Direct adenovirus-mediated gene delivery to the temporomandibular joint in guinea-pigs

Applications of Gene Therapy in Dentistry: A Review Article

Gene therapy promises to possess a good prospect in bridging the gap between dental applications and medicine. The dynamic therapeutic modalities of gene therapy have been advancing rapidly. Conventional approaches are being revamped to be more comprehensive and pre-emptive, which could do away with the need for surgery and medicine altogether. The complementary base sequences known as genes convey the instructions required to manufacture proteins. The oral cavity is one of the most accessible locations for the therapeutic intervention of gene therapy for several oral tissues. In 1990, the first significant trial of gene therapy was overseen to alleviate adenosine deaminase deficiency. The notion of genetic engineering has become increasingly appealing as a reflection of its benefits over conventional treatment modalities. An example of how this technology may alter dentistry is the implementation of gene therapy for dental and oral ailments. The objective of this article is to examine the effects of gene therapy on the field of dentistry, periodontology and implantology. Furthermore, the therapeutic factors of disease therapy, minimal invasion, and appropriate outcome have indeed been taken into consideration.

Gene Therapy for Bone Defects in Oral and Maxillofacial Surgery: A Systematic Review and Meta-Analysis of Animal Studies

Craniofacial bone defects are challenging problems for maxillofacial surgeons over the years. With the development of cell and molecular biology, gene therapy is a breaking new technology with the aim of regenerating tissues by acting as a delivery system for therapeutic genes in the craniofacial region rather than treating genetic disorders. A systematic review was conducted summarizing the articles reporting gene therapy in maxillofacial surgery to answer the question: Was gene therapy successfully applied to regenerate bone in the maxillofacial region? Electronic searching of online databases was performed in addition to hand searching of the references of included articles. No language or time restrictions were enforced. Meta-analysis was done to assess significant bone formation after delivery of gene material in the surgically induced maxillofacial defects. The search identified 2081 articles, of which 57 were included with 1726 animals. Bone morphogenetic proteins were commonly used proteins for gene therapy. Viral vectors were the universally used vectors. Sprague-Dawley rats were the frequently used animal model in experimental studies. The quality of the articles ranged from excellent to average. Meta-analysis results performed on 21 articles showed that defects favored bone formation by gene therapy. Funnel plot showed symmetry with the absence of publication bias. Gene therapy is on the top list of innovative strategies that developed in the last 10 years with the hope of developing a simple chair-side protocol in the near future, combining improvement of gene delivery as well as knowledge of the molecular basis of oral and maxillofacial structures.

Non-primate Lentiviral Vector Administration in the TMJ

Gene therapy is emerging as a novel treatment method for the management of temporomandibular joint disorders. The aim of this investigation was to study the effects of lentiviral vectors on the temporomandibular joint. Consequently, we injected into the articular joint space a defective feline immunodeficiency virus capable of infecting dividing as well as terminally differentiated cells with the reporter gene lacZ, the expression of which was studied by means of PCR, X-gal histochemistry, and β-galactosidase immunocytochemistry. Our results showed successful transduction of hard and soft tissues of the temporomandibular joint. Interestingly, a subset of primary sensory neurons of the ipsilateral trigeminal ganglion also stained positive for the reporter gene, presumably following uptake of the lentiviral vector by peripheral nerve fibers and retrograde transport to the nucleus. These findings suggest that lentiviral vectors can potentially serve as a platform for the transfer of anti-nociceptive genes for the management of temporomandibular joint pain.

Gene Therapy: A Paradigm Shift in Dentistry

Gene therapy holds a promising future for bridging the gap between the disciplines of medicine and clinical dentistry. The dynamic treatment approaches of gene therapy have been advancing by leaps and bounds. They are transforming the conventional approaches into more precise and preventive ones that may limit the need of using drugs and surgery. The oral cavity is one of the most accessible areas for the clinical applications of gene therapy for various oral tissues. The idea of genetic engineering has become more exciting due to its advantages over other treatment modalities. For instance, the body is neither subjected to an invasive surgery nor deep wounds, nor is it susceptible to systemic effects of drugs. The aim of this article is to review the gene therapy applications in the field of dentistry. In addition, therapeutic benefits in terms of treatment of diseases, minimal invasion and maximum outcomes have been discussed.

Gene Therapy and its Implications in Dentistry

Background

The concept of transferring genes to tissues for clinical applications has been discussed for nearly half a century. The exponential increase in our ability to manipulate the genetic material of a cell via recombinant DNA technology has brought this goal closer to realization. The original perception that gene therapy should be considered only for a few major organs as a means of treating life-threatening disorders that are refractory to conventional treatment has changed. There are many non-life-threatening conditions that adversely affect a patient’s quality of life, for which there are no effective treatments. The lack of suitable treatment has permitted morbidity to become a rational basis for extending the scope of gene therapy. In the past few years, remarkable progress has been made in the field of gene therapy. While considerable problems remain, thus impeding the routine clinical use of gene transfer, gene therapy will have a pervasive and significant impact on areas that are based on biological science.

Aim

The purpose of this review is to examine the progress made in addressing gene transfer strategies for correcting various diseases and problems that are relevant to dental practice.

Animal models for target diseases in gene therapy--using DNA and siRNA delivery strategies

Nanoparticles, including lipopolyamines leading to lipoplexes, liposomes, and polyplexes are targeted drug carrier systems in the current search for a successful delivery system for polynucleic acids. This review is focused on the impact of gene and siRNA delivery for studies of efficacy, pharmacodynamics, and pharmacokinetics within the setting of the wide variety of in vivo animal models now used. This critical appraisal of the recent literature sets out the different models that are currently being investigated to bridge from studies in cell lines through towards clinical reality. Whilst many scientists will be familiar with rodent (murine, fecine, cricetine, and musteline) models, few probably think of fish as a clinically relevant animal model, but zebrafish, madake, and rainbow trout are all being used. Larger animal models include rabbit, cat, dog, and cow. Pig is used both for the prevention of foot-and-mouth disease and human diseases, sheep is a model for corneal transplantation, and the horse naturally develops arthritis. Non-human primate models (macaque, common marmoset, owl monkey) are used for preclinical gene vector safety and efficacy trials to bridge the gap prior to clinical studies. We aim for the safe development of clinically effective delivery systems for DNA and RNAi technologies.

Suppression of early experimental osteoarthritis by in vivo delivery of the adenoviral vector-mediated NF-kappaBp65-specific siRNA

OBJECTIVE

This study was to use adenoviral vector-mediated nuclear factor-kappaBp65 (NF-kappaBp65)-specific siRNA (Ad-siRNA(NF-kappaBp65)) to suppress the progression of early osteoarthritis (OA) in rat model, and therefore to explore a new gene therapy for OA.

METHODS

Reverse transcription polymerase chain reaction was performed to confirm the silencing effect of Ad-siRNA(NF-kappaBp65) in cultured rat chondrocytes. Transection of the medial collateral ligament plus partial medial meniscectomy was operated in the knee of rats to establish OA model. Histological analysis was made to assess the morphological change of cartilage and synovium, and enzyme-linked immunosorbent assay was made to measure the expression of cytokines, such as interleukin-1beta (IL-1beta) and tumor necrosis factor-alpha (TNF-alpha), in synovial fluid. The silencing effect of Ad-siRNA(NF-kappaBp65) on NF-kappaBp65 in cartilage and synovium of knee was measured with Western blot and the activation of NF-kappaB was measured with electrophoretic mobility shift assays.

RESULTS

Ad-siRNA(NF-kappaBp65) can inhibit the activation of NF-kappaB and the expression of NF-kappaBp65 in cartilage and synovium of the knee, restrain the induction of IL-1beta and TNF-alpha in synovial fluid, alleviate the inflammation of synovium and reduce the degradation of cartilage in early phase of experimental OA.

CONCLUSIONS

Ad-siRNA(NF-kappaBp65) can suppress the progression of the early experimental OA which suggests that Ad-siRNA(NF-kappaBp65) has potential to be a useful preventive and therapeutic agent for OA.

The use of recombinant adeno-associated virus for skeletal gene therapy

OBJECTIVES

To provide a comprehensive literature review describing recent developments of the recombinant adeno-associated virus (rAAV) vector and exploring the therapeutic application of rAAV for bone defects, cartilage lesions and rheumatoid arthritis.

DESIGN

Narrative review.

RESULT

The review outlines the serotypes and genome of AAV, integration and life cycle of the rAAV vectors, the immune response and regulating system for AAV gene therapy. Furthermore, the advancements of rAAV gene therapy for bone growth together with cartilage repair are summarized.

CONCLUSION

Recombinant adeno-associated virus vector is perceived to be one of the most promising vector systems for bone and cartilage gene therapy approaches and further investigations need to be carried out for craniofacial research.

Growth factor delivery for oral and periodontal tissue engineering

The treatment of oral and periodontal diseases and associated anomalies accounts for a significant proportion of the healthcare burden, with the manifestations of these conditions being functionally and psychologically debilitating. Growth factors are critical to the development, maturation, maintenance and repair of craniofacial tissues, as they establish an extracellular environment that is conducive to cell and tissue growth. Tissue-engineering principles aim to exploit these properties in the development of biomimetic materials that can provide an appropriate microenvironment for tissue development. These materials have been constructed into devices that can be used as vehicles for delivery of cells, growth factors and DNA. In this review, different mechanisms of drug delivery are addressed in the context of novel approaches to reconstruct and engineer oral- and tooth-supporting structures, namely the periodontium and alveolar bone.

Local gene transfer to calcified tissue cells using prolonged infusion of a lentiviral vector

Gene transfer using viral vectors offers the potential for the sustained expression of proteins in specific target tissues. However, in the case of calcified tissues, in vivo delivery remains problematic because of limited accessibility. The aim of this study was to test the efficiency of lentiviral vectors (LVs) on osteogenic cells in vitro, and determine the feasibility of directly transducing resident bone cells in vivo. LVs encoding for green fluorescent protein (GFP) and ameloblastin (AMBN), a protein associated with mineralization not reported in bone, were generated. The transduction efficiency of the LVs was evaluated using the MC3T3 cell line and primary calvaria-derived osteogenic cells. For in vivo delivery, the LVs were infused using osmotic minipumps through holes created in the bone of the rat hemimandible and tibia. The production of GFP and AMBN in vitro and in vivo was monitored using fluorescence microscopy. Both transgenes were expressed in MC3T3 and primary osteogenic cells. In vivo, GFP was detected at the infusion site and fibroblast-like cells, osteoblasts, osteocytes and osteoclasts expressed AMBN. Our data demonstrate, for the first time, that primary osteogenic cells are efficiently transduced with LVs and that their infusion is advantageous for locally delivering DNA to bone cells.

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 gene expression using the lentiviral vector in rat chondrocytes

The optimal approach to a long-term stable transgene expression in chondrocytes has not been established. Recently, lentiviral vectors have been used for transfection of some cultured cell lines. Our study tests the hypothesis that lentiviral vectors lead to longer gene expression in primary chondrocytes. We transfected lentiviral and adenoviral vectors carrying the green fluorescence protein gene to chondrocytes at different infection rates and cultured them in collagen Type I gel for up to 6 weeks. We also transplanted the cells of gel-suspended chondrocytes into the backs of nude mice. The mRNA expression of collagen Type II and aggrecan core protein was tested by real time polymerase chain reaction. The morphologic features and proliferation of chondrocytes were observed. Lentiviral vectors could transfect the green fluorescence protein gene to chondrocytes and the adenoviral vector, and there was no influence on the proliferation and phenotype of the chondrocytes. The percentage of lentiviral green fluorescence protein positive cells was much greater than the adenoviral green fluorescence protein at the end of 6 weeks. Stable green fluorescence protein expression was observed only in the lentivirus-transfected implants. The gene transfected by the lentiviral vector can be expressed efficiently for a long time and may be useful for gene transfer in cartilage defect repair.

In vivo gene delivery to articular chondrocytes mediated by an adeno-associated virus vector

PURPOSES

(1) To investigate the efficiency of direct in vivo adeno-associated virus (AAV) vector-mediated gene transduction to chondrocytes in relation to normal and injured articular cartilage. (2) To evaluate the effects of ultra-violet light-activated gene transduction (LAGT) in chondrocytes in vivo. (3) To determine dissemination of active rAAV vector after intra-articular administration.

METHODS

Rabbit knees with either normal or injured cartilage received an intra-articular injection with 1.5x10(12) infectious rAAV-eGFP particles. The right knees received rAAV-eGFP alone, whereas the left knees were given LAGT-treatment. The transduction efficiencies were determined at 1 and 3 weeks after infection by fluorescence-activated cell scanning. The occurrence of active shedding was monitored in serum and various tissues.

RESULTS

After 1 week, 7% of the chondrocytes in normal cartilage were transduced by direct rAAV transduction technique. Chondrocytes in cartilage defects demonstrated higher transduction rates compared to chondrocytes in normal cartilage. LAGT increased the cellular eGFP expression in the internal zones to 12%, but did not have any effect in the external zones in defects. Finally, infectious particles were not detected in either serum or tissue samples.

CONCLUSIONS

Direct rAAV-mediated gene transfer in vivo to articular chondrocytes is possible. LAGT improves rAAV transduction of chondrocytes in vivo but appears to have a very limited range of effect induction. Expression of eGFP was not determined in other tissues than synovium and cartilage in the treated joints.

Tools and techniques for craniofacial tissue engineering

Craniofacial surgery is an important conduit for tissue-engineering applications. As interdisciplinary collaborations improve, we can expect to see remarkable progress in de novo tissue synthesis, replacement, and repair. Ultimately, we may one day find that gene-modified cell-based tissue-engineering strategies will succeed today's reconstructive strategies. In this review, we highlight the major gene- and cell-based preclinical tools and techniques that are currently being developed to solve common craniofacial problems.

CTGF/Hcs24, a hypertrophic chondrocyte-specific gene product, stimulates proliferation and differentiation, but not hypertrophy of cultured articular chondrocytes

We previously reported that connective tissue growth factor/hypertrophic chondrocyte-specific gene product 24 (CTGF/Hcs24) stimulated the proliferation and differentiation of rabbit growth cartilage (RGC) cells in vitro. In this study, we investigated the effects of CTGF/Hcs24 on the proliferation and differentiation of rabbit articular cartilage (RAC) cells in vitro. RAC cells transduced by recombinant adenoviruses generating mRNA for CTGF/Hcs24 synthesized more proteoglycan than the control cells. Also, treatment of RAC cells with recombinant CTGF/Hcs24 (rCTGF/Hcs24) increased DNA and proteoglycan syntheses in a dose-dependent manner. Northern blot analysis revealed that the rCTGF/Hcs24 stimulated the gene expression of type II collagen and aggrecan core protein, which are markers of chondrocyte maturation, in both RGC and RAC cells. However, the gene expression of type X collagen, a marker of hypertrophic chondrocytes, was stimulated by rCTGF/Hcs24 only in RGC cells, but not in RAC cells. Oppositely, gene expression of tenascin-C, a marker of articular chondrocytes, was stimulated by rCTGF/Hcs24 in RAC cells, but not in RGC cells. Moreover, rCTGF/Hcs24 effectively increased both alkaline phosphatase (ALPase) activity and matrix calcification of RGC cells, but not of RAC cells. These results indicate that CTGF/Hcs24 promotes the proliferation and differentiation of articular chondrocytes, but does not promote their hypertrophy or calcification. Taken together, the data show that CTGF/Hcs24 is a direct growth and differentiation factor for articular cartilage, and suggest that it may be useful for the repair of articular cartilage.

The impact of gene therapy on dentistry: a revisiting after six years

BACKGROUND

Gene therapy is an emerging field of biomedicine that has commanded considerable scientific and popular attention. The procedure involves the transfer of genes to patients for clinical benefit. Transferred genes can b e used for either reparative or pharmacological purposes.

OVERVIEW

In 1995, the first author and a colleague described the potential impact of gene therapy on dentistry, on the basis of initial studies of gene transfer applications to salivary glands, keratinocytes and cancer cells. Their conclusion was that gene therapy would have a significant impact on the nature of dental practice within 20 years. In this article, the authors consider research progress since 1995 and reexamine the earlier conclusion.

PRACTICE IMPLICATIONS

In the past six years, remarkable progress has been made in the field of gene therapy, including seven areas relevant to dental practice: bone repair, salivary glands, autoimmune disease, pain, DNA vaccinations, keratinocytes and cancer. While considerable problems remain, thus impeding the routine clinical use of gene transfer, gene therapy will have a pervasive and significant impact on areas of dental practice that are based in biological science. By 2015, this will translate into practitioners' having a wide range of novel biological treatment options for their patients.