Influence of oxalic acid and calcium oxalate monohydrate crystals on human renal tubular epithelial cells / 中华泌尿外科杂志

ABSTRACT

Objective To evaluate the toxic effects of oxalic acid and calcium oxalate monohydrate crystals on human renal tubular epithelial cells (HK-2) as well as the influence on cell protein expression. Methods Normal HK-2 cells were cultured in vitro and the culture medium was changed to serum-free medium after cell growth to confluence. Oxalic acid with different concentration wasthen added and the formation of crystals and their adherence to cells were observed microscopically. A Fourier infrared spectrometer (FT-IR) was used to analyze the crystal composition. The toxic effects of 1, 2, 5 and 10 mmol/L oxalic acid on HK-2 cells after incubation for 4, 12 and 24 h were detected with a CCK-8 kit. Changes of protein express of HK-2 cells were determined using the Bradford method. Results Crystal formation and adherence to cell surface could be microscopically observed in a few minutes after oxalic acid was added to the DMED medium containing Caz+. The composition of the crystals was revealed to be calcium oxalate monohydrate by FT-IR. Oxalic acid and calcium oxalate monohydrate presented a concentration-dependent toxic effect on HK-2 cells which was, however, not merely increased with time lasting. The quantity of protein expressed by HK-2 cells incubated with 1,2, 5 mmol/L oxalic acid for 12 h and that of control was 358±51, 365±43, 328±52 and 329±60 mg/L, respectively (all P>0. 05), while the quantity of protein was significantly smaller than that of control after the incubation of 10 mmol/L oxalic acid for 12 h (264±76 vs 329±60 mg/L,P<0. 05).Conclusion Oxalic acid and calcium oxalate monohydrate crystals have toxic effects on normal human HK-2 cells and cause changes in protein expression,which may play an important role in the formation of renal calculi.