Automated in-line mixing system for large scale production of chitosan-based polyplexes

A review of chitosan in gene therapy: Developments and challenges

Gene therapy, as a revolutionary treatment, has been gaining more and more attention. The key to gene therapy is the selection of suitable vectors for protection of exogenous nucleic acid molecules and enabling their specific release in target cells. While viral vectors have been widely used in researches, non-viral vectors are receiving more attention due to its advantages. Chitosan (CS) has been widely used as non-viral organic gene carrier because of its good biocompatibility and its ability to load large amounts of nucleic acids. This paper summarizes and evaluates the potential of chitosan and its derivatives as gene delivery vector materials, along with factors influencing transfection efficiency, performance evaluation, ways to optimize infectious efficiency, and the current main research development directions. Additionally, it provides an outlook on its future prospects.

Fundamental and Practical Aspects in the Formulation of Colloidal Polyelectrolyte Complexes of Chitosan and siRNA

The formation of electrostatic interactions between polyanionic siRNA and polycations gives an easy access to the formation of colloidal particles capable of delivering siRNA in vitro or in vivo. Among the polycations used for siRNA delivery, chitosan occupies a special place due to its unique physicochemical and biological properties. In this chapter we describe the fundamental and practical aspects of the formation of colloidal complexes between chitosan and siRNA. The basis of the electrostatic complexation between oppositely charged polyelectrolytes is first introduced with a focus on the specific conditions to obtain stable colloid complex particles. Subsequent, the properties that make chitosan so special are described. In a third part, the main parameters influencing the colloidal properties and stability of siRNA/chitosan complexes are reviewed with emphasis on some practical aspects to consider in the preparation of complexes.

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.

Continuous production of antibacterial carboxymethyl chitosan-zinc supramolecular hydrogel fiber using a double-syringe injection device

Large-scale production of an antibacterial hydrogel is of critical importance for its practical application in biomedical field. In this regard, herein we report on the construction of a double-syringe injection device by using all the commercial parts and its use for continuous production of carboxymethyl chitosan-zinc (CMCh-Zn) supramolecular hydrogel fiber. The resultant CMCh-Zn hydrogel fibers exhibit good stretchability and knittability. The Zn loading into the hydrogel fibers can be easily controlled by adjusting the concentration of Zn²⁺ solution. Scanning electron microscope measurements indicate that the CMCh-Zn hydrogel fibers have a relatively smooth and thin skin layer, as well as, a 3-dimensional interconnected microporous interior architecture. Antibacterial activities of the CMCh-Zn hydrogel fibers against both Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli are also investigated. The results show that the intrinsic blue fluorescence of the as-prepared CMCh-Zn hydrogel fibers can be employed as optical indicator of their antibacterial effectiveness.

Efficiency of Chitosan/Hyaluronan-Based mRNA Delivery Systems In Vitro: Influence of Composition and Structure

Messenger RNA (mRNA)-containing nanoparticles were produced by electrostatic complexation with a library of pharmaceutical grade chitosans with different degrees of deacetylation and hyaluronic acids (HAs) (native vs. sulfated). Polymer length (Mn), HA degree of sulfation (DS), and amine to phosphate to carboxyl + sulfate (from HA) ratio (N:P:C) were controlled. In vitro transfections were performed in the presence/absence of trehalose and at different pH. Particle size and ζ-potential were correlated with transfection efficiency. Polymer length and charge densities (degree of deacetylation, degree of sulfation) of both HA and chitosan had a direct influence on transfection efficiency through modulation of avidity to mRNA. N:P:C ratio, trehalose, mixing concentration, and nucleic acid dose influenced transfection efficiency with optimized formulations reaching ∼60%-65% transfection efficiency relative to commercially available lipid control with no apparent toxicity for transfection at slightly acidic pH 6.5.

Bioaerogels: Synthesis approaches, cellular uptake, and the biomedical applications

Aerogels are a class of porous structures with promising physicochemical properties. Among aerogels with various origins, polysaccharide aerogels (e.g., cellulose, chitosan, alginate, starch, agar, and so on) have received more attention. This group of aerogels can be classified as bioaerogels, which are originated from natural, semi-synthetic, and synthetic sources with exceptional biomedical applications. This review focuses on bioaerogels from the viewpoints of synthesis approaches, cellular uptake, toxicity, biodegradability, and the biomedical application perspectives.

In vivo therapeutic efficacy of TNFα silencing by folate-PEG-chitosan-DEAE/siRNA nanoparticles in arthritic mice

BACKGROUND

Tumor necrosis factor-alpha (TNFα), a pro-inflammatory cytokine, has been shown to play a role in the pathophysiology of rheumatoid arthritis. Silencing TNFα expression with small interfering RNA (siRNA) is a promising approach to treatment of the condition.

METHODS

Towards this end, our team has developed a modified chitosan (CH) nanocarrier, deploying folic acid, diethylethylamine (DEAE) and polyethylene glycol (PEG) (folate-PEG-CH-DEAE15). The gene carrier protects siRNA against nuclease destruction, its ligands facilitate siRNA uptake via cell surface receptors, and it provides improved solubility at neutral pH with transport of its load into target cells. In the present study, nanoparticles were prepared with siRNA-TNFα, DEAE, and folic acid-CH derivative. Nanoparticle size and zeta potential were verified by dynamic light scattering. Their TNFα-knockdown effects were tested in a murine collagen antibody-induced arthritis model. TNFα expression was examined along with measurements of various cartilage and bone turnover markers by performing histology and microcomputed tomography analysis.

RESULTS

We demonstrated that folate-PEG-CH-DEAE15/siRNA nanoparticles did not alter cell viability, and significantly decreased inflammation, as demonstrated by improved clinical scores and lower TNFα protein concentrations in target tissues. This siRNA nanocarrier also decreased articular cartilage destruction and bone loss.

CONCLUSION

The results indicate that folate-PEG-CH-DEAE15 nanoparticles are a safe and effective platform for nonviral gene delivery of siRNA, and their potential clinical applications warrant further investigation.

siRNA Delivery with Chitosan: Influence of Chitosan Molecular Weight, Degree of Deacetylation, and Amine to Phosphate Ratio on in Vitro Silencing Efficiency, Hemocompatibility, Biodistribution, and in Vivo Efficacy

Chitosan (CS) shows in vitro and in vivo efficacy for siRNA delivery but with contradictory findings for incompletely characterized systems. For understanding which parameters produce effective delivery, a library of precisely characterized chitosans was produced at different degrees of deacetylation (DDAs) and average molecular weights (M_n). Encapsulation and transfection efficiencies were characterized in vitro. Formulations were selected to examine the influence of M_n and N:P ratio on nanoparticle uptake, metabolic activity, genotoxicity, and in vitro transfection. Hemocompatibility and in vivo biodistribution were then investigated for different M_n, N:P ratios, and doses. Nanoparticle uptake and gene silencing correlated with increased surface charge, which was obtained at high DDA and high M_n. A minimum polymer length of ∼60-70 monomers (∼10 kDa) was required for stability and knockdown. In vitro knockdown was equivalent to lipid control with no metabolic or genotoxicity. An inhibitory effect of serum on biological performance was dependent on DDA, M_n, and N:P. In vivo biodistribution in mice show accumulation of nanoparticles in kidney with 40-50% functional knockdown.

Co-delivery of hypoxia inducible factor-1α small interfering RNA and 5-fluorouracil to overcome drug resistance in gastric cancer SGC-7901 cells

BACKGROUND

Drug resistance cancer cells have become a major problem in chemotherapy. To solve this problem, the co-delivery of small interefering RNA (siRNA) and 5-fluorouracil chitosan nanoparticles was employed, aiming to reverse the multidrug resistance of gastric cancer SGC-7901 cells in vitro.

METHODS

Chitosan nanoparticles were prepared using an ionic gel method. siRNA nanoparticles were characterized by gel retardation assays. Particle size and zeta potential were measured to confirm nanoparticle formation. The transfection efficiency of siRNA was determined by flow cytometry and high-content screening. Western blotting and a quantitative real-time-polymerase chain reaction were used to assess the silencing efficiency of siRNA. Accumulation and efflux experiments for rhodamine-123, cell migration experiments, cell sensitivity analyses and cell apoptosis assays were used to determine whether siRNA could reverse multidrug resistance. A systemic toxicity assay was used to evaluate the safety of nanoparticles.

RESULTS

Compared to naked siRNA, the co-delivery system demonstrated a higher transfection efficiency and gene silencing efficiency by inhibiting the efflux of P-glycoprotein and cell migration. Moreover, the combination treatment with siRNA and 5-fluorouracil co-delivered by chitosan nanoparticles can increase the sensitivity of drug resistance cells and cell apoptosis. Finally, the safety of nanoparticles was evaluated in vivo and the results obtained suggested that nanoparticles did not have any obvious toxicity.

CONCLUSIONS

Co-delivery of siRNA and 5-fluorouracil chitosan nanoparticles is an attractive strategy for overcoming multidrug resistance.