Corn Silk Polysaccharides with Different Carboxyl Contents Reduce the Oxidative Damage of Renal Epithelial Cells by Inhibiting Endocytosis of Nano-calcium Oxalate Crystals

Objective: Renal epithelial cell injury and cell-crystalinteraction are closely related to kidney stone formation. Methods:This study aims to explore the inhibition of endocytosis of nano-sizedcalcium oxalate monohydrate (nano-COM) crystals and the cell protectionof corn silk polysaccharides (CCSPs) with different carboxyl contents(3.92, 7.75, 12.90, and 16.38%). The nano-COM crystals protected orunprotected by CCSPs were co-cultured with human renal proximal tubularepithelial cells (HK-2), and then the changes in the endocytosis ofnano-COM and cell biochemical indicators were detected. Results: CCSPscould inhibit the endocytosis of nano-COM by HK-2 cells and reducethe accumulation of nano-COM in the cells. Under the protection ofCCSPs, cell morphology is restored, intracellular superoxide dismutaselevels are increased, lipid peroxidation product malondialdehyde releaseis decreased, and mitochondrial membrane potential and lysosomal integrityare increased. The release of Ca2+ ions in the cell, thelevel of cell autophagy, and the rate of cell apoptosis and necrosisare also reduced. CCSPs with higher carboxyl content have better cellprotection abilities. Conclusion: CCSPs could inhibit the endocytosisof nano-COM crystals and reduce cell oxidative damage. CCSP3, withthe highest carboxyl content, shows the best biological activity.