Investigation of human embryonic stem cell-derived keratinocytes as an in vitro research model for mechanical stress dynamic response.

The epidermis is mainly composed of keratinocytes forming a protective barrier. It is perpetually subjected to mechanical stress and strain during development, homeostasis and disease. Perturbation of the normal strain with alteration of its biological response may lead to severe diseases such as psoriasis and epidermolysis bullosa. To date, most of the studies about skin response to mechanical stress used immortalized cell lines (i.e. HaCaT) or primary cells from donors, which suffer issues of limited physiological relevance and inter-donor variability. It is therefore necessary to develop a new human model for the study of normal skin physiology and response to mechanical stress. In this study, we investigated the use of keratinocytes derived from human embryonic stem cells (hESCs) as a reliable alternative model to HaCaT for study of the effects of mechanical tension. With comparison to HaCaT, hESC-derived keratinocytes (hESC-Kert) were exposed to up to 3 days of cyclic mechanical stress, and gene expression changes were analyzed. Dynamic expression of several key mechanical stress related-genes was studied at mRNA level using qPCR. The expression of matrix-metallopeptidase9 was studied at protein level using ELISA. The two cell types displayed similar gene expression kinetics for most of the genes including E-cadherin, cateninβ1, connexin43, desmoglein1, endothelin1, integrinα6, interleukinα1, keratin1, 6, and 10, keratinocyte growth-factor-receptor and lamininα5. Unlike HaCaT, hESC-Kert displayed early gene and protein expression of matrix metallopeptidase 9 following mechanical stimulation, suggesting that these cells have remodeling capacity that resembles that of normal human skin. Our study confirmed the use of hESC-Kert as a good model for study of skin response to mechanical stress.