A comparative study of endothelial cell transport in pig and human cornea

Purpose. To study the basic transport characteristics of human and pig corneal endothelial cells, including osmotic water permeability, activation of sodium transport from the cell after conservation, and the ability of the cells to restore their volume when transport mechanisms of the endothelial cells are activated at 37°C.

Material and methods. The experiments were held on the primary cell culture of human and pig cornea endothelia. Changes in cell volume were determined by a method based on quenching of Calcein fluorescence probe by the cytosol proteins. Changes in intracellular sodium ion concentration were studied using Sodium Green as a fluorescent probe. Restoration dynamics of cell volume and intracellular sodium concentration were studied under medium temperature changes from 20 to 37°C. Osmotic water permeability was calculated from the rate of cell volume changes under medium osmolality decreasing from 560 to 280 mOsm/kg H2 O.

Results. It was established that human endothelial cells plasma membrane has a significantly higher osmotic water permeability than pig endothelial cells (Pf = 1.90E-01 ± 4.66E-02 and 1.31E-01 ± 1.16E-02 cm/s, respectively; p < 0.01, n = 17). Human cells after the temperature restored to 37°C, sodium ions removal from human cells occurs more intensely than from pig cells (-3.2E-3 ± 3.1E-4 с-1 и -6.5E-4 ± 1.2E-5 s-1, respectively; p < 0.01, n = 6). The study of cell volume drop has shown that heat activation of cellular transport restores the endothelial cell volume in humans more slowly (-1,7E-4 ± 5,5E-5 с-1, n = 9) than that of pig cells (-1.7E-3 ± 4E-4 s-1, n = 4, p < 0.05).

Conclusion. When using the endothelium of pig cornea as an experimental model of human endothelium, we need to take into account the significant difference in parameters that determine cell volume regulation.

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