Reverse relation between cytotoxicity and Polyethylenimine/DNA ratio, the effect of using HEPES-buffered saline (HBS) medium in gene delivery.

Polyethyleneimine (PEI) is considered a promising cationic polymer in non-viral gene delivery. DNA binding properties and other biochemical characteristics of PEI such as the proton sponge phenomenon, offered the branched 25 kDa PEI to be widely used for therapeutic DNA delivery, although the possible cytotoxic effects and the best conditions of PEI preparation are not still well recognized. While higher PEI/Plasmid ratios have increased transfection efficiencies, it induces more cell stress and toxicity. Considering that the PEI particle size and resulting cytotoxicity are affected by media ions, we used Neuro2A cells to assess the cell stress properties of PEI/Plasmid complexes prepared in a HEPES-buffered saline medium. Delivery of a plasmid containing EGFP happened in all increasing ratios of PEI/plasmid from 0.5, 2, 4, and 6, while higher ratios induced less unfolded protein response as evidenced by lower transcription of ER stress markers Grp78, Atf4, Chop, Xbp1, and induced Xbp1 splicing. These data were also supported by MTT cytotoxicity assay results. These findings indicate that preparing higher PEI/plasmid ratio complexes (using the equivalent of 200 ng DNA) in the HBS medium leads to less cytotoxicity.

Viscoelastic and Deformation Characteristics of Structurally Different Commercial Topical Systems.

Rheological characteristics and shear response have potential implication in defining the pharmaceutical equivalence, therapeutic equivalence, and perceptive equivalence of commercial topical products. Three creams (C1 and C3 as oil-in-water and C2 as water-in-oil emulsions), and two gels (G1 and G2 carbomer-based) were characterized using the dynamic range of controlled shear in steady-state flow and oscillatory modes. All products, other than C3, met the Critical Quality Attribute criteria for high zero-shear viscosity (η0) of 2.6 × 104 to 1.5 × 105 Pa∙s and yield stress (τ0) of 55 to 277 Pa. C3 exhibited a smaller linear viscoelastic region and lower η0 (2547 Pa∙s) and τ0 (2 Pa), consistent with lotion-like behavior. All dose forms showed viscoelastic solid behavior having a storage modulus (G') higher than the loss modulus (G″) in the linear viscoelastic region. However, the transition of G' > G″ to G″ > G' during the continual strain increment was more rapid for the creams, elucidating a relatively brittle deformation, whereas these transitions in gels were more prolonged, consistent with a gradual disentanglement of the polymer network. In conclusion, these analyses not only ensure quality and stability, but also enable the microstructure to be characterized as being flexible (gels) or inelastic (creams).

Development of an Oil-in-Water Self-Emulsifying Microemulsion for Cutaneous Delivery of Rose Bengal: Investigation of Anti-Melanoma Properties.

The topical delivery route is proposed as an alternative or adjunctive approach to melanoma treatment, since the target site for melanoma treatment-the epidermal basal layer-is potentially accessible by this route. Microemulsion systems are effective delivery vehicles for enhanced, targeted skin delivery. This work investigated the effect of Rose Bengal (RB) and RB-loaded self-emulsifying microemulsions (SEMEs) on growth inhibition of human melanoma and normal skin cell monolayers, the safety of the excipients incorporated in SEMEs on human cell lines, and the in-vitro human skin penetration of RB delivered in SEMEs and control solution. Cellular toxicity was assessed by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, and the growth inhibitory mechanism of RB was investigated by flow cytometry using PI staining. Unloaded SEMEs caused reduced cellular toxicity compared to the surfactant excipient, Labrasol®. RB-loaded SEMEs increased cell growth inhibition compared to the RB aqueous solution. Flow cytometry revealed apoptotic cells after treatment with RB-loaded SEMEs, indicating that apoptosis may be one of the mechanisms of cell death. Preliminary results of multiphoton microscopy with fluorescence lifetime imaging (MPM-FLIM) analysis showed deeper penetration with greater skin concentrations of RB delivered from SEMEs compared to the RB aqueous solution. This study highlights the enhanced skin penetration and antimelanoma effects of RB loaded in a SEME system.

Quality by Design: Development of the Quality Target Product Profile (QTPP) for Semisolid Topical Products.

In recent years, the "quality by design" (QbD) approach has been used for developing pharmaceutical formulations. This is particularly important for complex dosage forms such as topical semisolid products. The first step for developing a product using this efficient approach is defining the quality target product profile (QTPP), a list of quality attributes (QAs) that are required to be present in the final product. These quality attributes are affected by the ingredients used as well as manufacturing procedure parameters. Hence, critical material attributes (CMAs) and critical process parameters (CPPs) need to be specified. Possible failure modes of a topical semisolid product can be determined based on the physiochemical properties of ingredients and manufacturing procedures. In this review, we have defined and specified QTPP, QAs, CMAs and CPPs that are required for developing a topical semisolid product based on the QbD approach.

Investigating the influence of polyplex size on toxicity properties of polyethylenimine mediated gene delivery.

AIMS: Gene therapy is a promising strategy for the treatment of various diseases. Polyethylenimine (PEI) has received considerable attention for gene delivery applications due to their appropriate properties. However, their toxicity has raised concerns which cause to be used with cautious. This study aimed to prepare different complexes of PEI/DNA and evaluate their parameters affecting in vitro cytotoxicity. Also, apoptosis rate was measured to determine the mechanism of cell toxicity. MATERIALS AND METHODS: The complexes were prepared through conjugation and characterized using dynamic light scattering, MTT and flow cytometry techniques. KEY FINDINGS: The particles' size was from 81 nm to 2785 nm and was increased in the HBS buffer compared to HBG buffer. In the case of branched PEIs, the size of particles was inversely associated with molecular weight. The cytotoxicity results showed that linear 250 KDa PEI was non-toxic whereas branched PEIs with lower molecular weights showed toxicity effects in a concentration dependent manner. Also, the cytotoxicity effects of branched PEIs were proportional with carrier/plasmid (C/P) ratio and were more for the polyplexes prepared in HBG buffer compared to HBS buffer after 24 h incubation. Flow cytometry results confirmed that apoptosis is the main mechanism of cell toxicity produced by polyplexes. SIGNIFICANCE: The results showed the effect of PEI size on its cytotoxicity. Also, the toxicity effects of PEI-derived polyplexes in vivo environment was evaluated.

Evaluating polyethyleneimine/DNA nanoparticles-mediated damage to cellular organelles using endoplasmic reticulum stress profile.

Gene therapy has emerged as an influential tool for treating the genetic and specific acquired disorders. Among all kinds of gene delivery systems, the cationic polymer polyethyleneimine (PEI) is considered as a promising non-viral gene delivery vector, although there are still concerns about its magnitude of cytotoxicity. While any cell insult leads to unfolded/misfolded protein accumulation and its consequent unfold protein response, evaluating the expression profile of ER-stress genes would be a sensitive indicator of cell stress. Beside cytotoxicity assays, real-time RT-PCR was used to investigate the effects of PEI nanoparticles on the endoplasmic reticulum. Treating Neuro2A cells revealed that PEI can induce cell toxicity in a concentration-dependent manner. Also, It increased the transcript levels of Grp78 (Bip), Atf4 and Chop, and splicing of Xbp1. To further optimize the transfection properties in Neuro2A cells, PEI was used to deliver a plasmid DNA containing GFP reporter. While different PEI/plasmid ratios revealed similar transfection efficiency, increasing the PEI/plasmid ratio led to induction of ER-stress markers. These results underscored that beside the effectiveness of PEI, using the lowest possible ratio of PEI/plasmid would minimize the detrimental effects of PEI on cells and confer it a beneficial therapeutic importance in nucleic acid delivery.