A Novel In Vitro Assay Using Human iPSC-Derived Sensory Neurons to Evaluate the Effects of External Chemicals on Neuronal Morphology: Possible Implications in the Prediction of Abnormal Skin Sensation.

Neuronal morphological changes in the epidermis are considered to be one of causes of abnormal skin sensations in dry skin-based skin diseases. The present study aimed to develop an in vitro model optimised for human skin to test the external factors that lead to its exacerbation. Human-induced pluripotent stem cell-derived sensory neurons (hiPSC-SNs) were used as a model of human sensory neurons. The effects of chemical substances on these neurons were evaluated by observing the elongation of nerve fibers, incidence of blebs (bead-like swellings), and the expression of nicotinamide mononucleotide adenylyl transferase 2 (NMNAT2). The nerve fiber length increased upon exposure to two common cosmetic preservatives-methylparaben and phenoxyethanol-but not to benzo[a]pyrene, an air pollutant at the estimated concentrations in the epidermis. Furthermore, the incidence of blebs increased upon exposure to benzo[a]pyrene. However, there was a decrease in the expression of NMNAT2 in nerve fibers, suggesting degenerative changes. No such degeneration was found after methylparaben or phenoxyethanol at the estimated concentrations in the epidermis. These findings suggest that methylparaben and phenoxyethanol promote nerve elongation in hiPSC-SNs, whereas benzo[a]pyrene induces nerve degeneration. Such alterations may be at least partly involved in the onset and progression of sensitive skin.

Preparation of well-defined brush-like block copolymers for gene delivery applications under biorelevant reaction conditions.

Well-defined oligo(ethylene glycol) methyl ether methacrylate (OEOMA) based block copolymers with cationic segments composed by N,N-(dimethylamino) ethyl methacrylate (DMAEMA) and/or 2-(diisopropylamino) ethyl methacrylate (DPA) were developed under biorelevant reaction conditions. These brush-type copolymers were synthesized through supplemental activator and reducing agent (SARA) atom transfer radical polymerization (ATRP) using sodium dithionite as SARA agent. The synthesis was carried out using an eco-friendly solvent mixture, very low copper catalyst concentration, and mild reaction conditions. The structure of the block copolymers was characterized by size exclusion chromatography (SEC) analysis and 1H nuclear magnetic resonance (NMR) spectroscopy. The pH-dependent protonation of these copolymers enables the efficient complexation with plasmid DNA (pDNA), yielding polyplexes with sizes ranging from 200 up to 700 nm, depending on the molecular weight of the copolymers, composition and concentration used. Agarose gel electrophoresis confirmed the successful pDNA encapsulation. No cytotoxicity effect was observed, even for N/P ratios higher than 50, for human fibroblasts and cervical cancer cell lines cells. The in vitro cellular uptake experiments demonstrated that the pDNA-loaded block copolymers were efficiently delivered into nucleus of cervical cancer cells. The polymerization approach, the unique structure of the block copolymers and the efficient DNA encapsulation presented can open new avenues for development of efficient tailor made gene delivery systems under biorelevant conditions.

Novel perspectives in the tuberculosis treatment: Administration of isoniazid through the skin.

Despite its high efficacy in anti-tuberculosis therapy, the oral administration of isoniazid (INH) may lead to poor patient compliance due to hepatotoxicity events. In this context, the transdermal administration of INH was evaluated, for the first time, since this route avoids hepatic first pass effect. INH was applied to porcine skin in Franz diffusion chambers alone and with 5% menthol, limonene or Transcutol(®). Infrared and DSC analyses were selected for mechanistic studies. The transdermal absorption of INH was sufficient to ensure a systemic therapeutic effect. Menthol was not able to improve the absorption of INH, but it increased the drug accumulation in skin compared to the control (1.4-fold). Transcutol(®) reduced permeation flux of INH (2.2-fold) and also increased the amount of drug retained in skin (1.7-fold). Limonene was the most effective excipient since it increased permeation flux of INH (1.5-fold) and lag time was greatly shortened (2.8-fold). DSC and FTIR analyses of limonene-treated skin suggest higher degree of disorder in lipid bilayers. Transdermal delivery of INH was positively correlated with logP of chemical enhancers. INH can be efficiently delivered by skin route and specific excipients may be selected depending on intended use.

Investigation of the utility of an in vitro release test for optimizing semisolid dosage forms.

Current literature indicates that an in vitro release test (IVRT) can serve as a research tool during the course of developing topical formulations. The purpose of this study was therefore to investigate the ability of an IVRT to select the topical semisolid formulations with the most rapid release rate of the model drug ketoprofen from two closely related hydrogels in a simulated product development process. Two glycols with distinct differences in their physical-chemical properties, Transcutol P (ethoxydiglycol) and propylene glycol, were incorporated into Carbopol 980 and Poloxamer 407 formulations. The release rate of ketoprofen was determined utilizing different receptor media and conditions, i.e., phosphate buffer pH 7.4, isopropyl myristate (IPM), and a combination of an IPM soaked membrane and phosphate buffer (pH 7.4) as receptor fluid. The results indicated that the conditions chosen could affect greatly the conclusions concerning the formulations. The only observable trend was that Transcutol P-containing formulations tended to permit a faster ketoprofen release than propylene glycol-containing formulations when utilizing IPM as a receptor component. This was attributed to the mutual miscibility of Transcutol P in IPM. It can be concluded that, for the purpose of formulation screening in the early phases of product development, an IVRT will only be useful for predicting the amount of drug available for absorption if the receptor medium has properties that closely mimic human skin. These results illustrate the importance of selecting suitable receptor components and indicate that it may be necessary to consider alternatives to the commonly used synthetic membranes.