Fibrillogenic amylin evokes the apoptosis of human mesangial cells

ObjectiveTo explore the apoptotic role of amylin on human mesangial cell (MC).Materials and methodsPrimarily cultured human MCs were applied and treated with fresh amylin preparation. Human MCs were identified by the morphology and immunofluorescence staining. The apoptotic cells were determined by ultrastructure changes, TUNEL, and DNA fragmentation analysis. Propidium iodide staining and flow cytometry was employed for quantitative measurement of apoptosis.ResultsUnder the light and transmission electronic microscopy (TEM), the human MCs with condensed chromatin, plasma shrinkage, marginated nuclear chromatin or apoptotic body were observed in amylin-treated MCs. Positive TUNEL staining, hypolipoid DNA peak, and typical DNA “ladder” pattern were also detected in amylin-treated MCs. Quantitative analysis of the apoptotic MCs showed that human amylin induced an increase of the percentage of apoptotic cells in a dose-dependent manner. Amylin nano-scale fibrils (5–18 nm) in diameter were detected in the cultured solution using negative staining under the TEM. Compared to the control, no significant changes of lactate dehydrogenase release were observed in amylin-treated MCs (P > 0.05).ConclusionsFibrillogenic amylin evokes the apoptosis of human MCs in vitro, which may explain the mechanism of the hypocellular mesangial damage and progressive glomerulosclerosis of the patients with diabetic nephropathy.