Liposomal gene transfer of multiple genes is more effective than gene transfer of a single gene

Glucose-Responsive Fibrin Hydrogel-Based Multimodal Nucleic Acid Delivery System

Nucleic acid therapy has emerged as a potential alternative for promoting wound healing by gene expression modification. On the other hand, protecting the nucleic acid payload from degradation, efficient bioresponsive delivery and effective transfection into cells remain challenging. A glucose-responsive gene delivery system for treating diabetic wounds would be advantageous as it would be responsive to the underlying pathology giving a regulated payload delivery with fewer side effects. Herein a GOx-based glucose-responsive delivery system is designed based on fibrin-coated polymeric microcapsules (FCPMC) using the layer-by-layer (LbL) approach that simultaneously delivers two nucleic acids in diabetic wounds. The designed FCPMC displays an ability to effectively load many nucleic acids in polyplexes and release it over a prolonged period with no cytotoxic effects seen in in vitro studies. Furthermore, the developed system does not show any undesired effects in vivo. When applied to wounds in genetically diabetic db/db mice, the fabricated system on its own improves reepithelialization and angiogenesis while decreasing inflammation. Also, key proteins involved in the wound healing process, i.e., Actn2, MYBPC1, and desmin, are upregulated in the glucose-responsive fibrin hydrogel (GRFHG) treated group of animals. In conclusion, the fabricated hydrogel promotes wound healing. Furthermore, the system may be encapsulated with various therapeutic nucleic acids that aid wound healing.

Gene therapy to enhance angiogenesis in chronic wounds

Skin injuries and chronic non-healing wounds are one of the major global burdens on the healthcare systems worldwide due to their difficult-to-treat nature, associated co-morbidities, and high health care costs. Angiogenesis has a pivotal role in the wound-healing process, which becomes impaired in many chronic non-healing wounds, leading to several healing disorders and complications. Therefore, induction or promotion of angiogenesis can be considered a promising approach for healing of chronic wounds. Gene therapy is one of the most promising upcoming strategies for the treatment of chronic wounds. It can be classified into three main approaches: gene augmentation, gene silencing, and gene editing. Despite the increasing number of encouraging results obtained using nucleic acids (NAs) as active pharmaceutical ingredients of gene therapy, efficient delivery of NAs to their site of action (cytoplasm or nucleus) remains a key challenge. Selection of the right therapeutic cargo and delivery methods is crucial for a favorable prognosis of the healing process. This article presents an overview of gene therapy and non-viral delivery methods for angiogenesis induction in chronic wounds.

Nanomaterials for the delivery of bioactive factors to enhance angiogenesis of dermal substitutes during wound healing

Dermal substitutes provide a template for dermal regeneration and reconstruction. They constitutes an ideal clinical treatment for deep skin defects. However, rapid vascularization remains as a major hurdle to the development and application of dermal substitutes. Several bioactive factors play an important regulatory role in the process of angiogenesis and an understanding of the mechanism of achieving their effective delivery and sustained function is vital. Nanomaterials have great potential for tissue engineering. Effective delivery of bioactive factors (including growth factors, peptides and nucleic acids) by nanomaterials is of increasing research interest. This paper discusses the process of dermal substitute angiogenesis and the roles of related bioactive factors in this process. The application of nanomaterials for the delivery of bioactive factors to enhance angiogenesis and accelerate wound healing is also reviewed. We focus on new systems and approaches for delivering bioactive factors for enhancing angiogenesis in dermal substitutes.

Influence of Recombinant Codon-Optimized Plasmid DNA Encoding VEGF and FGF2 on Co-Induction of Angiogenesis

Simple Summary

Over the past few decades, several methods have been proposed to stimulate skin wound healing. The most promising of these are gene therapy and stem cell therapy. Our present experiments have combined several approaches utilizing human umbilical cord blood mononuclear cells using cell therapy, and direct gene therapy using genetic constructs to accelerate complete healing of skin wounds in rats. Studies have shown that the transplantation of transfected cells stopped proliferative processes in regenerating wounds earlier than the transplantation of untransfected cells. The use of direct gene therapy using the VEGF and FGF2 genes stimulates the revascularization of the rat cutaneous wound.

Abstract

Several methods for the stimulation of skin wound repair have been proposed over the last few decades. The most promising among them are gene and stem cell therapy. Our present experiments combined several approaches via the application of human umbilical cord blood mononuclear cells (hUCB-MC) that were transfected with pBud-VEGF165-FGF2 plasmid (gene-cell therapy) and direct gene therapy using pBud-VEGF165-FGF2 plasmid to enhance healing of full thickness skin wounds in rats. The dual expression cassette plasmid pBud-VEGF165-FGF2 encodes both VEGF and FGF2 therapeutic genes, expressing pro-angiogenic growth factors. Our results showed that, with two weeks post-transplantation, some transplanted cells still retained expression of the stem cell and hematopoietic markers C-kit and CD34. Other transplanted cells were found among keratinocytes, hair follicle cells, endothelial cells, and in the derma. PCNA expression studies revealed that transplantation of transfected cells terminated proliferative processes in regenerating wounds earlier than transplantation of untransfected cells. In the direct gene therapy group, four days post-operatively, the processes of flap revascularization, while using Easy LDI Microcirculation Camera, was higher than in control wounded skin. We concluded that hUCB-MC can be used for the treatment of skin wounds and transfection these cells with VEGF and FGF2 genes enhances their regenerative abilities. We also concluded that the application of pBud-VEGF165-FGF2 plasmids is efficient for the direct gene therapy of skin wounds by stimulation of wound revascularization.

Re-epithelialization of adult skin wounds: Cellular mechanisms and therapeutic strategies

Cutaneous wound healing in adult mammals is a complex multi-step process involving overlapping stages of blood clot formation, inflammation, re-epithelialization, granulation tissue formation, neovascularization, and remodelling. Re-epithelialization describes the resurfacing of a wound with new epithelium. The cellular and molecular processes involved in the initiation, maintenance, and completion of epithelialization are essential for successful wound closure. A variety of modulators are involved, including growth factors, cytokines, matrix metalloproteinases, cellular receptors, and extracellular matrix components. Here, we focus on cellular mechanisms underlying keratinocyte migration and proliferation during epidermal closure. Inability to re-epithelialize is a clear indicator of chronic non-healing wounds, which fail to proceed through the normal phases of wound healing in an orderly and timely manner. This review summarizes the current knowledge regarding the management and treatment of acute and chronic wounds, with a focus on re-epithelialization, offering some insights into novel future therapies.

Nanomedicines and gene therapy for the delivery of growth factors to improve perfusion and oxygenation in wound healing

Oxygen plays a key role in wound healing, and hypoxia is a major cause of wound healing impairment; therefore, treatments to improve hemodynamics and increase wound oxygenation are of particular interest for the treatment of chronic wounds. This article describes the roles of oxygen and angiogenesis in wound healing as well as the tools used to evaluate tissue oxygenation and perfusion and then presents a review of nanomedicines and gene therapies designed to improve perfusion and oxygenation and accelerate wound healing.

A review of genetic engineering biotechnologies for enhanced chronic wound healing

Traditional methods for addressing chronic wounds focus on correcting dysfunction by controlling extracellular elements. This review highlights technologies that take a different approach - enhancing chronic wound healing by genetic modification to wound beds. Featured cutaneous transduction/transfection methods include viral modalities (ie adenoviruses, adeno-associated viruses, retroviruses and lentiviruses) and conventional non-viral modalities (ie naked DNA injections, microseeding, liposomal reagents, particle bombardment and electroporation). Also explored are emerging technologies, focusing on the exciting capabilities of wound diagnostics such as pyrosequencing as well as site-specific nuclease editing tools such as CRISPR-Cas9 used to both transiently and permanently genetically modify resident wound bed cells. Additionally, new non-viral transfection methods (ie conjugated nanoparticles, multi-electrode arrays, and microfabricated needles and nanowires) are discussed that can potentially facilitate more efficient and safe transgene delivery to skin but also represent significant advances broadly to tissue regeneration research.

Use of a fibrin-based system for enhancing angiogenesis and modulating inflammation in the treatment of hyperglycemic wounds

The complex pathophysiology of chronic ulceration in diabetic patients is poorly understood; diabetes-related lower limb amputation is a major health issue, which has limited effective treatment regimes in the clinic. This study attempted to understand the complex pathology of hyperglycemic wound healing by showing profound changes in gene expression profiles in wounded human keratinocytes in hyperglycemic conditions compared to normal glucose conditions. In the hyper-secretory wound microenvironment of hyperglycemia, Rab18, a secretory control molecule, was found to be significantly downregulated. Using a biomaterial platform for dual therapy targeting the two distinct pathways, this study aimed to resolve the major dysregulated pathways in hyperglycemic wound healing. To complement Rab18, and promote angiogenesis eNOS was also targeted, and this novel Rab18-eNOS therapy via a dynamically controlled 'fibrin-in-fibrin' delivery system, demonstrated enhanced wound closure, by increasing functional angiogenesis and reducing inflammation, in an alloxan-induced hyperglycemic preclinical ear ulcer model of compromised wound healing.

Wound coverage technologies in burn care: novel techniques

Improvements in burn wound care have vastly decreased morbidity and mortality in severely burned patients. Development of new therapeutic approaches to increase wound repair has the potential to reduce infection, graft rejection, and hypertrophic scarring. The incorporation of tissue-engineering techniques, along with the use of exogenous proteins, genes, or stem cells to enhance wound healing, heralds new treatment regimens based on the modification of already existing biological activity. Refinements to surgical techniques have enabled the creation of protocols for full facial transplantation. With new technologies and advances such as these, care of the severely burned will undergo massive changes over the next decade. This review centers on new developments that have recently shown great promise in the investigational arena.

The role of gene therapy in regenerative surgery: updated insights

BACKGROUND

In the past two decades, regenerative surgeons have focused increasing attention on the potential of gene therapy for treatment of local disorders and injuries. Gene transfer techniques may provide an effective local and short-term induction of growth factors without the limits of other topical therapies. In 2002, Tepper and Mehrara accurately reviewed the topic: given the substantial advancement of research on this issue, an updated review is provided.

METHODS

Literature indexed in the National Center for Biotechnology Information database (PubMed) has been reviewed using variable combinations of keywords ("gene therapy," "regenerative medicine," "tissue regeneration," and "gene medicine"). Articles investigating the association between gene therapies and local pathologic conditions have been considered. Attention has been focused on articles published after 2002. Further literature has been obtained by analysis of references listed in reviewed articles.

RESULTS

Gene therapy approaches have been successfully adopted in preclinical models for treatment of a large variety of local diseases affecting almost every type of tissue. Experiences in abnormalities involving skin (e.g., chronic wounds, burn injuries, pathologic scars), bone, cartilage, endothelia, and nerves have been reviewed. In addition, the supporting role of gene therapies to other tissue-engineering approaches has been discussed. Despite initial reports, clinical evidence has been provided only for treatment of diabetic ulcers, rheumatoid arthritis, and osteoarthritis.

CONCLUSIONS

Translation of gene therapy strategies into human clinical trials is still a lengthy, difficult, and expensive process. Even so, cutting-edge gene therapy-based strategies in reconstructive procedures could soon set valuable milestones for development of efficient treatments in a growing number of local diseases and injuries.

Acute and impaired wound healing: pathophysiology and current methods for drug delivery, part 2: role of growth factors in normal and pathological wound healing: therapeutic potential and methods of delivery

This is the second of 2 articles that discuss the biology and pathophysiology of wound healing, reviewing the role that growth factors play in this process and describing the current methods for growth factor delivery into the wound bed.

Adipose-derived stromal cells overexpressing vascular endothelial growth factor accelerate mouse excisional wound healing

Angiogenesis is essential to wound repair, and vascular endothelial growth factor (VEGF) is a potent factor to stimulate angiogenesis. Here, we examine the potential of VEGF-overexpressing adipose-derived stromal cells (ASCs) for accelerating wound healing using nonviral, biodegradable polymeric vectors. Mouse ASCs were transfected with DNA plasmid encoding VEGF or green fluorescent protein (GFP) using biodegradable poly (β-amino) esters (PBAE). Cells transfected using Lipofectamine 2000, a commercially available transfection reagent, were included as controls. ASCs transfected using PBAEs showed enhanced transfection efficiency and 12-15-fold higher VEGF production compared with cells transfected using Lipofectamine 2000 (*P < 0.05). When transplanted into a mouse wild-type excisional wound model, VEGF-overexpressing ASCs led to significantly accelerated wound healing, with full wound closure observed at 8 days compared to 10-12 days in groups treated with ASCs alone or saline control (*P < 0.05). Histology and polarized microscopy showed increased collagen deposition and more mature collagen fibers in the dermis of wound beds treated using PBAE/VEGF-modified ASCs than ASCs alone. Our results demonstrate the efficacy of using nonviral-engineered ASCs to accelerate wound healing, which may provide an alternative therapy for treating many diseases in which wound healing is impaired.

Combined gene and stem cell therapy for cutaneous wound healing

In current medical practice, wound therapy remains a clinical challenge and much effort has been focused on the development of novel therapeutic approaches for wound treatment. Gene therapy, initially developed for treatment of congenital defects, represents a promising option for enhancing wound repair. In order to accelerate wound closure, genes encoding for growth factors or cytokines have shown the most potential. The majority of gene delivery systems are based on viral transfection, naked DNA application, high pressure injection, and liposomal vectors. Besides advances stemming from breakthroughs in recombinant growth factors and bioengineered skin, there has been a significant increase in the understanding of stem cell biology in the field of cutaneous wound healing. A variety of sources, such as bone marrow, umbilical cord blood, adipose tissue and skin/hair follicles, have been utilized to isolate stem cells and to modulate the healing response of acute and chronic wounds. Recent data have demonstrated the feasibility of autologous adult stem cell therapy in cutaneous repair and regeneration. Very recently, stem cell based skin engineering in conjunction with gene recombination, in which the stem cells act as both the seed cells and the vehicle for gene delivery to the wound site, represents the most attractive field for generating a regenerative strategy for wound therapy. The aim of this article is to discuss the use and the potential of these novel technologies in order to improve wound healing capacities.

Pre-clinical evaluation of liposomal gene transfer to improve dermal and epidermal regeneration

Liposomal gene transfer effectively enhances dermal and epidermal regeneration in burned rodents. To advance this treatment to clinical studies, we investigated the efficacy of liposomal gene transfer in a clinically relevant porcine wound model. Mimicking the clinical scenario, six female Yorkshire pigs (40-50 kg) received up to 12 burns of 50 cm(2) area that were fully excised and covered with skin autograft meshed at 4:1 ratio 24 h post-burn. Animals received control injections (empty liposomes), liposomes (DMRIE-C) containing 1 mg LacZ-cDNA, or liposomes (DMRIE-C) with 1 mg of platelet-derived growth factor (PDGF)-cDNA, or the naked PDGF gene. Serial biopsies were taken from different wound sites at multiple time points up to 12 days post-wounding. Transfection efficacy and transfection rate of LacZ and localization of beta-gal were determined by immunohistochemical and immunofluorescent techniques. RT-PCR and multiplex protein analysis (ELISA) were used to measure levels of growth factor mRNA transcribed and growth factor protein translated. Wound re-epithelialization and graft adhesion was evaluated using planimetric analysis and clinical scores. We found that peak transfection of liposomal beta-galactosidase occurred on day 2, with a fluorescence increase of 154% to baseline (P<0.001). Transfection intensity dropped to 115% above baseline on day 4 (P<0.001) and 109% on day 7. Immunohistochemistry showed a maximum transfection rate of 34% of cells in wound tissue. Gene transfer of liposomal PDGF-cDNA resulted in increased PDGF-mRNA and protein expression on days 2 and 4, and accelerated wound re-epithlialization as well as graft adhesion on day 9 (P<0.05). In this study, we showed that liposomal cDNA gene transfer is possible in a porcine wound model, and by using PDGF-cDNA we further showed that dermal and epidermal regeneration can be improved. These data indicate that liposomal gene transfer can be a new therapeutic approach to improve wound healing in humans.

Accelerated adhesion of grafted skin by laser-induced stress wave-based gene transfer of hepatocyte growth factor

Gene therapy using wound healing-associated growth factor gene has received much attention as a new strategy for improving the outcome of tissue transplantation. We delivered plasmid DNA coding for human hepatocyte growth factor (hHGF) to rat free skin grafts by the use of laser-induced stress waves (LISWs); autografting was performed with the grafts. Systematic analysis was conducted to evaluate the adhesion properties of the grafted tissue; angiogenesis, cell proliferation, and reepithelialization were assessed by immunohistochemistry, and reperfusion was measured by laser Doppler imaging as a function of time after grafting. Both the level of angiogenesis on day 3 after grafting and the increased ratio of blood flow on day 4 to that on day 3 were significantly higher than those in five control groups: grafting with hHGF gene injection alone, grafting with control plasmid vector injection alone, grafting with LISW application alone, grafting with LISW application after control plasmid vector injection, and normal grafting. Reepithelialization was almost completed on day 7 even at the center of the graft with LISW application after hHGF gene injection, while it was not for the grafts of the five control groups. These findings demonstrate the validity of our LISW-based HGF gene transfection to accelerate the adhesion of grafted skins.

Single subcutaneous administration of RGDK-lipopeptide:rhPDGF-B gene complex heals wounds in streptozotocin-induced diabetic rats

Development of effective therapeutics for chronic wounds remains a formidable clinical challenge. Deficiency of growth factors is of paramount importance among the multitude of factors contributing to the pathogenesis of diabetic wounds. Clinical interest has been witnessed in the past for exogenous applications of platelet derived growth factor B (PDGF-B) in chronic nonhealing wounds. However, accomplishing even modest favorable clinical effects in such topical applications requires large and repeated doses of PDGF-B proteins. Chronic wounds are being increasingly circumvented by gene therapy approach and to this end, cationic liposomes are emerging as promising nonviral carriers for delivering various growth factors encoding therapeutic genes to wound beds. However, as in case of topical application of growth factors, all the prior studies on the use of cationic liposomes in nonviral gene therapy of wounds involved repeated injections of cationic liposome:cDNA complexes over several weeks for ensuring complete wound healing. Herein, we show that a single subcutaneous administration of an electrostatic complex of rhPDGF-B plasmid, integrin receptor selective RGDK-lipopeptide 1 and cholesterol (as auxiliary lipid) is capable of healing wounds in streptozotocin-induced diabetic Sprague-Dawley rats (as model of chronic wounds). Western blot analysis revealed significant expression of rhPDGF-B in mouse fibroblast cells transfected with RGDK-lipopeptide 1:rhPDGF-B lipoplex. The transfection efficiencies of the RGDK-lipopeptide 1 in mouse and human fibroblast cells preincubated with various monoclonal anti-integrin receptor antibodies support the notion that the cellular uptake of the RGDK-lipopeptide 1:DNA complexes in fibroblast cells is likely to be selectively mediated by alpha5beta1 integrin receptors. Findings in the histopathological stainings using both hematoxylin and eosin (H & E) as well as Masson's Trichrome staining revealed a significantly higher degree of epithelization, keratization, fibrocollagenation and blood vessel formation in rats treated with RGDK-lipopeptide 1:rhPDGF compared to those in rats treated with vehicle alone.

Gene delivery systems for gene therapy in tissue engineering and central nervous system applications

The present review aims to describe the potential applications of gene delivery systems to tissue engineering and central nervous system diseases. Some key experimental work has been done with interesting results, but the subject is far from being fully explored. The combined approach of gene therapy and material science has a huge potential to improve the therapeutic approaches now available for a wide range of medical applications. Focus is given to this multidisciplinary strategy in neurodegenerative pathologies, where the use of polymeric matrices as gene carriers might make a crucial difference.

Immobilization of plasmid DNA on an anti-DNA antibody modified coronary stent for intravascular site-specific gene therapy

BACKGROUND

The aim of the present study was to investigate the incorporation of plasmid DNA (pDNA) onto a coronary stent by chemo-immunoconjugation for achieving site-specific gene delivery.

METHODS

Anti-DNA immunoglobulin M antibody was chemically linked onto collagen-coated stent by using N-succinimidyl-3-(2-pyridyldithiol)-propionate as cross-linker. pDNA was tethered on the antibody-immobilized stent by highly specific antigen-antibody affinity interaction. Radioactive-labeled antibody and pDNA were used to evaluate binding capacity and stability. A reporter plasmid pEGFP was tethered on the antibody-immobilized stents that was assessed in cell culture and in rabbit carotid model.

RESULTS

The amount of antibody chemically linked on the stents was 15-fold higher than that of the control and its retention time was also significantly longer. The pEGFP-tethered stents had no detrimental effects on cell growth. In cell culture studies, numerous green fluorescent protein (GFP)-transfected cells were only found on the stent, which demonstrated high localization and efficiency of gene delivery. The overall GFP transfection efficiency in treated rabbit carotid arteries was 2.8 +/- 0.7% of the total cells. However, the rate of neointima transfection was 7.0 +/- 0.8% of total cells in this region. Importantly, no distal spreading of the vector was detected by polymerase chain reaction, either in distal organs or in the downstream segments of the stented arteries.

CONCLUSIONS

For the first time, our group reports the successful use of anti-DNA antibody-immobilized metal stent as plasmid gene delivery system that possess high efficiency and site-specificity in vitro and in vivo.

A review of gene and stem cell therapy in cutaneous wound healing

Different therapies that effect wound repair have been proposed over the last few decades. This article reviews the emerging fields of gene and stem cell therapy in wound healing. Gene therapy, initially developed for treatment of congenital defects, is a new option for enhancing wound repair. In order to accelerate wound closure, genes encoding for growth factors or cytokines showed the greatest potential. The majority of gene delivery systems are based on viral transfection, naked DNA application, high pressure injection, or liposomal vectors. Embryonic and adult stem cells have a prolonged self-renewal capacity with the ability to differentiate into various tissue types. A variety of sources, such as bone marrow, peripheral blood, umbilical cord blood, adipose tissue, skin and hair follicles, have been utilized to isolate stem cells to accelerate the healing response of acute and chronic wounds. Recently, the combination of gene and stem cell therapy has emerged as a promising approach for treatment of chronic and acute wounds.

Modeling growth factor activity during proinflammatory stress: methodological considerations in assessing cytokine modulation of IGF binding proteins released by cultured bovine kidney epithelial cells

The present research was conducted to model potential mechanisms through which IGFBPs might be affected by a key proinflammatory response initiating cytokine tumor necrosis factor (TNF-)-alpha. Madin-Darby bovine kidney epithelial (MDBK) cells, known to release IGFBPs in response to several stimuli, were grown under several conditions and challenged with forskolin (F) or recombinant TNF-alpha for 24h. Forskolin increased IGFBP-3 gene expression and media content of BP-3 protein. TNF-alpha increased basal and augmented F-mediated IGFBP-3 gene expression. However, TNF-alpha effects on the measurable media content of IGFBPs were influenced by culture conditions; in the absence of added protease inhibitors (PIs) or sufficient media albumin concentration (high BSA, 1mg/ml), the effect of TNF-alpha was to decrease (P<0.02) measurable IGFBPs. In the presence of PI and high BSA, media IGFBP-3 levels were shown to be increased by TNF-alpha consistent with the gene expression data. Changes in media IGFBP-3 protease activity were examined further to explain the observed effects of TNF-alpha on production and destruction of IGFBPs in media. When recombinant human IGFBP-3 (500 ng/ml) was added to PI-free, low BSA 100 microg/ml) media from TNF-treated MDBK cells, less than 10% of the BP-3 was recognizable by Western blot in 30 min; conversely, inclusion of High BSA and PI in media resulted in attenuation of the protease effect on the IGFBPs. The data suggest that the MDBK model of cellular response to proinflammatory stimulus is affected by culture conditions and that TNF-alpha affects media content of IGFBPs through effects on IGFBP gene expression coupled with degradation of IGFBPs via enhanced proteolytic enzyme release.

The combination of IGF-I and KGF cDNA improves dermal and epidermal regeneration by increased VEGF expression and neovascularization

Insulin-like growth factor-I (IGF-I) and keratinocyte growth factor (KGF) cDNA gene transfer individually improves dermal and epidermal regeneration. The aim of the present study was to determine whether the combination of IGF-I plus KGF cDNA further improves wound healing and by which mechanisms these changes occur. Rats received an acute wound and were divided into four groups to receive weekly subcutaneous injections of liposomes plus Lac Z cDNA, liposomes plus IGF-I cDNA, liposomes plus KGF cDNA, or liposomes plus IGF-I/KGF cDNA. Planimetry, immunological assays, histological and immunohistochemical techniques were used to determine IGF-I, KGF, platelet-derived growth factor, fibroblast growth factor (FGF), transforming growth factor-beta and vascular endothelial growth factor (VEGF) expression and different types of collagen (I, III and IV). IGF-I, KGF and their combination cDNA treatment significantly (P<0.05) accelerated re-epithelization, increased IGF-I, KGF, FGF, VEGF and collagen type IV expression, while it had no effect on collagen type I and III expression. The combination of IGF-I plus KGF cDNA increased (P<0.05) neovascularization and VEGF expression when compared to IGF-I cDNA, KGF cDNA groups and controls. In conclusion, exogenous administration of liposomal IGF-I plus KGF cDNA enhanced dermal and epidermal regeneration which is due to increased neovascularization.

Liposomal gene transfer of keratinocyte growth factor improves wound healing by altering growth factor and collagen expression

BACKGROUND

Growth factors affect the complex cascade of wound healing; however, interaction between different growth factors during dermal and epidermal regeneration are still not entirely defined. In the present study, we thought to determine the interaction between keratinocyte growth factor (KGF) administered as liposomal cDNA with other dermal and epidermal growth factors and collagen synthesis in an acute wound.

MATERIALS AND METHODS

Rats received an acute wound and were divided into two groups to receive weekly subcutaneous injections of liposomes plus the Lac-Z gene (0.22 microg, vehicle), or liposomes plus the KGF cDNA (2.2 microg) and Lac-Z gene (0.22 microg). Histological and immunohistochemical techniques were used to determine growth factor, collagen expression, and dermal and epidermal structure.

RESULTS

KGF cDNA increased insulin-like growth factor-I (IGF-I), insulin-like growth factor binding protein-3 (IGFBP-3), and fibroblast growth factor (FGF), decreased transforming growth factor-beta (TGF-beta), while it had no effect on platelet-derived growth factor (PDGF) levels in the wound. KGF cDNA significantly increased collagen Type IV at both the wound edge as well as the wound bed, while it had no effect on collagen Type I and III. KGF cDNA increased re-epithelialization, improved dermal regeneration, and increased neovascularization.

CONCLUSIONS

Exogenous administered KGF cDNA causes increases in IGF-I, IGF-BP3, FGF, and collagen IV and decreases TGF-beta concentration. KGF gene transfer accelerates wound healing without causing an increase in collagen I or III.

Cutaneous gene therapy

Possibilities of using the skin for somatic gene therapy have been investigated for more than 20 years. Strategies have included both direct gene transfer into the skin and indirect gene transfer utilizing cultured cells as an intermediate step for gene manipulation. Viral as well as nonviral vectors have been used, and both gene addition and gene editing have been performed. Although cutaneous gene therapy has now begun translating into clinical medicine (as seen by the first clinical gene therapy project of an inherited skin disorder) further developments are still required.

Gene therapy in wound healing: present status and future directions

Gene therapy was traditionally considered a treatment modality for patients with congenital defects of key metabolic functions or late-stage malignancies. The realization that gene therapy applications were much vaster has opened up endless opportunities for therapeutic genetic manipulations, especially in the skin and external wounds. Cutaneous wound healing is a complicated, multistep process with numerous mediators that act in a network of activation and inhibition processes. Gene delivery in this environment poses a particular challenge. Numerous models of gene delivery have been developed, including naked DNA application, viral transfection, high-pressure injection, liposomal delivery, and more. Of the various methods for gene transfer, cationic cholesterol-containing liposomal constructs are emerging as a method with great potential for non-viral gene transfer in the wound. This article aims to review the research on gene therapy in wound healing and possible future directions in this exciting field.

Biomimetic approaches to protein and gene delivery for tissue regeneration

Novel therapeutic strategies that promote wound healing seek to mimic the response of the body to wounding, to regenerate rather than repair injured tissues. Many synthetic or natural biomaterials have been developed for this purpose and are used to deliver wound therapeutics in a controlled manner that prevents unwanted and potentially harmful side-effects. Here, we review the natural and synthetic biomaterials that have been developed for protein and gene delivery to enhance tissue regeneration. Particular emphasis is placed on novel biomimetic materials that respond to environmental stimuli or release their cargo according to cellular demand. Engineering biomaterials to release therapeutic agents in response to physiologic signals mimics the natural healing process and can promote faster tissue regeneration and reduce scarring in severe acute or chronic wounds.

The structure and composition of liposomes can affect skin regeneration, morphology and growth factor expression in acute wounds

Liposomal gene transfer is an effective therapeutic approach to improve dermal and epidermal regeneration. The purpose of the present study was to define whether the biological or chemical structure of a liposome influences cellular and biological regeneration in the skin, and to determine by which mechanisms possible changes occur. Rats were inflicted a full-excision acute wound and divided into three groups to receive weekly subcutaneous injections of DMRIE liposomes plus the Lac Z gene, or DOTAP/Chol liposomes plus the Lac Z gene, or saline. Planimetry, immunological assays, histological and immunohistochemical techniques were used to determine cellular responses after gene transfer, protein expression, dermal and epidermal regeneration. DOTAP/Chol increased IGF-I and KGF protein concentration and caused concomitant cellular responses, for example, by increasing IGFBP-3, P<0.05. DOTAP/Chol liposomes improved epidermal regeneration by exhibiting the most rapid area and linear wound re-epithelization compared to DMRIE or control, P<0.001. DOTAP/Chol and DMRIE exerted promitogenic and antiapoptotic effects on basal keratinocytes, P<0.05. Dermal regeneration was improved in DOTAP/Chol-treated animals by an increased collagen deposition and morphology, P<0.001. DOTAP/Chol liposomes increased vascular endothelial growth factor concentrations and thus neovascularization when compared with DMRIE and saline, P<0.001. In the present study, we showed that different liposomes have different effects on intracellular and biological responses based on its chemical and molecular structure. For gene transfer in acute wounds, the administration of DOTAP/Chol liposomes appears to be beneficial.