RNA interference by nanofiber-based siRNA delivery system

Synthetic-polymer-assisted antisense oligonucleotide delivery: targeted approaches for precision disease treatment

This review explores the recent advancements in polymer-assisted delivery systems for antisense oligonucleotides (ASOs) and their potential in precision disease treatment. Synthetic polymers have shown significant promise in enhancing the delivery, stability, and therapeutic efficacy of ASOs by addressing key challenges such as cellular uptake, endosomal escape, and reducing cytotoxicity. The review highlights key studies from the past decade demonstrating how these polymers improve gene silencing efficiencies, particularly in cancer and neurodegenerative disease models. Despite the progress achieved, barriers such as immunogenicity, delivery limitations, and scalability still need to be overcome for broader clinical application. Emerging strategies, including stimuli-responsive polymers and advanced nanoparticle systems, offer potential solutions to these challenges. The review underscores the transformative potential of polymer-enhanced ASO delivery in personalised medicine, emphasising the importance of continued innovation to optimise ASO-based therapeutics for more precise and effective disease treatments.

Development of Polyvinyl Alcohol (PVA) Nanofibers Containing Cationic Lipid/siRNA Complexes via Electrospinning: The Impact of PVA Characterization

This study aimed to develop polyvinyl alcohol (PVA) nanofibers encapsulating 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP)/siRNA complexes via electrospinning for the delivery of nucleic acid-based drugs. It also focused on the influence of the intrinsic properties of PVA on the efficacy of the system. PVA nanofibers, with diameters of 300-400 nm, were obtained, within which the siRNA remained intact and the DOTAP/siRNA complexes were uniformly dispersed. By incorporating DOTAP/siRNA complexes into the PVA nanofibers and assessing the impact of their RNA interference (RNAi) activity in A549-Luc cells, a stable inhibition of luciferase expression was observed. An examination of the nanofiber preparation process revealed that even when DOTAP or siRNA were added separately to the PVA solution without forming complexes, the RNAi effect was retained. The DOTAP/siRNA complexes released from the PVA nanofibers were internalized by the cells, with some PVA residues remaining on their surfaces. The significance of the degree of hydrolysis and polymerization of PVA on the performance of nanofibers was highlighted. Notably, PVA with a low degree of hydrolysis substantially enhanced RNAi effects, with luciferase expression inhibition reaching 91.5 ± 0.7%. Nanofibers made of PVA grades with anionic or cationic modifications were also evaluated, suggesting that they affect the efficacy of siRNA delivery. The insights obtained suggest avenues for future research to optimize drug delivery systems further.

Advanced nanoparticle strategies for optimizing RNA therapeutic delivery in neurodegenerative disorders

Neurodegenerative diseases affect many people worldwide, and as the population ages, the incidence of these conditions increases. Alzheimer's disease (AD) and Parkinson's disease (PD) are the most prevalent neurodegenerative disorders worldwide. Different medicines are being used to control symptoms related to these conditions, but no treatment has yet been approved. Both genetic and environmental factors are involved in disease pathogenesis, and research on the pathophysiological pathways is still ongoing. The role of subcellular pathways and dysregulation in RNA pathways has been highlighted in pathophysiological studies, and treatment strategies focused on these pathways can be a promising approach. Many experiments have been conducted on delivering RNA cargo to the CNS to modulate various pathways involved. Yet another challenge to be faced is the effective transport of desired molecules to targets, which can be greatly hindered by distinct barriers limiting transport to the CNS, most noticeably the blood-brain barrier (BBB). Nanotechnology and the use of different nano-carriers for the delivery of nucleotides, peptides, proteins, and drug molecules are currently of great interest as these carriers help with better delivery and protection and, as a result, improve the effectiveness of the cargo. Nanocarriers can protect susceptible RNA molecules from possible degradation or destruction and improve their ability to reach the brain by enhancing BBB penetration. Different mechanisms for this process have been hypothesized. This review will go through the therapeutic application of RNA molecules in the treatment of AD and PD and the role of nanocarriers in overcoming delivery challenges and enhancing efficacy.

Electrospinning technologies for the delivery of Biopharmaceuticals: Current status and future trends

This review provides an in-depth exploration of electrospinning techniques employed to produce micro- or nanofibres of biopharmaceuticals using polymeric solutions or melts with high-voltage electricity. Distinct from prior reviews, the current work narrows its focus on the recent developments and advanced applications in biopharmaceutical formulations. It begins with an overview of electrospinning principles, covering both solution and melt modes. Various methods for incorporating biopharmaceuticals into electrospun fibres, such as surface adsorption, blending, emulsion, co-axial, and high-throughput electrospinning, are elaborated. The review also surveys a wide array of biopharmaceuticals formulated through electrospinning, thereby identifying both opportunities and challenges in this emerging field. Moreover, it outlines the analytical techniques for characterizing electrospun fibres and discusses the legal and regulatory requirements for their production. This work aims to offer valuable insights into the evolving realm of electrospun biopharmaceutical delivery systems.

Polymeric Nanofibers for Drug Delivery Applications: A Recent Review

With the rapid development of biomaterials and biotechnologies, various functional materials-based drug delivery systems (DDS) are developed to overcome the limitations of traditional drug release formulations, such as uncontrollable drug concentration in target organs/tissues and unavoidable adverse reactions. Polymer nanofibers exhibit promising characteristics including easy preparation, adjustable features of wettability and elasticity, tailored surface and interface properties, and surface-to-volume ratio, and are used to develop new DDS. Different kinds of drugs can be incorporated into the polymer nanofibers. Additionally, their release kinetics can be modulated via the preparation components, component proportions, and preparation processes, enabling their applications in several fields. A timely and comprehensive summary of polymeric nanofibers for DDS is thus highly needed. This review first describes the common methods for polymer nanofiber fabrication, followed by introducing controlled techniques for drug loading into and release from polymer nanofibers. Thus, the applications of polymer nanofibers in drug delivery were summarized, particularly focusing on the relation between the physiochemical properties of polymeric nanofibers and their DDS performance. It is ended by listing future perspectives. Graphical abstract.

Design of Hybrid Polymer Nanofiber/Collagen Patches Releasing IGF and HGF to Promote Cardiac Regeneration

Cardiovascular diseases are the leading cause of death globally. Myocardial infarction in particular leads to a high rate of mortality, and in the case of survival, to a loss of myocardial functionality due to post-infarction necrosis. This functionality can be restored by cell therapy or biomaterial implantation, and the need for a rapid regeneration has led to the development of bioactive patches, in particular through the incorporation of growth factors (GF). In this work, we designed hybrid patches composed of polymer nanofibers loaded with HGF and IGF and associated with a collagen membrane. Among the different copolymers studied, the polymers and their porogens PLA-Pluronic-PLA + PEG and PCL + Pluronic were selected to encapsulate HGF and IGF. While 89 and 92% of IGF were released in 2 days, HGF was released up to 58% and 50% in 35 days from PLA-Pluronic-PLA + PEG and PCL + Pluronic nanofibers, respectively. We also compared two ways of association for the loaded nanofibers and the collagen membrane, namely a direct deposition of the nanofibers on a moisturized collagen membrane (wet association), or entrapment between collagen layers (sandwich association). The interfacial cohesion and the degradation properties of the patches were evaluated. We also show that the sandwich association decreases the burst release of HGF while increasing the release efficiency. Finally, we show that the patches are cytocompatible and that the presence of collagen and IGF promotes the proliferation of C2C12 myoblast cells for 11 days. Taken together, these results show that these hybrid patches are of interest for cardiac muscle regeneration.

Designing electrospun fiber platforms for efficient delivery of genetic material and genome editing tools

Electrospun fibers are versatile biomaterial platforms with great potential to support regeneration. Electrospun fiber characteristics such as fiber diameter, degree of alignment, rate of degradation, and surface chemistry enable the creation of unique, tunable scaffolds for various drug or gene delivery applications. The delivery of genetic material and genome editing tools via viral and non-viral vectors are approaches to control cellular protein production. However, immunogenicity, off-target effects, and low delivery efficiencies slow the progression of gene delivery strategies to clinical settings. The delivery of genetic material from electrospun fibers overcomes such limitations by allowing for localized, tunable delivery of genetic material. However, the process of electrospinning is harsh, and care must be taken to retain genetic material bioactivity. This review presents an up-to-date summary of strategies to incorporate genetic material onto or within electrospun fiber platforms to improve delivery efficiency and enhance the regenerative potential of electrospun fibers for various tissue engineering applications.

On-Demand Drug Delivery Systems Using Nanofibers

On-demand drug-delivery systems using nanofibers are extensively applicable for customized drug release based on target location and timing to achieve the desired therapeutic effects. A nanofiber formulation is typically created for a certain medication and changing the drug may have a significant impact on the release kinetics from the same delivery system. Nanofibers have several distinguishing features and properties, including the ease with which they may be manufactured, the variety of materials appropriate for processing into fibers, a large surface area, and a complex pore structure. Nanofibers with effective drug-loading capabilities, controllable release, and high stability have gained the interest of researchers owing to their potential applications in on-demand drug delivery systems. Based on their composition and drug-release characteristics, we review the numerous types of nanofibers from the most recent accessible studies. Nanofibers are classified based on their mechanism of drug release, as well as their structure and content. To achieve controlled drug release, a suitable polymer, large surface-to-volume ratio, and high porosity of the nanofiber mesh are necessary. The properties of nanofibers for modified drug release are categorized here as protracted, stimulus-activated, and biphasic. Swellable or degradable polymers are commonly utilized to alter drug release. In addition to the polymer used, the process and ambient conditions can have considerable impacts on the release characteristics of the nanofibers. The formulation of nanofibers is highly complicated and depends on many variables; nevertheless, numerous options are available to accomplish the desired nanofiber drug-release characteristics.

Short interfering RNA (siRNA)-Based Therapeutics for Cartilage Diseases

Articular cartilage injury, as a hallmark of arthritic diseases, is difficult to repair and causes joint pain, stiffness, and loss of mobility. Over the years, the most significant problems for the drug-based treatment of arthritis have been related to drug administration and delivery. In recent years, much research has been devoted to developing new strategies for repairing or regenerating the damaged osteoarticular tissue. The RNA interference (RNAi) has been suggested to have the potential for implementation in targeted therapy in which the faulty gene can be edited by delivering its complementary Short Interfering RNA (siRNA) at the post-transcriptional stage. The successful editing of a specific gene by the delivered siRNA might slow or halt osteoarthritic diseases without side effects caused by chemical inhibitors. However, cartilage siRNA delivery remains a challenging objective because cartilage is an avascular and very dense tissue with very low permeability. Furthermore, RNA is prone to degradation by serum nucleases (such as RNase H and RNase A) due to an extra hydroxyl group in its phosphodiester backbone. Therefore, successful delivery is the first and most crucial requirement for efficient RNAi therapy. Nanomaterials have emerged as highly advantage tools for these studies, as they can be engineered to protect siRNA from degrading, address barriers in siRNA delivery to joints, and target specific cells. This review will discuss recent breakthroughs of different siRNA delivery technologies for cartilage diseases.

Polymeric Delivery of Therapeutic Nucleic Acids

The advent of genome editing has transformed the therapeutic landscape for several debilitating diseases, and the clinical outlook for gene therapeutics has never been more promising. The therapeutic potential of nucleic acids has been limited by a reliance on engineered viral vectors for delivery. Chemically defined polymers can remediate technological, regulatory, and clinical challenges associated with viral modes of gene delivery. Because of their scalability, versatility, and exquisite tunability, polymers are ideal biomaterial platforms for delivering nucleic acid payloads efficiently while minimizing immune response and cellular toxicity. While polymeric gene delivery has progressed significantly in the past four decades, clinical translation of polymeric vehicles faces several formidable challenges. The aim of our Account is to illustrate diverse concepts in designing polymeric vectors towards meeting therapeutic goals of in vivo and ex vivo gene therapy. Here, we highlight several classes of polymers employed in gene delivery and summarize the recent work on understanding the contributions of chemical and architectural design parameters. We touch upon characterization methods used to visualize and understand events transpiring at the interfaces between polymer, nucleic acids, and the physiological environment. We conclude that interdisciplinary approaches and methodologies motivated by fundamental questions are key to designing high-performing polymeric vehicles for gene therapy.

Stimuli-Sensitive Self-Assembled Tubules Based on Lysine-Derived Surfactants for Delivery of Antimicrobial Proteins

Drug delivery vectors based on amphiphiles have important features such as versatile physicochemical properties and stimuli-responsiveness. Amino acid-based surfactants are especially promising amphiphiles due to their enhanced biocompatibility compared to conventional surfactants. They can self-organize into micelles, vesicles and complex hierarchical structures, such as fibers, twisted and coiled ribbons, and tubules. In this work, we investigated the self-assembly and drug loading properties of a family of novel anionic double-tailed lysine-derived surfactants, with variable degree of tail length mismatch, designated as mLys10 and 10Lysn, where m and n are the number of carbon atoms in the tails. These surfactants form tubular aggregates with assorted morphologies in water that undergo gelation due to dense entanglement, as evidenced by light and electron microscopy. Lysozyme (LZM), an enzyme with antimicrobial properties, was selected as model protein for loading. After the characterization of the interfacial properties and phase behavior of the amphiphiles, the LZM-loading ability of the tubules was investigated, under varying experimental conditions, to assess the efficiency of the aggregates as pH- and temperature-sensitive nanocarriers. Further, the toxicological profile of the surfactants per se and surfactant/LZM hydrogels was obtained, using human skin fibroblasts (BJ-5ta cell line). Overall, the results show that the tubule-based hydrogels exhibit very interesting properties for the transport and controlled release of molecules of therapeutic interest.

Electrospun Nanofibers for Cancer Therapy

Lately, a remarkable progress has been recorded in the field of electrospinning for the preparation of numerous types of nanofiber scaffolds. These scaffolds present some remarkable features including high loading capacity and encapsulation efficiency, superficial area and porosity, potential for modification, structure for the co-delivery of various therapies, and cost-effectiveness. Their present and future applications for cancer diagnosis and treatment are promising and pioneering. In this chapter we provide a comprehensive overview of electrospun nanofibers (ESNFs) applications in cancer diagnosis and treatment, covering diverse types of drug-loaded electrospun nanofibers.

A laser microdissection-based axotomy model incorporating the use of biomimicking fiber scaffolds reveals that microRNAs promote axon regeneration over long injury distances

The regeneration of injured neurons over long injury distances remains suboptimal. In order to successfully stimulate nerve regrowth, potent biomolecules are necessary. Furthermore, reproducible and translatable methods to test the potency of candidate drugs for enhancing nerve regeneration over long axotomy distances are also needed. To address these issues, we report a novel laser microdissection-based axotomy model that involves the use of biomimicking aligned fiber substrates to precisely control neuronal axotomy distances. Correspondingly, we demonstrate that in the absence of therapeutics, dorsal root ganglion (DRG) explants (consisting of neurons) axotomized within short distances from the main cell somas regenerated significantly longer than axons that were injured more distally (p < 0.05). However, when treated with a cocktail of microRNAs (miR-132/miR-222/miR-431), robust neurite outgrowth was observed (p < 0.05). Specifically, microRNA treatment promoted neurite outgrowth by ∼2.2-fold as compared to untreated cells and this enhancement was more significant under the less conducive regeneration condition of a long axotomy distance (i.e. 1000 μm from the cell soma). Besides that, we demonstrated that the treatment of miR-132/miR-222/miR-431 led to a longer length of nerve regeneration as well as a bigger nerve extension area after sciatic nerve transection injury. These results indicate that distance effects on axonal regrowth may be overcome by the effects of microRNAs and that these microRNAs may serve as promising therapeutics for nerve injury treatment.

Electrospun nanofibers in cancer research: from engineering of in vitro 3D cancer models to therapy

Electrospinning is historically related to tissue engineering due to its ability to produce nano-/microscale fibrous materials with mechanical and functional properties that are extremely similar to those of the extracellular matrix of living tissues. The general interest in electrospun fibrous matrices has recently expanded to cancer research both as scaffolds for in vitro cancer modelling and as patches for in vivo therapeutic delivery. In this review, we examine electrospinning by providing a brief description of the process and overview of most materials used in this process, discussing the effect of changing the process parameters on fiber conformations and assemblies. Then, we describe two different applications of electrospinning in service of cancer research: firstly, as three-dimensional (3D) fibrous materials for generating in vitro pre-clinical cancer models; and secondly, as patches encapsulating anticancer agents for in vivo delivery.

Electrospun Nanofibers as Carriers of Microorganisms, Stem Cells, Proteins, and Nucleic Acids in Therapeutic and Other Applications

Electrospinning is a technique that uses polymer solutions and strong electric fields to produce nano-sized fibers that have wide-ranging applications. We present here an overview of the use of electrospinning to incorporate biological products into nanofibers, including microorganisms, cells, proteins, and nucleic acids. Although the conditions used during electrospinning limit the already problematic viability/stability of such biological products, their effective incorporation into nanofibers has been shown to be feasible. Synthetic polymers have been more frequently applied to make nanofibers than natural polymers. Polymer blends are commonly used to achieve favorable physical properties of nanofibers. The majority of nanofibers that contain biological product have been designed for therapeutic applications. The incorporation of these biological products into nanofibers can promote their stability or viability, and also allow their delivery to a desired tissue or organ. Other applications include plant protection in agriculture, fermentation in the food industry, biocatalytic environmental remediation, and biosensing. Live cells that have been incorporated into nanofibers include bacteria and fungi. Nanofibers have served as scaffolds for stem cells seeded on a surface, to enable their delivery and application in tissue regeneration and wound healing. Viruses incorporated into nanofibers have been used in gene delivery, as well as in therapies against bacterial infections and cancers. Proteins (hormones, growth factors, and enzymes) and nucleic acids (DNA and RNA) have been incorporated into nanofibers, mainly to treat diseases and enhance their stability. To summarize, incorporation of biological products into nanofibers has numerous advantages, such as providing protection and facilitating controlled delivery from a solid form with a large surface area. Future studies should address the challenge of transferring nanofibers with biological products into practical and industrial use.

Micro-RNA-incorporated electrospun nanofibers improve osteogenic differentiation of human-induced pluripotent stem cells

Smart scaffolds have a great role in the damaged tissue reconstruction. The aim of this study was developing a scaffold that in addition to its fiber's topography has also content of micro-RNAs (miRNAs), which play a regulatory role during osteogenesis. In this study, we inserted two important miRNAs, including miR-22 and miR-126 in the electrospun polycaprolactone (PCL) nanofibers and after scaffold characterization, osteoinductivity of the fabricated nanofibers was investigated by evaluating of the osteogenic differentiation potential of induced pluripotent stem cells (iPSCs) when grown on miRNAs-incorporated PCL nanofibers (PCL-miR) and empty PCL. MiRNAs incorporation had no effect on the fibers size and morphology, cell attachment, and protein adsorption, although viability and proliferation rate of the human iPSCs were increased after a week in PCL-miR compared to the empty PCL. The results obtained from alkaline phosphatase activity, calcium content, bone-related genes, and proteins expression assays demonstrated that the highest osteogenic markers were observed in iPSCs grown on the PCL-miR compared to the cells cultured on PCL and culture plate. According to the results, miR-incorporated PCL nanofibers could be considered as a promising potential tissue-engineered construct for the treatment of patients with bone lesions and defects.

Hybrid polymer/porous silicon nanofibers for loading and sustained release of synthetic DNA-based responsive devices

Synthetic DNA-based oligonucleotides are loaded into porous silicon nanoparticles (pSiNPs) and incorporated into nanofibers of poly(lactide-co-glycolide) (PLGA), poly-l-lactic acid (PLA), or polycaprolactone (PCL). The resulting hybrid nanofibers are characterized for their ability to release the functional oligonucleotide payload under physiologic conditions. Under temperature and pH conditions mimicking physiological values, the PLGA-based nanofibers release >80% of their DNA cargo within 5 days, whereas the PLA and PCL-based fibers require 15 days to release >80% of their cargo. The quantity of DNA released scales with the quantity of DNA-loaded pSiNPs embedded in the nanofibers; mass loadings of between 2.4 and 9.1% (based on mass of DNA-pSiNP construct relative to mass of polymer composite) are investigated. When a responsive DNA-based nanodevice (i.e. molecular beacon) is used as a payload, it retains its functionality during the release period, independent of the polymer used for the formation of the nanofibers.

Scaffold-mediated non-viral delivery platform for CRISPR/Cas9-based genome editing

Genome editing, especially via the simple and versatile type II CRISPR/Cas9 system, offers an effective avenue to precisely control cell fate, an important aspect of tissue regeneration. Unfortunately, most CRISPR/Cas9 non-viral delivery strategies only utilise micro-/nano-particle delivery methods. While these approaches provide reasonable genomic editing efficiencies, their systemic delivery may lead to undesirable off-target effects. For in vivo applications, a more localized and sustained delivery approach may be useful, particularly in the context of tissue regeneration. Here, we developed a scaffold that delivers the CRISPR/Cas9 components (i.e. single guide RNA (sgRNA) and Cas9 protein complexes) in a localized and non-viral manner. Specifically, using mussel-inspired bioadhesive coating, polyDOPA-melanin (pDOPA), we adsorbed Cas9:sgRNA lipofectamine complexes onto bio-mimicking fiber scaffolds. To evaluate the genome-editing efficiency of this platform, U2OS.EGFP cells were used as the model cell type. pDOPA coating was essential in allowing Cas9:sgRNA lipofectamine complexes to adhere onto the scaffolds with a higher loading efficiency, while laminin coating was necessary for maintaining cell viability and proliferation on the pDOPA-coated fibers for effective gene editing (21.5% editing efficiency, p < 0.001). Importantly, U2OS.EGFP cells took up Cas9:sgRNA lipofectamine complexes directly from the scaffolds via reverse transfection. Overall, we demonstrate the efficacy of such fiber scaffolds in providing localized, sustained and non-viral delivery of Cas9:sgRNA complexes. Such genome editing scaffolds may find useful applications in tissue regeneration. STATEMENT OF SIGNIFICANCE: Currently, there is a lack of effective non-viral means to deliver CRISPR/Cas9 components for genome editing. Most existing approaches only utilize micro-/nano-particles by injection or systemic delivery, which may lead to undesirable off-target effects. Here, we report a platform that delivers the CRISPR/Cas9 components (i.e. single guide RNA (sgRNA) and Cas9 protein complexes) in a localized and sustained manner. We used mussel-inspired bioadhesive coating to functionalize the bio-mimicking fiber scaffolds with Cas9:sgRNA lipofectamine complexes, to allow effective gene editing for the cells seeded on the scaffolds. Importantly, the cells took up Cas9:sgRNA lipofectamine complexes directly from the scaffolds. Such genome editing scaffolds may find useful applications in tissue regeneration.

Electrospinning Nanofibers for Therapeutics Delivery

The limitations of conventional therapeutic drugs necessitate the importance of developing novel therapeutics to treat diverse diseases. Conventional drugs have poor blood circulation time and are not stable or compatible with the biological system. Nanomaterials, with their exceptional structural properties, have gained significance as promising materials for the development of novel therapeutics. Nanofibers with unique physiochemical and biological properties have gained significant attention in the field of health care and biomedical research. The choice of a wide variety of materials for nanofiber fabrication, along with the release of therapeutic payload in sustained and controlled release patterns, make nanofibers an ideal material for drug delivery research. Electrospinning is the conventional method for fabricating nanofibers with different morphologies and is often used for the mass production of nanofibers. This review highlights the recent advancements in the use of nanofibers for the delivery of therapeutic drugs, nucleic acids and growth factors. A detailed mechanism for fabricating different types of nanofiber produced from electrospinning, and factors influencing nanofiber generation, are discussed. The insights from this review can provide a thorough understanding of the precise selection of materials used for fabricating nanofibers for specific therapeutic applications and also the importance of nanofibers for drug delivery applications.

Gene Silencing via PDA/ERK2-siRNA-Mediated Electrospun Fibers for Peritendinous Antiadhesion

Sustained delivery of small interfering RNA (siRNA) is a challenge in gene silencing for managing gene-related disorders. Although nanoparticle-mediated electrospun fibers enable sustainable gene silencing, low efficiency, loss of biological activity, toxicity issues, and complex electrospinning techniques are all bottlenecks of these systems. Preventing peritendinous adhesion is crucial for their successful use, which involves blocking cellular signaling via physical barriers. Here, a multifunctional, yet structurally simple, cationic 2,6-pyridinedicarboxaldehyde-polyethylenimine (PDA)-mediated extracellular signal-regulated kinase (ERK)2-siRNA polymeric delivery system is reported, in the form of peritendinous antiadhesion electrospun poly-l-lactic acid/hyaluronan membranes (P/H), with the ability to perform sustained release of bioactive siRNA for long-term prevention of adhesions and ERK2 silencing. After 4 days of culture, the cell area and proliferation rate of chicken embryonic fibroblasts on siRNA+PDA+P/H membrane are significantly less than those on P/H and siRNA+P/H membranes. The in vivo results of average optical density of collagen type III (Col III) and gene expression of ERK2 and its downstream SMAD3 in the siRNA+PDA+P/H group are less than those of P/H and siRNA+P/H groups. Consequently, siRNA+PDA+P/H electrospun membrane can protect the bioactivity of ERK2-siRNA and release it in a sustained manner. Moreover, adhesion formation is inhibited by reducing fibroblast proliferation and Col III deposition, and downregulating ERK2 and its downstream SMAD3.

Sputtering of Electrospun Polymer-Based Nanofibers for Biomedical Applications: A Perspective

Electrospinning has gained wide attention recently in biomedical applications. Electrospun biocompatible scaffolds are well-known for biomedical applications such as drug delivery, wound dressing, and tissue engineering applications. In this review, the synthesis of polymer-based fiber composites using an electrospinning technique is discussed. Formerly, metal particles were then deposited on the surface of electrospun fibers using sputtering technology. Key nanometals for biomedical applications including silver and copper nanoparticles are discussed throughout this review. The formulated scaffolds were found to be suitable candidates for biomedical uses such as antibacterial coatings, surface modification for improving biocompatibility, and tissue engineering. This review briefly mentions the characteristics of the nanostructures while focusing on how nanostructures hold potential for a wide range of biomedical applications.

Formulation, Characterization and In vitro Cytotoxicity of 5-Fluorouracil Loaded Polymeric Electrospun Nanofibers for the Treatment of Skin Cancer

BACKGROUND

The purpose of this study was to formulate, characterize and conduct in vitro cytotoxicity of 5-fluorouracil loaded polymeric electrospun nanofibers for the treatment of skin cancer. The patents on electrospun nanofibers (US9393216B2), (US14146252), (WO2015003155A1) etc. helped in the selection of polymers and method for the preparation of nanofibers.

METHODS

In the present study, the fabrication of nanofibers was done using a blend of chitosan with polyvinyl alcohol and processed using the electrospinning technique. 5-fluorouracil with known chemotherapeutic potential in the treatment of skin cancer was used as a drug carrier. 24-1 fractional factorial screening design was employed to study the effect of independent variables like the concentration of the polymeric solution, applied voltage (kV), distance (cm), flow rate (ml / hr) on dependent variables like % entrapment efficiency and fiber diameter.

RESULTS

Scanning electron microscopy was used to characterize fiber diameter and morphology. Results showed that the fiber diameter of all batches was found in the range of 100-200 nm. The optimized batch results showed the fiber diameter of 162.7 nm with uniform fibers. The tensile strength obtained was 190±37 Mpa. Further in vitro and ex vivo drug release profile suggested a controlled release mechanism for an extended period of 24 hr. The 5-fluorouracil loaded electrospun nanofibers were found to decrease cell viability up to ≥50% over 24 hr, with the number of cells dropping by ~ 10% over 48 hr. As the cell viability was affected by the release of 5-fluorouracil, we believe that electrospun nanofibers are a promising drug delivery system for the treatment of Basal Cell Carcinoma (BCC) skin cancer.

CONCLUSION

These results demonstrate the possibility of delivering 5-Fluorouracil loaded electrospun nanofiber to skin with enhanced encapsulation efficiency indicating the effectiveness of the formulation for the treatment of basal cell carcinoma type of skin cancer.

Biomedical Applications of Electrospun Nanofibers: Drug and Nanoparticle Delivery

The electrospinning process has gained popularity due to its ease of use, simplicity and diverse applications. The properties of electrospun fibers can be controlled by modifying either process variables (e.g., applied voltage, solution flow rate, and distance between charged capillary and collector) or polymeric solution properties (e.g., concentration, molecular weight, viscosity, surface tension, solvent volatility, conductivity, and surface charge density). However, many variables affecting electrospinning are interdependent. An optimized electrospinning process is one in which these parameters remain constant and continuously produce nanofibers consistent in physicochemical properties. In addition, nozzle configurations, such as single nozzle, coaxial, multi-jet electrospinning, have an impact on the fiber characteristics. The polymeric solution could be aqueous, a polymeric melt or an emulsion, which in turn leads to different types of nanofiber formation. Nanofiber properties can also be modified by polarity inversion and by varying the collector design. The active moiety is incorporated into polymeric fibers by blending, surface modification or emulsion formation. The nanofibers can be further modified to deliver multiple drugs, and multilayer polymer coating allows sustained release of the incorporated active moiety. Electrospun nanofibers prepared from polymers are used to deliver antibiotic and anticancer agents, DNA, RNA, proteins and growth factors. This review provides a compilation of studies involving the use of electrospun fibers in biomedical applications with emphasis on nanoparticle-impregnated nanofibers.

Localised non-viral delivery of nucleic acids for nerve regeneration in injured nervous systems

Axons damaged by traumatic injuries are often unable to spontaneously regenerate in the adult central nervous system (CNS). Although the peripheral nervous system (PNS) has some regenerative capacity, its ability to regrow remains limited across large lesion gaps due to scar tissue formation. Nucleic acid therapy holds the potential of improving regeneration by enhancing the intrinsic growth ability of neurons and overcoming the inhibitory environment that prevents neurite outgrowth. Nucleic acids modulate gene expression by over-expression of neuronal growth factor or silencing growth-inhibitory molecules. Although in vitro outcomes appear promising, the lack of efficient non-viral nucleic acid delivery methods to the nervous system has limited the application of nucleic acid therapeutics to patients. Here, we review the recent development of efficient non-viral nucleic acid delivery platforms, as applied to the nervous system, including the transfection vectors and carriers used, as well as matrices and scaffolds that are currently used. Additionally, we will discuss possible improvements for localised nucleic acid delivery.

Influence of polymer composition and drug loading procedure on dual drug release from PLGA:PEG electrospun fibers

Poly(lactide-co-glycolide) (PLGA) has been widely investigated for fabricating electrospun fibers due to their biocompatibility, paired with the capacity for encapsulating different drugs. However, such scaffolds shrink and distort upon contact with biological media, which is undesired for local drug application. To address this issue, we fabricated composite fiber scaffolds with the combination of PLGA and poly(ethylene glycol) (PEG). Scaffold shrinkage could successfully be overcome, however, the release kinetics of the encapsulated drug was strongly dependent on the amount of PEG. The addition of 5% PEG resulted in slower drug release due to a significant increase in fiber diameters. In contrast, the drug release rate was accelerated for fibers containing 10% PEG due to the water-soluble nature of the polymer. Furthermore, co-delivery of two different drugs, the small molecule acyclovir and the model protein bovine serum albumin was realized by two different approaches, coaxial electrospinning and immobilization of the drugs on the surface of the fibers, and drug release was found to be strongly dependent on the loading procedure. Based on our findings, key factors for understanding and controlling physicochemical properties of PLGA/PEG composite fibers as well as tuning drug release could be identified, providing an essential basis for rational design of electrospun fiber-based drug carriers.

Recent advances in electrospun for drug delivery purpose

Electrospun, an advanced technology, has been successfully employed for fibre production and offers many merits in novel drug delivery systems (DDSs). In recent years, electrospun has gained significant attention and attraction of the scientists in soaring numbers. This technology is superior to other technologies in fabricating the fibres which range from micrometers to manometers scale. The selection of appropriate polymers, electrospun processes and electrospun parameters play important roles in controlling the drug release while, treating serious illness. Besides, electrospraying process has similar characteristics to the electrospun and is presented briefly here. Further, in vivo and in vitro evaluations of the electrospun nanofibers are comprehensively discussed. In addition, the electrospun nanotechnology has been exploited to design drug release systems, investigate drug's pharmacokinetics and further develop DDS. The electrospun nanofibers improve bioactivity of various types of drugs including water-insoluble, soluble, anticancer and antibacterial drugs and genetic materials. In the end, the prospects and challenges in the process of designing drug-loaded electrospun nanofibers are discussed in detail.

Sustained delivery of siRNA/mesoporous silica nanoparticle complexes from nanofiber scaffolds for long-term gene silencing

A low toxicity and efficient delivery system is needed to deliver small interfering RNAs (siRNA) in vitro and in vivo. The use of mesoporous silica nanoparticles (MSN) is becoming increasingly common due to its biocompatibility, tunable pore size and customizable properties. However, bolus delivery of siRNA/MSN complexes remains suboptimal, especially when a sustained and long-term administration is required. Here, we utilized electrospun scaffolds for sustained delivery of siRNA/MSN-PEI through surface adsorption and nanofiber encapsulation. As a proof-of-concept, we targeted collagen type I expression to modulate fibrous capsule formation. Surface adsorption of siRNA/MSN-PEI provided sustained availability of siRNA for at least 30 days in vitro. As compared to conventional bolus delivery, such scaffold-mediated transfection provided more effective gene silencing (p < 0.05). On the contrary, a longer sustained release was attained (at least 5 months) when siRNA/MSN-PEI complexes were encapsulated within the electrospun fibers. In vivo subcutaneous implantation and biodistribution analysis of these scaffolds revealed that siRNA remained localized up to ∼290 μm from the implants. Finally, a fibrous capsule reduction of ∼45.8% was observed after 4 weeks in vivo as compared to negative scrambled siRNA treatment. Taken together, these results demonstrate the efficacy of scaffold-mediated sustained delivery of siRNA/MSN-PEI for long-term non-viral gene silencing applications.

STATEMENT OF SIGNIFICANCE

The bolus delivery of siRNA/mesoporous silica nanoparticles (MSN) complexes shows high efficiency to silence protein agonists of tumoral processes as cancer treatments. However, in tissue engineering area, scaffold mediated delivery is desired to achieve a local and sustained release of therapeutics. We showed the feasibility and the efficacy of siRNA/MSN delivered from electrospun scaffolds through surface adsorption and nanofiber encapsulation. We showed that this method enhances siRNA transfection efficiency and sustained targeted proteins silencing in vitro and in vivo. As a proof of concept, in this study, we targeted collagen type I expression to modulate fibrous capsule formation. However this platform can be applied to the release and transfection of siRNA or miRNA in cancer and tissue engineering applications.

RNA interfering molecule delivery from in situ forming biodegradable hydrogels for enhancement of bone formation in rat calvarial bone defects

RNA interference (RNAi) may be an effective and valuable tool for promoting the growth of functional tissue, as short interfering RNA (siRNA) and microRNA (miRNA) can block the expression of genes that have negative effects on tissue regeneration. Our group has recently reported that the localized and sustained presentation of siRNA against noggin (siNoggin) and miRNA-20a from in situ forming poly(ethylene glycol) (PEG) hydrogels enhanced osteogenic differentiation of encapsulated human bone marrow-derived mesenchymal stem cells (hMSCs). Here, the capacity of the hydrogel system to accelerate bone formation in a rat calvarial bone defect model is presented. After 12 weeks post-implantation, the hydrogels containing encapsulated hMSCs and miRNA-20a resulted in more bone formation in the defects than the hydrogels containing hMSCs without siRNA or with negative control siRNA. This localized and sustained RNA interfering molecule delivery system may provide an excellent platform for healing bony defects and other tissues.

STATEMENT OF SIGNIFICANCE

Delivery of RNAi molecules may be a valuable strategy to guide cell behavior for tissue engineering applications, but to date there have been no reports of a biomaterial system capable of both encapsulation of cells and controlled delivery of incorporated RNA. Here, we present PEG hydrogels that form in situ via Michael type reaction, and that permit encapsulation of hMSCs and the concomitant controlled delivery of siNoggin and/or miRNA-20a. These RNAs were chosen to suppress noggin, a BMP-2 antagonist, and/or PPAR-γ, a negative regulator of BMP-2-mediated osteogenesis, and therefore promote osteogenic differentiation of hMSCs and subsequent bone repair in critical-sized rat calvarial defects. Simultaneous delivery of hMSCs and miRNA-20a enhanced repair of these defects compared to hydrogels containing hMSCs without siRNA or with negative control siRNA. This in situ forming PEG hydrogel system offers an exciting platform for healing critical-sized bone defects by localized, controlled delivery of RNAi molecules to encapsulated hMSCs and surrounding cells.

Application of electrospun fibers for female reproductive health

Here, we present the current challenges in women's reproductive health and the current state-of-the-art treatment and prevention options for STI prevention, contraception, and treatment of infections. We discuss how the versatile platform of electrospun fibers can be applied to each challenge, and postulate at how these technologies could be improved. The void of approved electrospun fiber-based products yields the potential to apply this useful technology to a number of medical applications, many of which are relevant to women's reproductive health. Given the ability to tune drug delivery characteristics and three-dimensional geometry, there are many opportunities to pursue new product designs and routes of administration for electrospun fibers. For each application, we provide an overview of the versatility of electrospun fibers as a novel dosage form and summarize their advantages in clinical applications. We also provide a perspective on why electrospun fibers are well-suited for a variety of applications within women's reproductive health and identify areas that could greatly benefit from innovations with electrospun fiber-based approaches.

Preparation and characterization of polycaprolactone–polyethylene glycol methyl ether and polycaprolactone–chitosan electrospun mats potential for vascular tissue engineering

Recently, natural polymers are frequently comingled with synthetic polymers either by physical or chemical modification to prepare numerous tissue-engineered graft with promising biological function, strength, and stability. The aim of this study was to determine the efficiency for vascular tissue engineering of two distinctly different mats, one that comprised polycaprolactone–polyethylene glycol methyl ether and other that comprised polycaprolactone–chitosan. Nano/microfibrous mats prepared from electro-spinning were characterized for fiber diameter, porosity, wettability, and mechanical strength. Biological efficacy on both biodegradable mats was assessed by rat bone marrow mesenchymal stem cells, and polycaprolactone–polyethylene glycol methyl ether showed feasibility for use as an inner layer by inducing endothelial-specific gene expression and polycaprolactone–chitosan as an outer layer on dual layered without sacrificing tensile strength, small-diameter blood vessels. Therefore, scaffolds fabricated from this research could be potential sources for tissue-engineered vascular graft and could also overcome the well-known drawbacks, such as thrombogenicity and stenosis, in managing vascular disease.

Fabrication of self-assembling nanofibers with optimal cell uptake and therapeutic delivery efficacy

Effective strategies to fabricate finite organic nanoparticles and understanding their structure-dependent cell interaction is highly important for the development of long circulating nanocarriers in cancer therapy. In this contribution, we will capitalize on our recent development of finite supramolecular nanofibers based on the self-assembly of modularly designed cationic multidomain peptides (MDPs) and use them as a model system to investigate structure-dependent cell penetrating activity. MDPs self-assembled into nanofibers with high density of cationic charges at the fiber-solvent interface to interact with the cell membrane. However, despite the multivalent charge presentation, not all fibers led to high levels of membrane activity and cellular uptake. The flexibility of the cationic charge domains on self-assembled nanofibers plays a key role in effective membrane perturbation. Nanofibers were found to sacrifice their dimension, thermodynamic and kinetic stability for a more flexible charge domain in order to achieve effective membrane interaction. The increased membrane activity led to improved cell uptake of membrane-impermeable chemotherapeutics through membrane pore formation. In vitro cytotoxicity study showed co-administering of water-soluble doxorubicin with membrane-active peptide nanofibers dramatically reduced the IC50 by eight folds compared to drug alone. Through these detailed structure and activity studies, the acquired knowledge will provide important guidelines for the design of a variety of supramolecular cell penetrating nanomaterials not limited to peptide assembly which can be used to probe various complex biological processes.

Advances and perspectives in tooth tissue engineering

Bio-engineered teeth that can grow and remodel in a manner similar to that of natural teeth have the potential to serve as permanent replacements to the currently used prosthetic teeth, such as dental implants. A major challenge in designing functional bio-engineered teeth is to mimic both the structural and anisotropic mechanical characteristics of the native tooth. Therefore, the field of dental and whole tooth regeneration has advanced towards the molecular and nanoscale design of bio-active, biomimetic systems, using biomaterials, drug delivery systems and stem cells. The focus of this review is to discuss recent advances in tooth tissue engineering, using biomimetic scaffolds that provide proper architectural cues, exhibit the capacity to support dental stem cell proliferation and differentiation and sequester and release bio-active agents, such as growth factors and nucleic acids, in a spatiotemporal controlled manner. Although many in vitro and in vivo studies on tooth regeneration appear promising, before tooth tissue engineering becomes a reality for humans, additional research is needed to perfect methods that use adult human dental stem cells, as opposed to embryonic dental stem cells, and to devise the means to generate bio-engineered teeth of predetermined size and shape. Copyright © 2016 John Wiley & Sons, Ltd.

Efficiency and Safety of β-CD-(D3)7 as siRNA Carrier for Decreasing Matrix Metalloproteinase-9 Expression and Improving Wound Healing in Diabetic Rats

Overexpression of matrix metalloproteinase-9 (MMP-9) is critical for diabetic chronic wounds involved in the refractory wound healing process. We aimed to develop a strategy through RNAi to decrease MMP-9 expression and improve diabetic wound healing. We had explored β-CD-(D₃)₇ as a gene carrier to take siRNA and effectively interfere with MMP-9 expression. It has been proven that β-CD-(D₃)₇ could be used as an effective siRNA delivery system. In this study, we want to know about the efficiency and safety of β-CD-(D₃)₇/MMP-9 siRNA for improving wound healing in diabetic rats. β-CD-(D3)7/MMP-9 siRNA treated animals show lower levels of MMP-9 expression, which induce faster wound-close rates. Histological evaluation indicates that β-CD-(D3)7/MMP-9 siRNA significantly increases the content of collagen around the injured tissues. The number of neutrophilic ganulocytes was significantly decreased through treatment of β-CD-(D3)7/MMP-9 siRNA. In vivo fluorescence imaging assessment shows that β-CD-(D3)7/MMP-9 siRNA could not cause organ damage and organ accumulation. The results suggest that β-CD-(D₃)₇/MMP-9 siRNA might be developed as a novel topical agent for the diabetic wounds treatment.

The generation of compartmentalized nanoparticles containing siRNA and cisplatin using a multi-needle electrohydrodynamic strategy

This study outlines a novel manufacturing technique for the generation of compartmentalized trilayered nanoparticles loaded with an anti-cancer agent and siRNA as a platform for the combination treatment of cancers. More specifically, we describe the use of a multi-needle electrohydrodynamic approach to produce nanoparticles with high size specificity and scalable output, while allowing suitable environments for each therapeutic agent. The inner polylactic-glycolic-acid (PLGA) layer was loaded with cisplatin while the middle chitosan layer was loaded with siRNA. The corresponding polymeric solutions were characterized for their viscosity, surface tension and conductivity, while particle size was determined using dynamic light scattering. The internal structure was studied using transmission electron microscopy (TEM) and Structured Illumination Microscopy (SIM). The inclusion of cisplatin was studied using electron dispersive spectroscopy (EDS). We were able to generate nanoparticles of approximate size 130 nm with three distinct layers containing an outer protective PLGA layer, a middle layer of siRNA and an inner layer of cisplatin. These particles have the potential not only for uptake into tumors via the enhanced permeability and retention (EPR) effect but also the sequential release of the siRNA and chemotherapeutic agent, thereby providing a means of overcoming challenges of targeting and tumor drug resistance.

Encapsulation of Anticancer Drugs (5-Fluorouracil and Paclitaxel) into Polycaprolactone (PCL) Nanofibers and In Vitro Testing for Sustained and Targeted Therapy

We report a continuous nanoscale encapsulation of cancer drugs 5-Fluorouracil (FU) and Paclitaxel into biocompatible polycaprolactone (PCL) nanofibers (NFs) using core-sheath electrospinning process. A high potential electric field of 19-23.2 kV was used to draw a compound solution jet from a specialized coaxial spinneret. Using of DMF in both core and Sheath resulted in NFs within 50-160 nm along with large beaded structures. Addition of Trichloromethane (TCM) or Trifluoroethanol (TFE) in sheath turned NFs in more uniform and thin fiber structure. The diameter range for paclitaxel encapsulated fibers was 22-90 nm with encapsulation efficiency of 77.5% and the amount of drug was only 4 to 5% of sheath polymer. Addition of PVA within core resulted drug nanocrystal formation outside of sheath and poor encapsulation efficiency (52%) with rapid initial release (52-53%) in first 3 days. Drug release test of NFs in different pH exhibited increase of release rate with the decrease of media pH. In-vitro cell viability test with FU encapsulated NFs in human prostatic cancer PC3 cells exhibited 38% alive cells at 5 μM concentration while in pristine FU 43% cells were alive. Paclitaxel encapsulated NFs with breast cancer cells also exhibited increased efficacy in comparison to pristine anticancer drugs. Continuous decrease of cell density indicated the slow release of cancer drugs from the NFs. Both PCL+Paclitaxel and PCL+5FU treated conditions caused breast cancer cell death between 40% to 50%.

Three-dimensional aligned nanofibers-hydrogel scaffold for controlled non-viral drug/gene delivery to direct axon regeneration in spinal cord injury treatment

Spinal cord injuries (SCI) often lead to persistent neurological dysfunction due to failure in axon regeneration. Unfortunately, currently established treatments, such as direct drug administration, do not effectively treat SCI due to rapid drug clearance from our bodies. Here, we introduce a three-dimensional aligned nanofibers-hydrogel scaffold as a bio-functionalized platform to provide sustained non-viral delivery of proteins and nucleic acid therapeutics (small non-coding RNAs), along with synergistic contact guidance for nerve injury treatment. A hemi-incision model at cervical level 5 in the rat spinal cord was chosen to evaluate the efficacy of this scaffold design. Specifically, aligned axon regeneration was observed as early as one week post-injury. In addition, no excessive inflammatory response and scar tissue formation was triggered. Taken together, our results demonstrate the potential of our scaffold for neural tissue engineering applications.

Engineered Hydrogels for Local and Sustained Delivery of RNA-Interference Therapies

It has been nearly two decades since RNA-interference (RNAi) was first reported. While there are no approved clinical uses, several phase II and III clinical trials suggest the great promise of RNAi therapeutics. One challenge for RNAi therapies is the controlled localization and sustained presentation to target tissues, to both overcome systemic toxicity concerns and to enhance in vivo efficacy. One approach that is emerging to address these limitations is the entrapment of RNAi molecules within hydrogels for local and sustained release. In these systems, nucleic acids are either delivered as siRNA conjugates or within nanoparticles. A plethora of hydrogels has been implemented using these approaches, including both traditional hydrogels that have already been developed for other applications and new hydrogels developed specifically for RNAi delivery. These hydrogels have been applied to various applications in vivo, including cancer, bone regeneration, inflammation and cardiac repair. This review will examine the design and implementation of such hydrogel RNAi systems and will cover the most recent applications of these systems.

Electrospun PCL-PIBMD/SF blend scaffolds with plasmid complexes for endothelial cell proliferation

PCL-PIBMD/SF scaffolds can maintain the integrity of plasmid complexes loaded in scaffolds, and thereby enhance the proliferation of endothelial cells.