Viral gene therapy strategies: from basic science to clinical application

Optimizing in vivo gene transfer into mouse corpus cavernosum by use of surface electroporation

Purpose

Electroporation is known to enhance the efficiency of gene transfer through a transient increase in cell membrane permeability. The aim of this study was to determine the optimal conditions for in vivo electroporation-mediated gene delivery into mouse corpus cavernosum.

Materials and Methods

Diabetes was induced in C57BL/6 mice by intraperitoneal injections of streptozotocin. After intracavernous injection of pCMV-Luc (100 µg/40 µL), different electroporation settings (5-50 V, 8-16 pulses with a duration of 40-100 ms) were applied to the penis to establish the optimal conditions for electroporation. Gene expression was evaluated by luciferase assay. We also assessed the undesired consequences of electroporation by visual inspection and hematoxylin-eosin staining of penile tissue.

Results

Electroporation profoundly induced gene expression in the corpus cavernosum tissue of normal mice in a voltage-dependent manner. We observed electrical burn scars in the penis of normal mice who received electroporation with eight 40-ms pulses at a voltage of 50 V and sixteen 40-ms pulses, eight 100-ms pulses, and sixteen 100-ms pulses at a voltage of 30 V. No detectable burn scars were noted in normal mice stimulated with eight 40-ms pulses at a voltage of 30 V. Electroporation also significantly induced gene expression in diabetic mice stimulated with 40-ms pulse at a voltage of 30 V without injury to the penis.

Conclusions

We have established the optimal electroporation conditions for maximizing gene transfer into the corpus cavernosum of mice while avoiding damage to the erectile tissue. The electroporation-mediated gene delivery technique will be a valuable tool for gene therapy in the field of erectile dysfunction.

Gene therapy in keratoconus

Keratoconus (KC) is the most common ectasia of the cornea and is a common reason for corneal transplant. Therapeutic strategies that can arrest the progression of this disease and modify the underlying pathogenesis are getting more and more popularity among scientists. Cumulating data represent strong evidence of a genetic role in the pathogenesis of KC. Different loci have been identified, and certain mutations have also been mapped for this disease. Moreover, Biophysical properties of the cornea create an appropriate candidate of this tissue for gene therapy. Immune privilege, transparency and ex vivo stability are among these properties. Recent advantage in vectors, besides the ability to modulate the corneal milieu for accepting the target gene for a longer period and fruitful translation, make a big hope for stupendous results reasonable.

Effects of olmesartan therapy on the expression of lung adrenoceptors in rats with chronic heart failure

INTRODUCTION

Adrenergic receptors (AR) play important roles in regulating lung function. However, there are few reports concerning AR expression and the protective effect of angiotensin II receptor blockers (ARB) on the lung in chronic heart failure (CHF). In this study, we aimed to investigate the protective effects of the ARB olmesartan on the lung in CHF.

MATERIALS AND METHODS

Wistar rats were randomly divided into four groups: normal control, sham-operated rats, rats with CHF induced by ligating the left anterior descending coronary arteries, and rats with CHF treated with olmesartan (1 mg/kg) once daily for 8 weeks. Heart function, plasma renin activity (PRA) and angiotensin II (Ang II) levels, lung microscopic structure inspection and mRNA and protein expressions of α1A-, β1- and β2-AR in lung were tested.

RESULTS

Compared with the CHF group, PRA and Ang II levels were decreased while heart function and mRNA and protein expression of α1A-AR, β1-AR and β2-AR were up-regulated in the olmesartan group (p<0.05 or p<0.01). The inflammation and cell proliferation in CHF lung tissue were reduced in the olmesartan group.

CONCLUSION

Olmesartan may play a beneficial role in protecting lung in CHF by up-regulating AR and decreasing levels of PRA and Ang II.

Dental pulp cells that express adeno-associated virus serotype 2-mediated BMP-7 gene enhanced odontoblastic differentiation

This present study investigated the potential of adeno-associated virus serotype 2 (AAV2) mediated BMP-7 (AAV2-BMP-7) to induce odontoblastic differentiation of human dental pulp cells (DPCs) in vitro. AAV2-BMP-7 was constructed to overexpress BMP-7, and the biologic effects of BMP-7 on DPCs were investigated by the evaluation of the activity of alkaline phosphatase (ALPase), the detection of the expression of dentin sialophosphoprotein (DSPP) and osteocalcin (OCN) expression and the analysis of the proliferative ability of the cells. DPCs that were infected with AAV2-BMP-7 displayed significantly upregulated ALP activity and formed mineralized nodules. Moreover, AAV2-BMP-7 promoted the expression of mineralization-related genes, which included DSPP and OCN. In addition, there was no significant difference between the proliferative ability of AAV2-BMP-7 and the control group. In conclusion, AAV2-BMP-7 promoted the odontoblastic differentiation in DPCs, a clear indication of the therapeutic potential of AAV2-BMP-7 in dental tissue regeneration.

Stimulation of cerebral angiogenesis by gene delivery

Angiogenesis, an important process for long term neurological recovery, could be induced by ischemic brain injury. In this chapter, we describe a system to deliver adeno-associated viral (AAV) vector-mediated gene therapy for ischemic stroke. This includes the methods to construct, produce, and purify an AAV vector expressing target gene and an approach to quantify the number of microvessels and capillary density with synchrotron radiation angiography (SRA) imaging.

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.

The prospect of molecular therapy for Angelman syndrome and other monogenic neurologic disorders

BACKGROUND

Angelman syndrome is a monogenic neurologic disorder that affects 1 in 15,000 children, and is characterized by ataxia, intellectual disability, speech impairment, sleep disorders, and seizures. The disorder is caused by loss of central nervous system expression of UBE3A, a gene encoding a ubiquitin ligase. Current treatments focus on the management of symptoms, as there have not been therapies to treat the underlying molecular cause of the disease. However, this outlook is evolving with advances in molecular therapies, including artificial transcription factors a class of engineered DNA-binding proteins that have the potential to target a specific site in the genome.

RESULTS

Here we review the recent progress and prospect of targeted gene expression therapies. Three main issues that must be addressed to advance toward human clinical trials are specificity, toxicity, and delivery.

CONCLUSIONS

Artificial transcription factors have the potential to address these concerns on a level that meets and in some cases exceeds current small molecule therapies. We examine the possibilities of such approaches in the context of Angelman syndrome, as a template for other single-gene, neurologic disorders.

Synthesis, characterization, and evaluation of poly (D,L-lactide-co-glycolide)-based nanoformulation of miRNA-150: potential implications for pancreatic cancer therapy

MicroRNAs are small (18–22 nucleotide long) noncoding RNAs that play important roles in biological processes through posttranscriptional regulation of gene expression. Their aberrant expression and functional significance are reported in several human malignancies, including pancreatic cancer. Recently, we identified miR-150 as a novel tumor suppressor microRNA in pancreatic cancer. Furthermore, expression of miR-150 was downregulated in the majority of tumor cases, suggesting that its restoration could serve as an effective approach for pancreatic cancer therapy. In the present study, we developed a nanoparticle-based miR-150 delivery system and tested its therapeutic efficacy in vitro. Using double emulsion solvent evaporation method, we developed a poly (D,L-lactide-co-glycolide) (PLGA)-based nanoformulation of miR-150 (miR-150-NF). Polyethyleneimine (a cationic polymer) was incorporated in PLGA matrix to increase the encapsulation of miR-150. Physical characterization of miR-150-NF demonstrated that these nanoparticles had high encapsulation efficiency (~78%) and exhibited sustained release profile. Treatment of pancreatic cancer cells with miR-150-NF led to efficient intracellular delivery of miR-150 mimics and caused significant downregulation of its target gene (MUC4) expression. Inhibition of MUC4 correlated with a concomitant decrease in the expression of its interacting partner, HER2, and repression of its downstream signaling. Furthermore, treatment of pancreatic cancer cells with miR-150-NF suppressed their growth, clonogenicity, motility, and invasion. Together, these findings suggest that PLGA-based nanoformulation could potentially serve as a safe and effective nanovector platform for miR-150 delivery to pancreatic tumor cells.

One-step repair for cartilage defects in a rabbit model: a technique combining the perforated decalcified cortical-cancellous bone matrix scaffold with microfracture

BACKGROUND

Cartilage repair still presents a challenge to clinicians and researchers alike. A more effective, simpler procedure that can produce hyaline-like cartilage is needed for articular cartilage repair.

HYPOTHESIS

A technique combining microfracture with a biomaterial scaffold of perforated decalcified cortical-cancellous bone matrix (DCCBM; composed of cortical and cancellous parts) would create a 1-step procedure for hyaline-like cartilage repair.

STUDY DESIGN

Controlled laboratory study.

METHODS

For the in vitro portion of this study, mesenchymal stem cells (MSCs) were isolated from bone marrow aspirates of New Zealand White rabbits. Scanning electron microscopy (SEM), confocal microscopy, and 1,9-dimethylmethylene blue assay were used to assess the attachment, proliferation, and cartilage matrix production of MSCs grown on a DCCBM scaffold. For the in vivo experiment, full-thickness defects were produced in the articular cartilage of the trochlear groove of 45 New Zealand White rabbits, and the rabbits were then assigned to 1 of 3 treatment groups: perforated DCCBM combined with microfracture (DCCBM+M group), perforated DCCBM alone (DCCBM group), and microfracture alone (M group). Five rabbits in each group were sacrificed at 6, 12, or 24 weeks after the operation, and the repair tissues were analyzed by histological examination, assessment of matrix staining, SEM, and nanoindentation of biomechanical properties.

RESULTS

The DCCBM+M group showed hyaline-like articular cartilage repair, and the repair tissues appeared to have better matrix staining and revealed biomechanical properties close to those of the normal cartilage. Compared with the DCCBM+M group, there was unsatisfactory repair tissues with less matrix staining in the DCCBM group and no matrix staining in the M group, as well as poor integration with normal cartilage and poor biomechanical properties.

CONCLUSION

The DCCBM scaffold is suitable for MSC growth and hyaline-like cartilage repair induction when combined with microfracture.

CLINICAL RELEVANCE

Microfracture combined with a DCCBM scaffold is a promising method that can be performed and adopted into clinical treatment for articular cartilage injuries.

A preliminary step of a novel strategy in suicide gene therapy with lentiviral vector

Background:

One of the challenges in lentiviral vector–based suicide gene therapy by toxin or apoptosis-inducing genes is death of packaging cells. Therefore, the process of production of these lentiviral particles would be stopped in this step. We proposed that insertion of a reverse promoter between R and U5 regions of 5′ long terminal repeat (LTR) in transfer plasmid could be considered as a solution for this problem. But it is not known, whether the insertion of RΔU3 sequence between the promoter and target gene in proviral genome during the life-cycle of lentivirus may interfere whit gene expression in target cells.

Materials and Methods:

These following methods were performed in this study: insertion of RΔU3 sequence in pEGFP-N1 plasmid, evaluation of the expression of eGFP gene after calcium phosphate co-precipitation transfection of pCMV-RΔU3-GFP construction in 293T cells, and quantitative assay of eGFP gene by flow cytometry technique.

Results:

Our results from flow cytometry technique analysis showed that there was no significant difference between the expression of eGFP gene in transfected cells with pEGFP-N1 and pCMV-RΔU3-GFP plasmids (P > 0.05).

Conclusion:

In this step of our strategy, we demonstrated that modification of orientation and location of promoter may overcome some issues in lentiviral suicide gene therapy, especially when toxin or apoptosis-inducing genes are used.

Beyond Gene Delivery: Strategies to Engineer the Surfaces of Viral Vectors

Viral vectors have been extensively studied due to their great transduction efficiency compared to non-viral vectors. These vectors have been used extensively in gene therapy, enabling the comprehension of, not only the advantages of these vectors, but also the limitations, such as the activation of the immune system after vector administration. Moreover, the need to control the target of the vector has led to the development of chemical and non-chemical modifications of the vector surface, allowing researchers to modify the tropism and biodistribution profile of the vector, leading to the production of viral vectors able to target different tissues and organs. This review describes recent non-genetic modifications of the surfaces of viral vectors to decrease immune system activation and to control tissue targeting. The developments described herein provide opportunities for applications of gene therapy to treat acquired disorders and genetic diseases and to become useful tools in regenerative medicine.

Simplified production and concentration of lentiviral vectors to achieve high transduction in primary human T cells

Background

Lentiviral vectors have emerged as efficient vehicles for transgene delivery in both dividing and non-dividing cells. A number of different modifications in vector design have increased biosafety and transgene expression. However, despite these advances, the transduction of primary human T cells is still challenging and methods to achieve efficient gene transfer are often expensive and time-consuming.

Results

Here we present a simple optimised protocol for the generation and transduction of lentivirus in primary human CD45RA⁺ T cells. We show that generation of high-titre lentivirus with improved primary T cell transduction is dependent upon optimised ultracentrifuge speed during viral concentration. Moreover, we demonstrate that transduction efficiency can be increased with simple modifications to the culturing conditions. Overall, a transduction efficiency of up to 89% in primary human CD45RA⁺ cells is achievable when these modifications are used in conjunction.

Conclusion

The optimised protocol described here is easy to implement and should facilitate the production of high-titre lentivirus with superior transduction efficiency in primary human T cells without the need for further purification methods.

Systemic tumor-specific gene delivery

The objective of a systemically administered cancer gene therapy is to achieve gene expression that is isolated to the tumor tissue. Unfortunately, viral systems have strong affinity for the liver, and delivery from non-viral cationic systems often results in high expression in the lungs. Non-specific delivery to these organs must be overcome if tumors are to be aggressively treated with genes such as IL-12 which activates a tumor immune response, and TNF-alpha which can induce tumor cell apoptosis. Techniques which have led to specific expression in tumor tissue include receptor targeting through ligand conjugation, utilization of tumor specific promoters and viral mutation in order to take advantage of proteins overexpressed in tumor cells. This review analyzes these techniques applied to liposomal, PEI, dendrimer, stem cell and viral gene delivery systems in order to determine the techniques that are most effective in achieving tumor specific gene expression after systemic administration.

Update on oncolytic viral therapy - targeting angiogenesis

Oncolytic viruses (OVs) have the ability to selectively replicate in and lyse cancer cells. Angiogenesis is an essential requirement for tumor growth. Like OVs, the therapeutic effect of many angiogenesis inhibitors has been limited, leading to the development of more effective approaches to combine antiangiogenic therapy with OVs. Angiogenesis can be targeted either directly by OV infection of vascular endothelial cells, or by arming OVs with antiangiogenic transgenes, which are subsequently expressed locally in the tumor microenvironment. In this review, we describe the development and targeting of OVs, the role of angiogenesis in cancer, and the progress made in arming viruses with antiangiogenic transgenes. Future developments required to optimize this approach are addressed.

Gene therapy for high-grade glioma

High-grade glioma is the most frequently occurring primary brain tumor and is associated with a poor prognosis. Current treatment regimens have had only a modest effect on the progressive course despite recent advances in surgery, radiotherapy, and chemotherapy. Gene therapy for brain tumors represents a novel and promising therapeutic approach and has been investigated clinically for the last two decades. The strategies of gene therapy include suicide gene therapy, immune gene therapy, oncolytic viral therapy, tumor suppressor gene therapy, and antisense therapy. Here, we review gene therapy approaches considering the clinical results, limitations, and future directions.

Nanomaterials as Non-viral siRNA Delivery Agents for Cancer Therapy

Gene therapy has been recently shown as a promising tool for cancer treatment as nanotechnology-based safe and effective delivery methods are developed. Generally, genes are wrapped up in extremely tiny nanoparticles which could be taken up easily by cancer cells, not to their healthy neighboring cells. Several nanoparticle systems have been investigated primarily to address the problems involved in other methods of gene delivery and observed improved anticancer efficacy suggesting that nanomedicine provides novel opportunities to safely deliver genes, thus treat cancer. In this review, various nanoparticle types and related strategies, used in gene delivery for cancer treatment, have been discussed.

Virotherapy of neuroendocrine tumors

Most patients with small intestinal neuroendocrine tumors (SI-NETs), also referred to as midgut carcinoids, present with systemic disease at the time of diagnosis with metastases primarily found in regional lymph nodes and the liver. Curative treatment is not available for these patients and there is a need for novel and specific therapies. Engineered oncolytic viruses may meet the need and play an important role in the future management of SI-NET liver metastases. This review focuses on adenovirus as the oncolytic anti-cancer agent and its potential curative role for SI-NET liver metastases, but it also summarizes the use of oncolytic viruses for NETs in general. It discusses how specific features of neuroendocrine cell biology can be used to engineer viruses to become selective for infection of NET cells and/or replication within NET cells. In addition, it points out the advantages and shortcomings of using replicating viruses in the treatment of cancer and addresses research fields that can increase the efficacy of virus-based therapy.

Glucose-responsive artificial promoter-mediated insulin gene transfer improves glucose control in diabetic mice

AIM: To investigate the effect of insulin gene therapy using a glucose-responsive synthetic promoter in type 2 diabetic obese mice.

METHODS: We employed a recently developed novel insulin gene therapy strategy using a synthetic promoter that regulates insulin gene expression in the liver in response to blood glucose level changes. We intravenously administered a recombinant adenovirus expressing furin-cleavable rat insulin under the control of the synthetic promoter (rAd-SP-rINSfur) into diabetic Lepr^db/db mice. A recombinant adenovirus expressing β-galactosidase under the cytomegalovirus promoter was used as a control (rAd-CMV-βgal). Blood glucose levels and body weights were monitored for 50 d. Glucose and insulin tolerance tests were performed. Immunohistochemical staining was performed to investigate islet morphology and insulin content.

RESULTS: Administration of rAd-SP-rINSfur lowered blood glucose levels and normoglycemia was maintained for 50 d, whereas the rAd-CMV-βgal control virus-injected mice remained hyperglycemic. Glucose tolerance tests showed that rAd-SP-rINSfur-treated mice cleared exogenous glucose from the blood more efficiently than control virus-injected mice at 4 wk [area under the curve (AUC): 21  508.80 ± 2248.18 vs 62  640.00 ± 5014.28, P < 0.01] and at 6 wk (AUC: 29  956.60 ± 1757.33 vs 60  016.60 ± 3794.47, P < 0.01). In addition, insulin sensitivity was also significantly improved in mice treated with rAd-SP-rINSfur compared with rAd-CMV-βgal-treated mice (AUC: 9150.17 ± 1007.78 vs 11  994.20 ± 474.40, P < 0.05). The islets from rAd-SP-rINSfur-injected mice appeared to be smaller and to contain a higher concentration of insulin than those from rAd-CMV-βgal-injected mice.

CONCLUSION: Based on these results, we suggest that insulin gene therapy might be one therapeutic option for remission of type 2 diabetes.

Progress in gene therapy for prostate cancer

Gene therapy has held promise to correct various disease processes. Prostate cancer represents the second leading cause of cancer death in American men. A number of clinical trials involving gene therapy for the treatment of prostate cancer have been reported. The ability to efficiently transduce tumors with effective levels of therapeutic genes has been identified as a fundamental barrier to effective cancer gene therapy. The approach utilizing gene therapy in prostate cancer patients at our institution attempts to address this deficiency. The sodium-iodide symporter (NIS) is responsible for the ability of the thyroid gland to transport and concentrate iodide. The characteristics of the NIS gene suggest that it could represent an ideal therapeutic gene for cancer therapy. Published results from Mayo Clinic researchers have indicated several important successes with the use of the NIS gene and prostate gene therapy. Studies have demonstrated that transfer of the human NIS gene into prostate cancer using adenovirus vectors in vitro and in vivo results in efficient uptake of radioactive iodine and significant tumor growth delay with prolongation of survival. Preclinical successes have culminated in the opening of a phase I trial for patients with advanced prostate disease which is currently accruing patients. Further study will reveal the clinical promise of NIS gene therapy in the treatment of prostate as well as other malignancies.

The use of oncolytic viruses to overcome lung cancer drug resistance

Intrinsic and acquired drug resistance remains a fundamental obstacle to successful applications of anticancer therapies for lung cancer. Combining conventional therapies with immunotherapeutic approaches is a promising strategy to circumvent lung cancer drug resistance. Genetically modified oncolytic viruses (OVs) kill tumor cells via completely unique mechanisms compared to small molecule chemotherapeutics typically used in lung cancer treatment and can also be used to deliver specific toxic, therapeutic or immunomodulatory genes to tumor cells. Recent pre-clinical and clinical studies with oncolytic vaccine approaches have revealed promising combination strategies that enhance oncolysis of tumor cells and circumvent tumor resistance mechanisms. As clinical trials with oncolytic vaccines progress, and as the knowledge acquired from these studies builds a foundation demonstrating OVs safety and efficacy, novel combination approaches could soon have a major impact on the clinical management of patients diagnosed with lung cancer.

Recombinant influenza viruses as delivery vectors for hepatis B virus epitopes

Purpose

Neuraminidase (NA) of influenza virus contains stalk region that shows a great deal of variability in both amino acid sequence and length. In this paper, we investigated generation of recombinant influenza viruses that had hepatitis B virus (HBV) B cell epitopes in the NA stalk region as a dual vaccine candidate.

Materials and Methods

We used the WSH-HK reassortant helper virus for rescue of recombinant influenza virus containing HBV epitopes and reverse genetic protocol based on the use of micrococcal nuclease-treated virus cores for reconstitution of ribonucleoproteins.

Results

We successfully generated a chimeric influenza viruses which contained 22 amino acid peptides in the stalk region derived from the surface and pre-surface protein HBV. The growth kinetics of the recombinant viruses was investigated after infection of Madin-Darby canine kidney (MDCK) and Madin-Darby bovine kidney (MDBK) cells and the rIV-BVPreS virus showed higher titer than other viruses in MDCK cells. We also confirmed the presence of HBV epitopes in the chimeric viruses by enzyme-linked immunosorbent assay (ELISA) using anti-HBV polyclonal antibody. When the ratio of recombinant virus verse wild type virus was calculated by ELISA, recombinant viruses exhibited 2 fold higher values than the wild type virus.

Conclusion

These results suggest that chimeric influenza virus which contained foreign antigens can be used as dual vaccine against both HBV and influenza viruses.

Prospects and applications of nanobiotechnology: a medical perspective

BACKGROUND

Nanobiotechnology is the application of nanotechnology in biological fields. Nanotechnology is a multidisciplinary field that currently recruits approach, technology and facility available in conventional as well as advanced avenues of engineering, physics, chemistry and biology.

METHOD

A comprehensive review of the literature on the principles, limitations, challenges, improvements and applications of nanotechnology in medical science was performed.

RESULTS

Nanobiotechnology has multitude of potentials for advancing medical science thereby improving health care practices around the world. Many novel nanoparticles and nanodevices are expected to be used, with an enormous positive impact on human health. While true clinical applications of nanotechnology are still practically inexistent, a significant number of promising medical projects are in an advanced experimental stage. Implementation of nanotechnology in medicine and physiology means that mechanisms and devices are so technically designed that they can interact with sub-cellular (i.e. molecular) levels of the body with a high degree of specificity. Thus therapeutic efficacy can be achieved to maximum with minimal side effects by means of the targeted cell or tissue-specific clinical intervention.

CONCLUSION

More detailed research and careful clinical trials are still required to introduce diverse components of nanobiotechnology in random clinical applications with success. Ethical and moral concerns also need to be addressed in parallel with the new developments.

Enhanced stabilization of the Tobacco mosaic virus using protic ionic liquids

We report on the use of protic ionic liquids, pILs, as solvents for the solubilisation and stabilization of viruses. We show that the shelf life of the pIL stabilized tobacco mosaic virus is significantly enhanced when compared to traditional phosphate buffer. This has new opportunities for the preparation, characterization and storage of viruses and virus based technologies.

Virosome: a novel vector to enable multi-modal strategies for cancer therapy

Despite advancements in treatments, cancer remains a life-threatening disease that is resistant to therapy. Single-modal cancer therapy is often insufficient to provide complete remission. A revolution in cancer therapy may someday be provided by vector-based gene and drug delivery systems. However, it remains difficult to achieve this aim because viral and non-viral vectors have their own advantages and limitations. To overcome these limitations, virosomes have been constructed by combining viral components with non-viral vectors or by using pseudovirions without viral genome replication. Viruses, such as influenza virus, HVJ (hemagglutinating virus of Japan; Sendai virus) and hepatitis B virus, have been used in the construction of virosomes. The HVJ-derived vector is particularly promising due to its highly efficient delivery of DNA, siRNA, proteins and anti-cancer drugs. Furthermore, the HVJ envelope (HVJ-E) vector has intrinsic anti-tumor activities including the activation of multiple anti-tumor immunities and the induction of cancer-selective apoptosis. HVJ-E is currently being clinically used for the treatment of melanoma. A promising multi-modal cancer therapy will be achieved when virosomes with intrinsic anti-tumor activities are utilized as vectors for the delivery of anti-tumor drugs and genes.

Plasmid DNA is internalized from the apical plasma membrane of the salivary gland epithelium in live animals

Non-viral-mediated gene delivery represents an alternative way to express the gene of interest without inducing immune responses or other adverse effects. Understanding the mechanisms by which plasmid DNAs are delivered to the proper target in vivo is a fundamental issue that needs to be addressed in order to design more effective strategies for gene therapy. As a model system, we have used the submandibular salivary glands in live rats and we have recently shown that reporter transgenes can be expressed in different cell populations of the glandular epithelium, depending on the modality of administration of plasmid DNA. Here, by using a combination of immunofluorescence and intravital microscopy, we have explored the relationship between the pattern of transgenes expression and the internalization of plasmid DNA. We found that plasmid DNA is internalized: (1) by all the cells in the salivary gland epithelium, when administered alone, (2) by large ducts, when mixed with empty adenoviral particles, and (3) by acinar cells upon stimulation of compensatory endocytosis. Moreover, we showed that plasmid DNA utilizes different routes of internalization, and evades both the lysosomal degradative pathway and the retrograde pathway towards the Golgi apparatus. This study clearly shows that in vivo approaches have the potential to address fundamental questions on the cellular mechanisms regulating gene delivery.

Connective tissue growth factor causes glaucoma by modifying the actin cytoskeleton of the trabecular meshwork

The most critical risk factor for optic nerve damage in cases of primary open-angle glaucoma (POAG) is an increased intraocular pressure (IOP) caused by a resistance to aqueous humor outflow in the trabecular meshwork (TM). The molecular pathogenesis of this increase in outflow resistance in POAG has not yet been identified, but it may involve transforming growth factor TGF-β2, which is found in higher amounts in the aqueous humor of patients with POAG. Connective tissue growth factor (CTGF) is a TGF-β2 target gene with high constitutive TM expression. In this study, we show that either adenoviral-mediated or transgenic CTGF overexpression in the mouse eye increases IOP and leads to optic nerve damage. CTGF induces TM fibronectin and α-SMA in animals, whereas actin stress fibers and contractility are both induced in cultured TM cells. Depletion of CTGF by RNA interference leads to a marked attenuation of the actin cytoskeleton. Rho kinase inhibitors cause a reversible decline in the IOP of CTGF-overexpressing mice to levels seen in control littermates. Overall, the effects of CTGF on IOP appear to be caused by a modification of the TM actin cytoskeleton. CTGF-overexpressing mice provide a model that mimics the essential functional and structural aspects of POAG and offer a molecular mechanism to explain the increase of its most critical risk factor.

Establishment of a HepG2 cell line stably transduced with a lentivirus expressing the HBV X gene

AIM: To establish a HepG2 cell line stably transduced with a lentivirus expressing the HBV X (HBx) gene for studying the biological function of HBx and its role in hepatocarcinogenesis.

METHODS: The HBV X gene was amplified from plasmid pIERES2-EGFP-HBV by PCR. The purified HBx gene fragment was inserted into a lentivirus vector (pZac2.1), and the insertion was identified by PCR, restriction endonuclease analysis and DNA sequencing. HepG2 cells were then transfected with the packaged recombinant lentivirus, and resistant cell clones were selected with puromycin. The expression of HBx was examined using RT-PCR, immunohistochemistry, and Western blot.

RESULTS: Restriction enzyme digestion and DNA sequencing showed that the full-length HBx (489 bp) gene had been successfully subcloned into the lentiviral vector to result in the recombinant vector pZac2.1-HBx. The titre of purified recombinant lentivirus was 1×10⁸ TU/mL. Monoclonal cell line HepG2-HBx was produced 8-10 d after transfection with the recombinant lentivirus and selected with puromycin. HBx mRNA could be detected on days 3, 14, 30 and at 2 mo after cell colony formation. Meanwhile, stable expression of HBx protein was verified by immunohistochemistry and Western blot.

CONCLUSION: A HepG2 cell line stably transduced with a lentivirus expressing the HBx gene has been successfully generated.

Degradable Dextran Particles for Gene Delivery Applications

Successful gene therapy depends both on the effective transport and the stable expression of therapeutic genes to produce and regulate disease related proteins. In this context, non-viral gene delivery vehicles are regarded as one of the most promising approaches for the efficient and safe transport of genetic material to and into the target cells. This short review describes the development of novel particulate delivery vehicles based on the biopolymer dextran. This multifunctional platform was designed to safely transport genetic material across cell membranes, followed by an acid triggered release that causes overall high transfection efficiency. The biocompatibility and its unique tunability differentiate this new carrier system from previous particle systems, showing high potential for the treatment of several disease models in RNA interference related applications.

Biotechnology in the treatment of sensorineural hearing loss: foundations and future of hair cell regeneration

PURPOSE

To provide an overview of the methodologies involved in the field of hair cell regeneration. First, the author provides a tutorial on the biotechnological foundations of this field to assist the reader in the comprehension and interpretation of the research involved in hair cell regeneration. Next, the author presents a review of stem cell and gene therapy and provides a critical appraisal of their application to hair cell regeneration. The methodologies used in these approaches are highlighted.

METHOD

The author conducted a narrative review of the fields of cellular, molecular, and developmental biology, tissue engineering, and stem cell and gene therapy using the PubMed database.

RESULTS

The use of biotechnological approaches to the treatment of hearing loss--approaches such as stem cell and gene therapy-has led to new methods of regenerating cochlear hair cells in mammals.

CONCLUSIONS

Incredible strides have been made in assembling important pieces of the puzzle that comprise hair cell regeneration. However, mammalian hair cell regeneration using stem cell and gene therapy are years--if not decades--away from being clinically feasible. If the goals of the biological approaches are met, these therapies may represent future treatments for hearing loss.

Gene therapy for lung neoplasms

Both advanced-stage lung cancer and malignant pleural mesothelioma are associated with a poor prognosis. Advances in treatment regimens for both diseases have had only a modest effect on their progressive course. Gene therapy for thoracic malignancies represents a novel therapeutic approach and has been evaluated in several clinical trials. Strategies have included induction of apoptosis, tumor suppressor gene replacement, suicide gene expression, cytokine-based therapy, various vaccination approaches, and adoptive transfer of modified immune cells. This review considers the clinical results, limitations, and future directions of gene therapy trials for thoracic malignancies.

Gene therapy in the cornea: 2005--present

Successful restoration of vision in human patients with gene therapy affirmed its promise to cure ocular diseases and disorders. The efficacy of gene therapy is contingent upon vector and mode of therapeutic DNA introduction into targeted cells/tissues. The cornea is an ideal tissue for gene therapy due to its ease of access and relative immune-privilege. Considerable progress has been made in the field of corneal gene therapy in last 5 years. Several new gene transfer vectors, techniques and approaches have evolved. Although corneal gene therapy is still in its early stages of development, the potential of gene-based interventions to treat corneal abnormalities has begun to surface. Identification of next generation viral and nanoparticle vectors, characterization of delivered gene levels, localization, and duration in the cornea, and significant success in controlling corneal disorders, particularly fibrosis and angiogenesis, in experimental animal disease models, with no major side effects have propelled gene therapy a step closer toward establishing gene-based therapies for corneal blindness. Recently, researchers have assessed the delivery of therapeutic genes for corneal diseases and disorders due to trauma, infections, chemical, mechanical, and surgical injury, and/or abnormal wound healing. This review provides an update on the developments in gene therapy for corneal diseases and discusses the barriers that hinder its utilization for delivering genes in the cornea.

Hydrophobic oxime ethers: a versatile class of pDNA and siRNA transfection lipids

The manipulation of the cationic lipid structures to increase polynucleotide binding and delivery properties, while also minimizing associated cytotoxicity, has been a principal strategy for developing next-generation transfection agents. The polar (DNA binding) and hydrophobic domains of transfection lipids have been extensively studied; however, the linking domain comprising the substructure used to tether the polar and hydrophobic domains has attracted considerably less attention as an optimization variable. Here, we examine the use of an oxime ether as the linking domain. Hydrophobic oxime ethers were readily assembled via click chemistry by oximation of hydrophobic aldehydes using an aminooxy salt. A facile ligation reaction delivered the desired compounds with hydrophobic domain asymmetry. Using the MCF-7 breast cancer, H1792 lung cancer and PAR C10 salivary epithelial cell lines, our findings show that lipoplexes derived from oxime ether lipids transfect in the presence of serum at higher levels than commonly used liposome formulations, based on both luciferase and green fluorescent protein (GFP) assays. Given the biological compatibility of oxime ethers and their ease of formation, this functional group should find significant application as a linking domain in future designs of transfection vectors.

Gene therapy for mesothelioma

Mesothelioma represents an especially good target for gene therapy since few effective therapies exist, the disease remained relatively localized until late in its course, the tumor can be accessed relatively easily through the chest wall, and the thin layer of mesothelial cells offers a large surface area for efficient, rapid, and diffuse gene transfer. Gene therapy trials in mesothelioma have shown safety, and some limited evidence of efficacy. We present a review of clinical trials that have been performed in mesothelioma and describe several new approaches currently being pursued.

DNA compaction by azobenzene-containing surfactant

We report on the interaction of cationic azobenzene-containing surfactant with DNA investigated by absorption and fluorescence spectroscopy, dynamic light scattering, and atomic force microscopy. The properties of the surfactant can be controlled with light by reversible switching of the azobenzene unit, incorporated into the surfactant tail, between a hydrophobic trans (visible irradiation) and a hydrophilic cis (UV irradiation) configuration. The influence of the trans-cis isomerization of the azobenzene on the compaction process of DNA molecules and the role of both isomers in the formation and colloidal stability of DNA-surfactant complexes is discussed. It is shown that the trans isomer plays a major role in the DNA compaction process. The influence of the cis isomer on the DNA coil configuration is rather small. The construction of a phase diagram of the DNA concentration versus surfactant/DNA charge ratio allows distancing between three major phases: colloidally stable and unstable compacted globules, and extended coil conformation. There is a critical concentration of DNA above which the compacted globules can be hindered from aggregation and precipitation by adding an appropriate amount of the surfactant in the trans configuration. This is because of the compensation of hydrophobicity of the globules with an increasing amount of the surfactant. Below the critical DNA concentration, the compacted globules are colloidally stable and can be reversibly transferred with light to an extended coil state.