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<div><p>Background</p><p>Kidney stone formation is a common disease that causes a significant threat to human health. The crystallization mechanism of calcium oxalate, the most common type of kidney stone, has been extensively researched, yet the damaging effects and mechanisms of calcium oxalate crystals on renal tubular epithelial cells remain incompletely elucidated. Regulated mitochondrial dynamics is essential for eukaryotic cells, but its role in the occurrence and progression of calcium oxalate (CaOx) nephrolithiasis is not yet understood.</p><p>Methods</p><p>An animal model of calcium oxalate-related nephrolithiasis was established in adult male Sprague‒Dawley (SD) rats by continuously administering drinking water containing 1% ethylene glycol for 28 days. The impact of calcium oxalate crystals on mitochondrial dynamics and apoptosis in renal tubular epithelial cells was investigated using HK2 cells <i>in vitro</i>. Blood samples and bilateral kidney tissues were collected for histopathological evaluation and processed for tissue injury, inflammation, fibrosis, oxidative stress detection, and mitochondrial dynamics parameter analysis.</p><p>Results</p><p>Calcium oxalate crystals caused higher levels of mitochondrial fission and apoptosis in renal tubular epithelial cells both in vivo and in vitro. Administration of a PPARγ agonist significantly alleviated mitochondrial fission and apoptosis in renal tubular epithelial cells, and improved renal function, accompanied by reduced levels of oxidative stress, increased antioxidant enzyme expression, alleviation of inflammation, and reduced fibrosis in vivo.</p><p>Conclusion</p><p>Our results indicated that increased mitochondrial fission in renal tubular epithelial cells is a critical component of kidney injury caused by calcium oxalate stones, leading to the accumulation of reactive oxygen species within the tissue and the subsequent initiation of apoptosis. Regulating mitochondrial dynamics represents a promising approach for calcium oxalate nephrolithiasis.</p></div>