overcome these barriers and efficiently deliver DNA to the nuclei of intact cells. This review focuses on the nucleocytoplasmic delivery of DNA and mechanisms to enhance to non-viral-mediated gene transfer.

Persistent and stable gene expression by a cytoplasmic RNA replicon based on a noncytopathic variant Sendai virus

Persistent and stable expression of foreign genes has been achieved in mammalian cells by integrating the genes into the host chromosomes. However, this approach has several shortcomings in practical applications. For example, large scale production of protein pharmaceutics frequently requires laborious amplification of the inserted genes to optimize the gene expression. The random chromosomal insertion of exogenous DNA also results occasionally in malignant transformation of normal tissue cells, raising safety concerns in medical applications. Here we report a novel cytoplasmic RNA replicon capable of expressing installed genes stably without chromosome insertion. This system is based on the RNA genome of a noncytopathic variant Sendai virus strain, Cl.151. We found that this variant virus establishes stable symbiosis with host cells by escaping from retinoic acid-inducible gene I-interferon regulatory factor 3-mediated antiviral machinery. Using a cloned genome cDNA of Sendai virus Cl.151, we developed a recombinant RNA installed with exogenous marker genes that was maintained stably in the cytoplasm as a high copy replicon (about 4 x 10(4) copies/cell) without interfering with normal cellular function. Strong expression of the marker genes persisted for more than 6 months in various types of cultured cells and for at least two months in rat colonic mucosa without any apparent side effects. This stable RNA replicon is a potentially valuable genetic platform for various biological applications.

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.

Histonefection: Novel and potent non-viral gene delivery

Protein/peptide-mediated gene delivery has recently emerged as a powerful approach in non-viral gene transfer. In previous studies, we and other groups found that histones efficiently mediate gene transfer (histonefection). Histonefection has been demonstrated to be effective with various members of the histone family. The DNA binding domains and natural nuclear localisation signal sequences make histones excellent candidates for effective gene transfer. In addition, their positive charge promotes binding to anionic molecules and helps them to overcome the negative charge of cells that is an important barrier to cellular penetration. Histonefection appears to have particular promise in cancer gene transfer and therapy.

Total Vascular Exclusion Safely Facilitates Liver Specific Gene Transfer by the HVJ (Sendai Virus)-Liposome Method in Rats

BACKGROUND

Most virus mediated transfection systems are efficient; however, their highly immunogenic properties do tend to cause clinical problems. HVJ-liposome vector is a hybrid vector consisting of liposome and inactivated sendai virus (hemagglutinating virus of Japan HVJ), which has been reported to be have a low immunogenicity, while it can also be repeatedly administered. To enhance the transfection efficiency, especially in the liver, we investigated the efficacy of total vascular exclusion (TVE) during the portal vein injection (PVI) of the vectors.

MATERIALS AND METHODS

beta-galactosidase and luciferase expression were used as reporter genes. Wistar rats were injected with HVJ-liposome through PVI without TVE (PVI group, n = 10) or PVI with TVE (PVI + TVE group, n = 10). The control rats were infused with equal volumes of saline through the portal vein (control group n = 12). The transfection efficiencies were assessed by beta-galactosidase staining and a luciferase assay. Biochemical and histological analyses were performed to evaluate the tissue toxicity after gene transfer.

RESULTS

The reporter genes expression in the liver dramatically increased after PVI + TVE in comparison to after PVI alone (1.2 x 10(5)versus 1.5 x 10(4) RLU/mg protein, P < 0.05 according to a luciferase assay). Notably, the extrahepatic "leaky" transgene expression could be minimized by PVI + TVE, whereas the general condition remained unchanged according to both the biochemical parameters and histological findings.

CONCLUSIONS

The present data indicate that PVI + TVE may thus facilitate the liver-specific gene delivery using the HVJ-liposome method and this modality might also be applicable to other gene transfer systems.

Eradication of hepatocellular carcinoma xenografts by radiolabelled, lipiodol-inducible gene therapy

The promoter region of the early-growth response-1(Egr-1) gene has been shown to be activated by external radiation, thus making a selective tumoricidal effect possible. A previous experiment showed that the Egr-1 promoter can be activated by internal radiation using radioisotopes as well as external radiation. Internal radiation using I-131 lipiodol (I-131-Lip) has been established as one of the most useful therapeutic strategies against hepatoma. We herein linked the Egr-1 promoter to the herpes simplex virus-thymidine kinase (HSV-TK) gene, and investigated its efficacy in hepatoma gene therapy in combination with I-131-Lip. A luciferase assay showed the Egr-1-promoter activity to be markedly increased in hepatoma tissue specimens in an I-131-dose-dependent manner, whereas a less than two-fold increase in this activity was observed in other organs. In addition, the radioactivity derived from I-131 was selectively accumulated in the tumor tissue specimens. To examine the efficacy of EgrTK/ganciclovir (GCV) gene therapy in vivo, subcutaneous hepatoma xenografts in nude mice were transfected using a hemagglutinating virus of Japan (HVJ)-liposome vector. Complete tumor regression was observed in all the EgrTK-transfected tumors following combination treatment with I-131-Lip and GCV 42 days after treatment without any side effects (n=8). In contrast, the tumors continued to grow in all control mice (n=10). Furthermore, the serum alpha-fetoprotein levels decreased in the combination therapy group, while they increased in the controls. In conclusion, these data indicate that Egr-1 promoter-based gene therapy combined with internal radiation has a selective effect on hepatoma tumors while also showing an improved in vivo efficacy. This combination therapy might, therefore, be an effective human hepatoma gene therapy, even in advanced multiple cases.

The efficacy and safety of gene transfer into the porcine liver in vivo by HVJ (Sendai virus) liposome

BACKGROUND

Gene transfer systems using viral vectors are efficient; however, most viral vectors also tend to evoke immunologic reactions, thereby clinically causing serial side effects. HVJ-liposome vector is a hybrid vector consisting of liposome and an inactivated Sendai virus (Hemmagglutinating Virus of Japan [HVJ]), which has been reported to be less immunogenic and can also be repeatedly administered. We examined the usefulness of this vector for hepatic gene therapy in a pig model.

METHODS

Genes encoding beta-galactosidase and luciferase were used as reporter genes. The pigs were injected with the reporter gene loaded-HVJ-liposome into the portal vein under total vascular exclusion of the liver. The transfection efficiencies were then assessed by beta-galactosidase staining, a luciferase assay, and RT-PCR for LacZ mRNA. Biochemical and histologic analyses were performed to evaluate tissue toxicity after gene transfer.

RESULTS

The luciferase gene expression in the liver reached its highest level at 7 days after transfection. It continued to be detected up to 28 days after transfection, while all pigs remained healthy throughout the observation period. The transfection efficiency was 15% in the hepatocytes according to beta-galactosidase staining. Extrahepatic transgene expression was slightly observed in the lung and kidney, but not in the spleen or ovary.

CONCLUSIONS

These data suggest for the first time that the use of the HVJ-liposome vector is a safe and feasible modality for liver-directed gene transfer in pigs, and it might therefore be suitable for clinical gene therapy trials.

Novel Mucosal Insulin Delivery Systems Based on Fusogenic Liposomes

PURPOSE

Fusogenic liposomes (FLs) are unique delivery vehicles capable of introducing their contents directly into the cytoplasm with the aid of envelope glycoproteins of Sendai virus (SeV). The objective of this study was to evaluate the potential of FL to improve the mucosal absorption of insulin from rat intestinal membranes.

METHOD

The FLs containing insulin were prepared by fusing insulin-loaded liposomes with inactivated SeV particles and were administered directly into the ileal, the colonic, and the rectal loops (10 IU/kg).

RESULTS

The FL successfully enhanced the insulin absorption and induced a significant hypoglycemic effect following the colonic and the rectal administration without detectable mucosal damage. This enhancing effect of insulin absorption was further improved by increasing the amount of insulin loaded in the FL and by coencapsulating insulin-degrading enzyme inhibitor. In contrast, the insulin absorption was not increased by the ileal administration of FL because the mucous/glycocalyx layers overlaid on the ileal epithelium impede the fusion of FL to the intestinal mucosa.

CONCLUSION

Our results indicated that FL is a useful carrier for improving the absorption of poorly absorbable drugs, such as insulin, via the intestinal tract.

Development of novel method of non-viral efficient gene transfer into neonatal cardiac myocytes

To establish new treatment for cardiovascular disease, the development of safe and highly efficient vectors is necessary. Especially, non-viral vectors are considered to be ideal for human gene therapy, since recent adverse events with retroviral or adenoviral vectors have highlighted the issue of safety. Although we previously reported safety and high efficiency of HVJ-liposome method, we have modified the envelope of HVJ (Sendai virus). In this novel non-viral vector, the envelope of HVJ alone was utilized as a carrier to deliver proteins, genes and oligodeoxynucleotides (ODN). Thus, we optimized the transfection efficiency of HVJ-envelope vector into neonatal cardiac myocytes in this study, since cardiac myocytes is one of the most difficult cells to be transfected. HVJ-envelope, obtained after complete destruction of HVJ genome, containing FITC-labeled ODN or luciferase plasmid was incubated with cardiac myocytes. In addition, the concentration of protamine sulfate was modified (0-700 microg/ml) to increase transfection efficacy. Without HVJ-envelope vector, few cells showed fluorescence, whereas most cells demonstrated fluorescence with HVJ-envelope vector. Consistent with the high transfection efficiency of ODN, high luciferase activity was also detected using HVJ-envelope vector. Moreover, the transfection efficiency varied according to the concentration of protamine sulfate. No obvious cytotoxicity was observed in cells transfected with HVJ-envelope vector. The present study demonstrated the development of a highly efficient novel non-viral vector for cardiac myocytes, suggesting that further development may provide a new useful tool for research and clinical gene therapy in the field of cardiovascular disease.

Downregulation of decorin and transforming growth factor-beta1 by decorin gene suppression in tendinocytes

Scars formed after tendonitis result in altered tissue mechanical properties after injury. The interaction of collagen molecules with decorin affects collagen fibrogenesis, and scar tissue is fragile as a consequence of a large amount of decorin in the scar. We hypothesized that scar formation could be prevented by controlling decorin expression in tendinocytes. As a preliminary experiment, we treated tendinocytes with decorin antisense oligodeoxynucleotides (ODNs). Tendinocytes were isolated from Achilles tendons of New Zealand white rabbits and treated with ODN. When tendinocytes were transfected with decorin sense ODN, there was no alteration, whereas decorin antisense ODN-treated tendinocytes showed suppression of transforming growth factor (TGF)-beta1 production. Decorin and TGF-beta1-production of tendinocytes is regulated by decorin gene suppression. The results showed that the antisense approach is an attractive therapeutic strategy not only for preventing decorin deposition in scar tissue, which decreases collagen fibril diameter, but also for controlling TGF-beta1 production, which leads to organ fibrosis.

Intrathecal injection of HVJ-E containing HGF gene to cerebrospinal fluid can prevent and ameliorate hearing impairment in rats

Hearing impairment, which is the most prevalent sensory deficit of human beings, needs a breakthrough in therapeutic technologies. One technology is the usage of a vector system to reach the inner ear, and another is by a therapeutic molecule. Here we developed a novel gene therapy strategy by combining hepatocyte growth factor (HGF) with hemagglutinating virus of Japan envelope (HVJ-E) vector. When HVJ-E containing human HGF gene was injected intrathecally into the cerebrospinal fluid via cisterna magna of rats, the vector reached the inner ear region, and human HGF gene expression was detected in the spiral ganglion cells (SGCs) of the inner ear. Expression of endogenous rat HGF and its receptor, c-Met, was also induced in SGCs by human HGF. Kanamycin treatment results in hearing impairment by inducing degeneration of hair cells (HCs) and apoptosis of SGCs in rats. By HGF gene transfer before kanamycin treatment, both loss of HCs and apoptosis of SGCs were prevented. Furthermore, hearing function, evaluated by auditory brainstem response, was maintained at a normal level. When HGF gene transfer was performed 2 wk after kanamycin treatment, hearing impairment was significantly recovered. These results indicate a novel and effective therapeutic strategy against sensorineural hearing impairment.

Hepatocyte growth factor gene transfer into the liver via the portal vein using electroporation attenuates rat liver cirrhosis

Although a variety of gene transfer methods to the liver have been designed, there are some problems such as the transfection efficiency and safety. In the present study, we developed a modified method of gene transfer into the liver by infusion of plasmid DNA via the portal vein followed by electroporation. After green fluorescence protein gene transfer, transgene expressions were detected in 24 h, and then maximally at 3 days, and persisted for 3 weeks. Histological analysis revealed that very mild tissue damage was induced in the liver to which electroporation was applied. In the second study, human hepatocyte growth factor (HGF) was more detected in the liver injected with 500 microg of human HGF gene than 100 microg of human HGF gene. However, serum HGF did not increase with 100 or 500 microg of human HGF gene. Moreover, 500 microg of HGF gene transfer into the liver by using this method could achieve the long survival of all dimethylnitrosamine-treated rats and attenuate the fibrous regions in the liver. These results suggest that HGF gene transfer into the liver via the portal vein using electroporation might be one of the useful methods for the treatment of various liver diseases.

Hemagglutinating virus of Japan (HVJ) envelope vector as a versatile gene delivery system

We have developed a simple method for converting the lipid envelope of an inactivated virus to a gene transfer vector. Hemagglutinating virus of Japan (HVJ; Sendai virus) envelope vector was constructed by incorporating plasmid DNA into inactivated HVJ particles. This HVJ envelope vector introduced plasmid DNA efficiently and rapidly into various cell lines, including cancer cells and several types of primary cell culture. Efficiency of gene transfer was greatly enhanced by protamine sulfate and centrifugation. Fluorescein isothiocyanate-labeled oligodeoxynucleotides (FITC-ODN) were also delivered to cells at > 95% efficiency. When HVJ envelope vector was injected into organs directly, reporter gene expression was observed in organs including liver, brain, skin, uterus, tumor masses, lung, and eye. When HVJ envelope vector containing luciferase gene was injected into mouse tail vein, luciferase gene expression was detected primarily in spleen. FITC-ODN were also delivered to spleen cells by intravenous injection of HVJ envelope. These results suggest that HVJ envelope vector will be useful for both ex vivo and in vivo gene therapy experiments.

Local overexpression of monocyte chemoattractant protein-1 at vessel wall induces infiltration of macrophages and formation of atherosclerotic lesion: synergism with hypercholesterolemia

Monocyte/macrophage infiltration to the arterial wall is an initial step in atherosclerosis, and monocyte chemoattractant protein-1 (MCP-1) is thought to play a central role in the recruitment of these cells. In the present study, we examined the role of local expression of MCP-1 at the vessel wall in the initiation and development of atherosclerosis. We transfected the cDNA encoding rat MCP-1 into the vessel wall of the rabbit carotid artery with the use of the hemagglutinating virus of Japan (HVJ)-liposome method. The rabbits were divided into the following groups: (1) those fed normal chow and transfected with MCP-1-HVJ, (2) those fed a high cholesterol diet (1% cholesterol) and transfected with MCP-1-HVJ, and (3) those fed a high cholesterol diet and transfected with control-HVJ. Prescribed diets were started 2 weeks before transfection and were continued for another 2 weeks. In group 1, vascular lesion formation was not found, and anti-rabbit monocyte/macrophage antibody (RAM-11) staining for monocytes/macrophages was negative, although anti-rat MCP-1 antibody (R-17) staining for rat MCP-1 was positive mainly in endothelial cells. Cholesterol feeding increased plasma cholesterol levels to 1801+/-444 mg/dL in group 2. In group 2, all rabbits displayed neointimal formation with infiltration of RAM-11-positive cells, and a part of the lesion was also positive for Sudan III lipid staining. In group 3, hypercholesterolemia did not induce the infiltration of monocytes/macrophages and subsequent lesion formation in the vessel wall despite definite upregulation of intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 on the endothelium. To initiate atherosclerotic changes, local MCP-1 overexpression at the vessel is not sufficient, and activation of other factors induced by hypercholesterolemia is required.

Pharmacotherapy by intracellular delivery of drugs using fusogenic liposomes: application to vaccine development

We prepared fusogenic liposomes by fusing conventional liposomes with an ultra-violet inactivated Sendai virus. Fusogenic liposomes can deliver encapsulated contents into the cytoplasm directly in a Sendai virus fusion-dependent manner. Based on the high delivery rates into the cytoplasm, we originally planned to apply the fusogenic liposomes to cancer chemotherapy and gene therapy. We have recently also examined the use of fusogenic liposomes as an antigen delivery vehicle. In terms of vaccine development, cytoplasmic delivery is crucial for the induction of the cytotoxic T lymphocyte (CTL) responses that play a pivotal role against infectious diseases and cancer. In this context, our recent studies suggested that fusogenic liposomes could deliver encapsulated antigens into the cytoplasm and induce MHC class I-restricted, antigen-specific CTL responses. In addition, fusogenic liposomes are also effective as a mucosal vaccine carrier. In this review, we present the feasibility of fusogenic liposomes as a versatile and effective antigen delivery system.

Gene therapy: principles and applications to hematopoietic cells

Ever since the development of technology allowing the transfer of new genes into eukaryotic cells, the hematopoietic system has been an obvious and desirable target for gene therapy. The last 10 years have witnessed an explosion of interest in this approach to treat human disease, both inherited and acquired, with the initiation of multiple clinical protocols. All gene therapy strategies have two essential technical requirements. These are: (1) the efficient introduction of the relevant genetic material into the target cell and (2) the expression of the transgene at therapeutic levels. Conceptual and technical hurdles involved with these requirements are still the objects of active research. To date, the most widely used and best understood vectors for gene transfer in hematopoietic cells are derived from retroviruses, although they suffer from several limitations. However, as gene transfer mechanisms become more efficient and long-term gene expression is enhanced, the variety of diseases that can be tackled by gene therapy will continue to expand. However, until the problem of delivery and subsequent expression is adequately resolved, gene therapy will not realize its full potential. The first part of this review gives an overview of the gene delivery technology available at present to transfer genetic sequences in human somatic cells. The relevance of the hematopoietic system to the development of gene therapy strategies as well as hematopoietic cell-based gene therapy is discussed in the second part.

Nuclear targeting of DNA

The nuclear membrane is a tight barrier for cytoplasmic proteins, but nuclear proteins have the intrinsic ability to overcome this barrier by an active signal-mediated process. Specific cytoplasmic carrier proteins have the responsibility to escort these proteins into the nucleus through the nuclear pore. The nuclear membrane is also a tight barrier for exogenous DNA delivered by synthetic vehicles, while many of the karyophilic viruses have a mechanism to actively deliver their genome through the nuclear pore. Virus DNA and RNA cannot move into the nucleus by themselves and require the viral structural proteins for efficient nuclear transport. In this article, we review the recent progress in understanding the mechanism of the nuclear transport of proteins and the virus genome, and discuss the possibility of developing synthetic gene-delivery systems based on these outcomes.

Safety evaluation of hemagglutinating virus of Japan--artificial viral envelope liposomes in nonhuman primates

We tested, in cynomolgus monkeys, the safety and effectiveness of a hybrid liposome vector, hemagglutinating virus of Japan (HVJ)--artificial viral envelope (AVE) liposomes, for human therapeutic gene transfer in a series of experiments. In a repetitive intramuscular administration study, vehicle control macaques (n = 2), which were treated with HVJ--AVE liposome suspension, received repetitive intramuscular injections of 2 ml of test substance. Human hepatocyte growth factor (HGF) cDNA-inserted expression vector (pUC-SR alpha/HGF) injection animals (n = 2), which were treated with HVJ--AVE liposome suspension containing pUC-SR alpha/HGF, received repetitive intramuscular injection of 2 ml of test substance. General body condition, hematology, blood chemistry, and serum HGF were determined sequentially before treatment and 7, 21, 28, and 29 days after treatment. Elevations in HGF were detected in monkeys injected with pUC-SR alpha/HGF. After this observation period, macaques were killed for autopsy and histological examination. pUC-SR alpha/HGF was detected by polymerase chain reaction (PCR) analysis in the liver, spleen, and at the injection site. In single intravenous administration study, control macaques (n = 4) received a single intravenous injection of 10 ml of physiological saline. Vehicle control animals (n = 5) received a single intravenous injection of 10 ml of HVJ--AVE liposome suspension. DNA-treated animals (n = 7) received a single intravenous injection of 10 ml of HVJ--AVE liposome suspension containing plasmid DNA [pcDNA 3.1(+)]. General body condition, body weight, hematology, blood chemistry, and urine composition were determined sequentially before treatment and 1, 14, 21, and 28 days after treatment. After this observation period, macaques were killed for autopsy and histological examination. pcDNA 3.1(+) was detected by PCR analysis on day 1 in lung, liver, and spleen of all monkeys, in kidney of one of two monkeys, and in heart of one of two monkeys. However, no DNA was detected in any of the tissues examined on days 14, 21, and 28. No virus genomic RNA was detected by reverse transcription (RT)-PCR analysis with HVJ-specific primers. In this series of safety evaluations, the animals tolerated the safety study with no change in body weight or general condition. No hematological changes or alterations in blood chemistry or urine composition was detected. Moreover, no histological changes were observed. This safety evaluation study demonstrates the safety, feasibility, and therapeutic potential of the novel transfection vehicle, HVJ--AVE liposomes, in humans.

Safe and efficient gene transfer into porcine hepatocytes using Sendai virus-cationic liposomes for bioartificial liver support

Establishment of a bioartificial liver support system using genetically modified hepatocytes is a potential approach to improve the treatment of severe liver failure. We describe the development of an efficient ex vivo method of gene transfer into a large number of porcine hepatocytes using hemagglutinating virus of Japan (HVJ)-liposome. The transfection efficiency of HVJ-liposome into isolated porcine hepatocytes attached to microcarrier beads was evaluated by beta-galactosidase (beta-gal) staining, fluorescence activated cell sorting analysis for beta-gal and luciferase assay, respectively. To examine the function and cellular damage of transduced hepatocytes, we used enzyme-linked immunosorbent assay for porcine albumin synthesis, lidocaine clearance test (P-450 activity), aspartate aminotransferase, and lactic dehydrogenase release assays. The optimal conditions for gene transfer into the beads-attached hepatocytes using HVJ-liposome included 4 microg of deoxyribonucleic acid with 200 microg of lipid/2 x 105 cells and exposure duration of 90 min. Under these conditions, beta-gal and luciferase genes were transduced to 2.5 x 108 isolated porcine hepatocytes following attachment to the beads. Positive beta-gal staining was observed in more than 30% of the beads-attached hepatocytes. The gene transfer activity of HVJ-liposome method determined by luciferase activities was about 100-fold of that of the lipofection method. Transfected porcine hepatocytes remained functional without any significant cell damage. Our results demonstrated that HVJ-liposome mediated gene transfer into microcarrier-attached porcine hepatocytes is an efficient and nontoxic method suitable for a bioartificial liver support sytem.

Systemic administration of HVJ viral coat-liposome complex containing human insulin vector decreases glucose level in diabetic mouse: A model of gene therapy

In this study, we examined the feasibility of a systemic administration of HVJ-liposome complex containing human insulin construct into the blood in mice via the tail vein. Transfection of human insulin vector resulted in a transient decrease in serum glucose in streptozotocin (SZT)-induced diabetic mice, accompanied by the detection of human insulin in the liver and spleen. In accordance with the decreased glucose, plasma immunoreactive insulin could be detected up to 14 days after a single transfection in mice transfected with insulin vector. Repeated intravenous injection of human insulin vector every week resulted in a sustained decrease in serum glucose over a 4-week period, accompanied by the detection of C-peptide fragments and a significant decrease in BUN and creatinine. Here, we demonstrated the feasibility of intravenous systemic administration of an insulin vector that results in a sustained improvement of diabetic glucose metabolism.

Hepatocyte-targeted in vivo gene expression by intravenous injection of plasmid DNA complexed with synthetic multi-functional gene delivery system

To achieve hepatocyte-targeted in vivo gene expression, a carrier that controls both the tissue and intracellular distribution of DNA was designed and synthesized. A cationic polymer, poly(L-ornithine) (pOrn), was modified first with galactose, then with a fusigenic peptide (mHA2) to obtain Gal-pOrn-mHA2. When applied with Gal-pOrn-mHA2 to asialoglycoprotein receptor-positive cells, fluorescein-labeled DNA showed a diffuse profile, suggesting the release of DNA from endosomes and/or lysosomes by the carrier. Then the biodistribution and gene expression after intravenous injection of DNA complexes (10 microg DNA per mouse) were examined. After injection of [32P]DNA/Gal-pOrn-mHA2, about 60% of the radioactivity was recovered in the liver, mostly in parenchymal cells. A large amount (81 ng/g tissue) of transgene product (luciferase) was detected in the liver of mice injected with DNA/Gal-pOm-mHA2, which was 280-fold greater than that obtained with DNA/DOTMA:Chol liposomes (50 microg DNA). Prior administration of galactosylated albumin reduced the gene expression to 1/100, indicating the asialoglycoprotein receptor-mediated gene transfer in liver parenchymal cells, ie hepatocytes. The luciferase activity in hepatocytes contributed more than 95% of the total activity in all the tissues examined. Thus, hepatocyte-targeted in vivo gene expression was achieved by the intravenous injection of DNA complex with the multifunctional gene carrier.

Biological barriers to cellular delivery of lipid-based DNA carriers

Although lipid-based DNA delivery systems are being assessed in gene therapy clinical trials, many investigators in this field are concerned about the inefficiency of lipid-based gene transfer technology, a criticism directed at all formulations used to enhance transfer of plasmid expression vectors. It is important to recognize that many approaches have been taken to improve transfection efficiency, however because of the complex nature of the formulation technology being developed, it has been extremely difficult to define specific carrier attributes that enhance transfection. We believe that these optimization processes are flawed for two reasons. First, a very defined change in formulation components affects the physical and chemical characteristics of the carrier in many ways. As a consequence, it has not been possible to define structure/activity relationships. Second, the primary endpoint used to assess plasmid delivery has been transgene expression, an activity that is under the control of cellular processes that have nothing to do with delivery. Gene expression following administration of a plasmid expression vector involves a number of critical steps: (i) DNA protection, (ii) binding to a specific cell population, (iii) DNA transfer across the cell membrane, (iv) release of DNA into the cytoplasm, (v) transport through the cell and across the nuclear membrane as well as (vi) transcription and translation of the gene. The objective of this review is to describe lipid-based DNA carrier systems and the attributes believed to be important in regulating the transfection activity of these formulations. Although membrane destabilization activity of the lipid-based carriers plays an important role, we suggest here that a critical element required for efficient transfection is dissociation of lipids bound to the plasmid expression vector following internalization.

Lipoplexes and tumours. A review

The need for genotherapy to refocus its attention on to laboratory evaluation of better methods rather than proceeding to the clinic with semi-apt tools for genetic transfer has been highlighted in clinical study reports documented to date. Quintessential for tumour genotherapy is the ability to target abnormal cells, hence reducing exposure of normal cells to genetic material whilst maximizing gene dosage to tumour cells. This becomes increasingly important as genotherapy establishes itself in the clinic alongside the older modes of treatment. This review has discussed the applicability of lipoplexes for genotherapy of solid tumours. Lipoplexes have been used extensively for gene transfer into cells, such as cancerous cells, deficient for a certain gene product. While cationic liposomes have many advantages over other forms of delivery mechanisms, several problems hinder their use in-vivo. A closer examination of the physical limitations of current lipoplex preparations, the development and testing of novel formulations, combined with more attention to the cellular processes of cell membrane breaching and nuclear entry, may enhance gene delivery. Essential for tumour genotherapy is the ability to target these lipoplexes into tumour sites whilst reducing gene dosage to other normal tissues. Development of a better lipofection agent may indeed require a collaboration of the fields of physiology, cell biology, molecular biology, biochemistry, chemistry and membrane physics.

Regression of hepatocellular carcinoma in vitro and in vivo by radiosensitizing suicide gene therapy under the inducible and spatial control of radiation

To improve the efficacy and selectivity of gene therapy for hepatocellular carcinoma (HCC), we designed a strategy for suicide gene therapy in conjunction with radiation therapy using an HVJ-liposome vector system. The radio-inducible suicide gene was constructed by insertion of the early growth response gene 1 (Egr-1) promoter upstream of the HSV-tk gene (EGF-tk). First, to test the tumor specificity of Egr-1, RT-PCR and immunohistochemistry were performed. The Egr-1 gene was highly expressed in HCC compared with normal liver, where expression was barely detectable. Next, radiation-inducible activity of the Egr-1 promoter was examined in primary cultured normal hepatocytes and human hepatoma cell lines Huh7, HepG2, and PLC/PRF/5 by luciferase assay as a reporter gene system. Egr-1 promoter activity was markedly increased in hepatoma cell lines in a radiation dose-dependent manner, with maximum activation (15- to 28-fold) 12 hr after irradiation. In contrast, only a twofold increase in activation was noted in normal hepatocytes. An in vitro gene therapy experiment showed that EGR-tk-transduced hepatoma cells became highly sensitive to ganciclovir (GCV) after irradiation, but not without irradiation. GCV with or without irradiation did not show any cytotoxic effects against control gene-transfected cells. In addition, a "radiosensitization effect" was also demonstrated by combination therapy with the HSV-tk/GCV system and irradiation. To examine the efficacy of this EGR-tk/GCV gene therapy in vivo, xenografted liver tumors in nude mice were targeted using the HVJ-liposome vector system. EGR-tk-transfected tumors regressed significantly after a combination therapy of irradiation and GCV in all mice (n = 8), and almost disappeared in 3 weeks without any side effects. In comparison, tumors continued to grow in all mice (n = 8 in each group) treated by transfer of EGR-tk followed by either irradiation without GCV or GCV without irradiation. Our data indicate that HSV-tk gene therapy under the control of a radioinducible promoter is effective, and might be selective for hepatoma cells because of its inducible and radiosensitive capacity after radiation exposure as well as its tumor-specific activation.

The challenge of vector development in gene therapy

Gene therapy is the treatment of diseases based on the transfer of genetic information. Agents that carry or deliver DNA to target cells are called vectors (Latin vector: carrier, deliverer). Ideally, a vector should accommodate an unlimited amount of inserted DNA, lack the ability of autonomous replication of its own DNA, be easily manufactured, and be available in concentrated form. Secondly, it should have the ability to target specific cell types or to limit its gene expression to specific cell types, and to achieve sustained gene expression in the long term or in a controlled fashion. Finally, it should not be toxic or immunogenic. Such a vector does not exist and none of the DNA delivery systems so far available for in vivo gene transfer is perfect with respect to any of these points. Gene therapy and the means to promote it depend heavily on the development and improvement of new gene vector systems.

PLGA microspheres containing plasmid DNA: preservation of supercoiled DNA via cryopreparation and carbohydrate stabilization

Biodegradable microspheres containing plasmid DNA have potential uses as mediators of transfection in cells, particularly phagocytic cells such as macrophages. However, the hydrophilic nature and the structural instability of supercoiled DNA preclude its facile encapsulation in polymer matrixes such as poly(d, l-lactic-co-glycolic acid) (PLGA) by traditional methods. We initially studied the microencapsulation of plasmid DNA using the established water-in-oil-in-water double-emulsion solvent-evaporation method and found that (1) the encapsulation efficiency was low (about 20%), (2) the microencapsulation procedure nicked (degraded) the supercoiled DNA, and (3) lyophilization of the microsphere also nicked the DNA. We have therefore designed a new microsphere preparation method (called cryopreparation) to specifically address these concerns. Using the cryopreparation method, the aqueous phase of the primary emulsion containing the plasmid DNA is frozen and then subjected to homogenization. Because there is no shear stress inside a solid, we hypothesized that freezing the aqueous phase of the primary emulsion would help to preserve the supercoiled plasmid DNA during formation of the secondary emulsion. We also hypothesized that the formation of crystals from buffers within the primary emulsion was a causative factor for nicking during freezing or lyophilization, and that disruption of the crystal formation by the addition of saccharides into the primary emulsion would improve the supercoiled-DNA content of the spheres. Our results support the two hypotheses. Not only was the supercoiled-DNA content increased from 39% to over 85%, but the encapsulation efficiency was also elevated from 23% to over 85%.

Gene delivery systems using the Sendai virus

Fusogenic liposome (FL) is a delivery system that can transfer encapsulated materials into living cells directly through membrane fusion. FL is a promising approach for gene therapy because it can deliver various genetic materials much more efficiently than other non-viral vectors without damaging the cell. FL-mediated gene transfer consists of two independent membrane fusion phenomena; generation of a FL by fusing a Sendai virus (SV) particle with a simple liposome encapsulating DNA, and successive fusion of the FL with cell membrane. The former requires viral F protein but no other special molecule on the liposomal membrane, whereas the latter may require the receptor (sialic acid) and unidentified assistant molecule(s) on the cell membrane. Further analysis suggests that these assistant molecule(s), not the receptor, may control the fusion and govern the cell specificity of FL-mediated delivery. This review has described a detailed analysis of these fusion phenomena and discussed possible applications of FL-mediated gene delivery to human gene therapy.

HVJ-liposome mediated gene transfer into hepatocytes in vivo

BACKGROUND/AIMS

The efficient transduction of appropriate target cells will be critical for gene therapy. We evaluated the suitability of hemagglutinating virus of Japan (HVJ)-liposome-mediated gene transfer for gene therapy of liver diseases.

METHODS

The Escherichia coli beta-galactosidase (beta-gal) gene was introduced into rat liver by HVJ-liposome to examine gene transfer efficacy and persistence of expression with or without partial hepatectomy prior to transfection.

RESULTS

About 30% of hepatocytes were transduced after portal vein injection. Gene expression was transient, with only 2% of hepatocytes expressing beta-gal after 4 weeks. However, partial hepatectomy performed 24 h prior to injection resulted in persistently high levels of beta-gal for 4 weeks after injection. A 247-bp beta-gal polymerase chain reaction fragment transcript was detected in livers of transfected rats, but not in livers of control rats. The rat livers following gene transfer were histologically normal, and serum glutamic-pyruvic transaminase was not found to be elevated in rats.

CONCLUSIONS

Our results demonstrate that HVJ-liposome-mediated gene transfer produced high gene transduction and persistent gene expression in the liver.

Peptide inhibitors of HIV-1 protease and viral infection of peripheral blood lymphocytes based on HIV-1 Vif

We recently reported that HIV-1 Vif (virion infectivity factor) inhibits HIV-1 protease in vitro and in bacteria, suggesting that it may serve as the basis for the design of new protease inhibitors and treatment for HIV-1 infection. To evaluate this possibility, we synthesized peptide derivatives from the region of Vif, which inhibits protease, and tested their activity on protease. In an assay of cleavage of virion-like particles composed of HIV-1 Gag precursor polyprotein, full-length recombinant Vif, and a peptide consisting of residues 21-65 of Vif, but not a control peptide or BSA, inhibited protease activity. Vif21-65 blocked protease at a molar ratio of two to one. We then tested this peptide and a smaller peptide, Vif41-65, for their effects on HIV-1 infection of peripheral blood lymphocytes. Both Vif peptides inhibited virus expression below the limit of detection, but control peptides had no effect. To investigate its site of action, Vif21-65 was tested for its effect on Gag cleavage by protease during HIV-1 infection. We found that commensurate with its reduction of virus expression, Vif21-65 inhibited the cleavage of the polyprotein p55 to mature p24. These results are similar to those obtained by using Ro 31-8959, a protease inhibitor in clinical use. We conclude that Vif-derived peptides inhibit protease during HIV-1 infection and may be useful for the development of new protease inhibitors.

Lipofection of purified adeno-associated virus Rep68 protein: toward a chromosome-targeting nonviral particle

Adeno-associated virus (AAV) integrates very efficiently into a specific site (AAVS1) of human chromosome 19. Two elements of the AAV genome are sufficient: the inverted terminal repeats (ITRs) and the Rep78 or Rep68 protein. The incorporation of the AAV integration machinery in nonviral delivery systems is of great interest for gene therapy. We demonstrate that purified recombinant Rep68 protein is functionally active when directly delivered into human cells by using the polycationic liposome Lipofectamine, promoting the rescue-replication of a codelivered ITR-flanked cassette in adenovirus-infected cells and its site-specific integration in noninfected cells. The sequencing of cloned virus-host DNA junctions confirmed that lipofected Rep68 protein triggers site-specific integration at the same sites in chromosome 19 already characterized in cells latently infected with AAV.

Gene transfer to vein graft wall by HVJ-liposome method: time course and localization of gene expression

BACKGROUND

A novel gene transfer method using liposomes with a viral envelope of hemagglutinating virus of Japan (HVJ) has been reported to be very effective for gene transfection into somatic cells and might be applicable to improve the patency of vein grafts. The present study examined the time course and localization of gene expression to assess the feasibility of ex vivo gene transfer into the vein graft by the HVJ-liposome method.

METHODS

The HVJ-liposome complex containing either beta-galactosidase plasmid DNA (deoxyribonucleic acid) or no genes (controls) (experiment 1) or fluorescein isothiocyanate-labeled oligonucleotides either with or without HVJ-liposomes (experiment 2) was infused into rabbit vein grafts and allowed to incubate before autologous transplantation to carotid arteries.

RESULTS

In experiment 1, all grafts incubated with beta-galactosidase plasmid with HVJ-liposomes showed the blue staining of X-gal 7 days after operation, whereas the controls did not. The blue granules were present in the medial and adventitial tissue and were still present after 14 days. In experiment 2, many fluorescein isothiocyanate-labeled nuclei were observed in the graft wall 2 and 4 days after operation and remained present mainly in the media of HVJ-liposome-treated grafts after 7 and 14 days, when no fluorescein isothiocyanate activity was observed without HVJ-liposome treatment.

CONCLUSIONS

These results demonstrated the feasibility of ex vivo transfection to the medial and adventitial tissue of the vein graft by the HVJ-liposome method and suggest the possibility of its clinical application to prevent vein graft failure.