Production and clinical development of nanoparticles for gene delivery

Review on Nanoparticles and Nanostructured Materials: Bioimaging, Biosensing, Drug Delivery, Tissue Engineering, Antimicrobial, and Agro-Food Applications

In the last few decades, the vast potential of nanomaterials for biomedical and healthcare applications has been extensively investigated. Several case studies demonstrated that nanomaterials can offer solutions to the current challenges of raw materials in the biomedical and healthcare fields. This review describes the different nanoparticles and nanostructured material synthesis approaches and presents some emerging biomedical, healthcare, and agro-food applications. This review focuses on various nanomaterial types (e.g., spherical, nanorods, nanotubes, nanosheets, nanofibers, core-shell, and mesoporous) that can be synthesized from different raw materials and their emerging applications in bioimaging, biosensing, drug delivery, tissue engineering, antimicrobial, and agro-foods. Depending on their morphology (e.g., size, aspect ratio, geometry, porosity), nanomaterials can be used as formulation modifiers, moisturizers, nanofillers, additives, membranes, and films. As toxicological assessment depends on sizes and morphologies, stringent regulation is needed from the testing of efficient nanomaterials dosages. The challenges and perspectives for an industrial breakthrough of nanomaterials are related to the optimization of production and processing conditions.

Active targeting via ligand-anchored pH-responsive strontium nanoparticles for efficient nucleic acid delivery into breast cancer cells

Purpose

Gene therapy is a promising and novel therapeutic strategy for many mutated gene-associated diseases, including breast cancer. However, it poses significant biological drawbacks such as rapid clearance from the circulatory system and low cellular uptake of the exogenously delivered functional nucleic acids. The development of efficient and biocompatible carriers for genetic materials has been extensively explored in the literature, and the functionalization of nanoparticles (NPs) with cancer cell-recognizing ligands has become an attractive approach to promote tumor targetability and efficient cellular internalization via endocytosis.

Methods

This study introduced self-assembling targeting ligands, including transferrin and fibronectin with the ability to electrostatically interact with strontium nanoparticles (SNPs), and then analyzed their influence on size and zeta potential of the resultant hybrid SNPs, cellular uptake and expression efficiency of transgene-loaded hybrid NPs.

Results

Smaller ligand-coated SNPs (LCSNPs) remarkably increased gene transfection activity in both MCF-7 and 4T1 cells as well as nucleic acid localization into tumor tissues with improved tumor regression activity in a 4T1-tumor xenograft mouse model.

Conclusion

LCSNPs-mediated delivery of p53 gene and MAPK siRNA provided a proof-of-concept for the functionalized nanocarrier formulation in order to inhibit breast cancer cell growth.

Extracellular Vesicle-Based Hybrid Systems for Advanced Drug Delivery

The continuous technological advancement of nanomedicine has enabled the development of novel vehicles for the effective delivery of therapeutic substances. Synthetic drug delivery systems are nano-sized carriers made from various materials that can be designed to deliver therapeutic cargoes to cells or tissues. However, rapid clearance by the immune system and the poor targeting profile of synthetic drug delivery systems are examples of the pressing obstacles faced in nanomedicine, which have directed the field toward the development of alternative strategies. Extracellular vesicles (EVs) are nanoscale particles enclosed by a protein-rich lipid bilayer; they are released by cells and are considered to be important mediators of intercellular communication. Owing to their natural composition, EVs have been suggested to exhibit good biocompatibility and to possess homing properties to specific cell types. Combining EVs with synthetic nanoparticles by defined hybridization steps gives rise to a novel potential drug delivery tool, i.e., EV-based hybrid systems. These novel therapeutic vehicles exhibit potential advantageous features as compared to synthetic drug delivery systems such as enhanced cellular uptake and cargo delivery, immuno-evasive properties, capability of crossing biological barriers, and tissue targeting profile. Here, we provide an overview of the various strategies practiced to produce EV-based hybrid systems and elucidate those advantageous features obtained by synthetic drug delivery systems upon hybridization with EVs.

A Peptide/MicroRNA-31 nanomedicine within an electrospun biomaterial designed to regenerate wounds in vivo

microRNA-31 (miR-31) has been identified to be downregulated in pathologies associated with delayed wound repair. Thus, it was proposed that the delivery of a plasmid encoding miR-31 (pmiR-31) to the skin could hold potential in promoting wound healing. Effective delivery of pmiR-31 was potentiated by encapsulation with the CHAT peptide to form nanocomplexes, this improved cellular entry and elicited a potent increase in miR-31 expression in vitro in both skin human keratinocyte cell line (HaCaT) and human microvascular endothelial cell line (HMEC-1). Transfection efficiencies with CHAT/pEFGP-N1 were significant at 15.2 ± 8.1% in HMEC-1 cells and >40% in HaCaT cells. In this study, the CHAT/pmiR-31 nanocomplexes at a N:P ratio of 10 had an average particle size of 74.2 nm with a cationic zeta potential of 9.7 mV. Delivery of CHAT/pmiR-31 to HaCaT and HMEC-1 cells resulted in significant improvements in cell migration capacity and increased angiogenesis. In vivo studies were conducted in C57BL/6 J mice were CHAT/pmiR-31 was delivered via electrospun PVA nanofibres, demonstrating a significant increase in epidermal (increase of ∼38.2 µm) and stratum corneum (increase of 8.2 µm) layers compared to controls. Furthermore, treatment in vivo with CHAT/pmiR-31 increased angiogenesis in wounds compared to controls, with a significant increase in vessel diameter by ∼20.4 µm compared against a commercial dressing control (Durafiber™). Together, these data demonstrate that the delivery of CHAT/pmiR-31 nanocomplexes from electrospun PVA nanofibres represent an innovative therapy for wound repair, eliciting a positive therapeutic response across both stromal and epithelial tissue compartments of the skin. STATEMENT OF SIGNIFICANCE: This study advances research regarding the development of our unique electrospun nanofibre patch to deliver genetic nanoparticles into wounds in vivo to promote healing. The genetic nanoparticles are comprised of: (a) plasmid micro-RNA31 that has been shown to be downregulated in pathologies with delayed wound repair and (b) a 15 amino acid linear peptide termed CHAT. The CHAT facilitates complexation of miR-31 and cellular uptake. Herein, we report for the first time on the use of CHAT to deliver a therapeutic cargo pmiR-31 for wound healing applications from a nanofibre patch. Application of the nanofibre patch resulted in the controlled delivery of the CHAT/pmiR-31 nanoparticles with a significant increase in both epidermal and stratum corneum layers compared to untreated and commercial controls.

Bioreducible polymer-mediated delivery of oncolytic adenovirus can attenuate antiviral immune response and concurrently enhance induction of antitumor immune response to effectively prevent metastasis

Oncolytic virotherapy is highly promising and novel treatment modality for cancer. Several clinical trials with oncolytic viruses have illustrated that the potent antitumor efficacy of these viruses may rely on...

Pharmaceutical liposomal delivery—specific considerations of innovation and challenges

Liposomal technology can enhance drug solubility and stability, achieving codelivery for combination therapy, and modulate the in vivo fate (e.g., site-specific distribution and controlled release), thereby improving treatment outcomes.

Biophysical Considerations in the Rational Design and Cellular Targeting of Flexible Polymeric Nanoparticles

How nanoparticle (NP) mechanical properties impact multivalent ligand-receptor-mediated binding to cell surfaces, the avidity, propensity for internalization, and effects due to crowding remains unknown or unquantified. Through computational analyses, the effects of NP composition from soft, deformable NPs to rigid spheres, effect of tethers, the crowding of NPs at the membrane surface, and the cell membrane properties such as cytoskeletal interactions are addressed. Analyses of binding mechanisms of three distinct NPs that differ in type and rigidity (core-corona flexible NP, rigid NP, and rigid-tethered NP) but are otherwise similar in size and ligand surface density are reported; moreover, for the case of flexible NP, NP stiffness is tuned by varying the internal crosslinking density. Biophysical modeling of NP binding to membranes together with thermodynamic analysis powered by free energy calculations is employed, and it is shown that efficient cellular targeting and uptake of NP functionalized with targeting ligand molecules can be shaped by factors including NP flexibility and crowding, receptor-ligand binding avidity, state of the membrane cytoskeleton, and curvature inducing proteins. Rational design principles that confer tension, membrane excess area, and cytoskeletal sensing properties to the NP which can be exploited for cell-specific targeting of NP are uncovered.

Biological nanoparticles: Relevance as novel target drug delivery systems and leading chromatographic isolation approaches

Nanotechnology is one of the most promising technologies of the 21st century, and it is now presenting an enormous impact on target drug delivery. In this context, the recent use of natural vesicle-like nanoparticles such as extracellular vesicles (i.e., exosomes, microvesicles, and apoptotic bodies) and virus-like particles is rendering encouraging results mostly because these delivery systems present cargo versatility, favorable body circulating advantages, biocompatibility, immunogenicity, and the capacity to be modified superficially to increase their affinity to a certain target or to control their entrance to the cell. However, some of the biggest challenges toward their clinical implementation are poorly standardized processing operations due to their inherent heterogeneity and expensive, long-lasting, and difficult to scale isolation procedures that can also affect the stability of the particles. Under these circumstances, chromatographic procedures represent an attractive and favorable alternative to overcome their downstream processing. Moreover, even when standardized chromatographic purification protocols are still in development, great achievements have been made using size exclusion, ionic exchange, hydrophobic interaction, and affinity protocols, mostly because of the correct harnessing of the nanovesicle membrane properties. In this sense, this review focuses on presenting the current understanding on the most promising therapeutic biological nanoparticles and the chromatographic isolation approaches employed in their recovery, providing at the same time recent findings and a general overview of the aspects that might impact the outcome of chromatographic techniques for this application.

Harnessing the combined potential of cancer immunotherapy and nanomedicine: A new paradigm in cancer treatment

Cancer immunotherapy has recently emerged as a rising star due to its ability to activate patients' immune systems to fight tumors and prevent relapse. Conversely, the interest in cancer nanomedicine has seemingly waned due to its lackluster clinical translation. Despite being hailed as a game-changer in oncology, cancer immunotherapy still faces numerous challenges. Combining both entities together has thus been one among several solutions proposed to circumvent these challenges. This solution has since gained traction and has also led to a renaissance of cancer nanomedicine. While most combinations are currently experimental at best, some have progressed on to clinical trials. This review thus seeks to examine the advantages and disadvantages of integrating both modalities as a cancer treatment. The opportunities, challenges and future directions of this emerging field will also be explored with the hope that such a combination will lead to a paradigm shift in cancer treatments.

Genetic Therapies for Alzheimer's Disease: A Scoping Review

Effective, disease modifying therapies for Alzheimer's disease (AD) remain a quandary, following a panoply of expensive failures in human clinical trials. Given the stagnation in therapeutics, alternative approaches are needed. Recent successes of genetic therapies in other neurodegenerative diseases may highlight the way forward. This scoping review explores suggested targets of genetic therapy in AD, with a focus on vector-based approaches in pre-clinical and clinical trials. Putative targets of genetic therapies tested in pre-clinical trials include amyloid pathway intermediates and enzymes modulation, tau protein downregulation, APOE4 downregulation and APOE2 upregulation, neurotrophin expression (nerve growth factor (NGF) and brain-derived neurotrophic factor), and inflammatory cytokine alteration, among several other approaches. There have been three completed human clinical trials for genetic therapy in AD patients, all of which upregulated NGF in AD patients, showing some mixed evidence of benefit. Several impediments remain to be surpassed before genetic therapies can be successfully applied to AD, including the challenge of delivering monogenic genetic therapies for complex polygenic disorders, risks in the dominant delivery method (intracranial injection), stability of genetic therapies in vivo, poor translatability of pre-clinical AD models, and the expense of genetic therapy production. Genetic therapies represent an exciting opportunity within the world of AD therapeutics, but clinical applications likely remain a long term, rather than short term, possibility.

Forms and Methods for Interferon's Encapsulation

Interferons (IFNs) are cytokines involved in the immune response that act on innate and adaptive immunity. These proteins are natural cell-signaling glycoproteins expressed in response to viral infections, tumors, and biological inducers and constitute the first line of defense of vertebrates against infectious agents. They have been marketed for more than 30 years with considerable impact on the global therapeutic protein market thanks to their diversity in terms of biological activities. They have been used as single agents or with combination treatment regimens, demonstrating promising clinical results, resulting in 22 different formulations approved by regulatory agencies. The 163 clinical trials with currently active IFNs reinforce their importance as therapeutics for human health. However, their application has presented difficulties due to the molecules' size, sensitivity to degradation, and rapid elimination from the bloodstream. For some years now, work has been underway to obtain new drug delivery systems to provide adequate therapeutic concentrations for these cytokines, decrease their toxicity and prolong their half-life in the circulation. Although different research groups have presented various formulations that encapsulate IFNs, to date, there is no formulation approved for use in humans. The current review exhibits an updated summary of all encapsulation forms presented in the scientific literature for IFN-α, IFN-ß, and IFN-γ, from the year 1996 to the year 2021, considering parameters such as: encapsulating matrix, route of administration, target, advantages, and disadvantages of each formulation.

Combining mannose receptor mediated nanovaccines and gene regulated PD-L1 blockade for boosting cancer immunotherapy

Tumor nanovaccines have potential applications in the prevention and treatment of malignant tumors. However, it remains a longstanding challenge in exploiting efficient nanocarriers for inducing potent specifically cellular immune responses. Toward this objective, we herein explore an intensive tumor immunotherapeutic strategy by combining mannosylated nanovaccines and gene regulated PD-L1 blockade for immune stimulation and killing activity. Here, we fabricate a mannose modified PLL-RT (Man-PLL-RT) mediated nanovaccines with dendritic cells (DCs) targeting capacity. Man-PLL-RT is capable of co-encapsulating with antigen (ovalbumin, OVA) and adjuvant (unmethylated cytosine-phosphate-guanine, CpG) by electrostatic interaction. This positively charged Man-PLL-RT/OVA/CpG nanovaccines can facilitate the endocytosis, maturation and cross presentation in DCs. However, the nanovaccines arouse limited inhibition of tumor growth, which is mainly due to the immunosuppressed microenvironment of tumors. Combining tumor nanovaccines with gene regulated PD-L1 blockade leads to an obvious tumor remission in B16F10 melanoma bearing mice. The collaborative strategy provides essential insights to boost the benefits of tumor vaccines by regulating the checkpoint blockade with gene therapy.

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The nanovaccines are composed of polypeptides, which are bio-safe and biodegradable.

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The nanovaccines have APCs target function.

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Blocking PD-1/PD-L1 through gene therapy can reverse the tumor immune-tolerant microenvironment.

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The combined strategy provides a potentially effective strategy for the clinical treatment of tumors.

Non-viral delivery of CRISPR-Cas9 complexes for targeted gene editing via a polymer delivery system

Recent advances in molecular biology have led to the CRISPR revolution, but the lack of an efficient and safe delivery system into cells and tissues continues to hinder clinical translation of CRISPR approaches. Polymeric vectors offer an attractive alternative to viruses as delivery vectors due to their large packaging capacity and safety profile. In this paper, we have demonstrated the potential use of a highly branched poly(β-amino ester) polymer, HPAE-EB, to enable genomic editing via CRISPRCas9-targeted genomic excision of exon 80 in the COL7A1 gene, through a dual-guide RNA sequence system. The biophysical properties of HPAE-EB were screened in a human embryonic 293 cell line (HEK293), to elucidate optimal conditions for efficient and cytocompatible delivery of a DNA construct encoding Cas9 along with two RNA guides, obtaining 15–20% target genomic excision. When translated to human recessive dystrophic epidermolysis bullosa (RDEB) keratinocytes, transfection efficiency and targeted genomic excision dropped. However, upon delivery of CRISPR–Cas9 as a ribonucleoprotein complex, targeted genomic deletion of exon 80 was increased to over 40%. Our study provides renewed perspective for the further development of polymer delivery systems for application in the gene editing field in general, and specifically for the treatment of RDEB.

The Ocular Gene Delivery Landscape

The eye is at the forefront of developing therapies for genetic diseases. With the FDA approval of the first gene-therapy drug for a form of congenital blindness, numerous studies have been initiated to develop gene therapies for other forms of eye diseases. These examinations have revealed new information about the benefits as well as restrictions to using drug-delivery routes to the different parts of the eye. In this article, we will discuss a brief history of gene therapy and its importance to the eye and ocular delivery landscape that is currently being investigated, and provide insights into their advantages and disadvantages. Efficient delivery routes and vehicle are crucial for an effective, safe, and longer-lasting therapy.

Calcium mediated DNA binding in non-lamellar structures formed by DOPG/glycerol monooleate

In order to test an encapsulation method of short fragmented DNA (∼ 20-300 bp), we study the solubilisation in 150 mM solution of NaCl of a cubic phase formed by glycerol monooleate (GMO) with negatively charged dioleoylphosphatidylglycerol (DOPG) up to the level of unilamellar vesicles and, subsequently, the restoration of the cubic phase using Ca²⁺ cations. We performed small angle X-ray and neutron scattering (SAXS and SANS) to follow structural changes in DOPG/GMO mixtures induced by increasing DOPG content. The cubic phase (Pn3m space group) is preserved up to ∼ 11 mol% of DOPG in DOPG/GMO. Above 20 mol%, the SANS curves are typical of unilamellar vesicles. The thickness of the DOPG/GMO lipid bilayer (d_L) decreases slightly with increasing fraction of DOPG. The addition of 15 mM of CaCl₂ solution shields the electrostatic repulsions of DOPG molecules, increases slightly d_L and restores the cubic structures in the mixtures up to ∼ 37 mol% of DOPG. Zeta potential shows negative surface charge. The analysis of the data provides the radius of the water nano-channels of the formed non-lamellar structures. We discuss their dimensions with respect to DNA binding. In addition, Ca²⁺ mediates DNA - DOPG/GMO binding. The formed hexagonal phase, H_II, binds less of DNA in comparison with cubic phases (∼ 6 wt% and ∼ 20 wt% of the total amount, respectively). The studied system can be utilized as anionic Q_II delivery vector for genetic material.

Exploiting Single-Cell Tools in Gene and Cell Therapy

Single-cell molecular tools have been developed at an incredible pace over the last five years as sequencing costs continue to drop and numerous molecular assays have been coupled to sequencing readouts. This rapid period of technological development has facilitated the delineation of individual molecular characteristics including the genome, transcriptome, epigenome, and proteome of individual cells, leading to an unprecedented resolution of the molecular networks governing complex biological systems. The immense power of single-cell molecular screens has been particularly highlighted through work in systems where cellular heterogeneity is a key feature, such as stem cell biology, immunology, and tumor cell biology. Single-cell-omics technologies have already contributed to the identification of novel disease biomarkers, cellular subsets, therapeutic targets and diagnostics, many of which would have been undetectable by bulk sequencing approaches. More recently, efforts to integrate single-cell multi-omics with single cell functional output and/or physical location have been challenging but have led to substantial advances. Perhaps most excitingly, there are emerging opportunities to reach beyond the description of static cellular states with recent advances in modulation of cells through CRISPR technology, in particular with the development of base editors which greatly raises the prospect of cell and gene therapies. In this review, we provide a brief overview of emerging single-cell technologies and discuss current developments in integrating single-cell molecular screens and performing single-cell multi-omics for clinical applications. We also discuss how single-cell molecular assays can be usefully combined with functional data to unpick the mechanism of cellular decision-making. Finally, we reflect upon the introduction of spatial transcriptomics and proteomics, its complementary role with single-cell RNA sequencing (scRNA-seq) and potential application in cellular and gene therapy.

Evaluation of the Benefits of Microfluidic-Assisted Preparation of Polymeric Nanoparticles for DNA Delivery

An effective delivery vehicle of genetic materials to their target site is the key to a successful gene therapy. In many cases, nanoparticles are used as the vehicle of choice and the efficiency of the delivery relies heavily on the physicochemical properties of the nanoparticles. Microfluidics, although being a low throughput method, has been increasingly researched for the preparation of nanoparticles. A range of superior properties were claimed in the literature for microfluidic-prepared platforms, but no evidence on direct comparison of the properties of the nanoparticles prepared by microfluidics and conventional high throughput method exists, leaving the industry with little guidance on how to select effective large-scale nanoparticle manufacturing method. This study used plasmid DNA-loaded PLGA-Eudragit nanoparticles as the model system to critically compare the nanoparticles prepared by conventional and microfluidics-assisted nanoprecipitation. The PLGA-Eudragit nanoparticles prepared by microfluidics were found to be statistically significantly larger than the ones prepared by conventional nanoprecipitation. PLGA-Eudragit nanoparticle prepared conventionally showed higher DNA loading efficiency. Although the DNA-loaded nanoparticles prepared by both methods did not induce significant cytotoxicity, the transfection efficiency was found to be higher for the ones prepared conventionally which has good potential for plasmid delivery. This study for the first time provides a direct comparison of the DNA-loaded nanoparticles prepared by microfluidic and conventional methods. The findings bring new insights into critical evaluation of the selection of manufacturing methods of nanoparticles for future gene therapy.

Non-adhesive and highly stable biodegradable nanoparticles that provide widespread and safe transgene expression in orthotopic brain tumors

Several generations of poly(β-amino ester) (PBAE) polymers have been developed for efficient cellular transfection. However, PBAE-based gene vectors, similar to other cationic materials, cannot readily provide widespread gene transfer in the brain due to adhesive interactions with the extracellular matrix (ECM). We thus engineered eight vector candidates using previously identified lead PBAE polymer variants but endowed them with non-adhesive surface coatings to facilitate their spread through brain ECM. Specifically, we screened for the ability to provide widespread gene transfer in tumor spheroids and healthy mouse brains. We then confirmed that a lead formulation provided widespread transgene expression in orthotopically established brain tumor models with an excellent in vivo safety profile. Lastly, we developed a method to store it long-term while fully retaining its brain-penetrating property. This new platform provides a broad utility in evaluating novel genetic targets for gene therapy of brain tumors and neurological disorders in preclinical and clinical settings. Graphical abstract We engineered biodegradable DNA-loaded brain-penetrating nanoparticles (DNA-BPN) possessing small particle diameters (< 70 nm) and non-adhesive surface coatings to facilitate their spread through brain tumor extracellular matrix (ECM). These DNA-BPN provide widespread gene transfer in models recapitulating the ECM barrier, including three-dimensional multicellular tumor spheroids and mice with orthotopically established brain tumor.

Vaginal drug delivery approaches for localized management of cervical cancer

Cervical cancer or cervical intraepithelial neoplasia (CIN) remain a major public health problem among women globally. Traditional methods such as surgery are often associated with possible complications which may impact future pregnancies and childbirth especially for young female patients. Vagina with a high contact surface is a suitable route for the local and systemic delivery of drugs but its abundant mucus in continuous exchange presents a barrier for the popularization of conventional vaginal formulations including suppositories, gel, patch, creams and so on. So the development of new pharmaceutical forms based on nanotechnology became appealing owing to its several advantages such as mucosa penetration, bioadhesion, controlled drug release, and decreased adverse effects. This review provided an overview of the development of topical treatment of cervical cancer or CIN through vaginal drug delivery ranging from conventional vaginal formulations to new nanocarriers to the newly developed phototherapy and gene therapy, analyzing the problems faced by current methods used, and advising the developing trend in future. The methods of establishing preclinical animal model are also discussed.

Chitosan nanoparticles as a promising tool in nanomedicine with particular emphasis on oncological treatment

The study describes the current state of knowledge on nanotechnology and its utilization in medicine. The focus in this manuscript was on the properties, usage safety, and potentially valuable applications of chitosan-based nanomaterials. Chitosan nanoparticles have high importance in nanomedicine, biomedical engineering, discovery and development of new drugs. The manuscript reviewed the new studies regarding the use of chitosan-based nanoparticles for creating new release systems with improved bioavailability, increased specificity and sensitivity, and reduced pharmacological toxicity of drugs. Nowadays, effective cancer treatment is a global problem, and recent advances in nanomedicine are of great importance. Special attention was put on the application of chitosan nanoparticles in developing new system for anticancer drug delivery. Pre-clinical and clinical studies support the use of chitosan-based nanoparticles in nanomedicine. This manuscript overviews the last progresses regarding the utilization, stability, and bioavailability of drug nanoencapsulation with chitosan and their safety.

Non-viral gene delivery of the oncotoxic protein NS1 for treatment of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is related to increasing incidence rates and poor clinical outcomes due to lack of efficient treatment options and emerging resistance mechanisms. The aim of the present study is to exploit a non-viral gene therapy enabling the expression of the parvovirus-derived oncotoxic protein NS1 in HCC. This anticancer protein interacts with different cellular kinases mediating a multimodal host-cell death. Lipoplexes (LPX) designed to deliver a DNA expression plasmid encoding NS1 are characterized using a comprehensive set of in vitro assays. The mechanisms of cell death induction are assessed and phosphoinositide-dependent kinase 1 (PDK1) is identified as a potential predictive biomarker for a NS1-LPX-based gene therapy. In an HCC xenograft mouse model, NS1-LPX therapeutic approach results in a significant reduction in tumor growth and extended survival. Data provide convincing evidence for future studies using a targeted NS1 gene therapy for PDK1 overexpressing HCC.

Protein-nanoparticle interactions and a new insight

The study of protein-nanoparticle interactions provides knowledge about the bio-reactivity of nanoparticles, and creates a database of nanoparticles for applications in nanomedicine, nanodiagnosis, and nanotherapy. The problem arises when nanoparticles come in contact with physiological fluids such as plasma or serum, wherein they interact with the proteins (or other biomolecules). This interaction leads to the coating of proteins on the nanoparticle surface, mostly due to the electrostatic interaction, called 'corona'. These proteins are usually partially unfolded. The protein corona can deter nanoparticles from their targeted functionalities, such as drug/DNA delivery at the site and fluorescence tagging of diseased tissues. The protein corona also has many repercussions on cellular intake, inflammation, accumulation, degradation, and clearance of the nanoparticles from the body depending on the exposed part of the proteins. Hence, the protein-nanoparticle interaction and the configuration of the bound-proteins on the nanosurface need thorough investigation and understanding. Several techniques such as DLS and zeta potential measurement, UV-vis spectroscopy, fluorescence spectroscopy, circular dichroism, FTIR, and DSC provide valuable information in the protein-nanoparticle interaction study. Besides, theoretical simulations also provide additional understanding. Despite a lot of research publications, the fundamental question remained unresolved. Can we aim for the application of functional nanoparticles in medicine? A new insight, given by us, in this article assumes a reasonable solution to this crucial question.

Manufacturing Challenges and Rational Formulation Development for AAV Viral Vectors

Adeno-associated virus (AAV) has emerged as a leading platform for gene delivery for treating various diseases due to its excellent safety profile and efficient transduction to various target tissues. However, the large-scale production and long-term storage of viral vectors is not efficient resulting in lower yields, moderate purity, and shorter shelf-life compared to recombinant protein therapeutics. This review provides a comprehensive analysis of upstream, downstream and formulation unit operation challenges encountered during AAV vector manufacturing, and discusses how desired product quality attributes can be maintained throughout product shelf-life by understanding the degradation mechanisms and formulation strategies. The mechanisms of various physical and chemical instabilities that the viral vector may encounter during its production and shelf-life because of various stressed conditions such as thermal, shear, freeze-thaw, and light exposure are highlighted. The role of buffer, pH, excipients, and impurities on the stability of viral vectors is also discussed. As such, the aim of this review is to outline the tools and a potential roadmap for improving the quality of AAV-based drug products by stressing the need for a mechanistic understanding of the involved processes.

Novel Strategy to Combat Antibiotic Resistance: A Sight into the Combination of CRISPR/Cas9 and Nanoparticles

Antibiotic resistance is a significant crisis that threatens human health and safety worldwide. There is an urgent need for new strategies to control multidrug-resistant (MDR) bacterial infections. The latest breakthrough in gene-editing tools based on CRISPR/Cas9 has potential application in combating MDR bacterial infections because of their high targeting ability to specifically disrupt the drug resistance genes that microbes use for infection or to kill the pathogen directly. Despite the potential that CRISPR/Cas9 showed, its further utilization has been hampered by undesirable delivery efficiency in vivo. Nanotechnology offers an alternative way to overcome the shortcomings of traditional delivery methods of therapeutic agents. Advances in nanotechnology can improve the efficacy and safety of CRISPR/Cas9 components by using customized nanoparticle delivery systems. The combination of CRISPR/Cas9 and nanotechnology has the potential to open new avenues in the therapy of MDR bacterial infections. This review describes the recent advances related to CRISPR/Cas9 and nanoparticles for antimicrobial therapy and gene delivery, including the improvement in the packaging and localizing efficiency of the CRISPR/Cas9 components in the NP (nanoparticle)/CRISPR system. We pay particular attention to the strengths and limitations of the nanotechnology-based CRISPR/Cas9 delivery system to fight nosocomial pathogens.We highlight the need for more scientific research to explore the combinatorial efficacy of various nanoparticles and CRISPR technology to control and prevent antimicrobial resistance.

Overcoming the barriers to optimization of adenovirus delivery using biomaterials: Current status and future perspective

Adenovirus (Ad) is emerging as a promising modality for cancer gene therapy due to its ability to induce high level of therapeutic transgene expression with no risk of insertional mutagenesis, ability to be facilely produced at a high titer, and capacity to induce robust antitumor immune response. Despite these excellent attributes of human serotype 5 Ad, poor systemic administration capability, coxsackie and adenovirus receptor (CAR)-dependent endocytic mechanism limiting potentially targetable cell types, nonspecific shedding to normal organs, and poor viral persistence in tumor tissues are major hindrances toward maximizing the therapeutic benefit of Ad in clinical setting. To address the abovementioned shortcomings, various non-immunogenic nanomaterials have been explored to modify Ad surface via physical or chemical interactions. In this review, we summarize the recent developments of different types of nanomaterials that had been utilized for modification of Ad and how tumor-targeted local and system delivery can be achieved with these nanocomplexes. Finally, we conclude by highlighting the key features of various nanomaterials-coated Ads and their prospects to optimize the delivery of virus.

Exosome-mediated delivery of RNA and DNA for gene therapy

Gene therapy promises to revolutionize biomedicine and personalized medicine by modulating or compensating the expression of abnormal genes. The biggest obstacle for clinical application is the lack of an effective, non-immunogenic delivery system. We show that bovine colostrum exosomes and polyethyleneimine matrix (EPM) delivers short interfering RNA (siRNA) or plasmid DNA (pDNA) for effective gene therapy. KRAS, a therapeutic focus for many cancers, was targeted by EPM-delivered KRAS siRNA (siKRAS) and inhibited lung tumor growth (>70%) and reduced KRAS expression (50%-80%). Aberrant p53 is another therapeutic focus for many cancers. EPM-mediated introduction of wild-type (WT) p53 pDNA (pcDNA-p53) resulted in p53 expression in p53-null H1299 cells in culture, subcutaneous lung tumor, and tissues of p53-knockout mice. Additionally, chemo-sensitizing effects of paclitaxel were restored by exogenous WT p53 in lung cancer cells. Together, this novel EPM technology represents an effective 'platform' for delivery of therapeutic nucleic acids to treat human disease.

Metformin-conjugated micellar system with intratumoral pH responsive de-shielding for co-delivery of doxorubicin and nucleic acid

A novel PMet-P(cdmPEG_2K) polymeric micellar carrier was developed for tumor-targeted co-delivery of DOX and nucleic acids (NA), based on polymetformin and a structure designed to lose the PEG shell in response to the acidic extracellular tumor environment. NA/DOX co-loaded micelleplexes exhibited enhanced inhibition of cell proliferation compared to DOX-loaded micelles, and displayed a higher level of cytotoxicity at an acidic pH (6.8) which mimicks the tumor microenvironment. The PMet-P(cdmPEG_2K) micelles achieved significantly improved transfection with either a reporter plasmid or Cy3-siRNA, and enhanced DOX intracellular uptake in 4T1.2 cells at pH 6.8. Importantly, PMet-P(cdmPEG_2K) micelles showed excellent pEGFP (EGFP expression plasmid) transfection in an aggressive murine breast cancer (4T1.2) model. By using a plasmid encoding IL-12 (pIL-12), we investigated the combined effect of chemotherapy and gene therapy. PMet-P(cdmPEG_2K) micelles co-loaded with DOX and pIL-12 were more effective at inhibiting tumor growth compared to micelles loaded with DOX or pIL-12 alone. In addition, this micellar system was effective in co-delivery of siRNA and DOX into tumor cells. Our results suggest that PMet-P(cdmPEG_2K) has the potential for chemo and nucleic acid combined cancer therapy.

Engineered Nanomaterials: The Challenges and Opportunities for Nanomedicines

The emergence of nanotechnology as a key enabling technology over the past years has opened avenues for new and innovative applications in nanomedicine. From the business aspect, the nanomedicine market was estimated to worth USD 293.1 billion by 2022 with a perception of market growth to USD 350.8 billion in 2025. Despite these opportunities, the underlying challenges for the future of engineered nanomaterials (ENMs) in nanomedicine research became a significant obstacle in bringing ENMs into clinical stages. These challenges include the capability to design bias-free methods in evaluating ENMs' toxicity due to the lack of suitable detection and inconsistent characterization techniques. Therefore, in this literature review, the state-of-the-art of engineered nanomaterials in nanomedicine, their toxicology issues, the working framework in developing a toxicology benchmark and technical characterization techniques in determining the toxicity of ENMs from the reported literature are explored.

Current Status and Challenges Associated with CNS-Targeted Gene Delivery across the BBB

The era of the aging society has arrived, and this is accompanied by an increase in the absolute numbers of patients with neurological disorders, such as Alzheimer’s disease (AD) and Parkinson’s disease (PD). Such neurological disorders are serious costly diseases that have a significant impact on society, both globally and socially. Gene therapy has great promise for the treatment of neurological disorders, but only a few gene therapy drugs are currently available. Delivery to the brain is the biggest hurdle in developing new drugs for the central nervous system (CNS) diseases and this is especially true in the case of gene delivery. Nanotechnologies such as viral and non-viral vectors allow efficient brain-targeted gene delivery systems to be created. The purpose of this review is to provide a comprehensive review of the current status of the development of successful drug delivery to the CNS for the treatment of CNS-related disorders especially by gene therapy. We mainly address three aspects of this situation: (1) blood-brain barrier (BBB) functions; (2) adeno-associated viral (AAV) vectors, currently the most advanced gene delivery vector; (3) non-viral brain targeting by non-invasive methods.

Organ-on-a-Chip: A Preclinical Microfluidic Platform for the Progress of Nanomedicine

Despite the progress achieved in nanomedicine during the last decade, the translation of new nanotechnology-based therapeutic systems into clinical applications has been slow, especially due to the lack of robust preclinical tissue culture platforms able to mimic the in vivo conditions found in the human body and to predict the performance and biotoxicity of the developed nanomaterials. Organ-on-a-chip (OoC) platforms are novel microfluidic tools that mimic complex human organ functions at the microscale level. These integrated microfluidic networks, with 3D tissue engineered models, have been shown high potential to reduce the discrepancies between the results derived from preclinical and clinical trials. However, there are many challenges that still need to be addressed, such as the integration of biosensor modules for long-time monitoring of different physicochemical and biochemical parameters. In this review, recent advances on OoC platforms, particularly on the preclinical validation of nanomaterials designed for cancer, as well as the current challenges and possible future directions for an end-use perspective are discussed.

Growth inhibitory and anti-metastatic activity of epithelial cell adhesion molecule targeted three-way junctional delta-5-desaturase siRNA nanoparticle for breast cancer therapy

8-Hydroxyoctanoic acid (8-HOA) produced through cyclooxygenase-2 (COX-2) catalyzed dihomo-γ-linolenic acid (DGLA) peroxidation in delta-5-desaturase inhibitory (D5D siRNA) condition showed an inhibitory effect on breast cancer cell proliferation and migration. However, in vivo use of naked D5D siRNA was limited by off-target silencing and degradation by endonucleases. To overcome the limitation and deliver the D5D siRNA in vivo, we designed an epithelia cell adhesion molecule targeted three-way junctional nanoparticle having D5D siRNA. In this study, we have hypothesized that 3WJ-EpCAM-D5D siRNA will target and inhibit the D5D enzyme in cancer cells leading to peroxidation of supplemented DGLA to 8-HOA resulting in growth inhibitory effect in the orthotopic breast cancer model developed by injecting 4T1 cells. On analysis, we observed a significant reduction in tumor size and metastatic lung nodules in animals treated with a combination of 3WJ-EpCAM-D5D siRNA and DGLA through activating intrinsic apoptotic signaling pathway and by reducing endothelial-mesenchymal damage.

The Future of Direct Cardiac Reprogramming: Any GMT Cocktail Variety?

Direct cardiac reprogramming has emerged as a novel therapeutic approach to treat and regenerate injured hearts through the direct conversion of fibroblasts into cardiac cells. Most studies have focused on the reprogramming of fibroblasts into induced cardiomyocytes (iCMs). The first study in which this technology was described, showed that at least a combination of three transcription factors, GATA4, MEF2C and TBX5 (GMT cocktail), was required for the reprogramming into iCMs in vitro using mouse cells. However, this was later demonstrated to be insufficient for the reprogramming of human cells and additional factors were required. Thereafter, most studies have focused on implementing reprogramming efficiency and obtaining fully reprogrammed and functional iCMs, by the incorporation of other transcription factors, microRNAs or small molecules to the original GMT cocktail. In this respect, great advances have been made in recent years. However, there is still no consensus on which of these GMT-based varieties is best, and robust and highly reproducible protocols are still urgently required, especially in the case of human cells. On the other hand, apart from CMs, other cells such as endothelial and smooth muscle cells to form new blood vessels will be fundamental for the correct reconstruction of damaged cardiac tissue. With this aim, several studies have centered on the direct reprogramming of fibroblasts into induced cardiac progenitor cells (iCPCs) able to give rise to all myocardial cell lineages. Especially interesting are reports in which multipotent and highly expandable mouse iCPCs have been obtained, suggesting that clinically relevant amounts of these cells could be created. However, as of yet, this has not been achieved with human iCPCs, and exactly what stage of maturity is appropriate for a cell therapy product remains an open question. Nonetheless, the major concern in regenerative medicine is the poor retention, survival, and engraftment of transplanted cells in the cardiac tissue. To circumvent this issue, several cell pre-conditioning approaches are currently being explored. As an alternative to cell injection, in vivo reprogramming may face fewer barriers for its translation to the clinic. This approach has achieved better results in terms of efficiency and iCMs maturity in mouse models, indicating that the heart environment can favor this process. In this context, in recent years some studies have focused on the development of safer delivery systems such as Sendai virus, Adenovirus, chemical cocktails or nanoparticles. This article provides an in-depth review of the in vitro and in vivo cardiac reprograming technology used in mouse and human cells to obtain iCMs and iCPCs, and discusses what challenges still lie ahead and what hurdles are to be overcome before results from this field can be transferred to the clinical settings.

Bound Protein- and Peptide-Based Strategies for Adeno-Associated Virus Vector-Mediated Gene Therapy: Where Do We Stand Now?

Recombinant adeno-associated virus (rAAV) vectors have become one of the most promising and efficacious delivery vehicles for human gene therapy; however, low infectivity remains a major ongoing obstacle in the clinical application of rAAV vectors. Multiple strategies, including rAAV capsid modification and the application of pharmacological reagents, have been explored to enhance rAAV vector gene delivery. Recently, a new strategy using native proteins or various peptides has shown promise for increasing rAAV transduction locally or globally. This review summarizes the current status of protein- and peptide-based strategies and mechanisms to modulate rAAV transduction. We also provide a potential insight regarding the design of effective approaches for rAAV transduction enhancement in future clinical studies.

In vivo gene delivery mediated by non-viral vectors for cancer therapy

Gene therapy by expression constructs or down-regulation of certain genes has shown great potential for the treatment of various diseases. The wide clinical application of nucleic acid materials dependents on the development of biocompatible gene carriers. There are enormous various compounds widely investigated to be used as non-viral gene carriers including lipids, polymers, carbon materials, and inorganic structures. In this review, we will discuss the recent discoveries on non-viral gene delivery systems. We will also highlight the in vivo gene delivery mediated by non-viral vectors to treat cancer in different tissue and organs including brain, breast, lung, liver, stomach, and prostate. Finally, we will delineate the state-of-the-art and promising perspective of in vivo gene editing using non-viral nano-vectors.

Efficient Delivery of Transducing Polymer Nanoparticles for Gene-Mediated Induction of Osteogenesis for Bone Regeneration

Developing non-viral gene therapy vectors that both protect and functionally deliver nucleic acid cargoes will be vital if gene augmentation and editing strategies are to be effectively combined with advanced regenerative medicine approaches. Currently such methodologies utilize high concentrations of recombinant growth factors, which result in toxicity and off-target effects. Herein we demonstrate the use of modified cell penetrating peptides (CPPs), termed Glycosaminoglycan (GAG)-binding Enhanced Transduction (GET) peptides with plasmid DNA (pDNA) encapsulated poly (lactic-co-glycolic acid) PLGA nanoparticles (pDNA-encapsulated PLGA NPs). In order to encapsulate the pDNA, it was first condensed with a cationic low molecular weight Poly L-Lysine (PLL) into 30-60 nm NPs followed by encapsulation in PLGA NPs by double emulsion; yielding encapsulation efficiencies (EE) of ∼30%. PLGA NPs complexed with GET peptides show enhanced intracellular delivery (up to sevenfold) and transfection efficiencies (up to five orders of magnitude). Moreover, the pDNA cargo has enhanced protection from nucleases (such as DNase I) promoting their translatability. As an example, we show these NPs efficiently deliver pBMP2 which can promote osteogenic differentiation in vitro. Gene delivery to human Mesenchymal Stromal Cells (hMSCs) inducing their osteogenic programming was confirmed by Alizarin red calcium staining and bone lineage specific gene expression (Q RT-PCR). By combining simplistic and FDA-approved PLGA polymer nanotechnology with the GET delivery system, therapeutic non-viral vectors could have significant impact in future cellular therapy and regenerative medicine applications.

Acellular oxidative potential assay for screening of amorphous silica nanoparticles

Silica nanoparticles (SiNPs) are used in a wide range of consumer products, engineering and medical applications, with likelihood of human exposure and potential health concerns. It is essential to generate toxicity information on SiNP forms and associated physicochemical determinants to conduct risk assessment on these new materials. To address this knowledge gap, we screened a panel of custom synthesized, well-characterized amorphous SiNPs pristine and surface-modified (-C3-COOH, -C11-COOH, -NH₂, -PEG) of 5 different sizes: (15, 30, 50, 75, 100 nm) for their oxidative potential using an acellular assay. The assay is based on oxidation of dithiothreitol (DTT) by reactive oxygen species and can serve as a surrogate test for oxidative stress. These materials were characterized for size distribution, aggregation, crystallinity, surface area, surface modification, surface charge and metal content. Tests for association between oxidative potential of SiNPs and their physicochemical properties were carried out using analysis of variance and correlation analyses. These test results suggest that the size of amorphous SiNPs influenced their oxidative potential irrespective of the surface modification, with 15 nm exhibiting relatively higher oxidative potential compared to the other sizes. Furthermore, SiNP surface area, surface modification and agglomeration in solution also appeared to affect oxidative potential of these SiNPs. These findings indicate that physicochemical properties are critical in influencing the oxidative behaviour of amorphous SiNPs, with potential to trigger cellular oxidative stress and thus toxicity, when exposed. This information advances our understanding of potential toxicities of these amorphous SiNPs and supports risk assessment efforts and the design of safer forms of silica nanomaterials.

The future of gene-targeted therapy for hereditary tyrosinemia type 1 as a lead indication among the inborn errors of metabolism

Introduction

Inborn errors of metabolism (IEMs) often result from single-gene mutations and collectively cause liver dysfunction in neonates leading to chronic liver and systemic disease. Current treatments for many IEMs are limited to maintenance therapies that may still require orthotropic liver transplantation. Gene therapies offer a potentially superior approach by correcting or replacing defective genes with functional isoforms; however, they face unique challenges from complexities presented by individual diseases and their diverse etiology, presentation, and pathophysiology. Furthermore, immune responses, off-target gene disruption, and tumorigenesis are major concerns that need to be addressed before clinical application of gene therapy.

Areas covered

The current treatments for IEMs are reviewed as well as the advances in, and barriers to, gene therapy for IEMs. Attention is then given to ex vivo and in vivo gene therapy approaches for hereditary tyrosinemia type 1 (HT1). Of all IEMs, HT1 is particularly amenable to gene therapy because of a selective growth advantage conferred to corrected cells, thereby lowering the initial transduction threshold for phenotypic relevance.

Expert opinion

It is proposed that not only is HT1 a safe indication for gene therapy, its unique characteristics position it to be an ideal IEM to develop for clinical investigation.

Applications of CRISPR for musculoskeletal research

The ability to edit DNA at the nucleotide level using clustered regularly interspaced short palindromic repeats (CRISPR) systems is a relatively new investigative tool that is revolutionizing the analysis of many aspects of human health and disease, including orthopaedic disease. CRISPR, adapted for mammalian cell genome editing from a bacterial defence system, has been shown to be a flexible, programmable, scalable, and easy-to-use gene editing tool. Recent improvements increase the functionality of CRISPR through the engineering of specific elements of CRISPR systems, the discovery of new, naturally occurring CRISPR molecules, and modifications that take CRISPR beyond gene editing to the regulation of gene transcription and the manipulation of RNA. Here, the basics of CRISPR genome editing will be reviewed, including a description of how it has transformed some aspects of molecular musculoskeletal research, and will conclude by speculating what the future holds for the use of CRISPR-related treatments and therapies in clinical orthopaedic practice.

Cite this article: Bone Joint Res 2020;9(7):351–359.

A Review of Gene, Drug and Cell-Based Therapies for Usher Syndrome

Usher syndrome is a genetic disorder causing neurosensory hearing loss and blindness from retinitis pigmentosa (RP). Adaptive techniques such as braille, digital and optical magnifiers, mobility training, cochlear implants, or other assistive listening devices are indispensable for reducing disability. However, there is currently no treatment to reduce or arrest sensory cell degeneration. There are several classes of treatments for Usher syndrome being investigated. The present article reviews the progress this research has made towards delivering commercial options for patients with Usher syndrome.

AAV8 Ins1-Cre can produce efficient β-cell recombination but requires consideration of off-target effects

In vivo genetic manipulation is used to study the impact of gene deletion or re-expression on β-cell function and organism physiology. Cre-LoxP is a system wherein LoxP sites flanking a gene are recognized by Cre recombinase. Cre transgenic mice are the most prevalent technology used to deliver Cre but many models have caveats of off-target recombination, impaired β-cell function, and high cost of animal production. Inducible estrogen receptor conjugated Cre models face leaky recombination and confounding effects of tamoxifen. As an alternative, we characterize an adeno associated virus (AAV) with a rat insulin 1 promoter driving Cre recombinase (AAV8 Ins1-Cre) that is economical and rapid to implement, and has limited caveats. Intraperitoneal AAV8 Ins1-Cre produced efficient β-cell recombination, alongside some hepatic, exocrine pancreas, α-cell, δ-cell, and hypothalamic recombination. Delivery of lower doses via the pancreatic duct retained good rates of β-cell recombination and limited rates of off-target recombination. Unlike inducible Cre in transgenic mice, AAV8 Ins1-Cre required no tamoxifen and premature recombination was avoided. We demonstrate the utility of this technology by inducing hyperglycemia in inducible insulin knockout mice (Ins1^−/−;Ins2^f/f). AAV-mediated expression of Cre in β-cells provides an effective alternative to transgenic approaches for inducible knockout studies.

Reprogramming of Non-myocytes into Cardiomyocyte-like Cells: Challenges and Opportunities

PURPOSE OF REVIEW

The high global incidence of heart disease drives the need for methods of mending damaged hearts. Direct reprogramming of cardiac fibroblasts into cardiomyocyte-like cells (called iCMs) has been successful in the creation of new muscle cells, in the repair of hearts post-myocardial injury, and therefore has great promise for the clinic. The purpose of this paper is to review and highlight the approaches for and underlying molecular mechanisms of direct cardiac reprogramming.

RECENT FINDINGS

Single-cell genomics and mechanistic studies have elucidated the stepwise transition of fibroblasts to iCMs as well as the molecular roadblocks that hinder reprogramming. Cardiac fibroblasts are able to be directly reprogrammed, in vitro and in vivo, into induced cardiomyocyte-like cells by the ectopic expression of a combination of transcription factors, microRNAs or small molecules. Recent works have illustrated methods that improve the efficiency of iCM generation and delivery of reprogramming cocktails as well as have revealed the molecular networks governing the reprogramming process. Current studies have also begun to identify and address the additional hurdles in human iCM reprogramming.

Nanoparticle Based Gene Therapy Approach: A Pioneering Rebellion in the Management of Psychiatric Disorders

The neuropsychiatric illnesses have been enigmatic, with no effective treatment to date. The complexity and heterogeneity of psychiatric disorders are daunting for the development of novel treatment modalities. The conventional treatment approaches are less effective and are associated with several side effects, thus creating the need for the development of more innovative strategies. Since psychiatric disorders are known to exhibit genetic linkage, gene therapy has created an interest among the researchers worldwide. The delivery of nucleic acids is a complex process requiring the transport of genetic material across various intracellular and extracellular barriers to reach the target cells eliciting the transfection process. Therefore, the identification or development of the delivery system for nucleic acid delivery still remains the challenge. Viral vectors are quite effective but are associated with toxicity and side effects. With the rapid advancement in the field of nanotechnology, nanosized materials were identified to be the perfect candidate for nonviral vectors in gene delivery. The biggest advantage of nanoparticles is that their surface can be engineered in many possible ways to deliver the drugs directly to the target site. Although gene therapy has already been established as an innovative treatment modality for several neurological diseases, its use in psychiatry still warrants more investigations for its translation into clinical use. The present manuscript discusses the prospects of gene therapy in psychiatric disorders, their benefits, and pitfalls. The review embarks upon the importance of nanoparticle-based gene therapy for effective management of psychiatric disorders.

Fluorescent Peptide Dendrimers for siRNA Transfection: Tracking pH Responsive Aggregation, siRNA Binding, and Cell Penetration

Transfecting nucleic acids into various cells is a key procedure in biological research also envisioned for therapeutic applications. In our effort to obtain simple reagents that would be readily accessible from commercial building blocks, we recently reported peptide dendrimers as single component siRNA transfection reagents accessible in pure form by solid-phase peptide synthesis. Here, we extend our studies of these dendrimers by identifying analogs bearing a coumarin or BODIPY fluorescent label in their core and displaying comparable siRNA transfection efficiencies, pH dependent aggregation, siRNA binding, and secondary structures. Fluorescence resonance energy transfer (FRET) studies show that the dendrimers are tightly associated with siRNA within the formed nanoparticles at pH 7.4 but are released into solution at pH 5.0 and can participate in endosome escape by destabilizing the membrane at this pH value. Colocalization studies furthermore suggest that peptide dendrimers and siRNA remain tightly associated throughout the transfection process.

Arginine-Modified Polymers Facilitate Poly (Lactide-Co-Glycolide)-Based Nanoparticle Gene Delivery to Primary Human Astrocytes

PURPOSE

Astrocyte dysfunction is a hallmark of central nervous system injury or infection. As a primary contributor to neurodegeneration, astrocytes are an ideal therapeutic target to combat neurodegenerative conditions. Gene therapy has arisen as an innovative technique that provides excellent prospect for disease intervention. Poly (lactide-co-glycolide) (PLGA) and polyethylenimine (PEI) are polymeric nanoparticles commonly used in gene delivery, each manifesting their own set of advantages and disadvantages. As a clinically approved polymer by the Federal Drug Administration, well characterized for its biodegradability and biocompatibility, PLGA-based nanoparticles (PLGA-NPs) are appealing for translational gene delivery systems. However, our investigations revealed PLGA-NPs were ineffective at facilitating exogenous gene expression in primary human astrocytes, despite their success in other cell lines. Furthermore, PEI polymers illustrate high delivery efficiency but induce cytotoxicity. The purpose of this study is to develop viable and biocompatible NPsystem for astrocyte-targeted gene therapy.

MATERIALS AND METHODS

Successful gene expression by PLGA-NPs alone or in combination with arginine-modified PEI polymers (A_nP_n) was assessed by a luciferase reporter gene encapsulated in PLGA-NPs. Cytoplasmic release and nuclear localization of DNA were investigated using fluorescent confocal imaging with YOYO-labeled plasmid DNA (pDNA). NP-mediated cytotoxicity was assessed via lactate dehydrogenase in primary human astrocytes and neurons.

RESULTS

Confocal imaging of YOYO-labeled pDNA confirmed PLGA-NPs delivered pDNA to the cytoplasm in a dose and time-dependent manner. However, co-staining revealed pDNA delivered by PLGA-NPs did not localize to the nucleus. The addition of A_nP_n significantly improved nuclear localization of pDNA and successfully achieved gene expression in primary human astrocytes. Moreover, these formulations were biocompatible with both astrocytes and neurons.

CONCLUSION

By co-transfecting two polymeric NPs, we developed an improved system for gene delivery and expression in primary human astrocytes. These findings provide a basis for a biocompatible and clinically translatable method to regulate astrocyte function during neurodegenerative diseases and disorders.