High-level expression of naked DNA delivered to rat liver via tail vein injection

Understanding the Role of miR-29a in the Regulation of RAG1, a Gene Associated with the Development of the Immune System

The process of Ag receptor diversity is initiated by RAGs consisting of RAG1 and RAG2 in developing lymphocytes. Besides its role as a sequence-specific nuclease during V(D)J recombination, RAGs can also act as a structure-specific nuclease leading to genome instability. Thus, regulation of RAG expression is essential to maintaining genome stability. Previously, the role of miR29c in the regulation of RAG1 was identified. In this article, we report the regulation of RAG1 by miR-29a in the lymphocytes of both mice (Mus musculus) and humans (Homo sapiens). The level of RAG1 could be modulated by overexpression of miR-29a and inhibition using anti-miRs. Argonaute2-immunoprecipitation and high-throughput sequencing of RNA isolated by crosslinking immunoprecipitation studies established the association of miR-29a and RAG1 with Argonaute proteins. We observed a negative correlation between miR-29a and RAG1 levels in mouse B and T cells and leukemia patients. Overexpression of pre-miR-29a in the bone marrow cells of mice led to the generation of mature miR-29a transcripts and reduced RAG1 expression, which led to a significant reduction in V(D)J recombination in pro-B cells. Importantly, our studies are consistent with the phenotype reported in miR-29a knockout mice, which showed impaired immunity and survival defects. Finally, we show that although both miR-29c and miR-29a can regulate RAG1 at mRNA and protein levels, miR-29a substantially impacts immunity and survival. Our results reveal that the repression of RAG1 activity by miR-29a in B cells of mice and humans is essential to maintain Ig diversity and prevent hematological malignancies resulting from aberrant RAG1 expression in lymphocytes.

Gene targeting in adult organs using in vivo cleavable donor plasmids for CRISPR-Cas9 and CRISPR-Cas12a

The CRISPR-Cas system for in vivo genome editing is a powerful tool for gene therapy against several diseases. We have previously developed the pCriMGET_9-12a system, an in vivo cleavable donor plasmid for precise targeted knock-in of exogenous DNA by both Cas9 and Cas12a. Here, we show that the pCriMGET_9-12a system can be applied for in vivo in-frame knock-in of exogenous DNA in adult mouse liver by hydrodynamic delivery of the targeting plasmids. The in vivo cleavable pCriMGET_9-12a donor plasmids significantly increased the knock-in efficiency of both CRISPR-Cas9 and CRISPR-Cas12a in the adult mouse liver compared to uncleavable donor plasmids. This strategy also achieved in-frame reporter gene knock-in without indel mutations. Therefore, in vivo gene targeting using the pCriMGET_9-12a system may contribute to the establishment of safer, more precise, versatile and efficient gene therapy methods in adult organs.

Forced Hepatic Expression of NRF2 or NQO1 Impedes Hepatocyte Lipid Accumulation in a Lipodystrophy Mouse Model

Lipodystrophy is a disorder featuring loss of normal adipose tissue depots due to impaired production of normal adipocytes. It leads to a gain of fat deposition in ectopic tissues such as liver and skeletal muscle that results in steatosis, dyslipidemia, and insulin resistance. Previously, we established a Rosa NIC/NIC::AdiCre lipodystrophy model mouse. The lipodystrophic phenotype that included hepatomegaly accompanied with hepatic damage due to higher lipid accumulation was attenuated substantially by amplified systemic NRF2 signaling in mice with hypomorphic expression of Keap1; whole-body Nrf2 deletion abrogated this protection. To determine whether hepatic-specific NRF2 signaling would be sufficient for protection against hepatomegaly and fatty liver development, direct, powerful, transient expression of Nrf2 or its target gene Nqo1 was achieved by administration through hydrodynamic tail vein injection of pCAG expression vectors of dominant-active Nrf2 and Nqo1 in Rosa NIC/NIC::AdiCre mice fed a 9% fat diet. Both vectors enabled protection from hepatic damage, with the pCAG-Nqo1 vector being the more effective as seen with a ~50% decrease in hepatic triglyceride levels. Therefore, activating NRF2 signaling or direct elevation of NQO1 in the liver provides new possibilities to partially reduce steatosis that accompanies lipodystrophy.

Evolution of molecular switches for regulation of transgene expression by clinically licensed gluconate

Synthetic biology holds great promise to improve the safety and efficacy of future gene and engineered cell therapies by providing new means of endogenous or exogenous control of the embedded therapeutic programs. Here, we focused on gluconate as a clinically licensed small-molecule inducer and engineered gluconate-sensitive molecular switches to regulate transgene expression in human cell cultures and in mice. Several switch designs were assembled based on the gluconate-responsive transcriptional repressor GntR from Escherichia coli. Initially we assembled OFF- and ON-type switches by rewiring the native gluconate-dependent binding of GntR to target DNA sequences in mammalian cells. Then, we utilized the ability of GntR to dimerize in the presence of gluconate to activate gene expression from a split transcriptional activator. By means of random mutagenesis of GntR combined with phenotypic screening, we identified variants that significantly enhanced the functionality of the genetic devices, enabling the construction of robust two-input logic gates. We also demonstrated the potential utility of the synthetic switch in two in vivo settings, one employing implantation of alginate-encapsulated engineered cells and the other involving modification of host cells by DNA delivery. Then, as proof-of-concept, the gluconate-actuated genetic switch was connected to insulin secretion, and the components encoding gluconate-induced insulin production were introduced into type-1 diabetic mice as naked DNA via hydrodynamic tail vein injection. Normoglycemia was restored, thereby showcasing the suitability of oral gluconate to regulate in situ production of a therapeutic protein.

Could artificial intelligence revolutionize the development of nanovectors for gene therapy and mRNA vaccines?

Gene therapy enables the introduction of nucleic acids like DNA and RNA into host cells, and is expected to revolutionize the treatment of a wide range of diseases. This growth has been further accelerated by the discovery of CRISPR/Cas technology, which allows accurate genomic editing in a broad range of cells and organisms in vitro and in vivo. Despite many advances in gene delivery and the development of various viral and non-viral gene delivery vectors, the lack of highly efficient non-viral systems with low cellular toxicity remains a challenge. The application of cutting-edge technologies such as artificial intelligence (AI) has great potential to find new paradigms to solve this issue. Herein, we review AI and its major subfields including machine learning (ML), neural networks (NNs), expert systems, deep learning (DL), computer vision and robotics. We discuss the potential of AI-based models and algorithms in the design of targeted gene delivery vehicles capable of crossing extracellular and intracellular barriers by viral mimicry strategies. We finally discuss the role of AI in improving the function of CRISPR/Cas systems, developing novel nanobots, and mRNA vaccine carriers.

Therapeutic effect of multiple functional minicircle vector encoding anti-CD25/IL-10/CXCR3 in allograft rejection model

BACKGROUND/AIMS

We previously proposed minicircle vector technology as the potential platform for the development and production of new biologics. In this study, we have designed a novel target molecule for the treatment of allograft rejection and evaluated its feasibility as the therapeutic agent in this disease using the minicircle vector system.

METHODS

We engineered vectors to carry cassette sequences for anti-CD25, interleukin-10 (IL-10), and C-X-C motif chemokine receptor 3 (CXCR3) fusion protein, and then isolated minicircle vectors from the parent vectors. We verified the substantial production of anti-CD25/IL-10/CXCR3 fusion protein from minicircles and their duration in HEK293T cells and mice models. We also evaluated whether minicircle-derived anti-CD25/IL-10/CXCR3 has therapeutic effects in a skin allograft in mice model.

RESULTS

We confirmed the production of anti-CD25/IL-10/CXCR3 from minicircle by its significant availability in cells transfected with the minicircle and in its conditioned media. After a single injection of minicircle by hydrodynamic injection via mouse tail vein, luminescence or red fluorescence was maintained until 40 days in the liver tissue, suggesting the production of anti-CD25/IL-10/CXCR3 protein from minicircles via protein synthesis machinery in the liver. Mice treated with the minicircle encoding anti-CD25/IL-10/CXCR3 showed prolonged skin allograft survival times accompanied by improved immunologic regulation e.g., reduction of the lymphocyte population of Th1, Th2, and Th17 and an induction of regulatory T cells.

CONCLUSION

These findings implied that self-generated anti-CD25/IL-10/CXCR3 protein drug by minicircle technology is functionally active and relevant for reducing allograft rejection. The minicircle vector system may be useful for developing new biological drugs, avoiding manufacturing or practical problems.

Hydrodynamic Injection for Developing NASH Model

The hydrodynamic tail vein injection (HTVi) is a technique that is used to deliver plasmid genes into live mice or rats. The HTVi leads to the in vivo transfection of exogenous DNA primarily in the liver, serving as a reliable approach of establishing animal models for the study of liver diseases. The nonalcoholic steatohepatitis (NASH) is liver inflammation and damage resulting from an accumulation of fat in the liver. With the rising prevalence of obesity worldwide, NASH is becoming an increasingly common health problem. The pathogenesis of NASH is a multi-step process involving complicated pathways. The molecular mechanisms of NASH remain poorly understood. Here, we describe the use of HTVi to establish animal models for the study of NASH.

Evolution of the Experimental Models of Cholangiocarcinoma

Cholangiocarcinoma (CCA) is a rare, aggressive disease with poor overall survival. In advanced cases, surgery is often not possible or fails; in addition, there is a lack of effective and specific therapies. Multidisciplinary approaches and advanced technologies have improved the knowledge of CCA molecular pathogenesis, highlighting its extreme heterogeneity and high frequency of genetic and molecular aberrations. Effective preclinical models, therefore, should be based on a comparable level of complexity. In the past years, there has been a consistent increase in the number of available CCA models. The exploitation of even more complex CCA models is rising. Examples are the use of CRISPR/Cas9 or stabilized organoids for in vitro studies, as well as patient-derived xenografts or transgenic mouse models for in vivo applications. Here, we examine the available preclinical CCA models exploited to investigate: (i) carcinogenesis processes from initiation to progression; and (ii) tools for personalized therapy and innovative therapeutic approaches, including chemotherapy and immune/targeted therapies. For each model, we describe the potential applications, highlighting both its advantages and limits.

Hydrodynamics-based liver transfection achieves gene silencing of CB1 using short hairpin RNA plasmid in cirrhotic rats

Background

There is a correlation between the endocannabinoid system and hepatic fibrosis based on the activation of CB1 and CB2 receptors; where CB1 has profibrogenic effects. Gene therapy with a plasmid carrying a shRNA for CB1 delivered by hydrodynamic injection has the advantage of hepatic tropism, avoiding possible undesirable effects of CB1 pharmacological inhibition.

Objective

To evaluate hydrodynamics-based liver transfection in an experimental model of liver cirrhosis of a plasmid with the sequence of a shRNA for CB1 and its antifibrogenic effects

Methods

Three shRNA (21pb) were designed for blocking CB1 mRNA at positions 877, 1232 and 1501 (pshCB1-A, B, C). Sequences were cloned in the pENTR^™/U6. Safety was evaluated monitoring CB1 expression in brain tissue. The silencing effect was determined in rat HSC primary culture and CCl₄ cirrhosis model. Hydrodynamic injection in cirrhotic liver was through iliac vein and with a dose of 3mg/kg plasmid. Serum levels of liver enzymes, mRNA levels of TGF-β1, Col IA1 and α-SMA and the percentage of fibrotic tissue were analyzed.

Results

Hydrodynamic injection allows efficient CB1 silencing in cirrhotic livers and pshCB1-B (position 1232) demonstrated the main CB1-silencing. Using this plasmid, mRNA level of fibrogenic molecules and fibrotic tissue considerably decrease in cirrhotic animals. Brain expression of CB1 remained unaltered.

Conclusion

Hydrodynamics allows a hepatotropic and secure transfection in cirrhotic animals. The sequence of the shCB1-B carried in a plasmid or any other vector has the potential to be used as therapeutic strategy for liver fibrosis.

Host cell in vivo production of the synthetic drug anti-CD25/IL-10 using minicircle vector

Synthetic biologic drugs are highly successful for induction therapy in transplantation, but the development of novel biologics is limited because of the high cost of synthesis and purification. In this study, we developed a novel strategy for the production of synthetic protein drugs in vivo by the host itself. We utilized minicircle (MC) technology, which can robustly express a target molecule and secrete it from cells, as an indirect method to produce a protein of interest in vivo. We designed an MC vector containing the sequences of basiliximab (anti-CD25 mAb) and IL-10. We verified the substantial production of the anti-CD25/IL-10 protein from the MC in vitro and in vivo. The therapeutic effect of MC-derived anti-CD25/IL-10 was evaluated in a skin allograft mouse model by single intravenous infusion. Mice treated with the MC encoding anti-CD25/IL-10 exhibited prolonged skin allograft survival times accompanied by improved histologic changes and immunologic regulation. These findings indicate that the anti-CD25/IL-10 protein drug obtained by MC technology is functionally active and relevant for reducing allograft rejection. This self-reproducible strategy for synthetic protein drugs using MCs is a promising tool for transplantation.-Lim, S. W., Shin, Y. J., Luo, K., Quan, Y., Ko, E. J., Chung, B. H., Yang, C. W. Host cell in vivo production of the synthetic drug anti-CD25/IL-10 using minicircle vector.

Overexpression of C‑sis inhibits H2O2‑induced Buffalo rat liver cell apoptosis in vitro and alleviates liver injury in a rat model of fulminant hepatic failure

The present study aimed to investigate the role of the C‑sis gene in the apoptosis of hepatocytes in vitro and in the liver function of a rat model of fulminant hepatic failure (FHF). Buffalo rat liver (BRL) cells were treated with hydrogen peroxide (H2O2) to induce apoptosis and then transfected with a C‑sis overexpression vector. A rat model of FHF was established, and C‑sis was overexpressed. The mRNA and protein expression of C‑sis were examined using reverse transcription‑polymerase chain reaction and western blot analyses, respectively. Cell viability was assessed by CCK8, and a TUNEL assay was used to examine cell apoptosis. Flow cytometry was used for cell cycle detection. Hematoxylin and eosin staining was used for histological examination. The levels of alanine transaminase (ALT) and aspartate transaminase (AST) were also examined in the rats. The results showed that C‑sis was successfully overexpressed in the cells and rat model. Compared with H2O2‑treated BRL cells, the overexpression of C‑sis significantly inhibited cell apoptosis, promoted cell viability, and decreased the expression of cleaved caspase-3. Similar results were observed in the FHF rats treated with the C‑sis overexpression plasmid, compared with those treated with empty plasmids. In addition, in the FHF rats overexpressing C‑sis, histological examination showed that liver injury was alleviated, the levels of ALT and AST were significantly decreased, and mortality rate was significantly decreased, compared with those observed in the rats treated with empty plasmids. In conclusion, the overexpression of C‑sis inhibited the H2O2‑induced apoptosis of BRL cells in vitro, and alleviated liver injury, improved liver function, and decreased mortality rates in rat models of FHF.

Effects of Simultaneous Downregulation of PHD1 and Keap1 on Prevention and Reversal of Liver Fibrosis in Mice

Background and Aim: To investigate whether double-knockdown of PHD1 and Keap1 in mice could enhance the resolution of carbon tetrachloride (CCl₄)-induced liver fibrosis. Methods: The liver fibrosis model of mice was established by intraperitoneal injection of 25% CCl₄ in olive oil (4 ul/g) twice a week for 8 weeks. PHD1shRNA and Keap1shRNA eukaryotic expression plasmids were simultaneously administered from the beginning of the first to fourth week (preventive group) or from the fifth to eighth week of CCl₄ injection (therapeutic group) via hydrodynamic-based tail vein injection. Successful transfection was confirmed with the expression of red fluorescent protein and green fluorescent protein in hepatocytes. Western blot was used for determining the expression of PHD1 and Keap1, HE, Sirius red, and Masson staining for evaluating the histopathological stages of fibrosis. Immunohistochemical techniques were applied to evaluate the expression of a-SMA. Results: The fluorescence of red and green were observed mainly in hepatocytes, and downregulation of PHD1 and Keap1 expression in liver was detected by western blot. Meanwhile, double-knockdown of PHD1 and Keap1 in mice alleviated liver fibrosis, and the effect was further enhanced especially in the preventive group. Immunocytochemical staining showed decreased expression of a-SMA when both PHD1 and Keap1 were knockdown. Conclusion: Downregulation of PHD1 and Keap1 expression in the liver could be achieved via hydrodynamic injection of PHD1shRNA and Keap1shRNA, thereby, preventing liver fibrosis.

Constitutive and Inducible Systems for Genetic In Vivo Modification of Mouse Hepatocytes Using Hydrodynamic Tail Vein Injection

In research models of liver cancer, regeneration, inflammation, and fibrosis, flexible systems for in vivo gene expression and silencing are highly useful. Hydrodynamic tail vein injection of transposon-based constructs is an efficient method for genetic manipulation of hepatocytes in adult mice. In addition to constitutive transgene expression, this system can be used for more advanced applications, such as shRNA-mediated gene knock-down, implication of the CRISPR/Cas9 system to induce gene mutations, or inducible systems. Here, the combination of constitutive CreER expression together with inducible expression of a transgene or miR-shRNA of choice is presented as an example of this technique. We cover the multi-step procedure starting from the preparation of sleeping beauty-transposon constructs, to the injection and treatment of mice, and the preparation of liver tissue for analysis by immunostaining. The system presented is a reliable and efficient approach to achieve complex genetic manipulations in hepatocytes. It is specifically useful in combination with Cre/loxP-based mouse strains and can be applied to a variety of models in the research of liver disease.

Preclinical and clinical advances in transposon-based gene therapy

Transposons derived from Sleeping Beauty (SB), piggyBac (PB), or Tol2 typically require cotransfection of transposon DNA with a transposase either as an expression plasmid or mRNA. Consequently, this results in genomic integration of the potentially therapeutic gene into chromosomes of the desired target cells, and thus conferring stable expression. Non-viral transfection methods are typically preferred to deliver the transposon components into the target cells. However, these methods do not match the efficacy typically attained with viral vectors and are sometimes associated with cellular toxicity evoked by the DNA itself. In recent years, the overall transposition efficacy has gradually increased by codon optimization of the transposase, generation of hyperactive transposases, and/or introduction of specific mutations in the transposon terminal repeats. Their versatility enabled the stable genetic engineering in many different primary cell types, including stem/progenitor cells and differentiated cell types. This prompted numerous preclinical proof-of-concept studies in disease models that demonstrated the potential of DNA transposons for ex vivo and in vivo gene therapy. One of the merits of transposon systems relates to their ability to deliver relatively large therapeutic transgenes that cannot readily be accommodated in viral vectors such as full-length dystrophin cDNA. These emerging insights paved the way toward the first transposon-based phase I/II clinical trials to treat hematologic cancer and other diseases. Though encouraging results were obtained, controlled pivotal clinical trials are needed to corroborate the efficacy and safety of transposon-based therapies.

Improved siRNA delivery efficiency via solvent-induced condensation of micellar nanoparticles

Efficient delivery of short interfering RNA (siRNA) remains one of the primary challenges of RNA interference therapy. Polyethylene glycol (PEG)ylated polycationic carriers have been widely used for the condensation of DNA and RNA molecules into complex-core micelles. The PEG corona of such nanoparticles can significantly improve their colloidal stability in serum, but PEGylation of the carriers also reduces their condensation capacity, hindering the generation of micellar particles with sufficient complex stability. This presents a particularly significant challenge for packaging siRNA into complex micelles, as it has a much smaller size and more rigid chain structure than DNA plasmids. Here, we report a new method to enhance the condensation of siRNA with PEGylated linear polyethylenimine using organic solvent and to prepare smaller siRNA nanoparticles with a more extended PEG corona and consequently higher stability. As a proof of principle, we have demonstrated the improved gene knockdown efficiency resulting from the reduced siRNA micelle size in mice livers following intravenous administration.

Effects of an intravitreal injection of interleukin-35-expressing plasmid on pro-inflammatory and anti-inflammatory cytokines

In order to explore the potential effects of interleukin (IL)-35 on IL-10, transforming growth factor-β (TGF-β), interferon-γ (INF)-γ, IL-12 and IL-17, a pcDNA3.1‑IL-35 plasmid was injected into the vitreous cavity of BALB/c mice. Enzyme-linked immunosorbent assay, western blot analysis and quantitative PCR analysis were performed to confirm the successful expression of IL-35. Slit-lamp biomicroscopy, hematoxylin and eosin staining and immunofluorescence were employed to detect the status of eyes, and western blot analysis was performed to examine the expression of corneal graft rejection-related cytokines. There were no abnormalities in the eyes pre-mydriasis or post-mydriasis and no injuries to the cornea or retina following the injection of IL-35-expressing plasmid. An immunofluorescence assay detected the positive expression of IL-35 in corneal epithelial cells from IL-35‑injected mice and negative staining in the control group. Further study revealed that IL-35 enhanced the expression of IL-10 and TGF-β which reached their highest levels at 1 and 2 weeks after injection, respectively (p<0.01). Moreover, the expression of INF-γ and IL-12 was decreased significantly at 2 weeks after the injection of IL-35-expressing plasmid (p<0.05), and the expression of IL-17 was suppressed notably at 4 weeks after the injection (p<0.05). The intravitreal injection of IL-35-expressing plasmid in mice downregulates the expression of pro-inflammatory cytokines and upregulates the expression of anti-inflammatory cytokines. Thus, IL-35 may further be assessed as a potential target for the treatment of corneal graft rejection.

Non-Invasive Imaging Serum Amyloid A Activation through the NF-κB Signal Pathway upon Gold Nanostructure Exposure

With the objective of investigating the acute activation of inflammatory cascades upon exposure to gold nanoparticles (GNPs) as well as detailing the mechanisms, a reporter mouse model that allows for non-invasive and longitudinal imaging of hepatic acute-phase serum amyloid A (SAA) activation is constructed. The model is able to visualize SAA activation at the transcriptional stage, with higher sensitivity than serum protein detection by ELISA. GNPs of various sizes (10-80 nm) and geometries are assessed using the reporter mice with results demonstrating that 50 nm nanospheres (GNS50) possess the highest capacity to induce hepatic SAA activation. Detailed analysis uncovers that resident macrophages in the liver are the main origins of these cytokines and that the exposure to GNS50 significantly induces the M1 macrophage phenotype. Moreover, those M1-polarized macrophages, together with the subsequently secreted pro-inflammatory cytokines, exert effects on hepatocytes and then initiate SAA transcription through the NF-κB signal pathway. The results detail the sequential reactions to GNPs among macrophages, inflammatory mediators, and SAA-synthesizing hepatocytes, which shed light on the acute effects of GNPs on the body. In addition, the established in situ and highly sensitive SAA detection system is expected to have vast applications in evaluating NP-induced acute inflammatory reactions.

Restoration of Haemoglobin Level Using Hydrodynamic Gene Therapy with Erythropoietin Does Not Alleviate the Disease Progression in an Anaemic Mouse Model for TGFβ1-Induced Chronic Kidney Disease

Erythropoietin, Epo, is a 30.4 kDa glycoprotein hormone produced primarily by the fetal liver and the adult kidney. Epo exerts its haematopoietic effects by stimulating the proliferation and differentiation of erythrocytes with subsequent improved tissue oxygenation. Epo receptors are furthermore expressed in non-haematopoietic tissue and today, Epo is recognised as a cytokine with many pleiotropic effects. We hypothesize that hydrodynamic gene therapy with Epo can restore haemoglobin levels in anaemic transgenic mice and that this will attenuate the extracellular matrix accumulation in the kidneys. The experiment is conducted by hydrodynamic gene transfer of a plasmid encoding murine Epo in a transgenic mouse model that overexpresses TGF-β1 locally in the kidneys. This model develops anaemia due to chronic kidney disease characterised by thickening of the glomerular basement membrane, deposition of mesangial matrix and mild interstitial fibrosis. A group of age matched wildtype littermates are treated accordingly. After a single hydrodynamic administration of plasmid DNA containing murine EPO gene, sustained high haemoglobin levels are observed in both transgenic and wildtype mice from 7.5 ± 0.6 mmol/L to 9.4 ± 1.2 mmol/L and 10.7 ± 0.3 mmol/L to 15.5 ± 0.5 mmol/L, respectively. We did not observe any effects in the thickness of glomerular or tubular basement membrane, on the expression of different collagen types in the kidneys or in kidney function after prolonged treatment with Epo. Thus, Epo treatment in this model of chronic kidney disease normalises haemoglobin levels but has no effect on kidney fibrosis or function.

A synthetic erectile optogenetic stimulator enabling blue-light-inducible penile erection

Precise spatiotemporal control of physiological processes by optogenetic devices inspired by synthetic biology may provide novel treatment opportunities for gene- and cell-based therapies. An erectile optogenetic stimulator (EROS), a synthetic designer guanylate cyclase producing a blue-light-inducible surge of the second messenger cyclic guanosine monophosphate (cGMP) in mammalian cells, enabled blue-light-dependent penile erection associated with occasional ejaculation after illumination of EROS-transfected corpus cavernosum in male rats. Photostimulated short-circuiting of complex psychological, neural, vascular, and endocrine factors to stimulate penile erection in the absence of sexual arousal may foster novel advances in the treatment of erectile dysfunction.

Hepatic dimethylarginine-dimethylaminohydrolase1 is reduced in cirrhosis and is a target for therapy in portal hypertension

BACKGROUND & AIMS

Portal hypertension is characterized by reduced hepatic eNOS activity. Asymmetric-dimethylarginine (ADMA), an eNOS inhibitor, is elevated in cirrhosis and correlates with the severity of portal hypertension. Dimethylarginine dimethylaminohydrolase-1 (DDAH-1) is the key enzyme metabolizing hepatic ADMA. This study characterized DDAH-1 in cirrhosis, and explored hepatic DDAH-1 reconstitution through farnesoid X receptor (FXR) agonism and DDAH-1 gene therapy.

METHODS

DDAH-1 immunohistochemistry was conducted on human cirrhosis and healthy liver tissue. Subsequently, sham-operated or bile-duct-ligated (BDL) cirrhosis rats were treated with the FXR agonist obeticholic acid (OA, 5 mg/kg) or vehicle for 5 days. Further, animals underwent hydrodynamic injection with DDAH-1-expressing plasmid or saline control, which resulted in the following groups: sham+saline, BDL+saline, BDL+DDAH-1-plasmid. Portal pressure (PP) measurements were performed. Plasma ALT was measured by COBAS INTEGRA, DDAH-1 expression by qPCR and Western blot, eNOS activity by radiometric assay.

RESULTS

Immunohistochemistry and Western-blotting confirmed hepatic DDAH-1 was restricted to hepatocytes, and expression decreased significantly in cirrhosis. In BDL rats, reduced DDAH-1 expression was associated with elevated hepatic ADMA, reduced eNOS activity and high PP. OA treatment significantly increased DDAH-1 expression, reduced hepatic tissue ADMA, and increased liver NO generation. PP was significantly reduced in BDL+OA vs. BDL+vehicle (8±1 vs. 13.5±0.6 mmHg; p<0.01) with no change in the mean arterial pressure (MAP). Similarly, DDAH-1 hydrodynamic injection significantly increased hepatic DDAH-1 gene and protein expression, and significantly reduced PP in BDL+DDAH-1 vs. BDL+saline (p<0.01).

CONCLUSIONS

This study demonstrates DDAH-1 is a specific molecular target for portal pressure reduction, through actions on ADMA-mediated regulation of eNOS activity. Our data support translational studies, targeting DDAH-1 in cirrhosis and portal hypertension.

Hydrodynamic delivery

Hydrodynamic delivery (HD) is a broadly used procedure for DNA and RNA delivery in rodents, serving as a powerful tool for gene/protein drug discovery, gene function analysis, target validation, and identification of elements in regulating gene expression in vivo. HD involves a pressurized injection of a large volume of solution into a vasculature. New procedures are being developed to satisfy the need for a safe and efficient gene delivery in clinic. Here, we summarize the fundamentals of HD, its applications, and future perspectives for clinical use.

A new strategy to deliver synthetic protein drugs: self-reproducible biologics using minicircles

Biologics are the most successful drugs used in anticytokine therapy. However, they remain partially unsuccessful because of the elevated cost of their synthesis and purification. Development of novel biologics has also been hampered by the high cost. Biologics are made of protein components; thus, theoretically, they can be produced in vivo. Here we tried to invent a novel strategy to allow the production of synthetic drugs in vivo by the host itself. The recombinant minicircles encoding etanercept or tocilizumab, which are synthesized currently by pharmaceutical companies, were injected intravenously into animal models. Self-reproduced etanercept and tocilizumab were detected in the serum of mice. Moreover, arthritis subsided in mice that were injected with minicircle vectors carrying biologics. Self-reproducible biologics need neither factory facilities for drug production nor clinical processes, such as frequent drug injection. Although this novel strategy is in its very early conceptual stage, it seems to represent a potential alternative method for the delivery of biologics.

Transient expression of proteins by hydrodynamic gene delivery in mice

Efficient expression of transgenes in vivo is of critical importance in studying gene function and developing treatments for diseases. Over the past years, hydrodynamic gene delivery (HGD) has emerged as a simple, fast, safe and effective method for delivering transgenes into rodents. This technique relies on the force generated by the rapid injection of a large volume of physiological solution to increase the permeability of cell membranes of perfused organs and thus deliver DNA into cells. One of the main advantages of HGD is the ability to introduce transgenes into mammalian cells using naked plasmid DNA (pDNA). Introducing an exogenous gene using a plasmid is minimally laborious, highly efficient and, contrary to viral carriers, remarkably safe. HGD was initially used to deliver genes into mice, it is now used to deliver a wide range of substances, including oligonucleotides, artificial chromosomes, RNA, proteins and small molecules into mice, rats and, to a limited degree, other animals. This protocol describes HGD in mice and focuses on three key aspects of the method that are critical to performing the procedure successfully: correct insertion of the needle into the vein, the volume of injection and the speed of delivery. Examples are given to show the application of this method to the transient expression of two genes that encode secreted, primate-specific proteins, apolipoprotein L-I (APOL-I) and haptoglobin-related protein (HPR).

Hydrodynamic tail vein injection of SOCS3 eukaryotic expression vector in vivo promoted liver lipid metabolism and hepatocyte apoptosis in mouse

Suppressor of cytokine signaling 3 (SOCS3), a signal transduction cytokine, is involved in lipid metabolism as well as in cell proliferation, differentiation, apoptosis, and so on. To explore the effects of SOCS3 on apoptosis and lipid metabolism in liver, we used a simple effective method named hydrodynamic tail vein injection to overexpress SOCS3. Then orbital blood was obtained for the assessment of blood lipid after injection. Lipid metabolism related genes were detected by Western blot after the determination of serum lipids. Meanwhile, liver cell apoptosis was observed by Hoechst and TUNEL staining and the expression of apoptosis related proteins Bax, Bcl-2, and Caspase3 were detected as well as the JAK2/STAT3 signaling pathway. In addition, we also demonstrated the effect of SOCS3 in prime hepatocyte by overexpression or interference of SOCS3 along with SD1008, which is a specific inhibitor of the JAK2/STAT3 signaling pathway. Taken together, all the results indicated that SOCS3 promoted lipid synthesis in mice liver and promoted hepatocyte apoptosis by inhibiting the activation of the JAK2/STAT3 signaling pathway, however the detailed regulation mechanism had not yet been fully understood and needs further study.

Bioluminescence imaging of caspase-3 activity in mouse liver

Apoptosis is an essential process for the maintenance of liver physiology. The ability to noninvasively image apoptosis in livers would provide unique insights into its role in liver disease processes. In the present work, we established a stable mouse model by hydrodynamics methods to study the activity of caspase-3 and evaluate the effect of the apoptosis inhibitors in mouse livers under true physiological conditions by bioluminescence imaging. The reporter plasmid attB-ANLuc(DEVD)BCLuc that contains fragment of attB and ANLuc(DEVD)BCLuc was codelivered with the mouse-codon optimized φC31 (φC31o) integrase plasmids specifically to mouse liver by hydrodynamic injection procedure. Then, φC31o integrase mediated intramolecular recombination between wild-type attB and attP site in mice, and thus the reporter expression cassette attB-ANLuc(DEVD)BCLuc was integrated permanently into mouse liver chromosome. We used these mice to characterize in vivo activation of caspase-3 upon treatment with LPS/D-GalN. Our data show that liver apoptosis could be reflected by the activity of luciferase. The shRNA targeting caspase-3 protein or apoptosis inhibitors could effectively downregulate luciferase activity in vivo. Also, this model could be used to measure caspase-3 activation during inflammatory and infectious events in vivo as verified by infected with MHV-3. This model could be used for screening anti-apoptosis compounds target mouse livers.

Hemodynamics of a hydrodynamic injection

The hemodynamics during a hydrodynamic injection were evaluated using cone beam computed tomography (CBCT) and fluoroscopic imaging. The impacts of hydrodynamic (5 seconds) and slow (60 seconds) injections into the tail veins of mice were compared using 9% body weight of a phase-contrast medium. Hydrodynamically injected solution traveled to the heart and drew back to the hepatic veins (HV), which led to liver expansion and a trace amount of spillover into the portal vein (PV). The liver volumes peaked at 165.6 ± 13.3% and 165.5 ± 11.9% of the original liver volumes in the hydrodynamic and slow injections, respectively. Judging by the intensity of the CBCT images at the PV, HV, right atrium, liver parenchyma (LP), and the inferior vena cava (IVC) distal to the HV conjunction, the slow injection resulted in the higher intensity at PV than at LP. In contrast, a significantly higher intensity was observed in LP after hydrodynamic injection in comparison with that of PV, suggesting that the liver took up the iodine from the blood flow. These results suggest that the enlargement speed of the liver, rather than the expanded volume, primarily determines the efficiency of hydrodynamic delivery to the liver.

Hemodynamics of a hydrodynamic injection

The hemodynamics during a hydrodynamic injection were evaluated using cone beam computed tomography (CBCT) and fluoroscopic imaging. The impacts of hydrodynamic (5 seconds) and slow (60 seconds) injections into the tail veins of mice were compared using 9% body weight of a phase-contrast medium. Hydrodynamically injected solution traveled to the heart and drew back to the hepatic veins (HV), which led to liver expansion and a trace amount of spillover into the portal vein (PV). The liver volumes peaked at 165.6 ± 13.3% and 165.5 ± 11.9% of the original liver volumes in the hydrodynamic and slow injections, respectively. Judging by the intensity of the CBCT images at the PV, HV, right atrium, liver parenchyma (LP), and the inferior vena cava (IVC) distal to the HV conjunction, the slow injection resulted in the higher intensity at PV than at LP. In contrast, a significantly higher intensity was observed in LP after hydrodynamic injection in comparison with that of PV, suggesting that the liver took up the iodine from the blood flow. These results suggest that the enlargement speed of the liver, rather than the expanded volume, primarily determines the efficiency of hydrodynamic delivery to the liver.

Induction of rat liver tumor using the Sleeping Beauty transposon and electroporation

The Sleeping Beauty (SB) transposon system has been receiving much attention as a gene transfer method of choice since it allows permanent gene expression after insertion into the host chromosome. However, low transposition frequency in higher eukaryotes limits its use in commonly-used mammalian species. Researchers have therefore attempted to modify gene delivery and expression to overcome this limitation. In mouse liver, tumor induction using SB introduced by the hydrodynamic method has been successfully accomplished. Liver tumor in rat models using SB could also be of great use; however, dose of DNA, injection volume, rate of injection and achieving back pressure limit the use of the hydrodynamics-based gene delivery. In the present study, we combined the electroporation, a relatively simple and easy gene delivery method, with the SB transposon system and as a result successfully induced tumor in rat liver by directly injecting the c-Myc, HRAS and shp53 genes. The tumor phenotype was determined as a sarcomatoid carcinoma. To our knowledge, this is the first demonstration of induction of tumor in the rat liver using the electroporation-enhanced SB transposon system.

Hydrodynamics-based delivery of an interleukin-1 receptor II fusion gene ameliorates rat autoimmune myocarditis by inhibiting IL-1 and Th17 cell polarization

Type II interleukin-1 receptor (IL-1RII) is a non-signaling decoy receptor that blocks the activity of interleukin-1 (IL-1), a pro-inflammatory cytokine involved in experimental autoimmune myocarditis (EAM). The aim of this study was to examine the effects of hydrodynamics-based delivery of a recombinant plasmid encoding IL-1RII-Ig and to elucidate the role of IL-1RII in EAM rats. Rats were immunized on day 0 and injected with a recombinant plasmid encoding IL-1RII-Ig or pCAGGS-SP-Ig (control plasmid) on day 6. IL-1RII-Ig gene therapy effectively controlled EAM as indicated by a decreased heart weight-to-body weight ratio, reduced areas of myocarditis, reduced expression of genes encoding atrial natriuretic peptide and brain natriuretic peptide in the heart, and improved cardiac function. IL-1RII-Ig significantly inhibited the expression of IL-1-related cytokines such as IL-1β, prostaglandin E2 synthase, cyclooxygenase, and monocyte chemotactic protein-1 in EAM hearts. Furthermore, the effect of serum containing IL-1RII-Ig on the expression of immune-related genes in IL-1-stimulated splenocytes cultured from EAM rats was examined. The results showed that the expression of IL-6, transforming growth factor-β, retinoic acid-related orphan nuclear receptor (RORγt) and IL-17, was significantly decreased upon exposure to serum containing IL-1RII-Ig. In conclusion, hydrodynamics-based delivery of a recombinant plasmid encoding IL-1RII-Ig effectively prevented progression of left ventricular remodeling and myocardial damage in EAM rats. Moreover, IL-1RII may ameliorate experimental autoimmune myocarditis by blocking IL-1 and inhibiting production of the cytokines important for the polarization of T cells toward a Th17 phenotype.

High levels of gene expression in the hepatocytes of adult mice, neonatal mice and tree shrews via retro-orbital sinus hydrodynamic injections of naked plasmid DNA

Hydrodynamic-based gene delivery has emerged as an efficient and simple method for the intracellular transfection of naked plasmid DNA (pDNA) in vivo. In this system, a hydrodynamic injection via the tail vein is the most effective non-viral method of liver-targeted gene delivery. However, this injection is often technically challenging when used in animals whose tail veins are difficult to visualize or too small to operate on. To overcome this limitation, an alternative in vivo gene delivery method, the rapid injection of large volume of pDNA solution through retro-orbital sinus, was established. Using this technique, we successfully delivered pDNA to the tissue of adult mice, neonatal mice and tree shrews. The efficient expression of exogenous genes was specifically detected in the liver of test animals treated with this gene delivery method. This study demonstrates for the first time that the hydrodynamic gene delivery via the retro-orbital sinus can not only reach the same transgene efficiency as a tradition hydrodynamic-based intravascular injection but also be used in animals that are difficult to inject via the tail vein. This method could open up new areas in gene function studies and gene therapy disease treatment.

Transfection of naked nuclear factor-κB decoy oligodeoxynucleotides into liver by rapid portal vein infusion in rats: its effect on ischemia-reperfusion injury of liver

This study was aimed at examining whether rapid portal vein infusion (RPVI) of a small volume of naked oligodeoxynucleotides (ODNs) could be used to transfect sufficient amounts of nuclear factor-κB (NF-κB) decoy ODN into the liver to suppress NF-κB activation during liver ischemia-reperfusion (I/R) injury, in which NF-κB plays a central role in regulating the production of inflammatory cytokines. One milliliter of naked NF-κB decoy ODN solution was administered into the portal vein for a few seconds. Transfection efficacy was examined by labeling the ODN with a fluorescent tag. Activation of NF-κB was investigated by electrophoretic mobility shift assay. Levels of serum liver enzymes and cytokines were measured during liver I/R injury. NF-κB decoy ODN was preferentially incorporated into Kupffer cells and sinusoidal endothelial cells, but not hepatocytes, in the rat liver. Transfected NF-κB decoy ODN suppressed the function of NF-κB in both Kupffer cells and sinusoidal endothelial cells during liver I/R injury, causing significant decreases in serum tumor necrosis factor-α and interleukin-6 levels 3 hr after reperfusion. Although the decrease in serum liver enzymes was not significant, naked NF-κB decoy ODN was successfully incorporated into Kupffer cells and sinusoidal endothelial cells by rapid portal vein infusion, inhibited NF-κB activation in both cells, and suppressed the production of inflammatory cytokines during the early phase of liver I/R injury.

Gene transfer of c-met confers protection against D-galactosamine/lipopolysaccharide-induced acute liver failure

BACKGROUND

Acute liver failure (ALF) is characterized by impaired regeneration of hepatocytes, partially resulting from the defective signaling between elevated levels of hepatocyte growth factor (HGF) and the downregulation of its receptor, c-met.

AIMS

In this study, we assess the therapeutic efficacy of in vivo c-met gene transfer in ALF.

METHODS

We established a D: -galactosamine/lipopolysaccharide (D: -GalN/LPS)-induced ALF model in rats. The levels of HGF and c-met in D: -GalN/LPS rats were compared with vehicle-injected rats and those undergoing liver regeneration following partial hepatectomy (PH). To deliver c-met in vivo, pcDNA-c-met was constructed and transfected into the rat liver via hydrodynamic injection. Control rats were transfected with the pcDNA3.1 plasmid. The expressions of c-met in different tissues were examined by immunohistochemistry. Hepatocyte proliferation and apoptosis were determined by PCNA staining and TUNEL assay, respectively. The survival of rats in the control and c-met-expressing rats was compared by Kaplan-Meier analysis.

RESULTS

Compared with control rats, D: -GalN/LPS or PH -treated rats had significantly higher levels of HGF (P < 0.01). D: -GalN/LPS also led to significantly lower c-met expression in the liver (P < 0.01) than PH. The in vivo c-met gene transfer led to its specific expression on hepatocytes, which was accompanied by the enhancement of hepatocyte proliferation, a reduction in apoptosis, as well as significant improvement in overall survival (P < 0.01).

CONCLUSIONS

This study provides the initial evidence that c-met may serve as a novel target for gene therapy, and may be of clinical benefit in the treatment of patients with ALF.

Efficacy and safety of Sleeping Beauty transposon-mediated gene transfer in preclinical animal studies

Sleeping Beauty (SB) transposons have been effective in delivering therapeutic genes to treat certain diseases in mice. Hydrodynamic gene delivery of integrating transposons to 5-20% of the hepatocytes in a mouse results in persistent elevated expression of the therapeutic polypeptides that can be secreted into the blood for activity throughout the animal. An alternative route of delivery is ex vivo transformation with SB transposons of hematopoietic cells, which then can be reintroduced into the animal for treatment of cancer. We discuss issues associated with the scale-up of hydrodynamic delivery to the liver of larger animals as well as ex vivo delivery. Based on our and others' experience with inefficient delivery to larger animals, we hypothesize that impulse, rather than pressure, is a critical determinant of the effectiveness of hydrodynamic delivery. Accordingly, we propose some alterations in delivery strategies that may yield efficacious levels of gene delivery in dogs and swine that will be applicable to humans. To ready hydrodynamic delivery for human application we address a second issue facing transposons used for gene delivery regarding their potential to "re-hop" from one site to another and thereby destabilize the genome. The ability to correct genetic diseases through the infusion of DNA plasmids remains an appealing goal.

Administration of naked plasmid encoding hepatic stimulator substance by hydrodynamic tail vein injection protects mice from hepatic failure by suppressing the mitochondrial permeability transition

Acute liver failure is a devastating illness of various causes with considerable mortality. Hepatic stimulator substance (HSS) has been suggested for use as a protective agent against acute hepatic injury induced by chemical poisons because it has a variety of biological activities. However, the mechanism whereby HSS protects against hepatotoxins is poorly understood. In this study, we established a hepatic gene transfer system via hydrodynamic tail vein injection to deliver a naked plasmid containing the human HSS gene (hHSS) and analyzed HSS-mediated protection of the liver during fulminant hepatic failure (FHF) induced by D-galactosamine (D-gal) and lipopolysaccharide (LPS). The results showed that the reporter gene, enhanced green fluorescent protein, was efficiently expressed in the liver of BALB/c mice. Hydrodynamic-based transfection of hHSS yielded a 70% survival rate compared with 36.7% for the control group at 24 h after D-gal/LPS treatment. In addition, hHSS expression preserved liver morphology and function. It is noteworthy that hHSS hydrodynamic-based transfer ameliorated indices of the mitochondrial permeability transition (MPT) resulting from the toxic effects of d-gal/LPS on the liver such as mitochondrial swelling, mitochondrial transmembrane potential disruption, and cytochrome c translocation. Furthermore, mitochondrial morphology and ATP levels were maintained in hHSS-administered mice. HSS-mediated protection was similar to that observed with the MPT inhibitor N-methyl-4-isoleucine-cyclosporin (NIM811), indicating a possible role for HSS in the regulation of MPT. In conclusion, a single dose of hHSS plasmid protected mice from FHF, and this hepatoprotective effect seemed to correlate with the inhibition of MPT.

Chronic alcohol-induced liver disease inhibits dendritic cell function

BACKGROUND/AIMS

We have compared dendritic cell (DC) function derived from the alcoholic liver disease (ALD) sensitive Long-Evans (LE) and resistant Fischer rat strains to determine if the influence of ethanol on DCs was dependent on ALD.

METHODS

The LE and Fischer rats were fed an ethanol-containing or isocaloric control liquid diet for 8 weeks and comparisons were made to LE rats injected with thioacetamide as a liver disease control. DCs were isolated from the spleen after expansion with human Fms-like tyrosine kinase receptor 3 ligand plasmid. Maturation markers CD86, CD80, CD40 and MHC-II were analysed by flow cytometry with or without lipopolysaccharide and poly I:C stimulation. Production of tumour necrosis factor-α (TNF-α), interferon-γ (IFN-γ), interleukin (IL)-12p40 and IL-10 cytokines and the antigen presentation ability of DCs was determined.

RESULTS

Only LE rats developed ALD characterized by liver injury, elevated alanine aminotransferase levels and steatosis; CD86 and CD40 expression was decreased in LE but not Fischer rats. Reduced TNF-α, IFN-γ, IL-12, proinflammatory and enhanced IL-10 cytokine production was found in DCs isolated from ethanol-fed LE but not Fischer rats. Allostimulatory activity was reduced in LE compared with the Fischer strain. In contrast, DCs isolated from thioacetamide-induced liver damage displayed a reduction only in IL-12p40; TNF-α, IL-10 and IFN-α production as well as antigen presenting ability remained intact compared with controls.

CONCLUSIONS

ALD sensitive LE rats exhibited characteristics of a suppressed DC phenotype that was not observed following thioacetamide-induced liver disease, which suggests an important role for ALD in altering the host cellular and humoral immune responses.

The Sleeping Beauty transposon system: a non-viral vector for gene therapy

Over the past decade, the Sleeping Beauty (SB) transposon system has been developed as the leading non-viral vector for gene therapy. This vector combines the advantages of viruses and naked DNA. Here we review progress over the last 2 years in vector design, methods of delivery and safety that have supported its use in the clinic. Currently, the SB vector has been validated for ex vivo gene delivery to stem cells, including T-cells for the treatment of lymphoma. Progress in delivery of SB transposons to liver for treatment of various systemic diseases, such as hemophilia and mucopolysaccharidoses types I and VII, has encountered some problems, but even here progress is being made.

Critical physiological and surgical considerations for hydrodynamic pressurization of individual segments of the pig liver

Hydrodynamic gene delivery to the liver is a promising approach for liver gene therapy in the clinic, but levels of gene expression in larger species have been much less than in rodents. The development of surgical techniques for pressurizing individual liver segments and the establishment of whether hepatic vascular anatomy in fact permits pressurization of individual segments are critical issues that need to be addressed. We have evaluated these issues using hydrodynamic delivery to individual segments of the pig liver, via branches of both portal and hepatic veins. Our objective was to develop surgical techniques that achieve elevated vascular pressures within individual liver segments with small volumes, but without interruption of portal blood flow or reduction in venous return to the heart. We report that, without specific surgical interventions to obstruct outflow of DNA solution from the targeted liver segment, little or no increase in intrahepatic vascular pressure occurs. We demonstrate, for the first time, that selective pressurization of individual liver segments is possible without compromising portal venous flow or venous return to the heart. Thus, hydrodynamic gene delivery to individual liver segments is technically achievable in a clinical setting, but will require open abdominal surgery rather than minimally invasive techniques.

Correction of hyperbilirubinemia in gunn rats using clinically relevant low doses of helper-dependent adenoviral vectors

Crigler-Najjar syndrome type I is a severe inborn error of bilirubin metabolism caused by a complete deficiency of uridine diphospho-glucuronosyl transferase 1A1 (UGT1A1) and results in life-threatening unconjugated hyperbilirubinemia. Lifelong correction of hyperbilirubinemia by liver-directed gene therapy using a helper-dependent adenoviral (HDAd) vector has been previously reported in the Gunn rat, a model of Crigler-Najjar syndrome, but was only achieved using high doses (≥ 3 × 10(12) viral particles [vp]/kg), which are likely to elicit a severe toxic response in humans. Therefore, in this study, we investigate strategies to achieve correction of hyperbilirubinemia in the Gunn rat using clinically relevant low HDAd doses. We have found that correction of hyperbilirubinemia in the Gunn rat can be achieved with a low dose of 5 × 10(11) vp/kg by using an HDAd vector bearing a more potent UGT1A1 expression cassette. Furthermore, by using hydrodynamic injection of the improved HDAd vector, correction of hyperbilirubinemia in the Gunn rat can be achieved using an even lower dose of 5 × 10(10) vp/kg. Although hydrodynamic injection as performed in rats is not acceptable in humans, clinically attractive, minimally invasive methods have been successfully developed to mimic hydrodynamic injection of HDAd vector in non-human primates. Therefore, using an improved expression cassette combined with a more efficient method of vector delivery permits correction of hyperbilirubinemia in the Gunn rat using clinically relevant low HDAd doses and may thus pave the way to clinical application of HDAd vectors for Crigler-Najjar syndrome gene therapy.

Hydrodynamic gene delivery and its applications in pharmaceutical research

Hydrodynamic delivery has emerged as the simplest and most effective method for intracellular delivery of membrane-impermeable substances in rodents. The system employs a physical force generated by a rapid injection of large volume of solution into a blood vessel to enhance the permeability of endothelium and the plasma membrane of the parenchyma cells to allow delivery of substance into cells. The procedure was initially established for gene delivery in mice, and its applications have been extended to the delivery of proteins, oligo nucleotides, genomic DNA and RNA sequences, and small molecules. The focus of this review is on applications of hydrodynamic delivery in pharmaceutical research. Examples are provided to highlight the use of hydrodynamic delivery for study of transcriptional regulation of CYP enzymes, for establishment of animal model for viral infections, and for gene drug discovery and gene function analysis.

Intracellular gene transfer in rats by tail vein injection of plasmid DNA

In this study, we examined the effect of various factors on gene delivery efficiency of tail vein injection of plasmid DNA into rats. We measured the level of reporter gene expression in the internal organs including the lung, heart, spleen, kidney, and liver as function of injection volume, injection time, and DNA dose. Persistency of reporter gene expression in transfected animals was also examined. We demonstrated that plasmid delivery to rats by the tail vein is effective as long as the volume of injected DNA solution is adjusted to 7-8% of body weight with an injection time of less than 10 s. With the exception of a short-term increase in serum concentration of alanine aminotransferase and transient irregularity in cardiac function during and soon after the injection, the procedure is well tolerated. Lac Z staining of the liver from transfected animals showed approximately 5-10% positive cells. Persistency test for transgene expression in animals using plasmid carrying cDNA of human alpha 1 antitrypsin gene driven by chicken beta actin gene promoter with CMV enhancers showed peak level of transgene product 1 day after the injection followed by a gradual decline with time. Peak level was regained by a second injection performed on day 38 after the first injection. These results show that tail vein injection is an effective means for introducing plasmid DNA into liver cells in rats. We believe that this procedure will be extremely useful for gene function studies in the context of whole animal in rats.

Single intravenous injection of plasmid DNA encoding human paraoxonase-1 inhibits hyperlipidemia in rats

Paraoxonase-1 (PON1, EC 3.1.8.1) is a high-density lipoprotein (HDL)-associated antioxidant enzyme, and its activity correlates negatively with the level of plasma low-density lipoprotein cholesterol (LDL-C) and triglyceridemia (TG). In this study, we examined the therapeutic effect of plasmid DNA containing the human PON1 gene (pcDNA/PON1) in hyperlipidemic model rats. The rats were fed a high-fat and high-cholesterol diet for 25 days to produce a hyperlipidemic animal model. Single intravenous injection of pcDNA/PON1 into model rats prevented dyslipidemia and hepatic lipid accumulation. The mechanisms of pcDNA/PON1 in treating hyperlipidemia were associated with increases of serum antioxidant PON1 and SOD activities, and with reduction of the levels of total cholesterol (TC), LDL-C and TG. The results suggest the potential therapeutic effect of pcDNA/PON1 on hyperlipidemia.

Hydrodynamics-based transfection of plasmid encoding receptor activator for nuclear factor kappa B-Fc protects against hepatic ischemia/reperfusion injury in mice

Hepatic ischemia/reperfusion (I/R) injury is very important in transplant surgery. To study the mechanism of receptor activator for nuclear factor kappa B-Fc (RANK-Fc) in protection against I/R injury, 90 male BALB/c mice were randomly divided into 3 groups: a phosphate-buffered saline (PBS) (sham) group, a pLNCX2-IRES-eGFP+I/R (Negative-control) group (where IRES means internal ribosome entry site and eGFP means enhanced green fluorescent protein), and a pLNCX2-RANK-Fc-IRES-eGFP+I/R (RANK-Fc) group. All mice were injected with 2.5 mL of PBS (with or without plasmids) within 6 seconds via the tail vein. After 3 days, hepatic I/R was induced under warm conditions by partial occlusion of the left and median lobes for 90 minutes followed by various periods of reperfusion. Hepatic injury was assessed by the levels of liver aminotransferases and histopathology. Tumor necrosis factor alpha, interleukin 6, and interleukin 1beta were measured by enzyme-linked immunosorbent assay, whereas RANK-Fc, phospho-c-Jun, c-Jun N-terminal kinase (JNK), hypoxia inducible factor 1 alpha (HIF-1alpha), nuclear p65, and total p65 were assessed with western blotting. Apoptosis was identified by terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling. RANK-Fc was efficiently expressed in the liver. In comparison with the negative-control group, RANK-Fc reduced nuclear factor kappa B (NF-kappaB) p65 nuclear translocation, JNK phosphorylation, and HIF-1alpha expression during I/R. RANK-Fc effectively suppressed proinflammatory cytokine expression. The results indicated that RANK-Fc could protect against hepatic I/R injury in mice at least in part via the inhibition of the proinflammatory NF-kappaB pathway as well as proapoptotic JNK and HIF-1alpha pathway activation.

Pim-3 protects against hepatic failure in D-galactosamine (D-GalN)-sensitized rats

BACKGROUND

Fulminant hepatic failure (FHF) has a high mortality resulted from massive hepatic apoptosis and haemorrhage necrosis; it is required to develop a valid therapy directed towards hepatocyte protection and regeneration. Pim-3, a hepatic growth stimulator, belongs to the serine/threonine kinase Pim-family that has been implicated in gp130-mediated induction of cell proliferation, protection from apoptosis downstream of Signal transducer and activator of transcription 3 (STAT3) and vascular endothelial growth factor-A-dependent vasculogenesis and angiogenesis, thus is suggested to possibly play a role in the tissue repair of FHF.

MATERIALS AND METHODS

Male Wistar rats received simultaneous intraperitoneal injections of lipopolysaccharide (LPS) (100 microg kg(-1)) and D-galactosamine (D-GalN) (600 mg kg(-1)). One day prior to LPS/D-GalN administration, naked plasmid or Ringer's solution was injected via tail vein by hydrodynamics-based procedure.

RESULTS

Exogenous Pim-3 gene protected against LPS/D-GalN-induced lethality with survival rate of more than 80% and improved the hepatic pathomorphism. The fractions of hepatic apoptotic-positive cells and the levels of caspase-3 activity were markedly lower in Pim-3-pretreated rats. Furthermore, exogenous Pim-3 significantly inhibited expression of tumour necrosis factor-alpha and interleukin-1beta in the liver, declined p53 and inducible nitric oxide synthase mRNAs levels, but elevated levels of Bcl-2 protein, an anti-apoptosis member of Bcl-2 family, in the liver. Exogenous Pim-3, however, showed little effect on expression of Bax, a pro-apoptosis member of Bcl-2 family.

CONCLUSIONS

Pim-3 gene could protect rats from FHF by inhibiting liver apoptosis and improving inflammatory response of liver tissues, which could be associated with inhibiting expression of inflammatory mediators and promoting expression of anti-apoptosis protein Bcl-2.

Technical requirements for effective regional hydrodynamic gene delivery to the left lateral lobe of the rat liver

Hydrodynamic gene delivery to the liver is an attractive approach for clinical liver gene therapy, but critical aspects of technique remain uncertain. There has not been to date any report of high levels of hydrodynamic gene delivery to the liver, except in rodents. Regional hydrodynamic delivery to individual lobes/segments of the liver is being pursued in preclinical pig models, where reporter gene expression has been <1% of rodent levels, and in one clinical study, where there was no substantive evidence of gene expression. In none of these studies did surgical technique include outflow obstruction of the DNA solution. Here we report a novel technique for regional hydrodynamic gene delivery to the left lateral lobe of the rat liver. The technique gives high levels of gene delivery specific to the left lateral lobe with low volumes ( approximately 1.5 ml) of DNA solution, and permits an evaluation of hydrodynamic delivery in the presence and in the absence of outflow obstruction. We report that outflow obstruction is an absolute requirement for effective hydrodynamic gene delivery to individual lobes/segments of the liver, and therefore that minimally invasive techniques will not be possible in the clinic.

Hydrodynamic delivery protocols

RNA interference (RNAi) holds considerable promise as a novel therapeutic strategy to silence disease-causing genes not amenable to conventional therapeutics. Since it relies on small interfering RNAs (siRNAs), which are the mediators of RNAi-induced specific mRNA degradation, a major issue is the delivery of therapeutically active siRNAs into the target tissue. In vivo gene silencing with RNAi has been reported using both viral vector delivery and high-pressure, high-volume intravenous (i.v.) injection of synthetic siRNAs. For safety reasons, strategies based on viral vector delivery may be only of limited clinical use. The more desirable approach is to directly deliver active siRNAs. We describe the use of hydrodynamic administration as a technique to deliver naked siRNA constructs into experimental animals as a method of transient gene knockdown. This approach demonstrates that RNAi can be used to silence endogenous genes, involved in the cause of human diseases, with a clinically acceptable formulation and route of administration.