Fibroblasts change spreading capability and mechanical properties in a direct interaction with keratinocytes in conditions mimicking wound healing

Keratinocytes are predominant in the uppermost layer of the skin, while fibroblasts dominate in the dermal layer. These cells interact with each other directly when fibroblasts migrate to a region of the wound where they induce keratinocytes proliferation through double paracrine signalling. Since a response from both keratinocytes and fibroblasts dominates during the inflammatory and proliferative phases, the exact knowledge how these two types of cells interact with each other is crucial for deeper understanding of mechanisms involved in the wound healing process. The aim of this study was to quantify alterations in mechanical properties of cells, i.e. fibroblasts and keratinocytes, in conditions mimicking direct cellular interactions observed in wound healing. Single cell elasticity was measured using atomic force microscope. To verify the influence of keratinocyte neighbors on fibroblasts elasticity (and vice versa), the effect of cellular confluency was studied in parallel. Our results enabled us to distinguish cellular density-related effects from intercellular interactions occurring between fibroblasts and keratinocytes. While the presence of keratinocytes affects fibroblasts spreading capability and mechanical properties, the keratinocytes remain unaffected by the fibroblasts. These results highlight the importance of the cellular deformability in understanding of the role of biomechanics in double paracrine signalling as fibroblast-keratinocyte interaction can change the potential of the wound healing.