Electroporation-mediated interleukin-10 overexpression in skeletal muscle reduces acute rejection in rat cardiac allografts

Efficacy of Combined in-vivo Electroporation-Mediated Gene Transfer of VEGF, HGF, and IL-10 on Skin Flap Survival, Monitored by Label-Free Optical Imaging: A Feasibility Study

Preventing surgical flaps necrosis remains challenging. Laser Doppler imaging and ultrasound can monitor blood flow in flap regions, but they do not directly measure the cellular response to ischemia. The study aimed to investigate the efficacy of synergistic in-vivo electroporation-mediated gene transfer of interleukin 10 (IL-10) with either hepatocyte growth factor (HGF) or vascular endothelial growth factor (VEGF) on the survival of a modified McFarlane flap, and to evaluate the effect of the treatment on cell metabolism, using label-free fluorescence lifetime imaging. Fifteen male Wistar rats (290–320 g) were randomly divided in three groups: group-A (control group) underwent surgery and received no gene transfer. Group-B received electroporation mediated hIL-10 gene delivery 24 h before and VEGF gene delivery 24 h after surgery. Group-C received electroporation mediated hIL-10 gene delivery 24 h before and hHGF gene delivery 24 h after surgery. The animals were assessed clinically and histologically. In addition, label-free fluorescence lifetime imaging was performed on the flap. Synergistic electroporation mediated gene delivery significantly decreased flap necrosis (P = 0.0079) and increased mean vessel density (P = 0.0079) in treatment groups B and C compared to control group-A. NADH fluorescence lifetime analysis indicated an increase in oxidative phosphorylation in the epidermis of the group-B (P = 0.039) relative to controls. These findings suggested synergistic in-vivo electroporation-mediated gene transfer as a promising therapeutic approach to enhance viability and vascularity of skin flap. Furthermore, the study showed that combinational gene therapy promoted an increase in tissue perfusion and a relative increase in oxidative metabolism within the epithelium.

Non-viral Gene Delivery Methods for Bone and Joints

Viral carrier transport efficiency of gene delivery is high, depending on the type of vector. However, viral delivery poses significant safety concerns such as inefficient/unpredictable reprogramming outcomes, genomic integration, as well as unwarranted immune responses and toxicity. Thus, non-viral gene delivery methods are more feasible for translation as these allow safer delivery of genes and can modulate gene expression transiently both in vivo, ex vivo, and in vitro. Based on current studies, the efficiency of these technologies appears to be more limited, but they are appealing for clinical translation. This review presents a summary of recent advancements in orthopedics, where primarily bone and joints from the musculoskeletal apparatus were targeted. In connective tissues, which are known to have a poor healing capacity, and have a relatively low cell-density, i.e., articular cartilage, bone, and the intervertebral disk (IVD) several approaches have recently been undertaken. We provide a brief overview of the existing technologies, using nano-spheres/engineered vesicles, lipofection, and in vivo electroporation. Here, delivery for microRNA (miRNA), and silencing RNA (siRNA) and DNA plasmids will be discussed. Recent studies will be summarized that aimed to improve regeneration of these tissues, involving the delivery of bone morphogenic proteins (BMPs), such as BMP2 for improvement of bone healing. For articular cartilage/osteochondral junction, non-viral methods concentrate on targeted delivery to chondrocytes or MSCs for tissue engineering-based approaches. For the IVD, growth factors such as GDF5 or GDF6 or developmental transcription factors such as Brachyury or FOXF1 seem to be of high clinical interest. However, the most efficient method of gene transfer is still elusive, as several preclinical studies have reported many different non-viral methods and clinical translation of these techniques still needs to be validated. Here we discuss the non-viral methods applied for bone and joint and propose methods that can be promising in clinical use.

In Vivo Electroporation-Mediated, Intrahepatic Alpha1 Antitrypsin Gene Transfer Reduces Pulmonary Emphysema in Pallid Mice

Rationale: Mutation in the alpha1 antitrypsin (AAT) gene leads to low circulating levels of AAT, which is associated with several disease processes including pulmonary emphysema. The standard of care relies on substitution with plasma-purified AAT. We studied a novel approach to obtain sustained therapeutic levels of circulating AAT using nonviral in vivo electroporation-mediated gene transfer to the liver. Methods: In vivo intrahepatic electroporation-mediated human AAT gene transfer was performed in C57 Bl/6J mice carrying a genetic deficiency of murine AAT (pallid mice) and suffering from pulmonary emphysema. The animals were evaluated for lung function using flexiVent and detailed stereological assessments. Lung neutrophilic burden was assessed. Results: Pallid mice showed morphologically detectable pulmonary emphysema. Thirty days after in vivo electroporation-mediated gene transfer directly aimed at the liver, circulating human AAT was elevated and lung function was significantly improved compared to non-treated pallid mice. Stereological analysis revealed a reduction in pulmonary emphysema. Conclusion: Our data indicate that in vivo intrahepatic electroporation-mediated gene transfer of AAT is a safe and efficient procedure resulting in reduction of pulmonary emphysema in pallid mice.

Improvement of Flap Necrosis in a Rat Random Skin Flap Model by In Vivo Electroporation-Mediated HGF Gene Transfer

BACKGROUND

Despite great understanding of underlying mechanisms for flap necrosis and advances in surgical techniques, flap necrosis remains a critical issue. In the present study, the authors investigated the efficacy of electroporation-mediated hepatocyte growth factor (HGF) gene delivery to random dorsal skin flaps (McFarlane) to accelerate wound healing and reduce flap necrosis.

METHODS

Fifteen male Wistar rats (290 to 320 g) were divided randomly into three groups. Group a, the control group (n = 5), underwent surgery and received no gene transfer. Group b received electroporation-mediated HGF gene delivery 24 hours after surgery as a treatment. Group c received electroporation-mediated HGF gene delivery 24 hours before surgery as prophylaxis (n = 5). Planimetry, laser Doppler imaging, and immunohistochemistry were used to assess the efficacy of HGF gene therapy among the groups.

RESULTS

Electroporation-mediated HGF gene delivery significantly decreased flap necrosis percentage compared with the control group in prophylactic and treatment groups (p = 0.0317 and p = 0.0079, respectively) and significantly increased cutaneous perfusion compared with the control group (p = 0.0317 and p = 0.0159, respectively). Moreover, Spearman rank correlation showed a significant negative correlation between flap necrosis percentage and laser index (p = 0.0213 and r = -0.5964, respectively). Furthermore, significantly higher mean CD31 vessel density was detected in treatment and prophylactic groups (p = 0.0079 and p = 0.0159, respectively). In addition, quantitative image analysis revealed significantly higher HGF protein expression in groups b and c (p = 0.0079 and p = 0.0079, respectively).

CONCLUSION

These findings suggested in vivo electroporation-mediated HGF gene delivery enhanced viability and vascularity of the ischemic skin flap.

Efficacy of In Vivo Electroporation-Mediated IL-10 Gene Delivery on Survival of Skin Flaps

Despite advances in understanding the underlying mechanisms of flap necrosis and improvement in surgical techniques, skin flap necrosis after reconstructive surgery remains a crucial issue. We investigated the efficacy of electroporation-mediated IL-10 gene transfer to random skin flap with an aim to accelerate wound healing and improve skin flap survival. Nine male Wistar rats (300-330 g) were divided in two groups (a) control group (n = 5), only surgery no gene transfer, and (b) experimental group, received electroporation-mediated IL-10 gene transfer 24 h before the surgery as prophylaxis (n = 4). Random skin flap (McFarlane) was performed in both groups. Planimetry, Laser Doppler imaging, and immunohistochemistry were used to evaluate the effect of IL-10 gene transfer between study groups at day 7. Electroporation-mediated IL-10 gene transfer decreased percentage of flap necrosis (p value = 0.0159) and increased cutaneous perfusion compared to the control group (p value = 0.0159). In addition, Spearman's rank correlation showed a significant negative correlation between percentage of flap necrosis and Laser Index (p value = 0.0083, r -0.83, respectively). Furthermore, significantly higher mean CD31⁺ vessel density was detected in the experimental group compared to the control group (p value = 0.0159). Additionally, semi-quantitative image analysis showed lower inflammatory cell count in experimental group compared to control group (p value = 0.0317). In vivo electroporation-mediated IL-10 gene transfer reduced necrosis, enhanced survival and vascularity in the ischemic skin flap.

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

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

In vivo electroporation mediated gene delivery to the beating heart

Gene therapy may represent a promising alternative strategy for cardiac muscle regeneration. In vivo electroporation, a physical method of gene transfer, has recently evolved as an efficient method for gene transfer. In the current study, we investigated the efficiency and safety of a protocol involving in vivo electroporation for gene transfer to the beating heart. Adult male rats were anesthetised and the heart exposed through a left thoracotomy. Naked plasmid DNA was injected retrograde into the transiently occluded coronary sinus before the electric pulses were applied. Animals were sacrificed at specific time points and gene expression was detected. Results were compared to the group of animals where no electric pulses were applied. No post-procedure arrhythmia was observed. Left ventricular function was temporarily altered only in the group were high pulses were applied; CK-MB (Creatine kinase) and TNT (Troponin T) were also altered only in this group. Histology showed no signs of toxicity. Gene expression was highest at day one. Our results provide evidence that in vivo electroporation with an optimized protocol is a safe and effective tool for nonviral gene delivery to the beating heart. This method may be promising for clinical settings especially for perioperative gene delivery.

Non-viral vectors in cystic fibrosis gene therapy: recent developments and future prospects

Gene therapy has been proposed for a wide range of human diseases but few have received the level of attention over such a prolonged period as cystic fibrosis (CF) with over 20 clinical studies undertaken. Following a 10-year interval, clinical trials of an aerosolisable non-viral gene transfer agent have recently been initiated by researchers in the United Kingdom. Here we review the rationale and requirements for effective gene therapy for CF lung disease. The previous non-viral gene therapy trials are discussed and the prospects for the current leading non-viral formulations for CF gene therapy are considered. Factors affecting the selection and design of the plasmid DNA molecule, likely to be of central importance to clinical efficacy, are reviewed and we describe the potential merits of the formulation that has been selected for the forthcoming UK trials.

Delivery of DNA into muscle for treating systemic diseases: advantages and challenges

An efficient and safe method to deliver DNA in vivo is a requirement for several purposes, such as the study of gene function and gene therapy applications. Among the different nonviral delivery methods currently under investigation, in vivo DNA electrotransfer has proven to be one of the most efficient and simple methods. This technique is a physical method of gene delivery consisting of a local application of electric pulses after injection of DNA. This technique can be applied to almost any tissue of a living animal, including tumors, skin, liver, kidney, artery, retina, cornea, or even brain, but the focus of this review will be on electrotransfer of plasmid DNA into skeletal muscle and its possible therapeutic uses for systemic diseases. Skeletal muscle is a good target for electrotransfer of DNA because of the following features: a large volume of easily accessible tissue, an endocrine organ capable of expressing several local and systemic factors, and muscle fibers as postmitotic cells have a long lifespan, which allows long-term gene expression. In this review, we will describe the main characteristics of DNA electrotransfer, including toxicity and safety issues related to this technique. We will focus on the important possible therapeutic applications of electrotransfer for systemic diseases demonstrated in animal models in the recent years, in the fields of monogenic diseases, tissue-specific diseases, metabolic disorders, immune-system-related diseases, and cancer. Finally, we will discuss the advantages and challenges of this technique.