Time-dependent subcellular structure injuries induced by nano-/micron-sized calcium oxalate monohydrate and dihydrate crystals

- The time sequence of organelle injury presenting significant variation caused by nano-/micron-sized crystals.
- COM crystals showed more obvious time-dependent effects than the same-sized COD crystals.
- Nano-sized CaOx crystals induced more serious damage to renal cells than micron-sized crystals.
- Nano-sized crystals lead organelle injury faster than micron-sized crystals.

Comparative studies were conducted to investigate the time effect of cell injury induced by nano-sized (50 nm) and micron-sized (10 μm) calcium oxalate monohydrate (COM) and dihydrate (COD) crystals in African green monkey renal epithelial (Vero) cells. The effects of nano-/micron-sized COM and COD exposure on Vero cells were investigated by detecting the cell viability, cell morphology, LDH release, reactive oxygen species, mitochondrial membrane potential, cell cycle, and cell apoptosis, as well as the intracellular and extracellular crystal distribution. Nano-/micron-sized COM and COD exposure lead to subcellular organelle injury in varying degrees, but the injury sequence of various organelles differed. The time sequence of organelle injury presenting significant variation was described as follows: cell membrane injury (1 h) < mitochondrial membrane potential decrease (3 h to 6 h) ≈ cell-cycle arrest (3 h to 6 h) < cell apoptosis (12 h). Nano-sized crystals lead organelle injury faster than micron-sized crystals, and COM crystals showed more obvious time-dependent effects than the same-sized COD crystals. This study may provide insights into the damage to renal epithelial cells induced by urinary crystals and the formation mechanism of kidney stones.

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