Electroporation-mediated HGF gene transfection protected the kidney against graft injury

A Critical Review of Electroporation as A Plasmid Delivery System in Mouse Skeletal Muscle

The gene delivery to skeletal muscles is a promising strategy for the treatment of both muscular disorders (by silencing or overexpression of specific gene) and systemic secretion of therapeutic proteins. The use of a physical method like electroporation with plate or needle electrodes facilitates long-lasting gene silencing in situ. It has been reported that electroporation enhances the expression of the naked DNA gene in the skeletal muscle up to 100 times and decreases the changeability of the intramuscular expression. Coelectransfer of reporter genes such as green fluorescent protein (GFP), luciferase or beta-galactosidase allows the observation of correctly performed silencing in the muscles. Appropriate selection of plasmid injection volume and concentration, as well as electrotransfer parameters, such as the voltage, the length and the number of electrical pulses do not cause long-term damage to myocytes. In this review, we summarized the electroporation methodology as well as the procedure of electrotransfer to the gastrocnemius, tibialis, soleus and foot muscles and compare their advantages and disadvantages.

Glomeruli or interstitium targeted by inter-renal injections supplemented by electroporation: Still a useful tool in renal research

BACKGROUND

Studies concerning proteins are always a crucial part of renal research. As a result of current technologies, scientists have mastered several techniques for generating genetically modified animals. However, in most cases, accessing these animals is still time-consuming and often expensive. This makes the alteration of protein expression by in vivo plasmid transfection an easily-accessible alternative. However, there is still no comprehensive study describing where plasmids would be expressed when they are injected into the kidneys.

METHODS

We injected pEGFP-N1 into rats via intra-/inter-renal channels and detected green fluorescent protein (GFP) by immunohistochemistry and immunofluorescence to localize plasmid expression.

RESULTS

Seven days post-injection, we found that GFP was expressed in the glomeruli when pEGFP-N1 was injected via the renal artery or vein enhanced by electroporation and in the interstitium following injection via the ureter. Other channels, including intraperitoneal, subcapsule and parenchymal injection, only led to scattered expression within the kidneys.

CONCLUSIONS

The present study provides evidence that plasmid transfection via the renal vessels is suitable for glomeruli research and that transfection via the ureter is appropriate for studies regarding interstitium lesions. Additionally, we provide evidence that plasmid transfection on live animals is still an applicable and useful tool, as well as being cost-effective and facile.

Late intervention with the small molecule BB3 mitigates postischemic kidney injury

Ischemia-reperfusion-mediated acute kidney injury can necessitate renal replacement therapy and is a major cause of morbidity and mortality. We have identified BB3, a small molecule, which when first administered at 24 h after renal ischemia in rats, improved survival, augmented urine output, and reduced the increase in serum creatinine and blood urea nitrogen. Compared with control kidneys, the kidneys of BB3-treated animals exhibited reduced levels of kidney injury molecule-1, neutrophil gelatinase-associated lipocalin, and reduced tubular apoptosis and acute tubular necrosis but enhanced tubular regeneration. Consistent with its hepatocyte growth factor-like mode of action, BB3 treatment promoted phosphorylation of renal cMet and Akt and upregulated renal expression of the survival protein Bcl-2. These data suggest that the kidney is amenable to pharmacotherapy even 24 h after ischemia-reperfusion and that activation of the hepatocyte growth factor signaling pathway with the small molecule BB3 confers interventional benefits late into ischemia-reperfusion injury. These data formed, in part, the basis for the use of BB3 in a clinical trial in kidney recipients presenting with delayed graft function.

Targeted electro-delivery of oligonucleotides for RNA interference: siRNA and antimiR

For more than a decade, the understanding of RNA interference (RNAi) has been a growing field of interest. Micro-RNAs (miRNAs) are small regulatory RNAs that play an important role in disease development and progression and therefore represent a potential new class of therapeutic targets. However, delivery of RNAi-based oligonucleotides is one of the most challenging hurdles to RNAi-based drug development. Electropermeabilization (EP) is recognized as a successful non-viral method to transfer nucleic acids into living cells both in vitro and in vivo. EP is the direct application of electric pulses to cells or tissues that transiently permeabilize plasma membranes, allowing the efficient delivery of exogenous molecules. The present review focused on the mechanism of RNAi-based oligonucleotides electrotransfer, from cellular uptake to intracellular distribution. Biophysical theories on oligonucleotide electrotransfer will be also presented. The advantages and few drawbacks of EP-mediated delivery will also be discussed.

Reduction of osteopontin in vivo inhibits tubular epithelial to mesenchymal transition in rats with chronic allograft nephropathy

OBJECTIVE

Chronic allograft nephropathy (CAN) is an important etiological factor causing graft loss. However, the mechanism of CAN is unclear. Osteopontin (OPN), a proinflammatory and profibrosis molecule, plays a key role in late stages of renal diseases. We investigated the potential role of OPN in the pathogenesis of CAN.

METHODS

Using a F344 to Lewis rat CAN model, we injected short hairpin RNA (shRNA) constructs targeting OPN or negative control plasmids through the renal vein following electroporation. At 12 weeks after the transplantation, we determined interstitial fibrosis (IF) and tubular atrophy (TA) of the tubular epithelial cells (TECs). OPN expression was examined using Western blots and immunohistochemistry (IHC). Molecules involved in epithelial to mesenchymal transition (EMT) of TECs were examined using IHC and Western blots.

RESULTS

OPN expression in kidney grafts was decreased by the RNA interference (RNAi) group. Histology observations showed IF and TA to be mild with stable renal function in the RNAi-treated group. EMT of TECs was significantly lessened after reducing OPN.

CONCLUSION

Reduction of OPN in vivo inhibited progression of CAN. OPN may be of therapeutic value in transplantation settings.

Delivery of RNAi-Based Oligonucleotides by Electropermeabilization

For more than a decade, understanding of RNA interference (RNAi) has been a growing field of interest. The potent gene silencing ability that small oligonucleotides have offers new perspectives for cancer therapeutics. One of the present limits is that many biological barriers exist for their efficient delivery into target cells or tissues. Electropermeabilization (EP) is one of the physical methods successfully used to transfer small oligonucleotides into cells or tissues. EP consists in the direct application of calibrated electric pulses to cells or tissues that transiently permeabilize the plasma membranes, allowing efficient in vitro and in vivo cytoplasmic delivery of exogenous molecules. The present review reports on the type of therapeutic RNAi-based oligonucleotides that can be electrotransferred, the mechanism(s) of their electrotransfer and the technical settings for pre-clinical purposes.

Plasmid pUDK-HGF encoding human hepatocyte growth factor gene attenuates gentamicin-induced kidney injury in rats

The clinical application of gentamicin has been limited by its nephrotoxicity, which is characterized by kidney injury, interstitial fibrosis and progressive renal impairment. In this paper, we examine effects of plasmid pUDK-HGF which encodes the human hepatocyte growth factor (HGF) gene on gentamicin-induced renal injury in rats. The kidney injury was intentionally induced by injecting gentamicin intraperitoneally. On the third day after last gentamicin treatment, pUDK-HGF was injected into the left kidney tissue only once via a sterile back incision. At day 30 after gentamicin treatment, RI, Scr, BUN, 24 h-UTP and apoptotic cell death were determined. Tubulointerstitial injury and the renal interstitial vessel regeneration were evaluated by histological scoring. pUDK-HGF treatment significantly improved the renal function with decreasing RI, Scr and BUN. 24 h-UTP also presented ameliorating trend compared to the control group with kidney injury. pUDK-HGF treatment significantly decreased the score of tubulointerstitial injury and enhanced angiogenesis, also prevented kidney cells from apoptosis. The tubulointerstitial injury was significantly reduced in the pUDK-HGF injected left kidney and right kidney also showed some improvements. Our results showed that pUDK-HGF may become a novel therapeutic agent for kidney injury and renal fibrosis.

shRNA-mediated gene knockdown in skeletal muscle

RNA interference appears as a promising tool for therapeutic gene silencing to block protein expression. A long-lived silencing is obtained through the in situ expression of shRNA. A safe approach is to use a physical method such as in vivo electropulsation with plate electrodes. This is presently validated in muscles by the in vivo coelectrotransfer of plasmids specifically coding for expression and silencing of a fluorescent protein. No long-lived tissue damage is observed by the proper choice of the electric pulsing parameters and the amount of injected plasmids. Using a noninvasive fluorescence imaging assay, electrodelivery in mouse muscles is observed to induce complete silencing over more than 2 months in a specific way. The proper choices of the plasmids (sequence, promoter, and relative amounts) appear as key parameters in the successful long-term silencing.

Preservation strategies to reduce ischemic injury in kidney transplantation: pharmacological and genetic approaches

PURPOSE OF REVIEW

In the current graft shortage, it is paramount to improve the quality of transplanted organs. Organ preservation represents an underused therapeutic window with great potential to reduce ischaemia-reperfusion injury (IRI) and improve graft quality. Herein, we review strategies using this window as well as other promising work targeting IRI pathways using pharmacological treatments and gene therapy.

RECENT FINDINGS

We highlight studies using molecules administered during kidney preservation to target key components of IRI such as inflammation, oxidative stress, mitochondrial activity and the coagulation pathway. We further expose recent studies of gene therapy directed against inflammation or apoptosis during cold storage. Other pathways with potential therapeutic molecules are cited.

SUMMARY

The use of cold preservation as a therapeutic window to deliver pharmacological or gene therapy treatments can significantly improve both short-term and long-term graft outcomes. Even if human gene therapy remains hampered by the quantity of agent needed and the potential harmfulness of the vector, it clearly offers a wide array of possibilities for the future. Although gene therapy is still too immature, we expose pharmacological strategies which can readily be applied to the clinic and improve both transplantation success rates and the patients' quality of life.

Protective effects of HGF-MSP chimer (metron factor-1) on liver ischemia-reperfusion injury in rat model

OBJECTIVE

It has been reported that metron factor-1 (MF-1), an engineered chimerical factor containing selected functional domains of hepatocyte growth factor and macrophage-stimulating protein (HGF-MSP), could prevent apoptosis and have an anti-inflammatory effect. In this study, we investigate the protective effect of MF-1 on liver ischemia-reperfusion (I/R) injury.

METHODS

Overall 30 Sprague Dawley rats were randomly divided into three groups: the I/R model group (n=12), the MF-1 treatment group (n=12), and the sham-operated group (n=6). Liver I/R injury was induced by clamping the blood supply to the left and median lobes of liver by an atraumatic clamp for 90 min, then removing the clamp and allowing reperfusion. Blood samples were obtained on days 1, 2, 3 and 7 to assess liver biochemistry and the histology of liver tissue. Levels of malondialdehyde (MDA), superoxide dismutase (SOD), nitric oxide (NO), endothelial nitric oxide synthase and inducible nitric oxide synthase were measured. In addition, the anti-oxidative effect of MF-1 on hepatocytes was assessed in vitro.

RESULTS

MF-1 treatment improved the rat survival rate significantly (P < 0.05). Liver biochemistry and histological changes were significantly ameliorated. MDA increased and SOD and NO decreased in the liver tissue. In vitro, MF-1 protected the human hepatic cell line HL-7702 from damage of oxidative stress.

CONCLUSION

MF-1 could protect the liver from I/R injury, which might involve the reduction of oxygen free radicals and the increase of NO synthesis in an injured liver.

Gene electrotransfer: from biophysical mechanisms to in vivo applications : Part 2 - In vivo developments and present clinical applications

Gene electrotransfer can be obtained not just on single cells in diluted suspension. For more than 10 years, this is a quasi routine strategy in tissue on the living animal and a few clinical trials have now been approved. New problems have been brought by the close contacts of cells in tissue both on the local field distribution and on the access of DNA to target cells. They need to be solved to provide a further improvement in the efficacy and safety of protein expression. There is a competition between gene transfer and cell destruction. Nevertheless, present results are indicative that electrotransfer is a promising approach for gene therapy. High level and long-lived expression of proteins can be obtained in muscles. This is used for a successful method of electrovaccination.

Metron factor-1 prevents liver injury without promoting tumor growth and metastasis

Hepatocyte growth factor (HGF) is the most powerful hepatotrophic factor identified so far. However, the ability of HGF to promote tumor cell "scattering" and invasion raises some concern about its therapeutic safety. We compared the therapeutic efficacy of HGF with that of Metron Factor-1 (MF-1), an engineered cytokine derived from HGF and the HGF-like factor macrophage stimulating protein (MSP), in mouse models of acute and chronic liver injury. At the same time, we tested the ability of HGF and MF-1 to promote tumor growth, angiogenesis, and invasion in several mouse models of cancer. We show that (1) MF-1 and HGF stimulate hepatocyte proliferation in vitro; (2) MF-1 and HGF protect primary hepatocytes against Fas-induced and drug-induced apoptosis; (3) HGF but not MF-1 induces scattering and matrigel invasion of carcinoma cell lines in vitro; (4) HGF but not MF-1 promotes migration and extracellular matrix invasion of endothelial cells in vitro; (5) MF-1 and HGF prevent CCl(4)-induced acute liver injury as measured by alanine aminotransferase (ALT) levels, histology, terminal deoxynucleotidyl transferase-mediated nick-end labeling (TUNEL) analysis, and phospho-histone-3 immunostaining; (6) MF-1 and HGF attenuate liver fibrosis caused by chronic CCl(4) intoxication and promote regeneration as measured by Sirius red staining, alpha-smooth muscle actin immunostaining, and Ki-67 analysis; (7) HGF but not MF-1 promotes tumor growth, angiogenesis, and metastasis in a variety of xenograft models; (8) HGF but not MF-1 promotes intrahepatic dissemination of hepatocarcinoma cells injected orthotopically.

CONCLUSION

These data suggest that MF-1 is as effective as HGF at preventing liver injury and at promoting hepatocyte regeneration, but therapeutically safer than HGF because it lacks proangiogenic and prometastatic activity.

Long-lasting In vivo Gene Silencing by Electrotransfer of shRNA Expressing Plasmid

RNA interference appears as a promising tool for therapeutic gene silencing. A key limit is the delivery of the siRNA. A safe approach is to use a physical method such as in vivo electropulsation with contact electrodes. Getting a long lived silencing can be better approached by using the in situ expression of shRNA. This is presently obtained by using co-electrotransfer of specific plasmids coding for expression and silencing of a fluorescent protein. Using a non invasive fluorescence imaging assay, electrodelivery in mouse muscles is observed to induce complete silencing over more than two months in a specific way. The proper choices of the plasmids (sequence and relative amounts) and of the electric pulsing conditions appear as key parameters in the successful silencing.

Improving islet transplantation by gene delivery of hepatocyte growth factor (HGF) and its downstream target, protein kinase B (PKB)/Akt

Clinical studies have demonstrated that islet transplantation may be a useful procedure to replace beta cell function in patients with Type 1 diabetes. Islet transplantation faces many challenges, including complications associated with the procedure itself, the toxicity of immunosuppression regimens, and to the loss of islet function and insulin-independence with time. Despite the current successes, and residual challenges, these studies have pointed out an enormous scarcity of islet tissue that precludes the use of islet transplantation in a clinical setting on a wider scale. To address this problem, many research groups are trying to identify different islet growth factors and intracellular molecules capable of improving islet graft survival and function, therefore reducing the number of islets needed for successful transplantation. Among these growth factors, hepatocyte growth factor (HGF), a factor known to improve transplantation of a variety of organs/cells, has shown promising results in increasing islet graft survival and reducing the number of islets needed for successful transplantation in four different rodent models of islet transplantation. Protein kinase B (PKB)/Akt, a pro-survival intracellular signaling molecule is known to be activated in the beta cell by several different growth factors, including HGF. PKB/Akt has also shown promising results for improving human islet graft survival and function in a minimal islet mass model of islet transplantation in diabetic SCID mice. Increasing our knowledge on how HGF, PKB/Akt and other emerging molecules work for improving islet transplantation may provide substrate for future therapeutic approaches aimed at increasing the number of patients in which beta cell function can be successfully replaced.

Electroporation-mediated gene therapy

Non-viral gene transfer is markedly enhanced by the application of in vivo electroporation. Electroporation is a safe and efficient system to introduce genes to a wide variety of tissues, including skeletal muscle, tumors, kidney, liver and skin. Electroporation has been demonstrated to be effective in numerous disease models. This review focuses on the principles of electroporation and the target tissues employed for gene therapy. Based on the accumulation of positive results, the first clinical study for the treatment of malignant melanoma is now underway, and preclinical studies have suggested that electroporation is useful as a gene therapy protocol.

Gene therapy targeting kidney diseases: routes and vehicles

Renal gene therapy may offer new strategies to treat diseases of native and transplanted kidneys. Several experimental techniques have been developed and employed using nonviral, viral, and cellular vectors. The most efficient viral vector for in vivo transfection appears to be adenovirus. In addition, enhanced naked plasmid techniques, such as the hemagglutinating virus of Japan (HVJ)-liposome method, electroporation, the hydrodynamic method, and ultrasound with microbubbles, are promising. Trapping genetically modified macrophages in the inflamed kidneys is an elegant method for site-specific gene delivery. The choice of delivery vehicle as well as the administration route determines the site of transduction. In conclusion, for both in vivo and ex vivo renal transfection, enhanced naked plasmids, adenoviruses, and modified cell vectors offer the best prospects for effective clinical application. Moreover, the development of safer and nonimmunogenic vectors may realize clinical renal gene therapy in the near future.

Fibroblasts in cancer

Tumours are known as wounds that do not heal - this implies that cells that are involved in angiogenesis and the response to injury, such as endothelial cells and fibroblasts, have a prominent role in the progression, growth and spread of cancers. Fibroblasts are associated with cancer cells at all stages of cancer progression, and their structural and functional contributions to this process are beginning to emerge. Their production of growth factors, chemokines and extracellular matrix facilitates the angiogenic recruitment of endothelial cells and pericytes. Fibroblasts are therefore a key determinant in the malignant progression of cancer and represent an important target for cancer therapies.

Therapeutic targets in the treatment of allograft fibrosis

The dramatic improvements in short-term graft survival and acute rejection rates could only have been dreamed of 20 years ago. Late graft loss following kidney transplantation is now the critical issue of this decade. Frequently, graft loss is associated with the development of tubular atrophy and interstitial fibrosis within the kidney (i.e. chronic allograft nephropathy; CAN). Major treatment strategies in this disorder are non-specific and the focus of intervention has been on limiting injurious events. Following graft injury is a fibrogenesis phase featuring both proliferative and infiltrative responses mediated by chemokines, cytokines and growth factors. In particular, TGFbeta has been strongly implicated in the pathogenesis of chronic injury and epithelial-mesenchymal transformation (EMT) may be part of this process. The cascade of events results in matrix accumulation, due to either increased production and/or reduced degradation of matrix. Recent investigations into the pathogenesis of tissue fibrosis have suggested a number of new strategies to ameliorate matrix synthesis. While the majority of therapies have focused on TGFbeta, this may not be an ideal maneuver in transplant settings and alternative targets identified in other fibrotic diseases will be discussed. Attacking graft fibrosis should be a new focus in organ transplantation.