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

Meeting Contemporary Challenges: Development of Nanomaterials for Veterinary Medicine

In recent decades, nanotechnology has been rapidly advancing in various fields of human activity, including veterinary medicine. The review presents up-to-date information on recent advancements in nanotechnology in the field and an overview of the types of nanoparticles used in veterinary medicine and animal husbandry, their characteristics, and their areas of application. Currently, a wide range of nanomaterials has been implemented into veterinary practice, including pharmaceuticals, diagnostic devices, feed additives, and vaccines. The application of nanoformulations gave rise to innovative strategies in the treatment of animal diseases. For example, antibiotics delivered on nanoplatforms demonstrated higher efficacy and lower toxicity and dosage requirements when compared to conventional pharmaceuticals, providing a possibility to solve antibiotic resistance issues. Nanoparticle-based drugs showed promising results in the treatment of animal parasitoses and neoplastic diseases. However, the latter area is currently more developed in human medicine. Owing to the size compatibility, nanomaterials have been applied as gene delivery vectors in veterinary gene therapy. Veterinary medicine is at the forefront of the development of innovative nanovaccines inducing both humoral and cellular immune responses. The paper provides a brief overview of current topics in nanomaterial safety, potential risks associated with the use of nanomaterials, and relevant regulatory aspects.

Radiolabelling small and biomolecules for tracking and monitoring

Radiolabelling small molecules with beta-emitters has been intensively explored in the last decades and novel concepts for the introduction of radionuclides continue to be reported regularly. New catalysts that induce carbon/hydrogen activation are able to incorporate isotopes such as deuterium or tritium into small molecules. However, these established labelling approaches have limited applicability for nucleic acid-based drugs, therapeutic antibodies, or peptides, which are typical of the molecules now being investigated as novel therapeutic modalities. These target molecules are usually larger (significantly >1 kDa), mostly multiply charged, and often poorly soluble in organic solvents. However, in preclinical research they often require radiolabelling in order to track and monitor drug candidates in metabolism, biotransformation, or pharmacokinetic studies. Currently, the most established approach to introduce a tritium atom into an oligonucleotide is based on a multistep synthesis, which leads to a low specific activity with a high level of waste and high costs. The most common way of tritiating peptides is using appropriate precursors. The conjugation of a radiolabelled prosthetic compound to a functional group within a protein sequence is a commonly applied way to introduce a radionuclide or a fluorescent tag into large molecules. This review highlights the state-of-the-art in different radiolabelling approaches for oligonucleotides, peptides, and proteins, as well as a critical assessment of the impact of the label on the properties of the modified molecules. Furthermore, applications of radiolabelled antibodies in biodistribution studies of immune complexes and imaging of brain targets are reported.

The Challenge of Gene Therapy for Neurological Diseases: Strategies and Tools to Achieve Efficient Delivery to the Central Nervous System

For more than 10 years, gene therapy for neurological diseases has experienced intensive research growth and more recently therapeutic interventions for multiple indications. Beneficial results in several phase 1/2 clinical studies, together with improved vector technology have advanced gene therapy for the central nervous system (CNS) in a new era of development. Although most initial strategies have focused on orphan genetic diseases, such as lysosomal storage diseases, more complex and widespread conditions like Alzheimer's disease, Parkinson's disease, epilepsy, or chronic pain are increasingly targeted for gene therapy. Increasing numbers of applications and patients to be treated will require improvement and simplification of gene therapy protocols to make them accessible to the largest number of affected people. Although vectors and manufacturing are a major field of academic research and industrial development, there is a growing need to improve, standardize, and simplify delivery methods. Delivery is the major issue for CNS therapies in general, and particularly for gene therapy. The blood-brain barrier restricts the passage of vectors; strategies to bypass this obstacle are a central focus of research. In this study, we present the different ways that can be used to deliver gene therapy products to the CNS. We focus on results obtained in large animals that have allowed the transfer of protocols to human patients and have resulted in the generation of clinical data. We discuss the different routes of administration, their advantages, and their limitations. We describe techniques, equipment, and protocols and how they should be selected for safe delivery and improved efficiency for the next generation of gene therapy trials for CNS diseases.

Current trends in targeted therapy for drug-resistant infections

Escalating antibiotic resistance is now a serious menace to global public health. It may be led to the emergence of "postantibiotic age" in which most of infections are untreatable. At present, there is an essential need to explore novel therapeutic strategies as a strong and sustainable pipeline to combat antibiotic-resistant infections. This review focuses on recent advances in this area including therapeutic antibodies, antimicrobial peptides, vaccines, gene therapy, genome editing, and phage therapy for tackling drug-resistant infections.

Cognition in movement disorders: where can we hope to be in ten years?

Cognitive impairment and dementia associated with movement disorders represent a major management challenge and area of unmet need. This article has focused upon Parkinson's disease as an exemplar condition, but many of the roadblocks and efforts to overcome these are applicable, in a general sense, to other disorders. Short of a "penicillin moment"-a chance discovery or piece of unintended good fortune-progress is likely to be incremental. Cognitive therapies may end up being multiple and possibly multimodal, parallel with the cancer therapy field. Ultimately, benefit for one condition may extend to others as commonality in protein aggregation, synergistic pathological effects between proteins, and pathological spread emerges. © 2014 International Parkinson and Movement Disorder Society.

Technologies for investigating the physiological barriers to efficient lipid nanoparticle-siRNA delivery

Small interfering RNA (siRNA) therapeutics have advanced from bench to clinical trials in recent years, along with new tools developed to enable detection of siRNA delivered at the organ, cell, and subcellular levels. Preclinical models of siRNA delivery have benefitted from methodologies such as stem-loop quantitative polymerase chain reaction, histological in situ immunofluorescent staining, endosomal escape assay, and RNA-induced silencing complex loading assay. These technologies have accelerated the detection and optimization of siRNA platforms to overcome the challenges associated with delivering therapeutic oligonucleotides to the cytosol of specific target cells. This review focuses on the methodologies and their application in the biodistribution of siRNA delivered by lipid nanoparticles.

Quantitative silencing of EGFP reporter gene by self-assembled siRNA lipoplexes of LinOS and cholesterol

Nonviral siRNA vectors prepared by the direct mixing of siRNA and mixtures of an asymmetric N(4),N(9)-diacyl spermine conjugate, N(4)-linoleoyl-N(9)-oleoyl-1,12-diamino-4,9-diazadodecane (LinOS), with either cholesterol or DOPE, at various molar ratios of the neutral lipids, are reported. The effects of varying the lipid formulation and changing the N/P charge ratio on the intracellular delivery of siRNA to HeLa cells and on the siRNA-mediated gene silencing of a stably expressed reporter gene (EGFP) were evaluated. The presence of either cholesterol or DOPE in the mixture resulted in a marked increase in the delivery of the siRNA as well as enhanced EGFP silencing as evaluated by FACS. A LinOS/Chol 1:2 mixture resulted in the highest siRNA delivery and the most efficient EGFP silencing (reduced to 20%) at N/P = 3.0. Lowering the amount of siRNA from 15 pmol to 3.75 pmol, thus increasing the N/P charge ratio to 11.9, resulted in decreasing the amount of delivered siRNA, while the efficiency of gene silencing was comparable to that obtained with 15 pmol (N/P = 3.0) of siRNA. Mixtures of symmetrical N(4),N(9)-dioleoyl spermine (DOS) with cholesterol at 1:2 molar ratio showed less siRNA delivery than with LinOS/Chol at N/P = 3.0 (15 pmol of siRNA), and comparable delivery at N/P = 11.9 (3.75 pmol of siRNA). The EGFP silencing was comparable with LinOS and with DOS when mixed with cholesterol 1:2 (lipoplexes prepared with 15 pmol of siRNA), but LinOS mixtures showed better EGFP silencing when the siRNA was reduced to 3.75 pmol. Lipoplex particle size determination by DLS of cholesterol mixtures was 106-118 nm, compared to 194-356 nm for lipoplexes prepared with the spermine conjugates only, and to 685 nm for the LinOS/DOPE 1:1 mixture. Confocal microscopy showed successful siRNA delivery of red tagged siRNA and quantitative EGFP knockdown in HeLa EGFP cells; Z-stack photomicrographs showed that the delivered siRNA is distributed intracellularly. Cryo-TEM of siRNA LinOS/Chol 1:2 lipoplexes shows the formation of multilamellar spheres with a size of ∼100 nm, in good agreement with the particle size measured by DLS. The constant distance between lamellar repeats is ∼6 nm, with the electron-dense layers fitting a monolayer of siRNA. AlamarBlue cell viability assay showed that the lipoplexes resulted in cell viability ≥81%, with LinOS/Chol 1:2 mixtures resulting in cell viabilities of 89% and 94% at siRNA 15 nM and 3.75 nM respectively. These results show that lipoplexes of siRNA and LinOS/Chol mixtures prepared by the direct mixing of the lipid mixture and siRNA, without any preceding preformulation steps, result in enhanced siRNA delivery and EGFP knockdown, with excellent cell viability. Thus, LinOS/Chol 1:2 mixture is a promising candidate as a nontoxic nonviral siRNA vector.

The pig as an experimental model for clinical craniofacial research

The pig represents a useful, large experimental model for biomedical research. Recently, it has been used in different areas of biomedical research. The aim of this study was to review the basic anatomical structures of the head region in the pig in relation to their use in current research. Attention was focused on the areas that are frequently affected by pathological processes in humans: the oral cavity with teeth, salivary gland, orbit, nasal cavity and paranasal sinuses, maxilla, mandible and temporomandibular joint. Not all of the structures have an equal morphology in the pig and human, and these morphological dissimilarities must be taken into account before choosing the pig as an experimental model for regenerative medicine.

Asymmetrical N4,N9-diacyl spermines: SAR studies of nonviral lipopolyamine vectors for efficient siRNA delivery with silencing of EGFP reporter gene

Our aim is to study the effects of varying the two acyl moieties in synthesized N(4),N(9)-diacyl spermines on siRNA formulations and their delivery efficiency in cell lines. Six novel asymmetrical lipopolyamines, [N(4)-cholesteryloxy-3-carbonyl-N(9)-oleoyl-, N(4)-decanoyl-N(9)-oleoyl-, N(4)-decanoyl-N(9)-stearoyl-, N(4)-lithocholoyl-N(9)-oleoyl-, N(4)-myristoleoyl-N(9)-myristoyl-, and N(4)-oleoyl-N(9)-stearoyl]-1,12-diamino-4,9-diazadodecane, were assessed for their abilities to bind to siRNA, studied using a RiboGreen intercalation assay, and to form nanoparticles. Their siRNA delivery efficiencies were quantified in FEK4 primary skin cells and in an immortalized cancer cell line (HtTA) using a fluorescein-tagged siRNA, and compared with formulations of N(4),N(9)-dioleoyl-1,12-diamino-4,9-diazadodecane and of a leading transfecting agent, TransIT-TKO. Transfection was measured in terms of siRNA delivery and silencing of EGFP reporter gene in HeLa cells. By incorporating two different acyl moieties, changing their length and oxidation level in a controlled manner, we show efficient fluorescein-tagged siRNA formulation, delivery, and knock-down of EGFP reporter gene. N(4)-Oleoyl-N(9)-stearoyl spermine and N(4)-myristoleoyl-N(9)-myristoyl spermine are effective siRNA delivery vectors typically resulting in 89% cell delivery and gene silencing to 34% in the presence of serum, comparable with the results obtained with TransIT-TKO; adding a second lipid chain is better than incorporating a steroid moiety.

Efficient silencing of EGFP reporter gene with siRNA delivered by asymmetrical N4,N9-diacyl spermines

It is important to obtain structure-activity relationship (SAR) data across cationic lipids for the self-assembly and nonviral intracellular delivery of siRNA. The aims of this work are to carry out a SAR study on the efficiency of asymmetrical N(4),N(9)-diacyl spermines in siRNA delivery and EGFP reporter gene silencing, with comparisons to selected mixtures composed of symmetrical N(4),N(9)-diacyl spermines. Another important aim of these studies is to quantify the changes in cell viability, assayed with alamarBlue, as a function of lipid structure. Therefore, we have designed, synthesized, purified, and assayed novel cationic lipids that are asymmetrical lipopolyamines based on spermine. Flow cytometry and fluorescence microscopy in an EGFP stably transfected HeLa cell line, measuring both delivery of fluorescently tagged siRNAs and silencing the EGFP signal, allowed quantitation of the differences between asymmetrical cationic lipids, mixtures of their symmetrical counterparts, and comparison with commercial nonviral delivery agents. Intracellular delivery of siRNA and gene silencing by siRNA differ with different hydrophobic domains. In these asymmetrical N(4),N(9)-diacyl spermines, lipids that enhance siRNA uptake do not necessarily enhance siRNA-induced inhibition of gene expression: C18 and longer saturated chains promote uptake, while more unsaturated C18 chains promote gene silencing. These properties are efficiently demonstrated in a new nontoxic cationic lipid siRNA vector, N(4)-linoleoyl-N(9)-oleoyl-1,12-diamino-4,9-diazadodecane (LinOS), which is also shown to be comparable with or superior to TransIT-TKO and Lipofectamine 2000.

Exosomal RNA as biomarkers and the therapeutic potential of exosome vectors

INTRODUCTION

Exosomes are nano-sized (40 - 100 nm), extracellular vesicles, of endosomal origin. They are released by cells and found in many body fluids, including plasma. Exosomes contain proteins, microRNAs (miRNAs), and messenger RNAs (mRNAs) that can be transferred between cells. The discovery that exosomes contain RNA, and that this encapsulated RNA could potentially be transferred over distances in vivo, reinforced the importance of exosomes in cell-to-cell communication.

AREAS COVERED

The existence of exosomes, as a naturally occurring delivery system of RNA, enables their use as both biomarkers and vectors in gene therapy. This review provides an overview of studies reporting that exosomal miRNA and mRNA in plasma can serve as a diagnostic marker in various types of cancers. In addition, the recent finding that exosomes can be used as vectors for delivery of small interfering RNA (siRNA) in mice, with therapeutic effects, is also reviewed.

EXPERT OPINION

The data reviewed here suggest that exosomal RNA has the potential to play an important role in the diagnosis, prognosis, and treatment of diseases in the future.

Single base mismatches in the mRNA target site allow specific seed region-mediated off-target binding of siRNA targeting human coagulation factor 7

We have analyzed the off-target activity of two siRNAs (F7-1, F7-2) that knock-down human blood coagulation factor 7 mRNA. F7-1 modulates a significant number of non-target transcripts while F7-2 shows high selectivity for the target transcript under various experimental conditions. The 3′-UTRs of all F7-1 off-target genes show statistically significant enrichment of the reverse complement of the F7-1 siRNA seed region located in the guide strand. Seed region enrichment was confirmed in off-target transcripts modulated by siRNA targeting the glucocorticoid receptor. To investigate how these sites contribute to off-target recognition of F7-1, we employed CXCL5 transcript as model system because it contains five F7-1 seed sequence motifs with single base mismatches. We show by transient transfection of reporter gene constructs into HEK293 cells that three out of five sites located in the 3′-UTR region are required for F7-1 off-target activity. For further mechanistic dissection, the sequences of these sites were synthesized and inserted either individually or joined in dimeric or trimeric constructs. Only the fusion constructs were silenced by F7-1 while the individual sites had no off-target activity. Based on F7-1 as a model, a single mismatch between the siRNA seed region and mRNA target sites is tolerated for target recognition and the CXCL5 data suggest a requirement for binding to multiple target sites in off-target transcripts.

Self-Assembled Lipoplexes of Short Interfering RNA (siRNA) Using Spermine-Based Fatty Acid Amide Guanidines: Effect on Gene Silencing Efficiency

Four guanidine derivatives of N4,N9-diacylated spermine have been designed, synthesized, and characterized. These guanidine-containing cationic lipids bound siRNA and formed nanoparticles. Two cationic lipids with C18 unsaturated chains, N1,N12-diamidino-N4,N9-dioleoylspermine and N1,N12-diamidino-N4-linoleoyl-N9-oleoylspermine, were more efficient in terms of GFP expression reduction compared to the other cationic lipids with shorter C12 (12:0) and very long C22 (22:1) chains. N1,N12-Diamidino-N4-linoleoyl-N9-oleoylspermine siRNA lipoplexes resulted in GFP reduction (26%) in the presence of serum, and cell viability (64%). These data are comparable to those obtained with TransIT TKO. Thus, cationic lipid guanidines based on N4,N9-diacylated spermines are good candidates for non-viral delivery of siRNA to HeLa cells using self-assembled lipoplexes.

Adenovirus-mediated transfer of tris-shRNAs induced apoptosis of nasopharyngeal carcinoma cell in vitro and in vivo

RNA interference (RNAi) is an evolutionary conserved mechanism for specific gene silencing. There are currently numerous cancer therapy clinical trials based on RNAi technology. Using an adenoviral system as a delivery mediator of RNAi, we investigated the therapeutic effects of targeting three genes simultaneously in vitro and in vivo. In this study, we constructed an recombinant adenoviral shRNA expression system as Adv-pEGFP-shVEGF-shTERT-shBcl-xl for multi-genes silencing. Our results showed that the adenoviral vector can achieve above 90% of transfection efficiency and induced obvious apoptosis in CNE-2 cell both in vitro and in vivo compared with targeting the TERT alone or controlled group.

Efficient Gene Silencing by Self-Assembled Complexes of siRNA and Symmetrical Fatty Acid Amides of Spermine

Gene silencing by siRNA (synthetic dsRNA of 21-25 nucleotides) is a well established biological tool in gene expression studies and has a promising therapeutic potential for difficult-to-treat diseases. Five fatty acids of various chain length and oxidation state (C12:0, C18:0, C18:1, C18:2, C22:1) were conjugated to the naturally occurring polyamine, spermine, and evaluated for siRNA delivery and gene knock-down. siRNA delivery could not be related directly to gene silencing efficiency as N⁴,N⁹-dierucoyl spermine resulted in higher siRNA delivery compared to N⁴,N⁹-dioleoyl spermine. GFP silencing in HeLa cells showed that the unsaturated fatty acid amides are more efficient than saturated fatty acid amides, with N⁴,N⁹-dioleoyl spermine resulting in the most efficient gene silencing in the presence of serum. The alamarBlue cell viability assay showed that fatty acid amides of spermine have good viability (75%–85% compared to control) except N⁴,N⁹-dilauroyl spermine which resulted in low cell viability. These results prove that unsaturated fatty acid amides of spermine are efficient, non-toxic, non-viral vectors for siRNA mediated gene silencing.

Recent advances of siRNA delivery by nanoparticles

INTRODUCTION

The field of RNA interference technology has been researched extensively in recent years. However, the development of clinically suitable, safe and effective drug delivery vehicles is still required.

AREAS COVERED

This paper reviews the recent advances of non-viral delivery of small interfering RNA (siRNA) by nanoparticles, including biodegradable nanoparticles, liposomes, polyplex, lipoplex and dendrimers. The characteristics, composition, preparation, applications and advantages of different nanoparticle delivery strategies are also discussed in detail, along with the recent progress of non-viral nanoparticle carrier systems for siRNA delivery in preclinical and clinical studies.

EXPERT OPINION

Non-viral carrier systems, especially nanoparticles, have been investigated extensively for siRNA delivery, and may be utilized in clinical applications in the future. So far, a few preliminary clinical trials of nanoparticles have produced promising results. However, further research is still required to pave the way to successful clinical applications. The most important issues that need to be focused on include encapsulation efficiency, formulation stability of siRNA, degradation in circulation, endosomal escape and delivery efficiency, targeting, toxicity and off-target effects. Pharmacology and pharmacokinetic studies also present another great challenge for nanoparticle delivery systems, owing to the unique nature of siRNA oligonucleotides compared with small molecules.

RNAa is conserved in mammalian cells

Background

RNA activation (RNAa) is a newly discovered mechanism of gene activation triggered by small double-stranded RNAs termed ‘small activating RNAs’ (saRNAs). Thus far, RNAa has only been demonstrated in human cells and is unclear whether it is conserved in other mammals.

Methodology/Principal Findings

In the present study, we evaluated RNAa in cells derived from four mammalian species including nonhuman primates (African green monkey and chimpanzee), mouse, and rat. Previously, we identified saRNAs leading to the activation of E-cadherin, p21, and VEGF in human cells. As the targeted sequences are highly conserved in primates, transfection of each human saRNA into African green monkey (COS1) and chimpanzee (WES) cells also resulted in induction of the intended gene. Additional saRNAs targeting clinically relevant genes including p53, PAR4, WT1, RB1, p27, NKX3-1, VDR, IL2, and pS2 were also designed and transfected into COS1 and WES cells. Of the nine genes, p53, PAR4, WT1, and NKX3-1 were induced by their corresponding saRNAs. We further extended our analysis of RNAa into rodent cell types. We identified two saRNAs that induced the expression of mouse Cyclin B1 in NIH/3T3 and TRAMP C1 cells, which led to increased phosphorylation of histone H3, a downstream marker for chromosome condensation and entry into mitosis. We also identified two saRNAs that activated the expression of CXCR4 in primary rat adipose–derived stem cells.

Conclusions/Significance

This study demonstrates that RNAa exists in mammalian species other than human. Our findings also suggest that nonhuman primate disease models may have clinical applicability for validating RNAa-based drugs.

Gene therapy in autoimmune diseases: challenges and opportunities

Clinical treatment of autoimmune disorders presents a special challenge. For decades, most clinical regimens in autoimmunity has been largely symptomatic and non-disease specific. Although data from vigorous research has lead to accumulating knowledge on the pathogenic and immunological mechanisms of many autoimmune diseases, their direct clinical applications have been sparse. Advances in biotechnology have laid the groundwork for potent and specific molecular targeting therapies by gene therapy, and have just begun to be investigated in the treatment of autoimmune disorders. Such work has been largely based on the availability of well-established animal models of common autoimmune disorders, and the efficacy of strategic approaches initially investigated and validated in these models. Although these preclinical animal model studies have provided the proof-of-concept for multiple potential applications, human clinical trials on gene therapy in autoimmunity are still at its infancy. The recent success of Phase I/II clinical trials of gene therapy in rheumatoid arthritis and multiple sclerosis, development of cutting edge technology in target identification, as well as gene delivery systems have now set the stage for a more thorough and vigorous pace in the near future to advance this exciting field.

Adenoviral-mediated gene transfer restores plasma ADAMTS13 antigen and activity in ADAMTS13 knockout mice

ADAMTS13 is a plasma metalloprotease that regulates the size of the von Willebrand factor (VWF) multimers. Genetic or acquired deficiency of ADAMTS13 causes thrombotic thrombocytopenic purpura (TTP) in humans. Plasma infusion is the treatment of choice for patients with congenital ADAMTS13 deficiency. However, this practice exposes patients to the risk of infections, allergies and fluid volume overload. The search for alternative treatments is required. Here, we tested the ability of systemically administered adenovirus encoding human ADAMTS13 to restore the deficient protein in the circulation of Adamts13(-/-) mice. Injection of the adenovirus efficiently transduced the liver, kidney, lung, heart and spleen, resulting in the secretion of ADAMTS13 into plasma. A reduced area of thrombi was observed when blood from Ad-ADAMTS13-treated mice was perfused over a collagen-coated surface in a parallel plate flow chamber compared with blood of Ad-betaGal-treated controls. The secreted ADAMTS13 protein was functionally active even after 2 months from injection. The data provide the proof of principle for developing a novel therapy for the correction of ADAMTS13 deficiency in patients with hereditary TTP.