The Response of Corneal Endothelial Cells to Shear Stress in an In Vitro Flow Model

Abstract

Purpose: Corneal endothelial cells are usually exposed to shear stress caused by the aqueous humour, which is similar to the exposure of vascular endothelial cells to shear stress caused by blood flow. However, the effect of fluid shear stress on corneal endothelial cells is still poorly understood. The purpose of this study was to explore whether the shear stress that results from the aqueous humour influences corneal endothelial cells.

Methods: An in vitro model was established to generate fluid flow on cells, and the effect of fluid flow on corneal endothelial cells after exposure to two levels of shear stress for different durations was investigated. The mRNA and protein expression of corneal endothelium-related markers in rabbit corneal endothelial cells was evaluated by real-time PCR and western blotting.

Results: The expression of the corneal endothelium-related markers ZO-1, N-cadherin, and Na⁺-K⁺-ATPase in rabbit corneal endothelial cells (RCECs) was upregulated at both the mRNA and protein levels after exposure to shear stress.

Conclusion: This study demonstrates that RCECs respond favourably to fluid shear stress, which may contribute to the maintenance of corneal endothelial cell function. Furthermore, this study also provides a theoretical foundation for further investigating the response of human corneal endothelial cells to the shear stress caused by the aqueous humour.

Figure 1

Diagram of the flow circuit system. The flow circuit included a parallel plate flow chamber, a peristaltic pump, a vacuum pump, and a medium reservoir, and these components were connected by silicone tubes and connectors.

Figure 2

Effect of shear stress on the mRNA expression of corneal endothelial cell-related markers. (a) ZO-1 mRNA expression was significantly increased after treatment with shear stress (0.5 dyn/cm² and 2 dyn/cm²) for 30 min and 2 h. (b) N-cadherin mRNA expression gradually increased as the shear stress intensity increased compared with the static control. (c) Na⁺-K⁺-ATPase mRNA expression was slightly increased after exposure to shear stress. The data are presented as the mean ± SD; ^∗P < 0.05, ^∗∗P < 0.01.

Figure 3

Effect of shear stress on the protein expression of corneal endothelial cell-related markers. (a) ZO-1 protein expression was significantly increased in the shear stress groups compared with the static group. (b) N-cadherin protein expression gradually increased with increasing shear rates and exposure time. (c) Na⁺-K⁺-ATPase protein expression was slightly increased after exposure to shear stress. All the experimental data were analysed in triplicate; ^∗P < 0.05, ^∗∗P < 0.01.