Factors influencing the transfection efficiency and cellular uptake mechanisms of Pluronic P123-modified polypropyleneimine/pDNA polyplexes in multidrug resistant breast cancer cells

Microfluidic Transfection System and Temperature Strongly Influence the Efficiency of Transient Transfection

For the process of transient transfection (TTF), DNA is often transported into the cells using polyplexes. The polyplex uptake and the subsequent transient expression of the gene of interest are of great importance for a successful transfection. In this study, we investigated a 3D-printed microfluidic system designed to facilitate direct TTF for suspension of CHO-K1 cells. The results demonstrate that this system achieves significantly better results than the manual approach. Furthermore, the effect of both post-transfection incubation time (t) and temperature (T) on polyplex uptake was explored in light of the membrane phase transitions. Attention was paid to obtaining the highest possible transfection efficiency (TFE), viability (V), and viable cell concentration (VCC). Our results show that transfection output measured as product of VCC and TFE is optimal for t = 1 h at T = 22 °C. Moreover, post-transfection incubation at T = 22 °C with short periods of increased T at T = 40 °C were observed to further increase the output. Finally, we found that around T = 19 °C, the TFE increases strongly. This is the membrane phase transition T of CHO-K1 cells, and those results therefore suggest a correlation between membrane order and permeability (and in turn, TFE).

Magnetic graphene oxide nanoflakes for dual RNA interfering delivery and gene knockdown in prostate and liver cancers

The development of synthetic carriers for small interfering RNA (siRNA) and plasmids is crucial for effective gene therapy. In this study, we synthesized magnetic graphene oxide nanoflakes as carriers for siRNA delivery, with the goal of knockdown specific genes such as the green fluorescence protein (GFP). Our approach combined magnetically reduced graphene oxide with polyethylenimine (PEI) crosslinked to its surface using carbonyl diimidazole. To evaluate the adsorption capacity of the PEI-modified nanocomposite, we investigated its ability to bind two types of nucleic acids: short-hairpin (sh)RNA plasmids and siRNA targeting GFP. The nanocomposite exhibited significant adsorption, with maximum capacities of 426 ng/μg for shRNA and 71 ng/μg for siRNA, respectively. Simultaneous delivery of siRNA and shRNA using our designed nanocomposites was successfully achieved in human hepatoma and prostate cancer cells. Under magnetic guidance, the knockdown efficiencies reached 73.5 % in hepatoma cells for dual delivery of siRNA and shRNA. Our findings revealed that the nanocomplexes were internalized by the cells through a caveolae-dependent endocytosis mechanism. The demonstrated ability of the nanoflakes to efficiently transport siRNA and shRNA, with high loading capacity, controlled release, and magnetic targeting, resulted in effective GFP knockdown in vitro. These findings highlight the potential of magnetic graphene oxide nanoflakes as promising carriers for siRNA delivery and gene knockdown in therapeutic applications.

Glycopolymers Mediate Suicide Gene Therapy in ASGPR-Expressing Hepatocellular Carcinoma Cells in Tandem with Docetaxel

Cationic glycopolymers stand out as gene delivery nanosystems due to their inherent biocompatibility and high binding affinity to the asialoglycoprotein receptor (ASGPR), a target receptor overexpressed in hepatocellular carcinoma (HCC) cells. However, their synthesis procedure remains laborious and complex, with problems of solubilization and the need for protection/deprotection steps. Here, a mini-library of well-defined poly(2-aminoethyl methacrylate hydrochloride-co-poly(2-lactobionamidoethyl methacrylate) (PAMA-co-PLAMA) glycopolymers was synthesized by activators regenerated by electron transfer (ARGET) ATRP to develop an efficient gene delivery nanosystem. The glycoplexes generated had suitable physicochemical properties and showed high ASGPR specificity and high transfection efficiency. Moreover, the HSV-TK/GCV suicide gene therapy strategy, mediated by PAMA₁₄₄-co-PLAMA₁₉-based nanocarriers, resulted in high antitumor activity in 2D and 3D culture models of HCC, which was significantly enhanced by the combination with small amounts of docetaxel. Overall, our results demonstrated the potential of primary-amine polymethacrylate-containing-glycopolymers as HCC-targeted suicide gene delivery nanosystems and highlight the importance of combined strategies for HCC treatment.

Advances in the therapeutic delivery and applications of functionalized Pluronics: A critical review

Pluronic (PEO-PPO-PEO) block copolymers can form nano-sized micelles with a structure composed of a hydrophobic PPO core and hydrophilic PEO shell layer. Pluronics are U.S. Food and Drug Administration approved polymers, which are widely used for solubilization of drugs and their delivery, gene/therapeutic delivery, diagnostics, and tissue engineering applications due to their non-ionic properties, non-toxicity, micelle forming ability, excellent biocompatibility and biodegradability. Although Pluronics have been employed as drug carrier systems for several decades, numerous issues such as rapid dissolution, shorter residence time in biological media, fast clearance and weak mechanical strength have hindered their efficacy. Pluronics have been functionalized with pH-sensitive, biological-responsive moieties, antibodies, aptamers, folic acid, drugs, different nanoparticles, and photo/thermo-responsive hydrogels. These functionalization strategies enable Pluronics to act as stimuli responsive and targeted drug delivery vehicles. Moreover, Pluronics have emerged in nano-emulsion formulations and have been utilized to improve the properties of cubosomes, dendrimers and nano-sheets, including their biocompatibility and aqueous solubility. Functionalization of Pluronics results in the significant improvement of target specificity, loading capacity, biocompatibility of nanoparticles and stimuli responsive hydrogels for the promising delivery of a range of drugs. Therefore, this review presents an overview of all advancements (from the last 15 years) in functionalized Pluronics, providing a valuable tool for industry and academia in order to optimize their use in drug or therapeutic delivery, in addition to several other biomedical applications.

Tyrosine-Modification of Polypropylenimine (PPI) and Polyethylenimine (PEI) Strongly Improves Efficacy of siRNA-Mediated Gene Knockdown

The delivery of small interfering RNAs (siRNA) is an efficient method for gene silencing through the induction of RNA interference (RNAi). It critically relies, however, on efficient vehicles for siRNA formulation, for transfection in vitro as well as for their potential use in vivo. While polyethylenimines (PEIs) are among the most studied cationic polymers for nucleic acid delivery including small RNA molecules, polypropylenimines (PPIs) have been explored to a lesser extent. Previous studies have shown the benefit of the modification of small PEIs by tyrosine grafting which are featured in this paper. Additionally, we have now extended this approach towards PPIs, presenting tyrosine-modified PPIs (named PPI-Y) for the first time. In this study, we describe the marked improvement of PPI upon its tyrosine modification, leading to enhanced siRNA complexation, complex stability, siRNA delivery, knockdown efficacy and biocompatibility. Results of PPI-Y/siRNA complexes are also compared with data based on tyrosine-modified linear or branched PEIs (LPxY or PxY). Taken together, this establishes tyrosine-modified PPIs or PEIs as particularly promising polymeric systems for siRNA formulation and delivery.

Polyplexes for gene and nucleic acid delivery: Progress and bottlenecks

Gene and nucleic acid delivery constitute a huge biological challenge and several attempts have been made by research laboratories to address this issue. Cationic polymers and cationic lipids (positively charged carriers) can be utilized for the transport of these biomolecules. Polyplexes (PPs) are interpolyelectrolyte complexes which are spontaneously formed through the electrostatic condensation between nucleic acid and a cationic polymer. PPs are capable of high-density payload condensation leading to cell internalization and subsequent protection from enzymatic degradation. Most cationic polymers can cross extracellular barriers, but it is more challenging to overcome intracellular barriers (efficient disassembly and endosomal escape). In this review, the use of PPs for gene and nucleic acid delivery is discussed.

Gene delivery into Siberian sturgeon cell lines by commercial transfection reagents

The optimal transfection conditions for efficient transgene delivery into a specific cell type should be empirically determined, particularly in cases involving unusual cell types. We compared the conditions for effective introduction of transgenes into Siberian sturgeon (Acipenser baerii) cell lines by evaluating the cytotoxicity and transfection efficiency of three commercially available transfection reagents: Lipofectamine 2000, X-tremeGENE HP DNA Transfection Reagent, and GeneJuice Transfection Reagent. Plasmid vectors containing the gene encoding enhanced green fluorescent protein were mixed with each of the transfection reagents using reagent-to-plasmid ratios of 1:1, 2:1, and 4:1. Then, the complexes were used to transfect three Siberian sturgeon cell lines derived from the heart, head kidney, and gonad. Cytotoxicity and transfection efficiency were measured via flow cytometry after propidium iodide staining. No significant cytotoxicity was observed at the optimal treatment conditions in all cases, with the exception of Lipofectamine 2000-treated gonad-derived cells. Although the transfection efficiencies in A. baerii cells were generally low, X-tremeGENE HP DNA Transfection Reagent showed the highest transfection efficiency at ratios of 2:1 or 4:1, depending on the cell type. Hence, X-tremeGENE HP DNA Transfection Reagent can be used to effectively transfer foreign genes into three A. baerii cell lines.

Protein moiety in oligochitosan modified vector regulates internalization mechanism and gene delivery: Polyplex characterization, intracellular trafficking and transfection

Oligochitosan-modified proteins have gained attention as efficient non-viral vectors for gene delivery. However, little information exists if protein moieties can serve as an important role for internalization and endosome escape ability of the genetic material. To explore this issue, we designed two cationic oligochitosan-modified vectors that consist of different proteins, namely a hydrophobic plant protein (zein) and a hydrophilic animal protein (ovalbumin (OVA)) to deliver pDNA to epithelial cell line CHO-K1 and HEK 293 T. These cationic vectors were systematically characterized by molecular weight, infrared (IR) structural analysis, transmission electron microscopy (TEM) morphology, and surface charge. A remarkable impact of protein moieties was observed on physiochemical properties of the developed vectors. Oligochitosan-modified zein containing hydrophobic protein exhibited high buffering capacity and excellent DNA binding ability compared to the oligochitosan-modified OVA. The data on transfection in the presence of endocytic inhibitors indicated that the caveolae-mediated pathway (CvME) played a key role in the internalization of the zein-based polyplex. However, the OVA-based polyplex was internalized in CHO-K1 cells via CvME and in HEK 293 T cells via the lipid-mediated pathway. Moreover, oligochitosan-modified zein exhibited lower cytotoxicity, greater lysosomal escape ability, better plasmid stability, and better transfection efficiency than the oligochitosan-modified OVA. This study offers a facile procedure for the synthesis of cationic vectors and elucidates the relationship that exists between protein moieties and transfection activity, thus providing an alternative, non-viral platform for the gene delivery.

Theranostic micelles combined with multiple strategies to effectively overcome multidrug resistance

AIM

To develop precise targeting and versatile Fe₃O₄@SiO₂-P123/PTX-ZnPc nanoparticles (FSP-PTX-ZnPc NPs) to reverse paclitaxel (PTX)-induced multidrug resistance in breast cancer.

MATERIALS & METHODS

PTX and zinc (II) phthalocyanine (ZnPc) co-loaded FSP-PTX-ZnPc NPs were designed. The resulting multifunctional NPs were evaluated systematically in vitro and in vivo, and the mechanism of drug-resistance reversal was investigated.

RESULTS

The NPs enhanced drug uptake in MCF-7/PDR cells by increasing drug solubility and impairing P-glycoprotein efflux. Additionally, magnetic targeting and enhanced permeation and retention (EPR) effect enhanced drug accumulation in tumor, facilitating the chemotherapeutic and photodynamic therapy effects. Moreover, FSP-PTX-ZnPc NPs could penetrate the blood-brain barrier, a desirable trait for brain disease therapy.

CONCLUSION

The multifunctional FSP-PTX-ZnPc NPs are an effective tool for overcoming drug resistance in breast cancer.

Efficient gene delivery by oligochitosan conjugated serum albumin: Facile synthesis, polyplex stability, and transfection

Chitosan and its derivatives have shown to be potential gene carriers with biocompatiblility and safety. However, their practical delivery is far from being ideal because of the low transfection efficiency. The present work describes the potential of a natural protein, bovine serum albumin (BSA), conjugated with a natural oligosaccharide, oligochitosan (OC), as a considerable promising approach for a safe and efficient non-viral gene delivery vector. The FTIR spectra proved the effective conjugation of BSA with OC through covalent bond. The condensation ability of plasmid DNA (pDNA) with a BSA-OC biopolymer was analyzed by gel retardation assay, competition binding assay, and dynamic light scattering used to measure the nanoparticle size. In addition, the BSA-OC biopolymer showed the protection of pDNA from enzymatic degradation by DNase I and showed good stability when exposed to 50% fetal bovine serum. The transfection efficiency was evaluated in the presence of 10% serum-supplemented media or serum-free media on three kinds of mammalian cells. Our results showed that the BSA-OC biopolymer is a good non-viral vehicle for gene delivery. We investigated the parameters such as the pDNA payload, temperature, incubating duration, and biopolymer/pDNA ratio on the transfection efficiency. This hybrid vehicle had the ability to transfect 90% of cells and to maintain 80% of cell viability. The aforementioned results suggest that the facile synthesis of the BSA-OC biopolymer could overcome the cytotoxicity problem and transfection barriers during in vitro gene delivery.

Retro-inverso d-peptide-modified hyaluronic acid/bioreducible hyperbranched poly(amido amine)/pDNA core-shell ternary nanoparticles for the dual-targeted delivery of short hairpin RNA-encoding plasmids

The active targeting of gene carriers is a powerful strategy for improving tumour-specific delivery and therapy. Although numerous l-peptide ligands play significant roles in the active targeting of nanomedicine, retro-inverso d-peptides have been explored as targeting ligands due to their superior stability and bioactivity in vivo. In this study, retro-inverso d-peptide (RIF7)-modified hyaluronic acid (HA)/bioreducible hyperbranched poly(amido amine) (RHB)/plasmid DNA (pDNA) ternary nanoparticles were successfully developed using the layer-by-layer method for the CD44-positive tumour-specific delivery of short hairpin RNA (shRNA)-encoding pDNA through the combination of the Anxa1 (tumour vasculature) and CD44 (tumour cell-surface) receptors, which mediated the dual targeting. The potential of these newly designed nanoparticles was evaluated by examining the efficacy of their cellular uptake and transfection in cell monolayers, tumour spheroids, and malignant xenograft animal models. With negligible cytotoxicity, the spherical-shaped RIF7-HA/RHB/pDNA nanoparticles were the direct result of an electrostatic complex that had efficiently targeted CD44-positive tumour delivery, penetration, and cellular uptake in vitro. The nanoparticles showed excellent target-specific gene transfection even in the presence of serum. The in vivo therapeutic effect of RIF7-HA/RHB/pDNA-shRNA nanoparticle-mediated shRNA targeting of the Cyclin gene (shCyclin) was evaluated in tumour-bearing mice. The RIF7-HA/RHB/pDNA-shCyclin nanoparticles significantly increased the survival time of tumour-bearing mice and substantially reduced tumour growth due to their extremely specific tumour-targeting activity. These results suggested that the combination of HA and retro-inverso peptide RIF7 significantly increased the therapeutic effect of pDNA-shCyclin-loaded nanoparticles for CD44-positive tumours. Thus, RIF7-HA-mediated multi-target ternary gene vectors are an efficient and promising strategy for the delivery of pDNA-shRNA in the targeted treatment of malignant and metastatic cancers.

STATEMENT OF SIGNIFICANCE

Although l-peptide ligands play significant roles in the active targeting of nanomedicine, retro-inverso d-peptides have been explored as targeting ligands due to their superior stability and bioactivity in vivo. Retro-inverso peptide RIF7 was designed as a ligand of Anxa1 receptor. The resultant peptide, RIF7, displayed high binding efficiency within Anxa1 receptor, which is highly expressed tumour vasculature cells and some tumour cells such as B16F10 and U87MG cells. The most important feature of RIF7 is its high stability in the blood, which is suitable and promising for application in vivo. Multifunctional RIF7-HA was then synthesized by conjugating the RIF7 peptide to HA, which was used to modify the surface of RHB/pDNA nanoparticles to prepare RIF7-HA/RHB/pDNA core-shell ternary nanoparticles for the dual-targeted delivery of shRNA-encoding plasmids in vitro and in vivo.

Delivery of siRNA silencing P-gp in peptide-functionalized nanoparticles causes efflux modulation at the blood–brain barrier

Aim: Explore the use of transferrin-receptor peptide-functionalized nanoparticles (NPs) targeting blood–brain barrier (BBB) as siRNA carriers to silence P-glycoprotein (P-gp). Materials & methods: Permeability experiments were assessed through a developed BBB cell-based model; P-gp mRNA expression was evaluated in vitro; rhodamine 123 permeability was assessed after cell monolayer treatment with siRNA NPs. Results: Beyond their ability to improve siRNA permeability through the BBB by twofold, 96-h post-transfection, functionalized polymeric NPs successfully reduced P-gp mRNA expression up to 52%, compared with nonfunctionalized systems. Subsequently, the permeability of rhodamine 123 through the human BBB model increased up to 27%. Conclusion: Developed BBB-targeted NPs induced P-gp downregulation and consequent increase on P-gp substrate permeability, revealing their ability to modulate drug efflux at the BBB.

A preliminary study on the interaction between Asn-Gly-Arg (NGR)-modified multifunctional nanoparticles and vascular epithelial cells

Previously developed Asn-Gly-Arg (NGR) peptide-modified multifunctional poly(ethyleneimine)–poly(ethylene glycol) (PEI–PEG)-based nanoparticles (TPIC) have been considered to be promising carriers for the co-delivery of DNA and doxorubicin (DOX). As a continued effort, the aim of the present study was to further evaluate the interaction between TPIC and human umbilical vein endothelial cells (HUVEC) to better understand the cellular entry mechanism. In the present investigation, experiments relevant to co-localization, endocytosis inhibitors and factors influencing the internalization were performed. Without any treatment, there was no co-localization between aminopeptidase N/CD13 (APN/CD13) and caveolin 1 (CAV1). However, co-localization between CD13 and CAV1 was observed when cells were incubated with an anti-CD13 antibody or TPIC. As compared with antibody treatment, TPIC accelerated the speed and enhanced the degree of co-localization. TPIC entered HUVEC not only together with CD13 but also together with CAV1. However, this internalization was not dependent on the enzyme activity of CD13 but could be inhibited by methyl-β-eyclodextfin (MβCD), further identifying the involvement of caveolae-mediated endocytosis (CvME). This conclusion was also verified by endocytosis inhibitor experiments.

Properties of polyplexes formed through interaction between hydrophobically-modified poly(ethylene imine)s and calf thymus DNA in aqueous solution

Polycationic polymers and DNA form soluble complexes in aqueous solution, which allows the transfer of genetic material into cells. Therefore, these chemically-modified polymers are of interest for use in studies aimed at better transfection efficiency and gene expression along with reduced cytotoxicity. In this study, branched poly(ethylene imine) (PEI) was modified by alkylation with n-alkyl groups (n = 4, 6, 8 and 12 carbons). The polyplexes formed through interaction of the modified PEIs and calf thymus DNA (ctDNA) were investigated using UV-Vis spectrophotometry, ethidium bromide fluorescence emission, circular dichroism spectroscopy, dynamic light scattering, and small-angle X-ray scattering techniques along with the determination of the zeta potential and viscosity. According to the results obtained, the formation of ctDNA-PEI polyplexes occurs in three steps. Firstly, when a small amount of polyelectrolyte is present the ctDNA chains are partially compacted. Subsequently, with the addition of more polyelectrolyte, the complexes have a null charge density and micrometric size. Lastly, with a higher concentration of PEI, the ctDNA is fully compacted by the PEI chains, leading to positively charged complexes with R_h values in the range of 52.0-86.0 nm. The viscosity and SAXS analysis suggested that the unmodified PEI exhibits the strongest interaction and promotes the best ctDNA condensation.

Recent progress in drug delivery of pluronic P123: pharmaceutical perspectives

This review focuses on recent investigations that used Pluronic P123 (P123) as pharmaceutical ingredients in vesicle, micelle, mixed micelle, in situ gel, tablet and emulsion. The main results from these studies show that P123 can significantly increase the stability of incorporated hydrophobic drugs with enhanced in vitro cytotoxicity and cellular uptake of anticancer drugs. Moreover, modified forms of P123 with RGD, folate or other targeted marker have shown its therapeutic potentials in various types of tumors and cancers. Furthermore, modified forms of P123 alone and/or mixed with other copolymers have less toxic effects and more tumor-specific delivery of anticancer drugs. They are promising materials as a nanoplatform for the drug delivery. Finally, the future perspectives of the field are briefly discussed.

Nano-polyplex based on oleoyl-carboxymethy-chitosan (OCMCS) and hyaluronic acid for oral gene vaccine delivery

Here we described nano-polyplexes (NPs) made of oleoyl-carboxymethy-chitosan (OCMCS)/hyaluronic acid (HA) as novel potential carriers for oral gene vaccines delivery. Aerolysin gene (aerA) of Aeromonas hydrophila as microbial antigen was efficiently loaded to form OCMCS-HA/aerA (OHA) NPs. OHA NPs performed the optimal parameters, i.e. smallest (154.5±9.4nm), positive charged (+7.9±0.5mV) and monodispersed system with the N/P ratio of 5 and OCMCS/HA weight ratio of 4. Upon the introduction of HA, OHA NPs was beneficial for the DNA release in intestinal environments in comparison to OA NPs. The mean fluorescence intensity detected in Caco-2 cells incubated with OHA NPs was about 2.5-fold higher than that of OA NPs; however, it decreased significantly in the presence of excess free HA. The OHA NPs and OA NPs decreased the transepithelial electric resistance (TEER) of Caco-2 monolayers obviously and induced increasing the apparent permeability coefficient (Papp) of DNA by 5.45-6.09 folds compared with free DNA. Significantly higher (P<0.05) antigen-specific antibodies were detected in serum after orally immunized with OHA NPs than that immunized with OA NPs and DNA alone in carps. These results enable the OHA NPs might resolve challenges arising from gastrointestinal damage to gene antigens, and offer an approach applicable for oral vaccination.