Keratinocytes of the basal layer function are to maintain tissue homoeostasis and to fulfil skin repair in response to an external aggression. In wound-healing, during re-epithelialization phase, epithelial precursor cells gradually migrate from the edges of the wound. The epidermal reconstruction model called standard model allows the vertical skin regeneration process (proliferation/differentiation) to being investigated, and keratinocyte function in preserving skin homoeostasis to being assessed. Here, we developed and characterized a 3D migration model, which introduces a step of keratinocytes migration such as the one observed in the phase of re-epithelialization in woundhealing process. We validated the added value and the discriminative potential of this model by demonstrating pro-epithelializing effects of compounds. This new model allows the role of keratinocytes in different biomechanical and environmental requests to being better understood, and brings a new tool for compound screening and the study of mechanisms involved in skin regeneration. | BACKGROUNDWound-healing is a process of tissue regeneration, which involves three phases that partially overlap: (i) a vascular or inflammatory phase, (ii) a tissue repair phase and (iii) a maturation phase .[1] During phase II, keratinocytes gradually migrate from the wound edges, a period during which basal keratinocytes may differ from precursors essentially observed in the basal layer. Live imaging of stem cells recently allowed in rodent to better understand how stem cells behaviour changes in response to wounding [2] ; however, no model has succeeded in reflecting the whole wound-healing process. The current approaches consist in sequencing the process, using models that focus on one phase. In spite of its limits, this strategy, associated with clinical observations, allows the mechanisms involved to being partially described | QUESTIONS ADDRESSEDWe developed and characterized a new epidermal regeneration 3Din vitro model in a keratinocyte migration situation called "migration model" (partially mimicking the suction blister in vivo clinical model) and compared it to the existing 3D RealSkin ® regeneration standard model [6] referred here as "standard model." The standard model allows vertical regeneration (homoeostasis maintenance) to being studied while migration model introduces the additional step of re-epithelialization as observed in the phase II of wound-healing process. We studied the effect of pro-regenerating/pro-wound-healing compounds to illustrate the added value of this model. are seeded around the ring, the centre remaining empty ( Figure 1A). | EXPERIMENTAL DESIGNRing is removed 10 days after seeding the keratinocytes. Compounds to be evaluated for their capacity to impact the epidermal regeneration and epithelialization speed process are added to the culture medium. Analysis of tissue morphology, quality and thickness of the reconstructed epidermis and keratinocyte migration kinetics were performed. Experimental protocol and metho...