Characterization of a human epidermis model reconstructed from hair follicle keratinocytes and comparison with two commercially models and native skin.

Objective: Outer root sheath (ORS) cells of human hair follicles are a readily available, non-invasive source of keratinocytes for epidermis reconstruction. The aim of this study was to characterize a model of epidermis reconstructed from ORS cells (ORS-derived model) and to evaluate its reproducibility, in comparison with native human skin and two marketed reconstructed skin models (model A, Episkin(®) and model B, Skinethic(®) ).
Methods: Cell morphology and tissue architecture of the three models were analysed histologically and proliferation and differentiation marker expression by immunohistochemistry and mRNA quantification.
Results: All models displayed the same general epidermal architecture as native epidermis, but with a thicker stratum corneum in models A and B. Compared with native epidermis, Ki67 was correctly localized in epidermal basal cells in all models, as K10 in suprabasal layers. In all skin models, transglutaminase 1 (TGM1) was prematurely expressed in suprabasal layers. However, this expression was only observed from the upper stratum spinosum in the ORS-derived model. In this model, filaggrin and loricrin were correctly located in the stratum granulosum. Filaggrin, involucrin, loricrin and TGM1 mRNAs (markers of keratinocyte terminal differentiation) were transcriptionally expressed in all models. In the ORS-derived model, transcriptional expression level was similar to that of native skin.
Conclusion: ORS cell-based reconstructed epidermis is a valid and reproducible model for human epidermis and it may be used to evaluate the effects of active substances and cosmetic formulations.
(© 2014 Society of Cosmetic Scientists and the Société Française de Cosmétologie.)