Objective To study the ultrastructure of PC12 cells before and after treatment with amyloid protein ( Ap25_35) by atomic force microscopy ( AFM) for further understanding the amyloid protein - induced membrane damage mechanism. Methods PC 12 cells were treated with different concentrations of A(325_35. The cell activity, cell apoptosis, membrane ultrastructure and size distribution were characterized by CCK-8 cell viability assay, flow cytometry (FCM) , and AFM. Results CCK -8 experiments showed that the significant decrease in cell viability was induced by increased concentrations of A(J25_35, which was significantly lower than that of the normal group, especially in the concentration of 25 u.moI/L. Flow cytometry analysis demonstrated that the apoptosis rate was (5. 60 ±0. 61) % when A|325 _35 concentration was 15 p,mol/L in low concentration group. However, the apoptosis rate was up to ( 16. 17 ± 0. 79 ) % (P < 0. 01 ) when A(325_35 concentration was increased to 25 u,mol/L in high concentrations group. This indicated that more apoptosis was appeared through increased concentrations of A(325_3;. AFM images demonstrated that the more collapse and more holes were appeared with increased concentrations of Ap25_35. Specially, cell membrane damage and increased particle size were observed. Conclusions When cells treated with increased concentration of Af$25 _35, cells is appeared apoptosis and membrane is damaged.%目的 利用原子力显微镜(Atomic force microscopy,AFM)对淀粉样蛋白(Aβ25 ～35)处理前后细胞全貌和表面超微结构进行成像分析,为进一步了解Aβ25-35诱导的细胞膜损伤机制提供可视化的依据.方法 用不同浓度的Aβ25 ～ 35处理PCl2细胞,CCK-8实验检测细胞活性,流式细胞术分析细胞凋亡,AFM对细胞进行表面超微结构成像和粒径分布分析.结果 CCK-8实验表明,随着Aβ25 ～35蛋白浓度的增加,细胞活性明显下降,特别是Aβ25 ～35 25 μmol/L时细胞活性明显低于正常组.流式细胞术分析细胞凋亡,Aβ25 ～35浓度在15 μmol/L(低浓度诱导组)时,细胞凋亡率为(5.60±0.61)％；但在25 μmol/L时(高浓度诱导组),细胞凋亡率达到(16.17±0.79)％(P＜0.01),可见,随Aβ25 ～35浓度增加,细胞凋亡越明显；AFM分析细胞形貌和超微结构,随着Aβ25～35蛋白浓度增加,细胞塌陷更严重,细胞表面孔洞增加,颗粒物质粒径减小,细胞膜损伤程度更大.结论 AFM分析数据表明,诱导组细胞活性下降,出现细胞凋亡,细胞膜受到损伤.
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