Optimization of adeno-associated virus vector-mediated gene transfer to the respiratory tract

Gene Therapy for Cystic Fibrosis: Recent Advances and Future Prospects

Gene replacement therapies are novel therapeutic approaches that seek to tackle hereditary diseases caused by a congenital deficiency in a particular gene, when a functional copy of a gene can be delivered to the cells and tissues using various delivery systems. To do this, viral particles carrying a functional copy of the gene of interest and various nonviral gene delivery systems, including liposomes, nanoparticles, etc., can be used. In this review, we discuss the state of current knowledge regarding the molecular mechanisms and types of genetic mutations that lead to cystic fibrosis and highlight recent developments in gene therapy that can be leveraged to correct these mutations and to restore the physiological function of the carrier protein transporting sodium and chlorine ions in the airway epithelial cells. Restoration of carrier protein expression could lead to the normalization of ion and water transport across the membrane and induce a decrease in the viscosity of airway surface fluid, which is one of the pathological manifestations of this disease. This review also summarizes recently published preclinical and clinical data for various gene therapies to allow one to make some conclusions about future prospects for gene therapy in cystic fibrosis treatment.

Various AAV Serotypes and Their Applications in Gene Therapy: An Overview

Despite scientific discoveries in the field of gene and cell therapy, some diseases still have no effective treatment. Advances in genetic engineering methods have enabled the development of effective gene therapy methods for various diseases based on adeno-associated viruses (AAVs). Today, many AAV-based gene therapy medications are being investigated in preclinical and clinical trials, and new ones are appearing on the market. In this article, we present a review of AAV discovery, properties, different serotypes, and tropism, and a following detailed explanation of their uses in gene therapy for disease of different organs and systems.

Intranasal application of adeno-associated viruses: a systematic review

Adeno-associated viruses (AAVs) represent some of the most commonly employed vectors for targeted gene delivery and their extensive study has resulted in the approval of multiple gene therapies to treat human diseases. The intranasal route of vector application in gene therapy offers several advantages over traditional ways of administration. In addition to targeting local tissue like the olfactory epithelium, it provides minimally invasive access to various organ systems, including the central nervous system and the respiratory tract. Through a systematic literature review, a total of 53 articles that investigated the intranasal application of AAVs were identified, included, and summarized in this manuscript. Within these studies, AAV-based gene therapy was mainly investigated for its application in various infectious, pulmonary, or neurologic and/or psychiatric diseases. This review gives a comprehensive overview of the current technological state of the art regarding the intranasal application of AAVs for gene transfer and discusses remaining hurdles, which still have to be resolved before this approach can effectively be implemented in the routine clinical setting.

Novel drug delivery systems and disease models for pulmonary fibrosis

Pulmonary fibrosis (PF) is a serious and progressive lung disease which is possibly life-threatening. It causes lung scarring and affects lung functions including epithelial cell injury, massive recruitment of immune cells and abnormal accumulation of extracellular matrix (ECM). There is currently no cure for PF. Treatment for PF is aimed at slowing the course of the disease and relieving symptoms. Pirfenidone (PFD) and nintedanib (NDNB) are currently the only two FDA-approved oral medicines to slow down the progress of idiopathic pulmonary fibrosis, a specific type of PF. Novel drug delivery systems and therapies have been developed to improve the prognosis of the disease, as well as reduce or minimize the toxicities during drug treatment. The drug delivery routes for these therapies are various including oral, intravenous, nasal, inhalant, intratracheal and transdermal; although this is dependent on specific treatment mechanisms. In addition, researchers have also expanded current animal models that could not fully restore the clinicopathology, and developed a series of in vitro models such as organoids to study the pathogenesis and treatment of PF. This review describes recent advances on pathogenesis exploration, classifies and specifies the progress of drug delivery systems by their delivery routes, as well as an overview on the in vitro and in vivo models for PF research.

Anticipating New Treatments for Cystic Fibrosis: A Global Survey of Researchers

Cystic fibrosis is a life-threatening disease that affects at least 100,000 people worldwide. It is caused by a defect in the cystic fibrosis transmembrane regulator (CFTR) gene and presently, 360 CFTR-causing mutations have been identified. Since the discovery of the CFTR gene, the expectation of developing treatments that can substantially increase the quality of life or even cure cystic fibrosis patients is growing. Yet, it is still uncertain today which developing treatments will be successful against cystic fibrosis. This study addresses this gap by assessing the opinions of over 524 cystic fibrosis researchers who participated in a global web-based survey. For most respondents, CFTR modulator therapies are the most likely to succeed in treating cystic fibrosis in the next 15 years, especially through the use of CFTR modulator combinations. Most respondents also believe that fixing or replacing the CFTR gene will lead to a cure for cystic fibrosis within 15 years, with CRISPR-Cas9 being the most likely genetic tool for this purpose.

Adenoviral Transduction of Dickkopf-1 Alleviates Silica-Induced Silicosis Development in Lungs of Mice

Silicosis is an occupational disease caused by inhalation of silica dust, which is hallmarked by progressive pulmonary fibrosis associated with poor prognosis. Wnt/β-catenin signaling is implicated in the development of fibrosis and is a therapeutic target for fibrotic diseases. Previous clinical studies of patients with pneumoconiosis, including silicosis, revealed an increased concentration of circulating WNT3A and DKK1 proteins and inflammatory cells in bronchoalveolar lavage compared with healthy subjects. The present study evaluated the effects of adenovirus-mediated transduction of Dickkopf-1 (Dkk1), a Wnt/β-catenin signaling inhibitor, on the development of pulmonary silicosis in mice. Consistent with previous human clinical studies, our experimental studies in mice demonstrated an aberrant Wnt/β-catenin signaling activity coinciding with increased Wnt3a and Dkk1 proteins and inflammation in lungs of silica-induced silicosis mice compared with controls. Intratracheal delivery of adenovirus expressing murine Dkk1 (AdDkk1) inhibited Wnt/β-catenin activity in mouse lungs. The adenovirus-mediated Dkk1 gene transduction demonstrated the potential to prevent silicosis development and ameliorate silica-induced lung fibrogenesis in mice, accompanied by the reduced expression of epithelia--mesenchymal transition markers and deposition of extracellular matrix proteins compared with mice treated with "null" adenoviral vector. Mechanistically, AdDkk1 is able to attenuate the lung silicosis by inhibiting a silica-induced spike in TGF-β/Smad signaling. In addition, the forced expression of Dkk1 suppressed silica-induced epithelial cell proliferation in polarized human bronchial epithelial cells. This study provides insight into the underlying role of Wnt/β-catenin signaling in promoting the pathogenesis of silicosis and is proof-of-concept that targeting Wnt/β-catenin signaling by Dkk1 gene transduction may be an alternative approach in the prevention and treatment of silicosis lung disease.

Intra-tracheal delivery of AAV6 vectors results in sustained transduction in murine lungs without genomic integration

Despite the progress made in AAV-based gene therapy targeting different organ systems, lung-targeted gene therapy using AAV vectors has not been effective, mostly due to the poor transduction and un-sustained gene expression in airway epithelium. Furthermore, concerns over possible harmful insertional mutagenesis seen in other cell types, particularly hepatocytes, raised a question about AAV safety. In this study, we evaluate the long-term persistence of this vector in mouse lungs and any possible harmful integration of these vectors into the host genome. AAV6 vectors expressing reporter gene (firefly luciferase) were delivered to the lungs of C57BL/6 mice through intra-tracheal intubation. Despite the large variation among individual animals, most animals had high and sustained luciferase activity with a peak from 2 to 3 weeks post-transduction before a significant decline between 15 and 19 weeks post-transduction. More importantly, even after its decline, most animals maintained detectable luciferase expression for 150 days or more, which was confirmed by post-necropsy qPCR analysis of luciferase gene expression. At the termination point of experiments, an average of one copy of AAV expression cassette per mouse genome was detected. We also found that partial overlaps between the AAV6 expression cassette and the mouse genome were distributed broadly with no apparent systematic preference in any mouse chromosomal map location. In summary, our data suggest that AAV6 mediated long-term gene expression in the lungs with no evidence of genomic integration, and thus, any insertional mutagenesis.

Rapid generation of mouse model for emerging infectious disease with the case of severe COVID-19

Since the pandemic of COVID-19 has intensely struck human society, small animal model for this infectious disease is in urgent need for basic and pharmaceutical research. Although several COVID-19 animal models have been identified, many of them show either minimal or inadequate pathophysiology after SARS-CoV-2 challenge. Here, we describe a new and versatile strategy to rapidly establish a mouse model for emerging infectious diseases in one month by multi-route, multi-serotype transduction with recombinant adeno-associated virus (AAV) vectors expressing viral receptor. In this study, the proposed approach enables profound and enduring systemic expression of SARS-CoV-2-receptor hACE2 in wild-type mice and renders them vulnerable to SARS-CoV-2 infection. Upon virus challenge, generated AAV/hACE2 mice showed pathophysiology closely mimicking the patients with severe COVID-19. The efficacy of a novel therapeutic antibody cocktail RBD-chAbs for COVID-19 was tested and confirmed by using this AAV/hACE2 mouse model, further demonstrating its successful application in drug development.

Upon the emergence of new infectious disease, animal model becomes a pivotal tool for study of disease mechanism and development of therapeutics. In this study, we propose a versatile approach that allows rapid generation of mouse model for novel infectious disease once the receptor of the pathogen is identified. We demonstrated this approach by generating a mouse model for COVID-19 in a month’s time. These mice were capable of recapitulating severe COVID-19 in patients, and successfully applied in the development of a therapeutic antibody cocktail for the disease. This not only suggests the usefulness of this mouse model for the research on COVID-19, but also exhibit the utility of the proposed approach for establishing animal model for infectious disease.

Tissue and cell-type-specific transduction using rAAV vectors in lung diseases

Gene therapy of genetically determined diseases, including some pathologies of the respiratory system, requires an efficient method for transgene delivery. Recombinant adeno-associated viral (rAAV) vectors are well studied and employed in gene therapy, as they are relatively simple and low immunogenic and able to efficiently transduce eukaryotic cells. To date, many natural and artificial (with modified capsids) AAV serotypes have been isolated, demonstrating preferential tropism toward different tissues and cells in accordance with the prevalent receptors on the cell surface. However, rAAV-mediated delivery is not strictly specific due to wide tropism of some viral serotypes. Thus, the development of the methods allowing modulating specificity of these vectors could be beneficial in some cases. This review describes various approaches for retargeting rAAV to respiratory cells, for example, using different types of capsid modifications and regulation of a transgene expression by tissue-specific promoters. Part of the review is devoted to the issues of transduction of stem and progenitor lung cells using AAV, which is a complicated task today.

GITRL on dendritic cells aggravates house dust mite-induced airway inflammation and airway hyperresponsiveness by modulating CD4+ T cell differentiation

Background

Glucocorticoid-induced tumor necrosis factor receptor family-related protein ligand (GITRL) plays an important role in tumors, autoimmunity and inflammation. However, GITRL is not known to modulate the pathogenesis of allergic asthma. In this study, we investigated whether regulating GITRL expressed on dendritic cells (DCs) can prevent asthma and to elucidate its mechanism of action.

Methods

In vivo, the role of GITRL in modulating house dust mite (HDM)-induced asthma was assessed in adeno-associated virus (AAV)-shGITRL mice. In vitro, the role of GITRL expression by DCs was evaluated in LV-shGITRL bone marrow dendritic cells (BMDCs) under HDM stimulation. And the direct effect of GITRL was observed by stimulating splenocytes with GITRL protein. The effect of regulating GITRL on CD4⁺ T cell differentiation was detected. Further, GITRL mRNA in the peripheral blood of asthmatic children was tested.

Results

GITRL was significantly increased in HDM-challenged mice. In GITRL knockdown mice, allergen-induced airway inflammation, serum total IgE levels and airway hyperresponsiveness (AHR) were reduced. In vitro, GITRL expression on BMDCs was increased after HDM stimulation. Further, knocking down GITRL on DCs partially restored the balance of Th1/Th2 and Th17/Treg cells. Moreover, GITRL stimulation in vitro inhibited Treg cell differentiation and promoted Th2 and Th17 cell differentiation. Similarly, GITRL mRNA expression was increased in the peripheral blood from asthmatic children.

Conclusions

This study identified a novel role for GITRL expressed by DCs as a positive regulator of CD4⁺ T cells responses in asthma, which implicates that GITRL inhibitors may be a potential immunotherapy for asthma.

Novel Lung Tropic Adeno-Associated Virus Capsids for Therapeutic Gene Delivery

Efforts to identify mutations that underlie inherited genetic diseases combined with strides in the development of gene therapy vectors over the last three decades have culminated in the approval of several adeno-associated virus (AAV)-based gene therapies. Genetic diseases that manifest in the lung such as cystic fibrosis (CF) and surfactant deficiencies, however, have so far proven to be elusive targets. Early clinical trials in CF using AAV serotype 2 (AAV2) achieved safety, but not efficacy endpoints; however, importantly, these studies provided critical information on barriers that need to be surmounted to translate AAV lung gene therapy toward clinical success. Bolstered with an improved understanding of AAV biology and more clinically relevant lung models, next-generation molecular biology and bioinformatics approaches have given rise to novel AAV capsid variants that offer improvements in transduction efficiency, immunological profile, and the ability to circumvent physical barriers in the lung such as mucus. This review discusses the principal limiting barriers to clinical success in lung gene therapy and focuses on novel engineered AAV capsid variants that have been developed to overcome those challenges.

Comprehensive analysis of drugs to treat SARS‑CoV‑2 infection: Mechanistic insights into current COVID‑19 therapies (Review)

The major impact produced by the severe acute respiratory syndrome coronavirus 2 (SARS‑CoV‑2) focused many researchers attention to find treatments that can suppress transmission or ameliorate the disease. Despite the very fast and large flow of scientific data on possible treatment solutions, none have yet demonstrated unequivocal clinical utility against coronavirus disease 2019 (COVID‑19). This work represents an exhaustive and critical review of all available data on potential treatments for COVID‑19, highlighting their mechanistic characteristics and the strategy development rationale. Drug repurposing, also known as drug repositioning, and target based methods are the most used strategies to advance therapeutic solutions into clinical practice. Current in silico, in vitro and in vivo evidence regarding proposed treatments are summarized providing strong support for future research efforts.

Duplex of Polyamidoamine Dendrimer/Custom-Designed Nuclear-Localization Sequence Peptide for Enhanced Gene Delivery

Background: Dendrimers are an attractive alternative to viral vectors due to the low cost of production, larger genetic insert-carrying capacity, and added control over immune- and genotoxic complications through versatile functionalization. However, their transfection rates pale in comparison to their viral counterparts, resulting in widespread research efforts in the attempt to improve transfection efficiency. Materials and Methods: In this work, we designed a synthetic diblock nuclear-localization sequence peptide (NLS) (DDDDDDVKRKKKP) and complexed it with polyamidoamine (PAMAM) dendrimer G4 to form a duplex for gene delivery. We conducted transmission electron microscopy, gel mobility shift assay, and intracellular trafficking studies. We also assessed its transfection efficiency for the delivery of a green fluorescent protein-encoding plasmid (pGFP) to NIH3T3 cells. Results: PAMAM dendrimer G4, NLS, and plasmid DNA can form a stable three-part polyplex and gain enhanced entry into the nucleus. We found transfection efficiency, in large part, depends on the ratio of G4:NLS:plasmid. The triplex prepared at the ratio of 1:60:1 for G4:NLS:pGFP has been shown to be more significantly efficient in transfecting cells than the control group (G4/pGFP, 0.5:1). Conclusions: This new diblock NLS peptide can facilely complex with dendrimers to improve dendrimer-based gene transfection. It can also complex with other polycationic polymers to produce more potent nonviral duplex gene delivery vehicles.

Effect of promoter, promoter mutation and enhancer on transgene expression mediated by episomal vectors in transfected HEK293, Chang liver and primary cells

The episomal vector cannot integrate into the host cell chromosome, which has no potential risk in gene therapy. However, the low level of transgene expression driven by episomal vectors needs to be solved. In this study, we investigated the effects of enhancers, promoters and promoter variants on transgene expression levels driven by episomal vectors in HEK293, Chang liver and primary cells. Results showed that all eight cis-acting elements used could increase transfection efficiency and transient eGFP expression in transfected HEK293 and Chang liver cells. In stably transfected mammalian cells, the elongation factor-1 alpha (EF-1α) promoter and mutant-404 showed high and stable transgene expression. The mechanisms might be related to the type and quantity of transcription factor regulatory elements. Moreover, quantitative reverse transcription polymerase chain reaction analysis showed that mRNA expression levels were not directly proportional to protein expression levels. Furthermore, the EF-1α promoter conferred high transgene expression levels in primary cells, and the plasmid was also present in the episomal state. Taken together, these results provided valuable information for improving transgene expression with episomal vectors in mammalian cells.

Intranasal Delivery of Adenoviral and AAV Vectors for Transduction of the Mammalian Peripheral Olfactory System

Intranasal delivery of solutions is a straightforward methodology for viral vector transduction and gene transfer to the epithelia within the nasal cavity. Beyond the simplicity of the technique, intranasal delivery has demonstrated restricted transduction of the olfactory and respiratory epithelial tissues. Here we outline the procedure of viral vector intranasal delivery in early postnatal and adult mice, as well as adult rats. The procedure allows for robust transduction and ectopic gene delivery that can be used for the visualization of cellular structures, protein distribution, and assessment of viral vector-mediated therapies.

Self-complementary and tyrosine-mutant rAAV vectors enhance transduction in cystic fibrosis bronchial epithelial cells

Recombinant adeno-associated virus (rAAV) vector platforms have shown considerable therapeutic success in gene therapy for inherited disorders. In cystic fibrosis (CF), administration of first-generation rAAV2 was safe, but clinical benefits were not clearly demonstrated. Therefore, next-generation vectors that overcome rate-limiting steps in rAAV transduction are needed to obtain successful gene therapy for this devastating disease. In this study, we evaluated the effects of single-strand or self-complementary (sc) rAAV vectors containing single or multiple tyrosine-to-phenylalanine (Y-F) mutations in capsid surface-exposed residues on serotypes 2, 8 or 9. For this purpose, CF bronchial epithelial (CFBE) cells were transduced with rAAV vectors, and the transgene expression of enhanced green fluorescence protein (eGFP) was analyzed at different time points. The effects of vectors on the cell viability, host cell cycle and in association with co-adjuvant drugs that modulate intracellular vector trafficking were also investigated. Six rAAV vectors demonstrated greater percentage of eGFP⁺ cells compared to their counterparts at days 4, 7 and 10 post-transduction: rAAV2 Y(272,444,500,730)F, with 1.95-, 3.5- and 3.06-fold increases; rAAV2 Y(252,272,444,500,704,730)F, with 1.65-, 2.12-, and 2-fold increases; scrAAV2 WT, with 1.69-, 2.68-, and 2.32-fold increases; scrAAV8 Y773F, with 57-, 6.06-, and 7-fold increases; scrAAV9 WT, with 7.47-, 4.64-, and 3.66-fold increases; and scrAAV9 Y446F, with 8.39-, 4.62-, and 4.4-fold increases. At days 15, 20, and 30 post-transduction, these vectors still demonstrated higher transgene expression than transfected cells. Although the percentage of eGFP⁺ cells reduced during the time-course analysis, the delta mean fluorescence intensity increased. These vectors also led to increased percentage of cells in G₁-phase without eliciting any cytotoxicity. Prior administration of bortezomib or genistein did not increase eGFP expression in cells transduced with either rAAV2 Y(272,444,500,730)F or rAAV2 Y(252,272,444,500,704,730)F. In conclusion, self-complementary and tyrosine capsid mutations on rAAV serotypes 2, 8, and 9 led to more efficient transduction than their counterparts in CFBE cells by overcoming the intracellular trafficking and second-strand DNA synthesis limitations.

Efficient transduction of adeno-associated virus vectors into gerbil hippocampus with an appropriate combination of viral capsids and promoters

Adeno-associated virus (AAV) is an ideal vector for gene transduction into the central nervous system because of its safety and efficiency. While it is currently widely used for clinical trials and is expected to become more widespread, the appropriate combination of viral serotypes and promoters have not been fully investigated. In this study, we compared the transduced gene expression of AAVrh10 to AAV5 in gerbil hippocampus using three different promoters, including cytomegalovirus (CMV), chicken β-actin promoter with the CMV immediate-early enhancer (CAG), and the Synapsin 1 (Syn1) promoter. Four-week-old male gerbils underwent stereotaxic injection with 1 × 10¹⁰ viral genome of AAV carrying green fluorescent protein (GFP). Quantification of the GFP-positive areas 3 weeks after injection showed that AAVrh10-CMV and AAVrh10-CAG were the most efficient (p < 0.001, compared with the control) and AAVrh10-Syn1 and AAV5-CMV were the next most efficient (p < 0.05, compared with the control). On the other hand, AAV5-Syn1 showed little expression, which was only observed at the injected site. In conclusion, we should note that some combinations of viral capsids and promoters can result in failure of gene delivery, while most of them will work appropriately in the transgene expression in the brain.

Systemic Gene Delivery by Single-Dose Intracardiac Administration of scAAV2/9 and scAAV2/rh10 Variants in Newborn Rats

Recombinant adeno-associated virus serotype 9 (rAAV2/9) and pseudotype rhesus-10 (rAAV2/rh10) are used for gene delivery, especially into the central nervous system. Both serotypes cross the blood-brain barrier and mediate stable long-term transduction in dividing and nondividing cells. Among possible routes of administration, intracardiac injection holds the potential for widespread vector diffusion associated with a relatively simple approach. In this study adopting the intracardiac route, we compare the cell-specific tropism and transfection efficacy of a panel of engineered rAAV2/9 and rAAV2/rh10 vectors encoding the enhanced green fluorescent protein. We observed transduction in the brain and peripherally, with a predominant neuronal tropism while the various serotypes achieved different expression patterns.

AAV6-Mediated IL-10 Expression in the Lung Ameliorates Bleomycin-Induced Pulmonary Fibrosis in Mice

Idiopathic pulmonary fibrosis (IPF) is a fibroproliferative disorder with limited therapeutic options. An aberrant wound healing process in response to repetitive lung injury has been suggested for its pathogenesis, and a number of cytokines including transforming growth factor β1 play pivotal roles in the induction and progression of fibrosis. Thus, the regulation of these pro-inflammatory conditions may reduce the progression of IPF and ameliorate its symptoms in patients. Interleukin-10 (IL-10), a pleiotropic cytokine, exerts anti-inflammatory and anti-fibrotic effects in numerous biological settings. In the present study, we investigated the preventive effects of IL-10 on bleomycin-induced pulmonary fibrosis in mice with the continuous expression of this cytokine via an adeno-associated virus serotype 6 vector. Mice were administered the adeno-associated virus serotype 6 vector encoding mouse IL-10 by intratracheal injection, and osmotic minipumps containing bleomycin were subcutaneously implanted seven days later. Lung histology and the expression levels of pro-inflammatory cytokines and fibrogenic cytokines were then analyzed. In mice exhibiting persistent IL-10 expression on day 35, the number of infiltrated inflammatory cells and the development of fibrosis in lung tissues were significantly reduced. Increases in transforming growth factor β1 and decreases in IFN-γ were also suppressed in treated animals, with changes in these cytokines playing important roles in the pathogenesis of pulmonary fibrosis. Furthermore, IL-10 significantly improved survival in bleomycin-induced mice. Our results provide insights into the potential benefit of the anti-fibrotic effects of IL-10 as a novel therapeutic approach for IPF.

An Adeno-Associated Viral Vector Capable of Penetrating the Mucus Barrier to Inhaled Gene Therapy

Diffusion of the viral vectors evaluated in inhaled gene therapy clinical trials to date are largely hindered within airway mucus, which limits their access to, and transduction of, the underlying airway epithelium prior to clearance from the lung. Here, we discovered that adeno-associated virus (AAV) serotype 6 was able to rapidly diffuse through mucus collected from cystic fibrosis (CF) patients, unlike previously tested AAV serotypes. A point mutation of the AAV6 capsid suggests a potential mechanism by which AAV6 avoids adhesion to the mucus mesh. Significantly greater transgene expression was achieved with AAV6 compared to a mucoadhesive serotype, AAV1, in air-liquid interface cultures of human CF bronchial epithelium with naturally secreted mucus or induced mucus hypersecretion. In addition, AAV6 achieved superior distribution and overall level of transgene expression compared to AAV1 in the airways and whole lungs, respectively, of transgenic mice with airway mucus obstruction. Our findings motivate further evaluation and clinical development of AAV6 for inhaled gene therapy.

Genetic therapies for cystic fibrosis lung disease

Gene therapy for cystic fibrosis (CF) has been the subject of intense research over the last twenty-five years or more, using both viral and liposomal delivery methods, but so far without the emergence of a clinical therapy. New approaches to CF gene therapy involving recent improvements to vector systems, both viral and non-viral, as well as new nucleic acid technologies have led to renewed interest in the field. The field of therapeutic gene editing is rapidly developing with the emergence of CRISPR/Cas9 as well as chemically modified mRNA therapeutics. These new types of nucleic acid therapies are also a good fit with delivery by non-viral delivery approaches which has led to a renewed interest in lipid-based and other nanoformulations.