Methods of gene delivery

Anti-Inflammatory Gene Therapy Improves Spatial Memory Performance in a Mouse Model of Alzheimer's Disease

The immune system plays a critical role in neurodegenerative processes involved in Alzheimer’s disease (AD). In this study, a gene-based immunotherapeutic method examined the effects of anti-inflammatory cellular immune response elements (CIREs) in the amyloid-β protein precursor (AβPP) mouse model. Bi-monthly intramuscular administration, beginning at either 4 or 6 months, and examined at 7.5 through 16 months, with plasmids encoding Interleukin (IL)-10, IL-4, TGF-β polynucleotides, or a combination thereof, into AβPP mice improved spatial memory performance. This work demonstrates an efficient gene therapy strategy to downregulate neuroinflammation, and possibly prevent or delay cognitive decline in AD.

Recent advances in the development of gene delivery systems

Background

Gene delivery systems are essentially necessary for the gene therapy of human genetic diseases. Gene therapy is the unique way that is able to use the adjustable gene to cure any disease. The gene therapy is one of promising therapies for a number of diseases such as inherited disorders, viral infection and cancers. The useful results of gene delivery systems depend open the adjustable targeting gene delivery systems. Some of successful gene delivery systems have recently reported for the practical application of gene therapy.

Main body

The recent developments of viral gene delivery systems and non-viral gene delivery systems for gene therapy have briefly reviewed. The viral gene delivery systems have discussed for the viral vectors based on DNA, RNA and oncolytic viral vectors. The non-viral gene delivery systems have also treated for the physicochemical approaches such as physical methods and chemical methods. Several kinds of successful gene delivery systems have briefly discussed on the bases of the gene delivery systems such as cationic polymers, poly(L-lysine), polysaccharides, and poly(ethylenimine)s.

Conclusion

The goal of the research for gene delivery system is to develop the clinically relevant vectors such as viral and non-viral vectors that use to combat elusive diseases such as AIDS, cancer, Alzheimer, etc. Next step research will focus on advancing DNA and RNA molecular technologies to become the standard treatment options in the clinical area of biomedical application.

Chitin/Chitosan: Versatile Ecological, Industrial, and Biomedical Applications

Chitin is a linear polysaccharide of N-acetylglucosamine, which is highly abundant in nature and mainly produced by marine crustaceans. Chitosan is obtained by hydrolytic deacetylation. Both polysaccharides are renewable resources, simply and cost-effectively extracted from waste material of fish industry, mainly crab and shrimp shells. Research over the past five decades has revealed that chitosan, in particular, possesses unique and useful characteristics such as chemical versatility, polyelectrolyte properties, gel- and film-forming ability, high adsorption capacity, antimicrobial and antioxidative properties, low toxicity, and biocompatibility and biodegradability features. A plethora of chemical chitosan derivatives have been synthesized yielding improved materials with suggested or effective applications in water treatment, biosensor engineering, agriculture, food processing and storage, textile additives, cosmetics fabrication, and in veterinary and human medicine. The number of studies in this research field has exploded particularly during the last two decades. Here, we review recent advances in utilizing chitosan and chitosan derivatives in different technical, agricultural, and biomedical fields.

Method for analysis of electrospray for gene transfer and the impact on cell viability of A549 alveolar epithelial like cells

Electrospray is a process based on creation and acceleration of small sized droplets based on electrostatic repulsion. Spraying plasmid containing liquids this process may be used to transfer genes into cells. Within this paper we report on a method for accessing and evaluating the spray modalities using high speed imaging system with a post processing of image data to obtain estimated volume and velocity of emerging droplets first. Second we investigate on the impact of different media on the spray modalities. Third we evaluate the impact of the spray on cell viability and on transfection efficiency of an eGFP plasmid as reporter gene obtained in an in vitro setup on alveolar epithelial like cells (A549).

Functionalized MoS2 Nanosheets as Multi-Gene Delivery Vehicles for In Vivo Pancreatic Cancer Therapy

Transition metal dichalcogenides (TMDCs) are categorized as novel two-dimensional (2D) nanomaterials with unique physical and chemical properties, bearing varied applications in medical and materials sciences. However, only a few works report the application of TMDCs for gene therapy in cancer treatment. Here, we engineer a multi-gene delivery system based on functionalized monolayer MoS2, which can co-deliver HDAC1 and KRAS small interfering RNAs (siRNAs) to Panc-1 cancer cells for combinational cancer therapy. The synergistic effect of gene silencing therapy and NIR phototherapy is demonstrated by inhibition of both genes, in vitro cell growth rate, and in vivo tumor volume growth rate, exemplifying pre-eminent anticancer efficacy. This anti-tumor effect is a result of the photothermal effect of MoS2 induced by NIR excitation and inactivation of HDAC1 and KRAS genes, which consequently bring about apoptosis, inhibit migration, and induce cell cycle arrest in the treated Panc-1 cells. Moreover, good biocompatibility and reduced cytotoxicity of MoS2-based nanocarriers enable their metabolism within in vitro and in vivo mouse models over a prolonged duration without any evident ill-effects. In summary, we demonstrate the promising potential of low-toxicity, functionalized MoS2 nanocarriers as a biocompatible gene delivery system for in vivo pancreatic adenocarcinoma therapy.

A new electrospray method for targeted gene delivery

A challenge for gene therapy is absence of safe and efficient local delivery of therapeutic genetic material. An efficient and reproducible physical method of electrospray for localized and targeted gene delivery is presented. Electrospray works on the principle of coulombs repulsion, under influence of electric field the liquid carrying genetic material is dispersed into micro droplets and is accelerated towards the targeted tissue, acting as a counter electrode. The accelerated droplets penetrate the targeted cells thus facilitating the transfer of genetic material into the cell. The work described here presents the principle of electrospray for gene delivery, the basic instrument design, and the various optimized parameters to enhance gene transfer in vitro. We estimate a transfection efficiency of up to 60% was achieved. We describe an efficient gene transfer method and a potential electrospray-mediated gene transfer mechanism.

Advanced Materials for Gene Delivery

Gene therapy is a widespread and promising treatment of many diseases resulting from genetic disorders, infections and cancer. The feasibility of the gene therapy is mainly depends on the development of appropriate method and suitable vectors. For an efficient gene delivery, it is very important to use a carrier that is easy to produce, stable, non-oncogenic and non-immunogenic. Currently most of the vectors actually suffer from many problems. Therefore, the ideal gene therapy delivery system should be developed that can be easily used for highly efficient delivery and able to maintain long-term gene expression, and can be applicable to basic research as well as clinical settings. This article provides a brief over view on the concept and aim of gene delivery, the different gene delivery systems and use of different materials as a carrier in the area of gene therapy.

An approach towards bronchoscopic-based gene therapy using electrical field accelerated plasmid droplets

Idiopathic pulmonary fibrosis (IPF) is a devastating disease affecting the distal lung, due to failure of the alveolar epithelium to heal after micro-injuries, leading to inefficient gas exchange and resulting in death. Therapeutic options are very limited. A new therapeutic approach based on gene therapy restores the self-healing process within the lung in the experimental setup. A basic requirement of this therapy is the successful transduction of genes into the alveolar epithelium in the distal part of the lung, for which a new therapeutic instrument is required. In this paper we present the concept and first experimental results of a device which uses an electrical field to accelerate the charged droplets of plasmid suspension toward the tissue and which overcomes cell membrane with its impact energy. The aim is to develop a therapeutic device capable of being integrated into minimally invasive procedures such as bronchoscopy.

Intracavitary therapeutics for pleural malignancies

Pleural malignancies are ideal for novel therapeutic approaches because they are invariably fatal. Intrapleural (IP) chemotherapy has only marginal benefit in pleural malignancies, but may prove efficacious with hyperthermic chemotherapy administered in combination with maximal tumor debulking. IP immunotherapies may be most effective in those patients with early-stage pleural malignancy, and may prove superior to standard pleurodesis methods in control of effusion and prolongation of survival. Immunogene therapy may be unable to successfully treat bulky tumors on its own, but success may be achieved with combination approaches that combine debulking surgery and chemotherapy with IP genetic immunotherapy.

LDLR-Gene therapy for familial hypercholesterolaemia: problems, progress, and perspectives

Coronary artery diseases (CAD) inflict a heavy economical and social burden on most populations and contribute significantly to their morbidity and mortality rates. Low-density lipoprotein receptor (LDLR) associated familial hypercholesterolemia (FH) is the most frequent Mendelian disorder and is a major risk factor for the development of CAD. To date there is no cure for FH. The primary goal of clinical management is to control hypercholesterolaemia in order to decrease the risk of atherosclerosis and to prevent CAD. Permanent phenotypic correction with single administration of a gene therapeutic vector is a goal still needing to be achieved. The first ex vivo clinical trial of gene therapy in FH was conducted nearly 18 years ago. Patients who had inherited LDLR gene mutations were subjected to an aggressive surgical intervention involving partial hepatectomy to obtain the patient's own hepatocytes for ex vivo gene transfer with a replication deficient LDLR-retroviral vector. After successful re-infusion of transduced cells through a catheter placed in the inferior mesenteric vein at the time of liver resection, only low-level expression of the transferred LDLR gene was observed in the five patients enrolled in the trial. In contrast, full reversal of hypercholesterolaemia was later demonstrated in in vivo preclinical studies using LDLR-adenovirus mediated gene transfer. However, the high efficiency of cell division independent gene transfer by adenovirus vectors is limited by their short-term persistence due to episomal maintenance and the cytotoxicity of these highly immunogenic viruses. Novel long-term persisting vectors derived from adeno-associated viruses and lentiviruses, are now available and investigations are underway to determine their safety and efficiency in preparation for clinical application for a variety of diseases. Several novel non-viral based therapies have also been developed recently to lower LDL-C serum levels in FH patients. This article reviews the progress made in the 18 years since the first clinical trial for gene therapy of FH, with emphasis on the development, design, performance and limitations of viral based gene transfer vectors used in studies to ameliorate the effects of LDLR deficiency.

Towards fibroid gene therapy: adenovirus-mediated delivery of herpes simplex virus 1 thymidine kinase gene/ganciclovir shrinks uterine leiomyoma in the Eker rat model

BACKGROUND/AIMS

The objective of this study was to assess in vivo gene therapy of uterine leiomyomas in the Eker rat model using adenovirus (Ad)-mediated delivery of herpes simplex virus 1 thymidine kinase gene (HSV1TK) followed by ganciclovir (GCV) treatment.

METHODS

We randomized 27 female Eker rats with MRI-confirmed uterine leiomyomas to a single treatment with direct intra-tumor injection of Ad-HSV1TK/GCV, Ad-LacZ/GCV, or medium alone. Samples were collected from tumors, other body organs, and blood at 10, 20, and 30 days after treatment to assess the safety and efficacy of the treatment.

RESULTS

Ad-HSV1TK/GCV treatment significantly decreased uterine fibroid volume by 75 +/- 16, 58.7 +/- 6.3, and 67.5 +/- 27.5%, of the pretreatment volume at days 10, 20, and 30, respectively. Ad-HSV1TK/GCV increased caspase-3 activity, Bax expression, and TUNEL apoptosis marker, and it decreased cyclin D1, PCNA, Bcl2, and PARP protein expressions. Ad transfection induced local CD4+ and CD8+ infiltration and serum anti-Ad antibodies. Additionally, Ad transfection was tumor-localized and safe to non-target tissues.

CONCLUSION

These studies demonstrate a marked efficiency and high safety for the Ad-HSV1TK/GCV therapeutic approach in the context of Eker rat uterine leiomyomas and provide essential preclinical data for the development of Ad-HSV1TK/GCV gene therapy for uterine fibroids.

Direct chitosan-mediated gene delivery to the rabbit knee joints in vitro and in vivo

Chitosan vector system is expected to be useful for direct gene therapy for joint disease. This study first sought to confirm that foreign genes can be transferred to articular chondrocytes in primary culture. Next, chitosan-DNA nanoparticles containing IL-1Ra or IL-10 gene were injected directly into the knee joint cavities of osteoarthritis rabbits to clarify the in vivo transfer availability of the chitosan vectors. Clear expression of IL-1Ra was detected in the knee joint synovial fluid of the chitosan IL-1Ra-injected group. While no expression was detected in the chitosan IL-10-injected group, this demonstrates that the transfection efficiency of chitosan-DNA nanoparticles was closely related to the type of the gene product. A significant reduction was also noted in the severity of histologic cartilage lesions in the group that received the chitosan IL-1Ra injection. This avenue may therefore represent a promising future treatment for osteoarthritis.

Long-term transgene expression and survival of transgene-expressing grafts following lentivirus transduction of bone marrow side population cells

BACKGROUND

Successful transduction of hematopoietic stem cells is essential if gene therapy is to be used clinically to induce immunologic tolerance.

METHODS

Hoechst 33342 staining was used to isolate a population of bone marrow cells enriched for stem cells, termed side population (SP) cells. Murine bone marrow SP cells were transduced with HLA-A2.1-expressing VSV-G-pseudotyped lentivirus or retrovirus vectors under identical conditions.

RESULTS

After transduction without prestimulating cytokines, which minimizes cell cycling and helps maintain stem cell pluripotency, the HLA-A2.1 gene was found in the DNA of 56% of CFU-GM colonies derived from lentivirus-transduced SP cells, but in only 4% of colonies derived from retrovirus-transduced SP cells. Lentivirus and retrovirus transduction including cytokine prestimulation produced the same degree of integration as that following lentivirus-transduction of non-prestimulated cells. Transplantation of 5,000 lentivirus-transduced SP cells into lethally irradiated mice resulted in long-term expression of the HLA-A2.1 transgene in peripheral blood progeny of bone marrow SP cells and prolonged skin graft survival across this class I MHC barrier until the time of animal sacrifice.

CONCLUSIONS

Recombinant lentivirus, but not retrovirus vectors, effectively transduced SP cells that were not prestimulated with cytokines and lentivirus-transduced SP cells successfully repopulated lethally irradiated C57BL/6 mice, animals where there is no selective advantage to repopulation with transduced cells. Transplantation of a relatively small number of transduced SP cells led to prolonged transgene mRNA expression and antigen-specific survival of grafts expressing the foreign MHC transgene.

Polymers for DNA delivery

Nucleic acid delivery has many applications in basic science, biotechnology, agriculture, and medicine. One of the main applications is DNA or RNA delivery for gene therapy purposes. Gene therapy, an approach for treatment or prevention of diseases associated with defective gene expression, involves the insertion of a therapeutic gene into cells, followed by expression and production of the required proteins. This approach enables replacement of damaged genes or expression inhibition of undesired genes. Following two decades of research, there are two major methods for delivery of genes. The first method, considered the dominant approach, utilizes viral vectors and is generally an efficient tool of transfection. Attempts, however, to resolve drawbacks related with viral vectors (e.g., high risk of mutagenicity, immunogenicity, low production yield, limited gene size, etc.), led to the development of an alternative method, which makes use of non-viral vectors. This review describes non-viral gene delivery vectors, termed "self-assembled" systems, and are based on cationic molecules, which form spontaneous complexes with negatively charged nucleic acids. It introduces the most important cationic polymers used for gene delivery. A transition from in vitro to in vivo gene delivery is also presented, with an emphasis on the obstacles to achieve successful transfection in vivo.

Gene Therapy for Pediatric Cancer: State of the Art and Future Perspectives

While modern treatments have led to a dramatic improvement in survival for pediatric malignancy, toxicities are high and a significant proportion of patients remain resistant. Gene transfer offers the prospect of highly specific therapies for childhood cancer. "Corrective" genes may be transferred to overcome the genetic abnormalities present in the precancerous cell. Alternatively, genes can be introduced to render the malignant cell sensitive to therapeutic drugs. The tumor can also be attacked by decreasing its blood supply with genes that inhibit vascular growth. Another possible approach is to modify normal tissues with genes that make them more resistant to conventional drugs and/or radiation, thereby increasing the therapeutic index. Finally, it may be possible to attack the tumor indirectly by using genes that modify the behavior of the immune system, either by making the tumor more immunogenic, or by rendering host effector cells more efficient. Several gene therapy applications have already been reported for pediatric cancer patients in preliminary Phase 1 studies. Although no major clinical success has yet been achieved, improvements in gene delivery technologies and a better understanding of mechanisms of tumor progression and immune escape have opened new perspectives for the cure of pediatric cancer by combining gene therapy with standard therapeutic available treatments.

Viruses in the treatment of brain tumors

The grave outlook for malignant glioma patients in spite of improvements to current modalities has ushered in new approaches to therapy. Viruses have emerged on the scene and gained attention for their ability to play essentially two roles: first, as vectors for therapeutic gene delivery and second, as engineered infectious agents capable of selectively lysing tumor cells. To date, clinical brain tumor trials using viruses for gene delivery have employed retroviral or adenoviral vectors to introduce ganciclovir susceptibility to tumors in the form of the HSV1-TK gene. Clinical oncolytic studies, on the other hand, have evaluated a conditionally replicating HSV as an antineoplastic agent. Despite some promise afforded by these trials, further studies are warranted; the investigation of additional viruses to play these roles is inevitable and is now precedented.

Quantitative analysis of adenovirus-specific CD4+ T-cell responses from healthy adults

Although nearly all adults are seropositive for adenoviruses, little is known about the cellular immune responses to these ubiquitous pathogens. We have previously identified adenovirus-specific proliferative T-cell responses in peripheral blood mononuclear cells (PBMC) from healthy adults. In this study, memory T-cell responses to adenovirus were further evaluated in healthy adult donors using a short term, quantitative enzyme-linked immunospot assay (ELISPOT) assay. Adenovirus antigen induced specific secretion of interferon-gamma (IFN-gamma) from PBMC within 12 hours of incubation. PBMC from 20 of 22 healthy donors (90.9%) expressed IFN-y in response to adenovirus. Responder cells were identified as CD4+ T cells by immunomagnetic depletion methods. Interleukin-4 (IL-4) secretion was not detected, consistent with a TH1 response. There was a 10-fold variation in the frequencies of adenovirus-specific CD4+ T cells between donors (range, 34 to 294; median, 122 per million PBMC). Adenovirus-specific T cell frequencies remained stable over periods up to 2 years among individual donors, but there was an inverse correlation between frequency and donor age. These quantitative data suggest that most adults retain adenovirus-specific cellular memory after childhood exposure. This assay may be useful for the evaluation of adenovirus-specific CD4+ T-cell responses in patients treated with adenovirus gene therapy vectors and the identification of major T-cell epitopes.

Antisense Bcl2 oligonucleotide in cisplatin-resistant bladder cancer cell lines

OBJECTIVE

To determine the change of expression of Bcl2 in cisplatin-resistant bladder cancer cell lines and the reversibility of chemoresistance to cisplatin with antisense oligonucleotide against Bcl2, as higher expression of Bcl2 is associated with drug resistance in many different cancer cell lines.

MATERIALS AND METHODS

In the cisplatin-resistant bladder tumour cell lines T24R1 and T24R2, the expression of Bcl2 was determined by reverse transcription-polymerase chain reaction and Western blot assay, and antisense oligonucleotide targeting of the Bcl2 coding sequence was administered with lipofectin.

RESULTS

The expression of Bcl2 mRNA and protein was greater in T24R1 and T24R2 cells than in the parent T24 cells. Short-term exposure to cisplatin up-regulated Bcl2 mRNA and protein expression in parent T24 cells. Treatment with antisense oligonucleotide down-regulated Bcl2 protein expression and significantly enhanced the cytotoxicity of cisplatin.

CONCLUSIONS

Up-regulation of Bcl2 protein expression might be one of the mechanisms of cisplatin resistance in bladder cancer cells, and antisense Bcl2 oligonucleotide may be helpful in chemotherapy for bladder cancer by reversing cisplatin resistance.

The adenovirus capsid protein hexon contains a highly conserved human CD4+ T-cell epitope

The immunogenicity of adenovirus vectors remains a major obstacle to their safe and efficacious use for gene therapy. In order to identify T-cell epitopes directly from adenoviruses, four viral protein sequences were screened for the well-characterized 9-mer HLA-A2 binding motif. Peripheral blood mononuclear cells (PBMC) from healthy adults were tested for responses to 17 selected viral peptides using a short-term interferon-gamma ELISPOT assay. Memory T-cell responses were identified to a single peptide derived from the major capsid protein hexon in 5 of 6 HLA-A2-positive donors. Unexpectedly, responses to this hexon peptide were also detected in 4 of 6 HLA-A2-negative donors, and responder cells were identified as CD4(+) T cells by immunomagnetic depletion experiments. A longer 15-mer peptide, H910-924, was identified as the optimal CD4(+) T-cell epitope. This hexon epitope induces strong proliferative T-cell responses that can be blocked by a monoclonal antibody against HLA-DR, and molecular HLA typing of donors suggests that the peptide response is restricted by multiple HLA-DR alleles. Additionally, quantitative analysis of responses to H910-924 and whole adenovirus reveals that the frequency of circulating CD4(+) T cells specific for this single hexon epitope (mean = 61 per 10(6) PBMC) represents up to one third of the total adenovirus-specific T-cell response. Finally, comparison of hexon sequences from over 20 different human adenovirus serotypes indicates that H910-924 is highly conserved. In most individuals, therefore, T-cell responses to this hexon epitope will be induced by all adenovirus vectors, including "gutted" vectors packaged with capsid proteins and vectors based on different serotypes.

Gene therapy and reproductive medicine

OBJECTIVE

To review the literature on the principles of gene therapy and its potential application in reproductive medicine.

DESIGN

Literature review.

SETTING

Gene therapy involves transfer of genetic material to target cells using a delivery system, or vector. Attention has primarily focused on viral vectors. Significant problems remain to be overcome including low efficacy of gene transfer, the transient expression of some vectors, safety issues with modified adenoviruses and retroviruses, and ethical concerns. If these issues can be resolved, gene therapy will be applicable to an increasing spectrum of single and multiple gene disorders, as the Human Genome Project data are analyzed, and the genetic component of human disease becomes better understood. Gynecologic gene therapy has advanced to human clinical trials for ovarian carcinoma, and shows potential for the treatment of uterine leiomyomata. Obstetric applications of gene therapy, including fetal gene therapy, remain more distant goals.

CONCLUSION(S)

Concerns about the safety of human gene therapy research are being actively addressed, and remarkable progress in improving DNA transfer has been made. The first treatment success for a genetic disease (severe combined immunodeficiency disease) has been achieved, and ongoing research efforts will eventually yield clinical applications in many spheres of reproductive medicine.

[Contribution of antineoplastic biotherapy in the treatment of leukemia in children]

Improvements in the chemotherapeutic and transplant regimens have had a significant impact in improving survival rates for pediatric leukemia. However, there are still major problems to address including what options are available for patients with chemoresistant disease and what strategies are available to avoid toxicity associated with highly cytotoxic treatment regimens. Gene and immunotherapy protocols hold great promise. Using gene transfer of a marker gene, a number of biologic issues in the therapy of leukemia have been addressed. For example, by gene marking autologous bone marrow grafts it has been possible to demonstrate that infused marrow contributes to relapse in acute and chronic myeloid leukemias. In the allogeneic transplant setting, genetically modified T-cells have proven valuable for the prophylaxis and treatment of viral diseases and may have an important role in preventing or treating disease relapse. Gene transfer is also being used to modify tumor function, enhance immunogenicity, and confer drug-resistance to normal hematopoietic stem cells. With the continued scientific advancements in this field, gene therapy will almost certainly have a major impact on the treatment of pediatric leukemia in the future.

Gene therapy for lung neoplasms

The field of gene therapy is still in its infancy, but significant accomplishments have been achieved. The ability to transfer genes safely and successfully into animals and patients clearly has been established. It is highly likely that in the near future, gene therapy will be shown to have clear therapeutic efficacy in diseases such as the treatment of hemophilia (using adeno-associated virus vectors) and the stimulation of angiogenesis in peripheral vascular disease and myocardial ischemia. Although only Phase 1 cancer gene therapy trials for thoracic malignancy have been conducted (usually in patients with large tumor burdens and at submaximal doses), there are some hints of efficacy at higher doses of vector in trials for localized malignancy. The studies reviewed in this article demonstrate the first attempts to use gene therapy vectors for lung cancer and mesothelioma. Although none of the diseases studied was "cured," valuable lessons have been learned from these trials, especially in defining the challenges of relatively inefficient and transient delivery of transgene in vivo. Using this knowledge, the second phase of gene therapy research has begun, with a strong focus on developing improved vector technology. Given the progress so far, there is little doubt that gene therapy will become a key approach for the treatment of thoracic malignancies in the near future.

Genetic targeting of the renin-angiotensin system for long-term control of hypertension

Although traditional approaches are effective for the treatment and control of hypertension, they have not succeeded in curing the disease, and have therefore reached a plateau. As a result of the completion of the Human Genome Project and the continuous advancement in gene delivery systems, it is now possible to investigate genetic means for the treatment and possible cure for hypertension. In this review we discuss the potential of genetic targeting of the renin-angiotensin system for the treatment of hypertension. We provide examples of various approaches that have used antisense technology with a high degree of success. We focus on our own research, which targets the use of antisense of the angiotensin type I receptor in various models of hypertension. Finally, we discuss the future of antisense technology in the treatment of human hypertension.

Gene therapy for superficial bladder cancer

In this review, the basics of gene therapy and the strategies to increase the therapeutic effect of gene therapy for superficial bladder cancer are discussed. Strategies considered in detail are modification of the structure of vectors, modification of the promoters of viral vectors and the timing and route of vector administration. Although all of these modifications have shown some degree of improvement for gene transfer, the use of polyamides intravesically in conjunction with an adenoviral system shows the most promise and the greatest potential to supplement or even replace the current treatment modalities for superficial bladder cancer.

Mechanism of cell transfection with plasmid/chitosan complexes

Chitosan is useful as a non-viral vector for gene delivery. Although there are several reports supporting the use of chitosan for gene delivery, studies regarding effects on transfection and the chitosan-specific transfection mechanism remain insufficient. In this report, the level of expression with plasmid/chitosan was observed to be no less than that with plasmid/lipofectin complexes in SOJ cells. The transfection mechanism of plasmid/chitosan complexes as well as the relationship between transfection activity and cell uptake was analyzed by using fluorescein isothiocyanate-labeled plasmid and Texas Red-labeled chitosan. In regard to effects on transfection, there were several factors to affect transfection activity and cell uptake, for example: the molecular mass of chitosan, stoichiometry of complex, as well as serum concentration and pH of transfection medium. The level of transfection with plasmid/chitosan complexes was found to be highest when the molecular mass of chitosan was 40 or 84 kDa, ratio of chitosan nitrogen to DNA phosphate (N/P ratio) was 5, and transfection medium contained 10% serum at pH 7.0. We also investigated the transfection mechanism, and found that plasmid/chitosan complexes most likely condense to form large aggregates (5-8 microm), which absorb to the cell surface. After this, plasmid/chitosan complexes are endocytosed, and possibly released from endosomes due to swelling of lysosomal in addition to swelling of plasmid/chitosan complex, causing the endosome to rupture. Finally, complexes were also observed to accumulate in the nucleus using a confocal laser scanning microscope.

Local gene delivery to the vessel wall

This review will provide an overview of delivery strategies that are being evaluated for vascular gene therapy. We will limit our discussion to those studies that have been demonstrated, utilizing in vivo model systems, to limit post-interventional restenosis. We also discuss the efficacy of the vectors and methods currently being used to transfer genetic material to the vessel wall. The efficiency of these techniques is a critical issue for the successful application of gene therapy.

Gene therapy of cystic fibrosis (CF) airways: a review emphasizing targeting with lactose

Cystic fibrosis is a disease for which a number of Phase I clinical trials of gene therapy have been initiated. Several factors account for the high level of interest in a gene therapy approach to this disease. CF is the most common lethal inherited disease in Caucasian populations. The lung, the organ that is predominantly responsible for the morbidity and mortality in CF patients, is accessible by a non-invasive method, the inhalation of aerosols. The vectors employed in the Phase I trials have included recombinant adenoviruses, adeno-associated viruses and cationic lipids. While there have been some positive results, the success of the vectors until now has been limited by either immunogenicity or low efficiency. A more fundamental obstacle has been the absence of appropriate receptors on the apical surface of airway epithelial cells. Molecular conjugates with carbohydrate substitution to provide targeting offer several potential advantages. Lactosylated polylysine in which 40% of the lysines have been substituted with lactose has been shown to provide a high efficiency of transfection in primary cultures of CF airway epithelial cells. Other important features include a relatively low immunogenicity and cytotoxicity. Most importantly, the lactosylated polylysine was demonstrated to give nuclear localization in CF airway epithelial cells. Until now, most non-viral vectors did not have the capability to provide nuclear localization. These unique qualities provided by the lactosylation of non-viral vectors, such as polylysine may help to advance the development of molecular conjugates sufficiently to warrant their use in future clinical trials for the gene therapy of inherited diseases of the lung.

Transcriptional targeting for ovarian cancer gene therapy

Ovarian carcinoma is a leading cause of cancer death in women. Though advances in conventional therapies have been achieved, long-term survival rates for most patients diagnosed with ovarian cancer are still low. Therefore, novel molecular therapeutic strategies such as gene therapy are being intensively pursued. Such approaches are based on the enormous progress that has been achieved in the elucidation of the molecular foundations of ovarian cancer. In this regard transcriptional control elements (promoters) of genes frequently upregulated or specifically expressed in tumors can be applied in a heterologous context to drive expression of therapeutic genes in targeted gene therapy strategies. This review discusses transcriptional targeting strategies in ovarian cancer gene therapy and gives an overview of tumor-specific promoters (TSPs) that have been applied for this purpose.

Gene therapy for paediatric leukaemia

Improvements in the chemotherapeutic and transplant regimens have had a significant impact in improving survival rates for paediatric leukaemia. However, there are still important problems to address including what options are available for patients with chemoresistant disease and what strategies are available to avoid the concerns regarding the toxicity associated with highly cytotoxic treatment regimens. Gene therapy and immunotherapy protocols hold great promise. Using gene transfer of a marker gene, a number of biological issues in the therapy of leukaemia have been addressed. For example, by gene marking autologous bone marrow grafts it has been possible to demonstrate that infused marrow contributes to relapse in acute and chronic myeloid leukaemias. In the allogeneic transplant setting, genetically modified T-cells have proven valuable for the prophylaxis and treatment of viral diseases and may have an important role in preventing or treating disease relapse. Gene transfer is also being used to modify tumour function, enhance immunogenicity, and confer drug-resistance to normal haematopoietic stem cells. With the continued scientific advancements in this field, gene therapy will almost certainly have a major impact on the treatment of paediatric leukaemia in the future.

Implications of the Human Genome Project for obstetrics and gynecology

The initial sequencing of the human genome should be regarded as a milestone in a road that stretches years into the future; the full ramifications of the Human Genome Project are still only being theorized. Researchers will benefit from the catalog of human genes in studies of the genetics of disease susceptibility and the cell biology of gene interactions. Clinicians will increasingly offer genetic or biochemical testing to identify those at highest risk for a number of diseases. Drug discovery will eventually follow newly possible studies of gene expression and protein function. However the Human Genome Project eventually shapes medicine, it is certain that physicians, particularly obstetricians and gynecologists, will need to be well versed in the scientific and ethical issues involved, inasmuch as we will likely be at the center of the most heated debates.

Gene-Marking studies of hematopoietic cells

Gene-marking studies were the first approved clinical protocols introducing exogenous genetic material into human cells. Such studies were never intended to provide direct therapeutic benefit. Instead, they were expected to provide information about normal cell biology and disease pathogenesis that could not be obtained in any other way. However, the information gained from such studies has had a significant impact on disease management. Gene-marking studies have provided valuable insights into the biology of the human stem cell, factors that influence the efficiency of gene transfer, mechanisms of relapse after stem cell transplantation, and the pharmacodynamics of adoptive cellular immunotherapy. With continuing advances in gene-marking technology, the value of the information provided by these studies increases, thereby ensuring their continued relevance to the field of gene transfer.

Use of quantitative TaqMan real-time PCR to track the time-dependent distribution of gene transfer vectors in vivo

To assess the biodistribution and pharmacokinetics of gene transfer vectors, real-time PCR with fluorescent TaqMan chemistry was used to quantify tissue levels of adenovirus gene transfer vectors (Ad) following myocardial administration. After optimizing the detection of the genome of Ad vectors expressing human vascular endothelial growth factor (Ad(GV)VEGF121.10) and Escherichia coli cytosine deaminase (Ad(GV)CD.10), a comparison was made of intramyocardial injection versus intracoronary delivery to the left ventricle of the pig. One hour post-intramyocardial administration, the left ventricular Ad genome level was 6.2 copies per cellular genome, 26-fold higher than the level of 0.24 copies per cellular genome following intracoronary administration. Relative to the vector levels after 1 h, the amount dropped 14- and 5.5-fold by 24 h following intramyocardial and intracoronary administration, respectively. Interestingly, the vector that escaped the left ventricle after intracoronary or intramyocardial administration to pigs was found primarily within the lung, an observation in marked variance to the biodistribution of Ad vector in rodents. In this regard, after intravenous injection to the pig, 90% of the recovered vector was found in the lung, and even after intrahepatic portal vein injection, 55% of the recovered vector was in the lung. These data have important implications regarding the use of experimental animals for safety studies on administration of Ad to humans.

Lentivirus vector mobilization and spread by human immunodeficiency virus

The rapid advancement of lentivirus-based gene transfer systems and their demonstrated utility in a variety of in vitro and in vivo settings has heightened the need for assays to evaluate the safety of these vectors prior to human clinical trials. Two major concerns relating to the use of lentivirus-based vectors in a clinical setting are the presence of contaminating replication-competent retroviruses in vector preparations and the efficiency of vector mobilization and spread by wild-type helper virus (rescue). This article describes an in vitro system to study the rescue of lentivirus-based vectors by wild-type HIV. We show that lentivirus-based vectors can be readily rescued from T cell lines and to a lesser extent from primary human lymphocytes by wildtype HIV, resulting in the spread of mobilized vector particles to previously untransduced cells. Furthermore, we show that vector mobilization can be prevented by antiretroviral drugs such as AZT. In contrast to recently published reports by Bukovsky et al. and An et al., the lentivirus vectors used in these studies had little or no effect on the replication and spread of HIV in transduced cells [Bukovsky et al. (1999). J. Virol. 73, 7087-7092; An et al. (1999). J. Virol. 73, 7671-7677]. Whereas vector spread is a significant concern for most gene therapy applications, in the context of gene therapy for HIV infection it may have beneficial effects.

Induction of angiogenesis by cationic lipid-mediated VEGF165 gene transfer in the rabbit ischemic hindlimb model

PURPOSE

The purpose of this study was to test the efficacy of a new cationic lipid formulation coupled with the cDNA encoding for the 165-residue form of vascular endothelial growth factor (VEGF(165)) to induce neovascularization and enhance blood flow in the rabbit ischemic hindlimb model.

METHODS

Two days after removal of their right femoral arteries, rabbits received intramuscular injections of different concentrations of VEGF(165) or saline solution in the ischemic thigh. Tissue perfusion and increased neovascularization of the ischemic limb were assessed weekly on the basis of the calf blood pressure ratio for the ischemic/nonischemic limbs, regional blood flow to the skeletal muscles as measured with radioactive microspheres, postmortem angiography, and histology.

RESULTS

At weeks 1 and 2 after surgery, animals treated with 1000 microgram of VEGF(165) had a 1.5-fold increase and a 2.5-fold increase, respectively, in the regional blood flow to both the adductor and gastrocnemius muscles of the ischemic limb. The blood pressure ratio was also greater in the treated animals than in the controls at weeks 2 and 3 after surgery. Early neovascularization in the VEGF(165) group was further documented at week 1 after surgery by more angiographically recognizable collateral vessels (angioscores were 64.13 +/- 2.51 and 38.28 +/- 3.82 for VEGF(165) and saline solution, respectively; P <.001) and by a threefold increase in the number of capillaries (vascular density) relative to the controls (P <.005).

CONCLUSIONS

Intramuscular administration of a single dose of plasmid-liposomes encoding for VEGF(165) accelerates angiogenesis and increases blood flow in the rabbit hindlimb ischemic model. Therefore, this nonviral vector could be recommended for further testing for use in therapeutic angiogenesis.

Molecular aspects and gene therapy prospects for diastolic failure

Because of safety issues, components of the beta-adrenergic signaling pathway cannot currently be viewed as attractive targets for human gene therapy. Rather, the balance of evidence supports strategies that will target gene products specifically and directly at diastolic regulation. Augmenting the activity of the SR Ca2+ ATPase by AAV-mediated delivery of the SERCA2a gene, directed by a cardiac-specific promoter with a tightly regulable on-off switch is perhaps the most attractive strategy. PLB and cTnI also are attractive targets but only if molecular techniques can be devised to modulate their activity specifically and conditionally. Such techniques may involve modifying the phosphorylation sites in vitro and replacing wild type proteins in the failing heart with the modified forms, again using regulated AAV vectors for gene delivery.

Emerging concepts in the management of the malignant haematological disorders

A comprehensive review of novel cytoreductive agents is presented. Such novel agents may be found among chemical compounds directed against specific molecular targets (cytostatics) or within the biological substances selectively aimed at the malignant clone (immunotherapy). It is stated that the purposes of immunotherapy in general are to generate a T-lymphocytic response against the tumour cells, e.g., graft versus leukaemia (GvL) effect, natural killer T-cell cytolysis, antibody-dependent cytolysis etc.; or to reprogramme the immune system of the tumour-bearing host by DNA and/or RNA manipulation with subsequent interference with the signalling pathway in the tumour cells. Some immunotherapeutic modalities are shortly described: donor T-lymphocyte infusion and GvL effect, polyclonal antibodies, monoclonal antibodies, vaccines, gene replacement therapy, suicide gene therapy, antisense oligonucleotides, alterations of DNA-RNA transcript factors and malignant antigenic drive etc. Most likely, a sequence of different treatment modalities will be used in the future comprising an initial debulking by means of standard chemotherapy and/or irradiation followed by target unspecific immunotherapy (polyclonal immunoglobulins, GvL effect etc.) and finally target specific elimination of residual tumour, probably with repeated use of the minimum effective pharmacologic dose (MEPD) of the agents used. In contrast, the current use of high-dose myeloablative chemotherapy with the use of maximum tolerable dose (MTD) and associated severe organ toxicity, and high rates of secondary malignancies will probably be substituted in the future. An effective supportive treatment will be highly necessary, especially related to prevention and treatment of infections.

Gene therapy for lung disease: hype or hope?

Gene therapy, the treatment of any disorder or pathophysiologic state on the basis of the transfer of genetic information, was a high-priority goal in the 1990s. The lung is a major target of gene therapy for genetic disorders, such as cystic fibrosis and alpha1-antitrypsin deficiency, and for other diseases, including lung cancer, malignant mesothelioma, pulmonary inflammation, surfactant deficiency, and pulmonary hypertension. This paper examines general concepts in gene therapy, summarizes the results of published clinical trials, and highlights areas of research aimed at overcoming challenges in the field. Although progress has been slower than anticipated, gene transfer has been safely achieved in patients with lung diseases. Recent advancements in understanding of the molecular basis of lung disease and the development of improved vector systems make it likely that gene therapy will be an important tool for the 21st-century clinician.

Lipopolycationic telomers for gene transfer: synthesis and evaluation of their in vitro transfection efficiency

We report on the synthesis of a series of lipopolyamine telomers I-14,n, I-18,n, and II-18,n and on their in vitro gene-transfer capability. Their structure consists of a polyamine polar moiety, including n primary amine functions (from 1 to 70), connected to a hydrophobic moiety, including two hydrocarbon C14 or C18 chains, through a mercaptopropanoyl or mercaptoglyceryl unit and an amide or ether function. They were obtained by telomerization of N-[2-[(BOC)aminoethyl]]acrylamide with N,N-ditetradecyl- and N,N-dioctadecylpropanamide-3-thiol and rac-1,2-dioctadecyloxypropane-3-thiol, respectively, then BOC deprotection. For N/P ratios (N = number of telomer amine equivalents; P = number of DNA phosphates) from 0.8 to 10, these lipopolyamines condensed DNA, with or without the use of DOPE, forming lipopolyplexes or teloplexes of mean sizes less than 200 nm. Some trends, structure-activity and structure-toxicity relationships, were established to achieve both highest in vitro transfection levels and cell viability. Thus, DNA formulations based on telomers I-14,20 and I-18,20 and for N/P ratios lower than 5 led to the most efficient teloplex formulations for plasmid delivery to lung epithelial A549 cells.

Gene therapy of brain tumors: problems presented by physiological barriers

The explosion of molecular techniques for gene discovery and their application to a variety of diseases has uncovered numerous gene abnormalities that can result in disease. These discoveries have provided the needed understanding and genetic materials to apply gene therapy approaches in the treatment of several diseases, including those of the central nervous system. A variety of different anticancer complementary DNAs (cDNA) have been shown to possess biological efficacy when used in the appropriate experimental setting. However, efficient and effective delivery of these cDNAs remains a major obstacle for future clinical applications. The focus of this review will be to describe the obstacles that impede the process of gene therapy and oncolytic viral therapy of brain tumors and to describe how important new discoveries derived from other disciplines are being used to address problems encountered in the gene/ viral therapy of this disease.

Gene Therapy for Lung Cancer

Gene therapy is emerging as a promising modality for the treatment of lung cancer. Diverse strategies employing gene therapy for lung cancer have been investigated in vitro and in animal models, and a number of these approaches have met with promising results. Several phase I and II clinical trials have been undertaken, and early results suggest that it may be safe to administer gene therapy to lung cancer patients. It remains to be determined whether this modality will be efficacious as primary or adjunctive therapy in the setting of lung cancer.

Viral gene delivery

Experimental studies of viral gene delivery generally support the principle that virus-mediated gene transfer is indeed possible. However, the field of gene therapy has not yet been realised as a practicable clinical intervention. The delay in translation of laboratory work to clinical utility largely reflects the inability of gene delivery vectors to convey adequate genetic material to a desired location, with adequate durability and low enough toxicity to be effective. Current studies of viral gene therapy vehicles have focused on re-engineering viruses being tested as vectors at present, treating the host to facilitate viral gene transfer and the development of new vectors. Initial enthusiasm for oncoretroviral and adenoviral vectors has cooled, while adeno-associated virus and lentiviral vectors are attracting more interest. Experimental studies with modified SV40-based vectors have also been very promising. The future of gene therapy will probably entail using an array of gene delivery vehicles, each with its own strengths and weaknesses. The vector systems will probably be as diverse as the applications to which they will be put.