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Cationic polymers that bind with the plasmids to form polyplexes protect the DNA from enzymatic degradation and improve cellular and tissue uptake. Complete or near complete gel retardation of the polyplex is an important assay to determine the optimal polymer: plasmid ratio for in vitro and in vivo studies. Nevertheless, despite minimal to moderate gel retardation of histidine-lysine (HK) polyplexes formed with low peptide: plasmid DNA ratios (1:2 and 1:4; w:w), the polyplexes effectively targeted the tumor in vivo. To understand the lack of predictability of the initial gel mobility shift assays, we revisited the retardation and stability of polyplexes with these electrophoresis assays. Because the histidine component with a pKa of about 6.0 will have a greater positive charge and may bind plasmids with a higher affinity at lower pHs, we compared the retardation of the two HK polyplexes when the pH of the running buffer of the gel mobility shift assay was altered. Both HK polyplexes were retarded significantly more when the running buffer had a pH of 7.3 instead of the standard pH of 8.3. Indeed, the HK polyplexes formed at the 1:2 ratio showed complete retardation at pH 7.3. Consequently, while both HK polyplexes formed at these low ratios targeted the tumor, the polyplex formed with the 1:2 ratio had reduced tumor gene expression variability and lower lung and liver values. Thus, the selection of the optimal ratios for the linear HK and plasmid for transfection studies in vivo was improved with a running buffer pH of 7.3., Competing Interests: Declaration of competing interest The authors of this manuscript declare that there are no competing interests., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Background: MicroRNAs have gained attention as key immunomodulators, with miR-155 specifically shown in various studies to drive macrophage polarization toward the classical phenotype. This polarization is crucial, as classical macrophages play a well-recognized role in differentiating type-1 immune responses and resisting Leishmania infection., Objective: The present study aims to evaluate the anti-leishmanial immunoadjuvant effects of the miR-155 chitosan polyplex (miR-155 CP)., Methods: The anti-leishmanial immunoadjuvant activity of miR-155 CP synthesized by the coacervation method was assessed against L. major (MRHO/IR/75/ER) by analyzing the infectivity rate on RAW 264.7 cells in vitro.MiR-155 CP as an adjuvant co-administrated with soluble Leishmania antigen (SLA) for immunization of BALB/c mice, then the challenge was performed by subcutaneous injection of 1 × 10 6 L. major promastigotes. Eight weeks following the challenge, lesion size, parasite load, cytokine assay, and nitric oxide production were evaluated., Results: The nanoparticles were produced with a size of 233.87 ± 8 nm and a zeta potential of + 22.6 ± 2 mV with good transfection efficiency. The mean infection index among pretreated cells with miR-155 CP (72±1.1) decreased significantly compared to the control group (420 ± 2.8). The parasite burden and the size of the lesions were significantly reduced in the immunized infected mice. Vaccination by miR-155 CP/SLA triggered the production of IFN-γ and NO and changed the cytokine profile of antigen-specific cells.Conclusion:The effectiveness of the SLA vaccine can be enhanced by including miR-155 CP as an adjuvant. SLA and miR-155 CP co-administration improve the type-1 immune response. This enhanced immune response helps prevent severe leishmaniasis.

Objective: Highly branched poly(β-amino ester) (HPAEs)-based gene therapy holds promise for treating lung cystic fibrosis (CF). However, the translation of HPAEs/DNA nanoparticles into clinical applications poses a significant challenge due to the requirement for high concentrations of the formulation., Methods: In this work, a straightforward and scalable concentration method was developed for concentrating HPAEs/DNA polyplexes. A series of different buffers with various pH values and ionic components were initially tested to develop the optimized HPAEs/DNA polyplex formulation. Subsequently, the optimized HPAEs/DNA polyplex formulation was concentrated through lyophilization and ultrafiltration., Results: The ultrafiltration outperformed the lyophilization in concentration capacity, showing a 24-fold increase in the concentrated formulation compared to the original non-concentrated formulation. The concentration does not disturb the transfection efficiency in lung CF epithelial cells, indicating its potential for lung delivery applications. Moreover, the concentrated HPAEs/DNA polyplex successfully restored the production of CF transmembrane conductance regulator (CFTR) protein in primary lung CF epithelial cells, surpassing the performance of the non-concentrated common gene transfection reagents such as Lipofectamine 3000 and Xfect., Conclusion: The concentrated HPAEs/DNA formulation represents a promising step forward for preclinical testing (e.g. in vivo evaluation), with further research needed to confirm its potential for clinical use.

Background: Poly (β-amino Ester) nanocarriers show promise for gene therapy, but their effectiveness can be limited by the environment within the body. This study aims to understand how common cell culture media components affect optimized PBAE nanocarrier performance in gene delivery., Methods: Optimized PBAE was synthesized based on Michael addition reaction and characterized by different assays, this study employed techniques like DLS and TEM to characterize PBAE nanocarriers, followed by cellular uptake analysis (flow cytometry and confocal imaging) and evaluation of gene expression under different polymer/DNA ratio ratios and media conditions., Results: The nanocarriers exhibited size under 200 nm and surface positive charge, with high encapsulation efficiency (up to 95%). Cellular uptake, transfection efficiency, and cytotoxicity were evaluated. Flow cytometry analysis revealed high cellular uptake (over 77% at 1 hour and up to 95% after 3 hours) and good viability. Transfection efficiency reached up to 80% with 2 μg DNA, particularly at weight ratios of 60 and 90., Conclusion: The study also identified factors affecting transfection efficiency, including serum concentration and antibiotics in the culture medium, highlighting the importance of optimizing these conditions for future applications.

Organ‐selective targeting of mRNA polyplexes has been rarely explored despite the substantial potential of polymer‐based systems in mRNA delivery. In this study, spleen‐selective delivery of polyplexes is achieved by employing mRNA engineering to coat them with poly(ethylene glycol) (PEG). In this approach, mRNA is hybridized with PEGylated complementary RNA oligonucleotides (PEG–OligoRNAs), followed by the addition of linear poly(ethyleneimine). In this method, it is ensured that nearly all added PEG strands bind to the polyplexes, thereby enabling precise control of PEG amounts on the surface. Following systemic injection into mice, non‐PEGylated polyplexes yield robust protein expression in the lung and spleen. Intriguingly, adding a small number of PEG–OligoRNAs drastically reduces protein expression efficiency in the lung while preserving it in the spleen, realizing spleen targeting of mRNA polyplexes. Furthermore, PEGylated polyplexes demonstrate their potential utility in mRNA vaccination. In mechanistic analyses, non‐PEGylated polyplexes immediately agglomerate in the blood and deposit in the lung. Coating polyplexes with a small amount of short PEG effectively prevents these processes. Notably, even slight changes in PEG amounts and lengths dramatically impact the physicochemical properties and biological functionalities of the polyplexes, emphasizing the benefits of an mRNA engineering‐based approach for fine‐tuning polyplex PEG coating.

The growing significance of messenger RNA (mRNA) therapeutics in diverse medical applications, such as cancer, infectious diseases, and genetic disorders, highlighted the need for efficient and safe delivery systems. Lipid nanoparticles (LNPs) have shown great promise for mRNA delivery, but challenges such as toxicity and immunogenicity still remain to be addressed. In this study, we aimed to compare the performance of polyplex nanomicelles, our original cationic polymer-based carrier, and LNPs in various aspects, including delivery efficiency, organ toxicity, muscle damage, immune reaction, and pain. Our results showed that nanomicelles (PEG-PAsp(DET)) and LNPs (SM-102) exhibited distinct characteristics, with the former demonstrating relatively sustained protein production and reduced inflammation, making them suitable for therapeutic purposes. On the other hand, LNPs displayed desirable properties for vaccines, such as rapid mRNA expression and potent immune response. Taken together, these results suggest the different potentials of nanomicelles and LNPs, supporting further optimization of mRNA delivery systems tailored for specific purposes.

The utilization of hydrogels for DNA/cationic polymer polyplex nanoparticle (polyplex) delivery has significantly advanced gene therapy in tissue regeneration and cancer treatment. However, persistent challenges related to the efficacy and safety of encapsulated polyplexes, stemming from issues such as aggregation, degradation, or difficulties in controlled release during or postintegration with hydrogel scaffolds, necessitate further exploration. Here, we introduce an injectable gene therapy gel achieved by incorporating concentrated polyplexes onto densely packed hydrogel microparticles (HMPs). Polyplexes, when uniformly adhered to the gene therapy gel through reversible electrostatic interactions, can detach from the HMP surface in a controlled manner, contrasting with free polyplexes, and thereby reducing dose-dependent toxicity during transfection. Additionally, the integration of RGD cell adhesion peptides enhances the scaffolding characteristics of the gel, facilitating cell adhesion, migration, and further minimizing toxicity during gene drug administration. Notably, despite the overall transfection efficiency showing average performance, utilizing confocal microscopy to meticulously observe and analyze the cellular states infiltrating into various depths of the gene therapy gel resulted in the groundbreaking discovery of significantly enhanced local transfection efficiency, with primary cell transfection approaching 80%. This phenomenon could be potentially attributed to the granular hydrogel-mediated delivery of polyplex nanoparticles, which revolutionizes the spatial and temporal distribution and thus the "encounter" mode between polyplexes and cells. Moreover, the gene therapy gel's intrinsic injectability and self-healing properties offer ease of administration, making it a highly promising candidate as a novel gene transfection gel dressing with significant potential across various fields, including regenerative medicine and innovative living materials.

Prostate cancer is the most common cancer in men in the UK with over 50 000 new cases diagnosed each year and although therapeutic advances in surgery, anti-androgens, radio- and chemotherapy have increased survival rates, there still remains a need for new treatments to combat the most aggressive forms of the disease. Gene therapy offers promise as an alternative approach but is reliant on selective targeting to the cancer cell surface. Herein we describe the novel construction of a prostate specific membrane antigen (PSMA) binding bioconjugate-polyplex, based on a glutamate-urea peptide scaffold using 'click' chemistry, which we demonstrate is capable of targeted delivery of a GFP gene to PSMA overexpressing prostate cancer cells, and therefore may have potential future application as part of a prostate cancer gene delivery therapy., Competing Interests: The authors declare no competing financial interest., (This journal is © The Royal Society of Chemistry.)

Nanomedicine is a field at the intersection of nanotechnology and medicine, promising due to its potential to revolutionize healthcare. Despite its long trajectory, there is still a long road ahead for its full development, and smart design of nanomedicines is still a challenge. Among other problems, this is due to the scarcity of tools available for the precise visualization and comprehension of nano-bio interactions, impeding progress towards the clinical phase. One of the developed tools that stands out to be a strong nanoscopy technique for studying nano-delivery systems within cellular environments is expansion microscopy (ExM). This technique was used for tissue and cell expansion and most recently for lipid molecule expansion inside cells. Herein, we present for the first time polyplex expansion microscopy (PExM); a comprehensive examination of ExM as an already developed technique, but adapted for expanding polymer based nanocarriers, in particular polyplexes within cells, allowing the analysis of their trafficking. With our method set up, PExM will be extensively used for the study of polyplex nanoparticle cell trafficking, becoming a high-resolution technique which can also be applied to primary amine containing polymeric nanoparticles without requiring expensive super-resolution microscopes.

Background: Type 1 diabetes is an autoimmune disorder characterized by the loss of pancreatic islets. Islet allotransplantation is a potentially beneficial therapeutic approach for diabetes. Islets suffer a variety of cellular insults including ischemia and partial vascular loss during isolation, resulting in a significant reduction in viability prior to transplantation. The present study aimed to investigate the effect of angiogenic microRNA (miRNA)-126 and -210 on islet function and viability in an indirect way. Methods: Poly Ethylenimine (PEI)-miRNA-126 and -210 polyplexes were constructed at various Nitrogen/Phosphate (N/P) ratios. After confirmation by gel retardation and ethidium bromide dye exclusion assay, its cytotoxicity and transfection efficiency were analyzed by MTT and fluorescent assays, respectively. After that, the selected polyplexes were used to transfect Human Umbilical Vein Endothelial Cells (HUVECs) in vitro and were indirectly co-cultured with islet cells for three days. Real-time polymerase chain reaction and enzyme-linked immunoassay were conducted to verify the regulation of target genes and the functionality of the islets. Results: The findings showed that PEI could condense miRNAs at N/P=5. The viability of the HUVECs was decreased by increasing the amount of PEI. Additionally, ployplex-126 and -210 led to a decrease in the expressions of target genes, phosphoinositol-3 kinase regulatory subunit 2, sprouty-related EVH1 domain-containing protein 1, and ephrin-A3 in the islets. Moreover, the expressions of Bax and Bcl2 and their ratio in the treated groups by polyplex-126 and -210 led to better survival and function of the islets, with a higher expression of insulin and response to glucose stimulations. Furthermore, polyplex-210 could downregulate the anti-angiogenic protein, thrombospondin 1, compared to the other groups. Finally, the secretion of C-peptide was higher in polyplex-210 than in the other groups, adjusted for insulin secretion. Conclusion: The results indicated that angiogenic miRNAs could promote the survival and function of islet cells by interacting with their targets.