Human Induced Pluripotent Stem Cell-Based Skin for Assessing Transdermal Drug Permeability and Irritancy.

To establish a system for assessing drug permeation and irritation of the skin, the permeation of benzoic acid and isosorbide dinitrate, which are listed in the Pharmacopoeia, and the chemical irritation were evaluated using skin generated from human induced pluripotent stem cells (iPSCs). Multilayer structures and cellular markers (keratin 14 and 10, which are in basal and suprabasal epidermal layers) were clearly detected in our iPSC-based skin. Transepidermal water loss (TEWL) decreased after iPSC-derived keratinocytes were cultured on collagen gels from human primary fibroblasts. These results indicate that the barrier function was partly increased by formation of the living epidermis. The cumulative amount of benzoic acid and isosorbide dinitrate across human iPSC-based skin gradually increased after an initial lag time. Moreover, the irritancy of various chemicals (non-irritants: ultrapure water, allyl phenoxy-acetate, isopropanol, and hexyl salicylate and irritants: 5% sodium dodecyl sulfate (SDS), heptanal, potassium hydroxide (5% aq.) and cyclamen aldehyde) to iPSC-based skin was almost met the irritation criteria of the Organisation for Economic Co-operation and Development (OECD) guideline. The results of our iPSC-based skin evaluation provide useful basic information for developing an assessment system to predict the permeation and safety of new transdermal drugs in human skin.

Utility of Three-Dimensional Skin From Human-Induced Pluripotent Stem Cells as a Tool to Evaluate Transdermal Drug Permeation.

Transdermal drug delivery is an attractive route for administration of drugs, and it offers several advantages such as painless administration. To accurately predict the rate of human skin permeation for new transdermal drug formulations, we developed a novel assessment system using induced pluripotent stem cells (iPSCs). Skin was generated from iPSC-derived keratinocytes and fibroblasts. In the histological and immunohistochemical examination, cellular markers (keratin 14 and keratin 10) for the epidermal basal and suprabasal layers were clearly detected within the multilayer structures produced in the human iPSC-based three-dimensional skin model. The results from our permeation study indicate that an initial lag time exists during permeation of 5(6)-carboxyfluorescein and fluorescein isothiocyanate dextran 4000. Furthermore, the permeation for these model drugs in human iPSC-based skin was inversely proportional to the molecular weight of the drugs. These results of the present iPSC-based skin are useful basic information as a first step for developing a new assessment system to predict the efficacy of drug permeation in human skin by using iPSC-based skin.