Stretching Promotes Wound Contraction Through Enhanced Expression of Endothelin Receptor B and TRPC3 in Fibroblasts

One factor that can contribute to the development of hypertrophic scar contracture is mechanical stress. Mechanical cyclic stretch stimuli enhance the secretion of endothelin-1 (ET-1) from keratinocyte. Cyclical stretching of fibroblasts also increases the expression level of the transient receptor potential ion channel (TRPC3), which is known to couple with the endothelin receptor and induce intracellular Ca2+ signaling via the calcineurin/nuclear factor of activated T cells (NFAT) pathway. The aim of this study was to investigate the relationship between keratinocytes and fibroblasts when they are stretched.

The conditioned medium from stretched keratinocyte was added to the fibroblast populated collagen lattice. Then, we analyzed the levels of endothelin receptor in the human hypertrophic scar tissue and stretched fibroblasts. To address the function of TRPC3, we have used an overexpression system with the collagen lattice. Finally, the TRPC3 overexpressing fibroblasts were transplanted to mouse dorsal skin, and the rate of skin wound contraction was assessed.

Conditioned medium from stretched keratinocytes increased the rate of contraction of fibroblast populated collagen lattice. In human hypertrophic scar and stretched fibroblasts, endothelin receptor type B was increased. Cyclic stretching of TRPC3 overexpressing fibroblasts activated NFATc4, and stretched human fibroblasts showed more activation of NFATc4 in response to ET-1. The wound treated with TRPC3 overexpressing fibroblasts showed more contraction than control wound.

These findings suggest that cyclical stretching of wounds have an effect on both keratinocytes and fibroblasts, where keratinocytes secret more ET-1, and fibroblasts develop more sensitivity to ET-1 by expressing more endothelin receptors and TRPC3.