Electrospinning of PVA/sericin nanofiber and the effect on epithelial-mesenchymal transition of A549 cells

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.

Inhalable Textile Microplastic Fibers Impair Airway Epithelial Differentiation

Rationale: Microplastics are a pressing global concern, and inhalation of microplastic fibers has been associated with interstitial and bronchial inflammation in flock workers. However, how microplastic fibers affect the lungs is unknown. Objectives: Our aim was to assess the effects of 12 × 31 μm nylon 6,6 (nylon) and 15 × 52 μm polyethylene terephthalate (polyester) textile microplastic fibers on lung epithelial growth and differentiation. Methods: We used human and murine alveolar and airway-type organoids as well as air-liquid interface cultures derived from primary lung epithelial progenitor cells and incubated these with either nylon or polyester fibers or nylon leachate. In addition, mice received one dose of nylon fibers or nylon leachate, and, 7 days later, organoid-forming capacity of isolated epithelial cells was investigated. Measurements and Main Results: We observed that nylon microfibers, more than polyester, inhibited developing airway organoids and not established ones. This effect was mediated by components leaching from nylon. Epithelial cells isolated from mice exposed to nylon fibers or leachate also formed fewer airway organoids, suggesting long-lasting effects of nylon components on epithelial cells. Part of these effects was recapitulated in human air-liquid interface cultures. Transcriptomic analysis revealed upregulation of Hoxa5 after exposure to nylon fibers. Inhibiting Hoxa5 during nylon exposure restored airway organoid formation, confirming Hoxa5's pivotal role in the effects of nylon. Conclusions: These results suggest that components leaching from nylon 6,6 may especially harm developing airways and/or airways undergoing repair, and we strongly encourage characterization in more detail of both the hazard of and the exposure to microplastic fibers.

Iron-Based Magnetic Nanosystems for Diagnostic Imaging and Drug Delivery: Towards Transformative Biomedical Applications

The advancement of biomedicine in a socioeconomically sustainable manner while achieving efficient patient-care is imperative to the health and well-being of society. Magnetic systems consisting of iron based nanosized components have gained prominence among researchers in a multitude of biomedical applications. This review focuses on recent trends in the areas of diagnostic imaging and drug delivery that have benefited from iron-incorporated nanosystems, especially in cancer treatment, diagnosis and wound care applications. Discussion on imaging will emphasise on developments in MRI technology and hyperthermia based diagnosis, while advanced material synthesis and targeted, triggered transport will be the focus for drug delivery. Insights onto the challenges in transforming these technologies into day-to-day applications will also be explored with perceptions onto potential for patient-centred healthcare.

The Bumpy Road to Stem Cell Therapies: Rational Design of Surface Topographies to Dictate Stem Cell Mechanotransduction and Fate

Cells sense and respond to a variety of physical cues from their surrounding microenvironment, and these are interpreted through mechanotransductive processes to inform their behavior. These mechanisms have particular relevance to stem cells, where control of stem cell proliferation, potency, and differentiation is key to their successful application in regenerative medicine. It is increasingly recognized that surface micro- and nanotopographies influence stem cell behavior and may represent a powerful tool with which to direct the morphology and fate of stem cells. Current progress toward this goal has been driven by combined advances in fabrication technologies and cell biology. Here, the capacity to generate precisely defined micro- and nanoscale topographies has facilitated the studies that provide knowledge of the mechanotransducive processes that govern the cellular response as well as knowledge of the specific features that can drive cells toward a defined differentiation outcome. However, the path forward is not fully defined, and the "bumpy road" that lays ahead must be crossed before the full potential of these approaches can be fully exploited. This review focuses on the challenges and opportunities in applying micro- and nanotopographies to dictate stem cell fate for regenerative medicine. Here, key techniques used to produce topographic features are reviewed, such as photolithography, block copolymer lithography, electron beam lithography, nanoimprint lithography, soft lithography, scanning probe lithography, colloidal lithography, electrospinning, and surface roughening, alongside their advantages and disadvantages. The biological impacts of surface topographies are then discussed, including the current understanding of the mechanotransductive mechanisms by which these cues are interpreted by the cells, as well as the specific effects of surface topographies on cell differentiation and fate. Finally, considerations in translating these technologies and their future prospects are evaluated.

Arginine induces protein self-assembly into nanofibers for triggering osteogenic differentiation of stem cells

Although silk proteins are considered promising in building a scaffold for tissue engineering, one of the silk proteins, Bombyx mori silk sericin (BS), has limited processability in producing nanofibrous scaffolds because its surface charge anisotropy promotes gelation instead. To overcome this daunting challenge, we developed a mild and simple procedure for assembling BS into nanofibers and nanofibrous scaffolds. Briefly, arginine was added to the aqueous BS solution to reduce the negative charge of BS, thereby inducing BS to self-assemble into nanofibers in the solution. Circular dichroism (CD) and Fourier transform infrared (FT-IR) spectra showed that arginine promoted the formation of β-sheet conformation in BS and increased its thermal stability. Furthermore, the arginine-induced BS nanofiber solution could be casted into scaffolds made of abundant network-like nanofibrous structures. The BS scaffolds promoted cell adhesion and growth and stimulated osteogenic differentiation of the bone marrow mesenchymal stem cells (BMSCs) in the absence of differentiation inducers in culture media. Our study presents a new strategy for assembling proteins into osteogenic nanofibrous scaffolds for inducing stem cell differentiation in regenerative medicine.

Cellular architecture response to aspect ratio tunable nanoarrays

Nanoarrays have been emerging as popular nanostructure platforms to investigate both cell behaviors and biological functions, due to the cell architecture respondence to the biointerface of nanostructures. Herein, we developed a series of aspect ratio tunable nanoarrays through a metal-assisted chemical etching method. Nanoarrays including nanoneedles, nanopillars, and nanoclusters were fabricated with a controllable aspect ratio. We found that nanostructures with a high aspect ratio (>10) induced significant alterations of cell physiological behaviors such as surface attachment, architecture deformation, viability, proliferation and motility. The cells on nanostructures with a high aspect ratio exhibited reorganized actin stress fibers and vimentin filaments, as well as reduced focal adhesion. This research enlarges the diversity of nanostructures on nano-bio interface investigation, provides a new insight for the surface-dependent architecture of cells, and offers unbiased understanding of factors influencing cell physiology.

Biointerface anisotropy modulates migration of breast cancer cell

Migration of cancer cell is a cyclic process, which involves dynamic interaction between extracellular biointerface and cellular responds. In tumors, collagen as extracellular matrix reorganizes biointerface from curl and isotropic fibers to straightened and anisotropic fibers during tumorigenesis, yet how cell migration respond to topography of biointerface is unknown. In this research, we introduced a facile fabrication method on nanofibers of varying topography, which was mimicking the alignment of extracellular nanofibers, to examine the change of cytoskeleton during cell migration. We took advantage of breast carcinoma cell line (MDA-MB-231) for time-lapse imaging analysis. We found that biointerface anisotropy modulated morphology of cell and mediated the pattern of migration. Morphologically, cells on anisotropic nanofiber showed extending spindle shape. The trajectories of migration templated the topographic pattern on biointerface. Besides, aligned nanofiber induced caterpillar-like model of migration through protrusion - retraction cycle, which was indicated by periodical variation of aspect ratio and velocity of cells. The biointerface anisotropy triggered vimentin filaments and microtubule networks preferentially oriented along the alignment of nanofibers. And the velocity of cell mobility by vimentin, β-catenin or CDC42 knockdown was significantly enhanced on aligned nanofibers. Thus, we implied that biointerface anisotropy modulated migration of breast cancer cell and it associated with reorganization of cytoskeleton filaments.

Extracellular nanofiber-orchestrated cytoskeletal reorganization and mediated directional migration of cancer cells

Extracellular matrix anisotropy tunes the organization and movement of surrounding cells. The primary mediators of the extracellular matrix are fiber-based materials. Natural collagen fibers reorganize from curled and isotropic fibers to straightened and anisotropic fibers during tumorigenesis, yet how the cytoskeleton is involved in the directional migration in response to the topography is unknown. To investigate this, we fabricated random, orthogonal, and aligned nanofibers to deconstruct the basic mechanisms for the migration of the human pancreatic cancer cells PANC-1 on different substrates. We found that the extracellular matrix orchestrated actin reorganization by templating the surface topography as an irregular pattern on random fibers, crossover feature on orthogonal fibers, and parallel characteristics on aligned fibers. The intermediate filament as vimentin was upregulated to form a perinuclear shape on orthogonal or aligned surfaces. We also found that the nanofiber topography mediated the directional migration via different mechanisms. The directionality ratio and velocity were statistically analyzed to unveil the pattern of directional migration. Cells on aligned nanofibers yielded a greater velocity. Rac1 and Cdc42 were involved in cell migration through regulating actin polymerization and membrane protrusions. Thus, our findings elucidate that nanofiber alignment orchestrates cytoskeletal reorganization and mediates the directional migration of cancer cells.

Nanomaterials as Inhibitors of Epithelial Mesenchymal Transition in Cancer Treatment

Abstract: Epithelial-mesenchymal transition (EMT) has emerged as a key regulator of cell invasion and metastasis in cancers. Besides the acquisition of migratory/invasive abilities, the EMT process is tightly connected with the generation of cancer stem cells (CSCs), thus contributing to chemoresistance. However, although EMT represents a relevant therapeutic target for cancer treatment, its application in the clinic is still limited due to various reasons, including tumor-stage heterogeneity, molecular-cellular target specificity, and appropriate drug delivery. Concerning this last point, different nanomaterials may be used to counteract EMT induction, providing novel therapeutic tools against many different cancers. In this review, (1) we discuss the application of various nanomaterials for EMT-based therapies in cancer, (2) we summarize the therapeutic relevance of some of the proposed EMT targets, and (3) we review the potential benefits and weaknesses of each approach.

Electrospun PCL/mupirocin and chitosan/lidocaine hydrochloride multifunctional double layer nanofibrous scaffolds for wound dressing applications

Background

An ideal wound dressing should exhibit good biocompatibility, minimize pain and infection, absorb excess exudates, and maintain a moist environment. However, few clinical products meet all these needs. Therefore, the aim of this study was to fabricate a multifunctional double layer nanofibrous scaffolds (DLS) as a potential material for wound dressing.

Materials and methods

The scaffold was formed from mupirocin and lidocaine hydrochloride homogeneously incorporated into polycaprolactone as the first layer of scaffolds and chitosan as the second layer of scaffolds nanofibers through electrospinning. The fabricated nanofibrous scaffolds were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis, differential scanning calorimetry, and measurement of swelling ratio, contact angle, drug release, and mechanical properties. Furthermore, antibacterial assessment, live/dead cell assays, and MTT assays were used to investigate the antibacterial activity and cytotoxicity of the nanofibrous scaffolds.

Results

The morphology of the nanofibrous scaffolds was studied by scanning electron microscopy, showing successful nanofibrous scaffolds. Fourier transform infrared spectroscopy demonstrated the successful incorporation of the material used to produce the produced nanofibrous scaffolds. Thermal studies with thermogravimetric analysis and differential scanning calorimetry indicated that the DLS had high thermal stability. The DLS also showed good in vitro characteristics in terms of improved swelling ratio and contact angle. The mechanical results revealed that the DLS had an improved tensile strength of 3.88 MPa compared with the second layer of scaffold (2.81 MPa). The release of drugs from the scaffold showed different profiles for the two drugs. Lidocaine hydrochlo ride exhibited an initial burst release (66% release within an hour); however, mupirocin exhibited only a 5% release. Furthermore, the DLS nanofibers displayed highly effective antibacterial activities against Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa and were nontoxic to fibroblasts.

Conclusion

The fabricated DLS exhibited excellent hydrophilicity, cytocompatibility, sustained drug release, and antibacterial activity, which are favorable qualities for its use as a multifunctional material for wound dressing applications.

Polymer-Magnetic Composite Fibers for Remote-Controlled Drug Release

An efficient method is reported, for the fabrication of composite microfibers that can be magnetically actuated and are biocompatible, targeting controlled drug release. Aqueous solutions of polyvinyl alcohol, incorporated with citric acid-coated Fe₃O₄ magnetic nanoparticles (MNPs), are subject to infusion gyration to generate 100-300 nm diameter composite fibers, with controllable MNP loading. The fibers are stable in polar solvents, such as ethanol, and do not show any leaching of MNPs for over 4 weeks. Using acetaminophen as an example, we demonstrate that this material is effective in immobilization and triggered release of drugs, which is achieved by a moving external magnetic field. The remote actuation ability, coupled with biocompatibility and lightweight property, renders enormous potential for these fibers to be used as a smart drug release agent.

Electrospun Fibers as a Dressing Material for Drug and Biological Agent Delivery in Wound Healing Applications

Wound healing is a complex tissue regeneration process that promotes the growth of new tissue to provide the body with the necessary barrier from the outside environment. In the class of non-healing wounds, diabetic wounds, and ulcers, dressing materials that are available clinically (e.g., gels and creams) have demonstrated only a slow improvement with current available technologies. Among all available current technologies, electrospun fibers exhibit several characteristics that may provide novel replacement dressing materials for the above-mentioned wounds. Therefore, in this review, we focus on recent achievements in electrospun drug-eluting fibers for wound healing applications. In particular, we review drug release, including small molecule drugs, proteins and peptides, and gene vectors from electrospun fibers with respect to wound healing. Furthermore, we provide an overview on multifunctional dressing materials based on electrospun fibers, including those that are capable of achieving wound debridement and wound healing simultaneously as well as multi-drugs loading/types suitable for various stages of the healing process. Our review provides important and sufficient information to inform the field in development of fiber-based dressing materials for clinical treatment of non-healing wounds.

Human lung epithelial cells A549 epithelial-mesenchymal transition induced by PVA/Collagen nanofiber

Epithelial-mesenchymal transition (EMT) is a process by which epithelial cells lose their cell-cell contact to become mesenchymal stem cells, which is important on development and embryogenesis, wound healing, and cancer metastasis. This research aims to investigate the effect of topological cue as modulating factor on the EMT by tuning the diameter of electrospinning nanofiber. The cell-nanofiber interaction between human lung epithelial cell A549 and electrospinning nanofibers composed of polyvinyl alcohol (PVA) and type I collagen were investigated. The electrospinning of regenerated PVA/Collagen nanofibers were performed with water/acetic acid as a spinning solvent and glutaraldehyde as a chemical cross-linker. Parameterization on concentration, applied voltage and feeding rate was finalized to generate smooth nanofibers with good homogeneity. The scanning electron microscopy result demonstrated that A549 cell appropriately achieved extended morphology by the filopodia attaching to the surface of the nanofibrous mats. When the diameter changed from 90nm to 240nm, the A549 cell was correspondingly express varied EMT related genes. Gene expression analysis was conducted by qPCR using three typical markers for detecting EMT: N-cadherin (NCad), Vimentin (Vim), and Fibronectin (Fib). An increasing expression pattern was observed on cell culturing on 170nm sample with respect to cell cultured on 90nm and 240nm. This result indicated the 170nm PVA/Collagen nanofibers induce A549 cells to process epithelial-mesenchymal transition more seriously than those on 90nm or 240nm.