Novel glycol chitosan-based polymeric gene carrier synthesized by a Michael addition reaction with low molecular weight polyethylenimine

Polyethylenimine (PEI) in gene therapy: Current status and clinical applications

Polyethlyenimine (PEI) was introduced 1995 as a cationic polymer for nucleic acid delivery. PEI and its derivatives are extensively used in basic research and as reference formulations in the field of polymer-based gene delivery. Despite its widespread use, the number of clinical applications to date is limited. Thus, this review aims to consolidate the past applications of PEI in DNA delivery, elucidate the obstacles that hinder its transition to clinical use, and highlight potential prospects for novel iterations of PEI derivatives. The present review article is divided into three sections. The first section examines the mechanism of action employed by PEI, examining fundamental aspects of cellular delivery including uptake mechanisms, release from endosomes, and transport into the cell nucleus, along with potential strategies for enhancing these delivery phases. Moreover, an in-depth analysis is conducted concerning the mechanism underlying cellular toxicity, accompanied with approaches to overcome this major challenge. The second part is devoted to the in vivo performance of PEI and its application in various therapeutic indications. While systemic administration has proven to be challenging, alternative localized delivery routes hold promise, such as treatment of solid tumors, application as a vaccine, or serving as a therapeutic agent for pulmonary delivery. In the last section, the outcome of completed and ongoing clinical trials is summarized. Finally, an expert opinion is provided on the potential of PEI and its future applications. PEI-based formulations for nucleic acid delivery have a promising potential, it will be an important task for the years to come to introduce innovations that address PEI-associated shortcomings by introducing well-designed PEI formulations in combination with an appropriate route of administration.

Carboxymethyl chitosan prolongs adenovirus-mediated expression of IL-10 and ameliorates hepatic fibrosis in a mouse model

Effective and safe liver-directed gene therapy has great promise in treating a broad range of liver diseases. While adenoviral (Ad) vectors have been widely used for efficacious in vivo gene delivery, their translational utilities are severely limited due to the short duration of transgene expression and solicitation of host immune response. Used as a promising polymeric vehicle for drug release and nucleic acid delivery, carboxymethyl chitosan (CMC) is biocompatible, biodegradable, anti-microbial, inexpensive, and easy accessible. Here, by exploiting its biocompatibility, controlled release capability and anti-inflammatory activity, we investigated whether CMC can overcome the shortcomings of Ad-mediated gene delivery, hence improving the prospect of Ad applications in gene therapy. We demonstrated that in the presence of optimal concentrations of CMC, Ad-mediated transgene expression lasted up to 50 days after subcutaneous injection, and at least 7 days after intrahepatic injection. Histologic evaluation and immunohistochemical analysis revealed that CMC effectively alleviated Ad-induced host immune response. In our proof-of-principle experiment using the CCl4-induced experimental mouse model of chronic liver damage, we demonstrated that repeated intrahepatic administrations of Ad-IL10 mixed with CMC effectively mitigated the development of hepatic fibrosis. Collectively, these results indicate that CMC can improve the prospect of Ad-mediated gene therapy by diminishing the host immune response while allowing readministration and sustained transgene expression.

Nanoparticles as Drug Delivery Systems of RNAi in Cancer Therapy

RNA interference (RNAi) can mediate gene-silencing by knocking down the expression of a target gene via cellular machinery with much higher efficiency in contrast to other antisense-based approaches which represents an emerging therapeutic strategy for combating cancer. Distinct characters of nanoparticles, such as distinctive size, are fundamental for the efficient delivery of RNAi therapeutics, allowing for higher targeting and safety. In this review, we present the mechanism of RNAi and briefly describe the hurdles and concerns of RNAi as a cancer treatment approach in systemic delivery. Furthermore, the current nanovectors for effective tumor delivery of RNAi therapeutics are classified, and the characteristics of different nanocarriers are summarized.

Triphenylphosphonium-conjugated glycol chitosan microspheres for mitochondria-targeted drug delivery

To develop an efficient vector for mitochondria-targeted drug delivery, we synthesized triphenylphosphonium (TPP)-modified glycol chitosan polymeric microspheres that had a unique chemical structure with both lipophilic phenyl groups and cationic phosphonium. Notably, TPP can easily pass through the phospholipid bilayer of mitochondria, thereby resulting in specific accumulation of a combined drug molecule in the mitochondria due to the membrane potential between TPP and its membrane. Therefore, TPP has been widely used as a mitochondria-targeting moiety. Triphenylphosphonium-glycol chitosan derivatives (GC-TPP and GME-TPP) with two different degrees of substitution (11% and 36%) were prepared by amidation and Michael addition. The chemical structures of GC-TPP and GME-TPP were characterized by ¹H nuclear magnetic resonance and Fourier-transform infrared spectroscopy, and their sizes were measured via field emission scanning electron microscopy and dynamic light scattering. Cellular uptake through flow cytometric analysis and confocal microscopy confirmed that both GC-TPP and GME-TPP were well introduced into cells, targeting the mitochondria. In addition, cytotoxicity testing of the most common cell lines, such as HEK293, HeLa, NIH3T3, and HepG2, indicated the absence of polymer toxicity. To evaluate the carrier effectiveness of TPP for drug delivery, doxorubicin (Dox) was used as an anticancer drug. Confocal microscopy images showed that Dox-loaded GME-TPP accumulated inside cells more than Dox-loaded GC-TPP. The anticancer effects of Dox were also determined by MTT assay, apoptosis/necrosis assay, and three-dimensional spheroids. In summary, the results indicate that GC-TPP and GME-TPP microspheres possess great potential as effective drug delivery carriers.

Chitosan-Based Drug Delivery System: Applications in Fish Biotechnology

Chitosan is increasingly used for safe nucleic acid delivery in gene therapy studies, due to well-known properties such as bioadhesion, low toxicity, biodegradability and biocompatibility. Furthermore, chitosan derivatization can be easily performed to improve the solubility and stability of chitosan-nucleic acid polyplexes, and enhance efficient target cell drug delivery, cell uptake, intracellular endosomal escape, unpacking and nuclear import of expression plasmids. As in other fields, chitosan is a promising drug delivery vector with great potential for the fish farming industry. This review highlights state-of-the-art assays using chitosan-based methodologies for delivering nucleic acids into cells, and focuses attention on recent advances in chitosan-mediated gene delivery for fish biotechnology applications. The efficiency of chitosan for gene therapy studies in fish biotechnology is discussed in fields such as fish vaccination against bacterial and viral infection, control of gonadal development and gene overexpression and silencing for overcoming metabolic limitations, such as dependence on protein-rich diets and the low glucose tolerance of farmed fish. Finally, challenges and perspectives on the future developments of chitosan-based gene delivery in fish are also discussed.

Polyethylenimine-dextran-coated magnetic nanoparticles loaded with miR-302b suppress osteosarcoma in vitro and in vivo

Aim: We attempted to synthesize a magnetic gene carrier with poly(ethylenimine), dextran and iron oxide nanoparticles (PDIs) for miR-302b transfection in vitro and in vivo. Materials & methods: The nanoparticles were characterized for hydrodynamic properties, ζ potential and DNA-binding ability, evaluated by transmission electron microscopy. Cellular internalization, magnetofection efficiency and anti-osteosarcoma effects were investigated in osteosarcoma (OS) cells and OS-bearing nude mice. Results: PDIs were successfully prepared and showed mild cytotoxicity. A magnetic field efficiently enabled transport of PDI/pmiR302b to OS cells in OS-bearing nude mice, exerting the anti-osteosarcoma effect of miR-302b at the tumor site. The inhibitory effect of miR-302b on osteosarcoma-bearing nude mice may be attributed to regulation of the Hippo pathway through YOD1. Conclusion: Low-cytotoxic PDIs have potential applications as a magnetic transport carrier for future osteosarcoma treatment.

Ligand targeting and peptide functionalized polymers as non-viral carriers for gene therapy

Ligand targeting and peptide functionalized polymers serve as gene carriers for efficient gene delivery.

Glycol Chitosan: A Water-Soluble Polymer for Cell Imaging and Drug Delivery

Glycol chitosan (GC), a water-soluble chitosan derivative with hydrophilic ethylene glycol branches, has both hydrophobic segments for the encapsulation of various drugs and reactive functional groups for facile chemical modifications. Over the past two decades, a variety of molecules have been physically encapsulated within or chemically conjugated with GC and its derivatives to construct a wide range of functional biomaterials. This review summarizes the recent advances of GC-based materials in cell surface labeling, multimodal tumor imaging, and encapsulation and delivery of drugs (including chemotherapeutics, photosensitizers, nucleic acids, and antimicrobial agents) for combating cancers and microbial infections. Besides, different strategies for GC modifications are also highlighted with the aim to shed light on how to endow GC and its derivatives with desirable properties for therapeutic purposes. In addition, we discuss both the promises and challenges of the GC-derived biomaterials.

Optimization of chitosan nanoparticles as an anti-HIV siRNA delivery vehicle

Chitosan has emerged as a promising polysaccharide for gene/siRNA delivery. However, additional works will be required to modify chitosan nanoparticles. In the present study, chitosan nanoparticles were well modified to introduce anti-HIV siRNA into two mammalian cell lines, macrophage RAW 264.7 and HEK293. We first generated two stable cell lines expressing HIV-1 Tat, and then designed and generated an efficient anti-tat siRNA. The nanoparticles were prepared by using different concentrations of chitosan, polyethylenimine (PEI) and carboxymethyl dextran (CMD) in various formulations and then their physicochemical and biological properties were investigated. The results demonstrated that the combination of chitosan with both CMD and PEI significantly improved both cell viability and siRNA delivery. The modified chitosan nanoparticles (ChNPs) at the N:P ratio of 50 were approximately uniform spheres with sizes ranging from 100 to 150 nm and a positive zeta potential of about +22 mV. In both cell types, the nanoparticles noticeably increased siRNA delivery efficiency with no significant cytotoxicity or apoptosis-inducing effects compared to the control cells. In addition, the nanoparticles significantly reduced the RNA and protein expression of HIV-1 tat in both stable cells. These data show that the nanoparticle formulation could potentially be used in gene therapy, especially against HIV infection.

Comparison of Rheological, Drug Release, and Mucoadhesive Characteristics upon Storage between Hydrogels with Unmodified or Beta-Glycerophosphate-Crosslinked Chitosan

The physicochemical characteristics of beta-glycerophosphate-crosslinked chitosan hydrogels were investigated upon long-term storage at ambient, accelerated, and refrigerated conditions and compared to unmodified chitosan formulations. Additionally, the impact of chitosan modification on the ex vivo mucoadhesive performance in contact with porcine vaginal mucosa and on the drug release profile from hydrogels was evaluated. Viscosity and mechanical properties of formulations with unmodified chitosan decreased significantly upon storage regardless of tested conditions as a result of hydrolytic depolymerization. Introduction of ion crosslinker exerted stabilizing effect on physicochemical performance of chitosan hydrogels but only upon storage at refrigerated conditions. Beta-glycerophosphate-modified chitosan formulations preserved organoleptic, rheological behavior, and hydrogel structure up to 3-month storage at 4 ± 2°C. Viscosity variations upon storage influenced markedly mucoadhesive properties and drug release rate from hydrogels.

Recent advances in smart biotechnology: Hydrogels and nanocarriers for tailored bioactive molecules depot

Over the past ten years, the global biopharmaceutical market has remarkably grown, with ten over the top twenty worldwide high performance medical treatment sales being biologics. Thus, biotech R&D (research and development) sector is becoming a key leading branch, with expanding revenues. Biotechnology offers considerable advantages compared to traditional therapeutic approaches, such as reducing side effects, specific treatments, higher patient compliance and therefore more effective treatments leading to lower healthcare costs. Within this sector, smart nanotechnology and colloidal self-assembling systems represent pivotal tools able to modulate the delivery of therapeutics. A comprehensive understanding of the processes involved in the self-assembly of the colloidal structures discussed therein is essential for the development of relevant biomedical applications. In this review we report the most promising and best performing platforms for specific classes of bioactive molecules and related target, spanning from siRNAs, gene/plasmids, proteins/growth factors, small synthetic therapeutics and bioimaging probes.

Versatile Chemical Derivatizations to Design Glycol Chitosan-Based Drug Carriers

Glycol chitosan (GC) and its derivatives have been extensively investigated as safe and effective drug delivery carriers because of their unique physiochemical and biological properties. The reactive functional groups such as the amine and hydroxyl groups on the GC backbone allow for easy chemical modification with various chemical compounds (e.g., hydrophobic molecules, crosslinkers, and acid-sensitive and labile molecules), and the versatility in chemical modifications enables production of a wide range of GC-based drug carriers. This review summarizes the versatile chemical modification methods that can be used to design GC-based drug carriers and describes their recent applications in disease therapy.

Preparation, characterization, and transfection efficiency of low molecular weight polyethylenimine-based nanoparticles for delivery of the plasmid encoding CD200 gene

Various strategies have been utilized to improve both gene transfer efficiency and cell-induced toxicity of polyethylenimine (PEI), the most extensively investigated cationic polymeric vector. In this study, we sought to enhance transfection efficiency of low molecular weight PEI (LMW PEI) while maintaining its low toxicity by cross-linking LMW PEI via succinic acid linker. These modifications were designed to improve the hydrophilic–hydrophobic balance of the polymer, by enhancing the buffering capacity and maintaining low cytotoxic effects of the final conjugate. Decreased expression of CD200 in the central nervous system has been considered as one of the proposed mechanisms associated with neuroinflammation in multiple sclerosis; therefore, we selected plasmid-encoding CD200 gene for transfection using the modified PEI derivatives. Dynamic light scattering experiments demonstrated that the modified PEIs were able to condense plasmid DNA and form polyplexes with a size of approximately 130 nm. The highest level of CD200 expression was achieved at a carrier to plasmid ratio of 8, where the expression level was increased by 1.5 fold in the SH-SY5Y cell line, an in vitro model of neurodegenerative disorders. Furthermore, the results of in vivo imaging of the LMW PEI-based nanoparticles in the mouse model of multiple sclerosis revealed that fluorescently labeled plasmid encoding CD200 was distributed from the injection site to various tissues and organs including lymph nodes, liver, brain, and finally, kidneys. The nanoparticles also showed the ability to cross the blood–brain barrier and enter the periventricular area.

Bioreducible, hydrolytically degradable and targeting polymers for gene delivery

Recently, synthetic gene carriers have been intensively developed owing to their promising application in gene therapy and considered as a suitable alternative to viral vectors because of several benefits. But cationic polymers still face some problems like low transfection efficiency, cytotoxicity, and poor cell recognition and internalization. The emerging engineered and smart polymers can respond to some changes in the biological environment like pH change, ionic strength change and redox potential, which is beneficial for cellular uptake. Redox-sensitive disulfide based and hydrolytically degradable cationic polymers serve as gene carriers with excellent transfection efficiency and good biocompatibility owing to degradation in the cytoplasm. Additionally, biodegradable polymeric micelles with cell-targeting function are recently emerging gene carriers, especially for the transfection of endothelial cells. In this review, some strategies for gene carriers based on these bioreducible and hydrolytically degradable polymers will be illustrated.