High transfection efficiency promoted by tailor-made cationic tri-block copolymer-based nanoparticles

Nanotechnology-based techniques for hair follicle regeneration

The hair follicle (HF) is a multicellular complex structure of the skin that contains a reservoir of multipotent stem cells. Traditional hair repair methods such as drug therapies, hair transplantation, and stem cell therapy have limitations. Advances in nanotechnology offer new approaches for HF regeneration, including controlled drug release and HF-specific targeting. Until recently, embryogenesis was thought to be the only mechanism for forming hair follicles. However, in recent years, the phenomenon of wound-induced hair neogenesis (WIHN) or de novo HF regeneration has gained attention as it can occur under certain conditions in wound beds. This review covers HF-specific targeting strategies, with particular emphasis on currently used nanotechnology-based strategies for both hair loss-related diseases and HF regeneration. HF regeneration is discussed in several modalities: modulation of the hair cycle, stimulation of progenitor cells and signaling pathways, tissue engineering, WIHN, and gene therapy. The HF has been identified as an ideal target for nanotechnology-based strategies for hair regeneration. However, some regulatory challenges may delay the development of HF regeneration nanotechnology based-strategies, which will be lastly discussed.

Poly(β-amino ester)s-based nanovehicles: Structural regulation and gene delivery

The first poly(β-amino) esters (PβAEs) were synthesized more than 40 years ago. Since 2000, PβAEs have been found to have excellent biocompatibility and the capability of ferrying gene molecules. Moreover, the synthesis process of PβAEs is simple, the monomers are readily available, and the polymer structure can be tailored to meet different gene delivery needs by adjusting the monomer type, monomer ratio, reaction time, etc. Therefore, PβAEs are a promising class of non-viral gene vector materials. This review paper presents a comprehensive overview of the synthesis and correlated properties of PβAEs and summarizes the progress of each type of PβAE for gene delivery. The review focuses in particular on the rational design of PβAE structures, thoroughly discusses the correlations between intrinsic structure and effect, and then finishes with the applications and perspectives of PβAEs.

Targeted downregulation of MYC mediated by a highly efficient lactobionic acid-based glycoplex to enhance chemosensitivity in human hepatocellular carcinoma cells

The chemosensitization of tumor cells by gene therapy represents a promising strategy for hepatocellular carcinoma (HCC) treatment. In this regard, HCC-specific and highly efficient gene delivery nanocarriers are urgently needed. For this purpose, novel lactobionic acid-based gene delivery nanosystems were developed to downregulate c-MYC expression and sensitize tumor cells to low concentration of sorafenib (SF). A library of tailor-made cationic glycopolymers, based on poly(2-aminoethyl methacrylate hydrochloride) (PAMA) and poly(2-lactobionamidoethyl methacrylate) (PLAMA) were synthesized by a straightforward activators regenerated by electron transfer atom transfer radical polymerization. The nanocarriers prepared with PAMA₁₁₄-co-PLAMA₂₀ glycopolymer were the most efficient for gene delivery. These glycoplexes specifically bound to the asialoglycoprotein receptor and were internalized through the clathrin-coated pit endocytic pathway. c-MYC expression was significantly downregulated by MYC short-hairpin RNA (MYC shRNA), resulting in efficient inhibition of tumor cells proliferation and a high levels apoptosis in 2D and 3D HCC-tumor models. Moreover, c-MYC silencing increased the sensitivity of HCC cells to SF (IC₅₀ for MYC shRNA+ SF 1.9 μM compared to 6.9 μM for control shRNA + SF). Overall, the data obtained demonstrated the great potential of PAMA₁₁₄-co-PLAMA₂₀/MYC shRNA nanosystems combined with low doses of SF for the treatment of HCC.

How does the polymer architecture and position of cationic charges affect cell viability?

Polymer chemistry, composition and molar mass are factors that are known to affect cytotoxicity, however the influence of polymer architecture has not been investigated systematically. In this study the influence of the position of the cationic charges along the polymer chain on cytotoxicity was investigated while keeping constant the other polymer characteristics. Specifically, copolymers of various architectures, based on a cationic pH responsive monomer, 2-(dimethylamino)ethyl methacrylate (DMAEMA) and a non-ionic hydrophilic monomer, oligo(ethylene glycol)methyl ether methacrylate (OEGMA) were engineered and their toxicity towards a panel of cell lines investigated. Of the seven different polymer architectures examined, the block-like structures were less cytotoxic than statistical or gradient/tapered architectures. These findings will assist in developing future vectors for nucleic acid delivery.

In Vivo Hematopoietic Stem Cell Genome Editing: Perspectives and Limitations

The tremendous evolution of genome-editing tools in the last two decades has provided innovative and effective approaches for gene therapy of congenital and acquired diseases. Zinc-finger nucleases (ZFNs), transcription activator- like effector nucleases (TALENs) and CRISPR-Cas9 have been already applied by ex vivo hematopoietic stem cell (HSC) gene therapy in genetic diseases (i.e., Hemoglobinopathies, Fanconi anemia and hereditary Immunodeficiencies) as well as infectious diseases (i.e., HIV), and the recent development of CRISPR-Cas9-based systems using base and prime editors as well as epigenome editors has provided safer tools for gene therapy. The ex vivo approach for gene addition or editing of HSCs, however, is complex, invasive, technically challenging, costly and not free of toxicity. In vivo gene addition or editing promise to transform gene therapy from a highly sophisticated strategy to a "user-friendly' approach to eventually become a broadly available, highly accessible and potentially affordable treatment modality. In the present review article, based on the lessons gained by more than 3 decades of ex vivo HSC gene therapy, we discuss the concept, the tools, the progress made and the challenges to clinical translation of in vivo HSC gene editing.

Application of vinyl polymer-based materials as nucleic acids carriers in cancer therapy

Nucleic acid-based therapies have changed the paradigm of cancer treatment, where conventional treatment modalities still have several limitations in terms of efficacy and severe side effects. However, these biomolecules have a short half-life in vivo, requiring multiple administrations, resulting in severe suffering, discomfort, and poor patient compliance. In the early days of (nano)biotechnology, these problems caused concern in the medical community, but recently it has been recognized that these challenges can be overcome by developing innovative formulations. This review focuses on the use of vinyl polymer-based materials for the protection and delivery of nucleic acids in cancer. First, an overview of the properties of nucleic acids and their versatility as drugs is provided. Then, key information on the achievements to date, the most effective delivery methods, and the evaluation of functionalization approaches (stimulatory strategies) are critically discussed to highlight the importance of vinyl polymers in the new cancer treatment approaches. This article is categorized under: Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease Biology-Inspired Nanomaterials > Nucleic Acid-Based Structures.

Engineering silica-polymer hybrid nanosystems for dual drug and gene delivery

In recent years, it has been shown that a combination of different antitumour strategies involving distinct therapeutic agents, such as chemical compounds and genetic material, could result in an effective therapeutic activity that is much higher than that obtained by conventionally used individual approaches. Therefore, the main goal of this work was to develop a new hybrid nanosystem based on mesoporous silica nanoparticles and polymers to efficiently transport and deliver drug and plasmid DNA into cancer cells. Moreover, its potential to mediate a combinatorial antitumour strategy involving epirubicin and herpes simplex virus thymidine kinase/ganciclovir (HSV-TK/GCV) gene therapy was evaluated. For this purpose, various cationic polymers were assessed, including poly(β-amino ester) homopolymer, gelatine type A, gelatine type B, and poly(ethylene glycol)-b-poly(2-aminoethyl methacrylate hydrochloride) block copolymer. The obtained results show that using different polymers leads to nanosystems with different physicochemical properties and, consequently, different biological activities. The best formulation was obtained for hybrid nanosystems coated with PEG-b-PAMA. They demonstrated the ability to cotransport and codeliver an anticancer drug and plasmid DNA and effectively mediate the combined antitumour strategy in 2D and 3D tumour cell culture models. In summary, we developed a novel silica- and polymer-based nanosystem able to mediate a dual chemotherapeutic and suicide gene therapy strategy with a much higher therapeutic effect than that obtained through the use of individual approaches, showing its potential for cancer treatment.

Poly (β amino esters) copolymers: Novel potential vectors for delivery of genes and related therapeutics

The unique properties of polymers have performed an essential contribution to the drug delivery system by providing an outstanding platform for the delivery of macromolecules and genes. However, the block copolymers have been the subject of many recently published works whose results have demonstrated excellent performance in drug targeting. Poly(β-amino esters) (PβAEs) copolymers are the synthetic cationic polymers that are tailored by chemically joining PβAEs with other additives to demonstrate extraordinary efficiency in designing pre-defined and pre-programmed nanostructures, site-specific delivery, andovercoming the distinct cellular barriers. Different compositional and structural libraries could be generated by combinatorial chemistry and by the addition of various novel functional additives that fulfill the multiple requirements of targeted delivery. These intriguing attributes allow PβAE-copolymers to have customized therapeutic functions such as excellent encapsulation capacity, high stability, and stimuli-responsive release. Here, we give an overview of PβAE copolymers-based formulations along with focusing on most notable improvements such as structural modifications, bio-conjugations, and stimuli-responsive approaches, for safe and effective nucleic acids delivery.

A novel method for DNA delivery into bacteria using cationic copolymers

Amphiphilic copolymers have a wide variety of medical and biotechnological applications, including DNA transfection in eukaryotic cells. Still, no polymer-primed transfection of prokaryotic cells has been described. The reversible addition-fragmentation chain transfer (RAFT) polymer synthesis technique and the reversible deactivation radical polymerization variants allow the design of polymers with well-controlled molar mass, morphology, and hydrophilicity/hydrophobicity ratios. RAFT was used to synthesize two amphiphilic copolymers containing different ratios of the amphiphilic poly[2-(dimethyl-amino) ethyl methacrylate] and the hydrophobic poly [methyl methacrylate]. These copolymers bound to pUC-19 DNA and successfully transfected non-competent Escherichia coli DH5α, with transformation efficiency in the range of 103 colony-forming units per µg of plasmid DNA. These results demonstrate prokaryote transformation using polymers with controlled amphiphilic/hydrophobic ratios.

Complexation design of cationized gelatin and molecular beacon to visualize intracellular mRNA

The objective of this study is to prepare cationized gelatin-molecular beacon (MB) complexes for the visualization of intracellular messenger RNA (mRNA). The complexes were prepared from cationized gelatins with different extents of cationization and different mixing ratios of MB to cationized gelatin. The apparent size of complexes was almost similar, while the zeta potential was different among the complexes. Irrespective of the preparation conditions, the complexes had a sequence specificity against the target oligonucleotides in hybridization. The cytotoxicity and the amount of complexes internalized into cells increased with an increase in the cationization extent and the concentration of cationized gelatin. After the incubation with complexes prepared from cationized gelatin with the highest extent of cationization and at mixing ratios of 10 and 20 pmole MB/μg cationized gelatin, a high fluorescent intensity was detected. On the other hand, the complex prepared with the mixing ratio at 20 pmole/μg did not show any cytotoxicity. The complex was the most effective to visualize the glyceraldehyde-3-phosphate dehydrogenase (GAPDH) mRNA endogenously present. In addition, even for enhanced green fluorescent protein (EGFP) mRNA exogenously transfected, the complex permitted to effectively detect it as well. It is concluded that both the endogenous and exogenous mRNA can be visualized in living cells by use of cationized gelatin-MB complexes designed.

Silica-Based Gene Delivery Systems: From Design to Therapeutic Applications

Advances in gene therapy have been foreshadowing its potential for the treatment of a vast range of diseases involving genetic malfunctioning. However, its therapeutic efficiency and successful outcome are highly dependent on the development of the ideal gene delivery system. On that matter, silica-based vectors have diverted some attention from viral and other types of non-viral vectors due to their increased safety, easily modifiable structure and surface, high stability, and cost-effectiveness. The versatility of silane chemistry and the combination of silica with other materials, such as polymers, lipids, or inorganic particles, has resulted in the development of carriers with great loading capacities, ability to effectively protect and bind genetic material, targeted delivery, and stimuli-responsive release of cargos. Promising results have been obtained both in vitro and in vivo using these nanosystems as multifunctional platforms in different potential therapeutic areas, such as cancer or brain therapies, sometimes combined with imaging functions. Herein, the current advances in silica-based systems designed for gene therapy are reviewed, including their main properties, fabrication methods, surface modifications, and potential therapeutic applications.

Enhancement of Liposomal Plasmid DNA and siRNA Delivery by Itraconazole through Intracellular Cholesterol Accumulation

PURPOSE

Efficient and safe vehicle that can enhance gene transfer is still needed. Since intracellular cholesterol is known to have an important role in gene delivery and itraconazole alters intracellular cholesterol trafficking, we investigated the effect of itraconazole on pDNA and siRNA delivery.

METHODS

The pDNA and Bcl2 siRNA transfection efficiency was measured by luciferase assay and cytotoxicity. Cellular cholesterol was observed using filipin staining, and intracellular uptake was analyzed by flow cytometry. Lipoplex localization was observed by fluorescent labeling of DNA and lysosome after treatment of itraconazole or co-treatment of itraconazole and bafilomycin A1.

RESULTS

Itraconazole enhanced the transfection efficiency of pDNA and siRNA compared to that of control through the accumulation of cholesterol. Bafilomycin A1 diminished the effect of itraconazole on gene delivery and the increment of cholesterol. Itraconazole did not increase the cellular uptake of lipoplex, but increased free pDNA during the endosome-lysosome pathway was observed during the endosome-lysosome pathway. Treating cells with both imipramine and itraconazole caused an additive effect in pDNA and siRNA delivery.

CONCLUSIONS

Itraconazole enhanced gene delivery of pDNA and siRNA, and it can be used to potentiate nucleic acid therapeutics.

3-Hydroxyhexanoate-based polycationic nanoparticle system for delivering reprogramming factors

Aim: In this study, we aimed to develop a polycationic non-viral carrier for the delivery of the reprogramming factors to the L929 fibroblast cell.Methods: We have prepared (3-hydroxybutyrate-co-3-hydroxyhexanoate) PHBHHx-based nanoparticles with the solvent diffusion method. Cytotoxicity of PXNs was determined via MTT assay. Transfection efficiency was evaluated via screening GFP expression by fluorescence microscopy. The expression of reprogramming factors (Oct4, Klf4, and Sox2) was determined by RT-qPCR.Results: PXNs with 32.9 ± 0.41 mV zeta potential and 177.6 ± 0.80 nm size were used for transfection of L929 Fbroblast cells. The percentage of cell viability of PXN were between 91.8%(±2.9) and 42.1%(±1.3). The transfection efficiency was found as 71.6%(±3,5). According to RT-qPCR data, the rate of transfection factors was significantly increased after the 11th cycle compared to non-transfected cells. Based on these results, it can be concluded that newly developed PXN is thought to be an effective tool for reprogramming cells.

Poly(ethylene glycol)- block-poly(2-aminoethyl methacrylate hydrochloride)-Based Polyplexes as Serum-Tolerant Nanosystems for Enhanced Gene Delivery

Incorporation of poly(ethylene glycol) (PEG) into polyplexes has been used as a promising approach to enhance their stability and reduce unwanted interactions with biomolecules. However, this strategy generally has a negative influence on cellular uptake and, consequently, on transfection of target cells. In this work, we explore the effect of PEGylation on biological and physicochemical properties of poly(2-aminoethyl methacrylate) (PAMA)-based polyplexes. For this purpose, different tailor-made PEG- b-PAMA block copolymers, and the respective homopolymers, were synthesized using the controlled/"living" radical polymerization method based on activators regenerated by electron transfer atom transfer radical polymerization. The obtained data show that PEG- b-PAMA-based polyplexes exhibited a much better transfection activity/cytotoxicity relationship than the corresponding non-PEGylated nanocarriers. The best formulation, prepared with the largest block copolymer (PEG₄₅- b-PAMA₁₆₈) at a 25:1 N/P ratio, presented a 350-fold higher transfection activity in the presence of serum than that obtained with polyplexes generated with the gold standard bPEI. This higher transfection activity was associated to an improved capability to overcome the intracellular barriers, namely the release from the endolysosomal pathway and the vector unpacking and consequent DNA release from the nanosystem inside cells. Moreover, these nanocarriers exhibit suitable physicochemical properties for gene delivery, namely reduced sizes, high DNA protection, and colloidal stability. Overall, these findings demonstrate the high potential of the PEG₄₅- b-PAMA₁₆₈ block copolymer as a gene delivery system.

Optimization of Chitosan-α-casein Nanoparticles for Improved Gene Delivery: Characterization, Stability, and Transfection Efficiency

Among non-viral vectors, the cationic polymer chitosan has gained attention as a gene delivery system. We hypothesized that the addition of casein into the nanoparticle's structure would facilitate a proper gene transfer. The work herein presented aimed to optimize the production method of chitosan-casein nanoparticles (ChiCas NPs) and to test their ability as a gene delivery system. ChiCas NPs formulation optimization was carried out by analyzing several characteristics such as NP size, zeta potential, and chitosan and casein incorporation efficacy. The best formulation developed presented small and homogenous particle size (around 335 nm) and positive zeta potential (≈ + 38 mV), and showed to be stable for 34 weeks both, at 4°C and 20°C. The particles were further used to entrap or to adsorb DNA and form NPs-DNA complexes. In vitro transfection studies, carried out in COS-7 cells, suggested a low transfection efficiency of the different NPs:DNA ratios tested, comparatively to the positive control. Nonetheless, we could observe that the complexes with larger sizes presented better transfection results than those with smaller diameters. To conclude, ChiCas NPs have great technological potential since the preparation process is very simple, and the DNA incorporation efficacy is very high and shows to be physically very stable. The NPs:DNA ratio still needs to be optimized with the aim of achieving better transfection results and being able to anticipate a high gene expression on DNA-based vaccination studies.

Zinc ion coordination significantly improved the transfection efficiency of low molecular weight polyethylenimine

A zinc ion coordination-contained polycationic gene delivery system.

Non-viral gene delivery systems for tissue repair and regeneration

Critical tissue defects frequently result from trauma, burns, chronic wounds and/or surgery. The ideal treatment for such tissue loss is autografting, but donor sites are often limited. Tissue engineering (TE) is an inspiring alternative for tissue repair and regeneration (TRR). One of the current state-of-the-art methods for TRR is gene therapy. Non-viral gene delivery systems (nVGDS) have great potential for TE and have several advantages over viral delivery including lower immunogenicity and toxicity, better cell specificity, better modifiability, and higher productivity. However, there is no ideal nVGDS for TRR, hence, there is widespread research to improve their properties. This review introduces the basic principles and key aspects of commonly-used nVGDSs. We focus on recent advances in their applications, current challenges, and future directions.