Mesenchymal cells and fluid flow stimulation synergistically regulate the kinetics of corneal epithelial cells at the air–liquid interface

Purpose In vivo microenvironments are critical to tissue homeostasis and wound healing, and the cornea is regulated by a specific microenvironment complex that consists of cell–cell interactions, air–liquid interfaces, and fluid flow stimulation. In this study, we aimed to clarify the effects of and the correlations among these three component factors on the cell kinetics of corneal epithelial cells. Methods Human corneal epithelial–transformed (HCE–T) cells were cocultured with either primary rat corneal fibroblasts or NIH 3T3 fibroblasts. We employed a double-dish culture method to create an air–liquid interface and a gyratory shaker to create fluid flow stimulation. Morphometric and protein expression analyses were performed for the HCE–T cells. Results Both the primary rat fibroblasts and the NIH 3T3 cells promoted HCE–T cell proliferation, and the presence of fluid flow synergistically enhanced this effect and inhibited the apoptosis of HCE–T cells. Moreover, fluid flow enhanced the emergence of myofibroblasts when cocultured with primary rat fibroblasts or NIH 3T3 cells. Extracellular signal-regulated kinase and p38 signaling were regulated either synergistically or independently by both fluid flow and cellular interaction between the HCE–T and NIH 3T3 cells. Conclusion The cell–cell interaction and fluid flow stimulation in the air–liquid interface synergistically or independently regulated the behavior of HCE–T cells. Fluid flow accelerated the phenotypic change from corneal fibroblasts and NIH 3T3 cells to myofibroblasts. Elucidation of the multicomponent interplay in this microenvironment will be critical to the homeostasis and regeneration of the cornea and other ocular tissues.