Atomic force microscopy (AFM) and fluorescence microscopy was applied to determine the influence of the anti-aging peptides on the morphology and the mechanical properties of keratinocytes. Immortalized human keratinocytes (HaCaT) were treated with two anti-aging bioactive peptides: Acetyl Tetrapeptide-2 and Acetyl Hexapeptide-50 (Lipotec). The AFM measurement of the keratinocyte stiffness were carried after 48 h exposure at an indentation depth of 200 nm. AFM analysis showed increase of the cell stiffness for cells treated with Acetyl Tetrapeptide-2 (P1) in concentration range. Acetyl Hexapeptide-50 (P2) at concentration of 0.05 µg/ml also increased the stiffness of HaCaT cells but at higher concentrations 0.5 and 5 µg/ml cell stiffness was lower as compared to untreated control. Fluorescence microscopy revealed remodeling of actin filaments dependent on the concentration of P2 peptide. The mechanical response of HaCaT cells treated with P2 peptide corresponds to change of transcription level of ACTN1 and SOD2 which activity was expected to be modulated by P2 treatment.

中文翻译：

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抗衰老肽对 HaCaT 角质形成细胞机械和生物学特性的影响。

应用原子力显微镜（AFM）和荧光显微镜确定抗衰老肽对角质形成细胞形态和机械性能的影响。用两种抗衰老生物活性肽处理永生化人角质细胞 (HaCaT)：Acetyl Tetrapeptide-2 和 Acetyl Hexapeptide-50 (Lipotec)。暴露 48 小时后，以 200 nm 的压痕深度进行角质形成细胞硬度的 AFM 测量。AFM 分析显示，在一定浓度范围内，用乙酰四肽-2 (P1) 处理的细胞的细胞硬度有所增加。浓度为 0.05 µg/ml 的乙酰基六肽-50 (P2) 也增加了 HaCaT 细胞的硬度，但浓度较高时，0.5 和 5 µg/ml 的细胞硬度比未处理的对照更低。荧光显微镜显示肌动蛋白丝的重塑依赖于 P2 肽的浓度。用 P2 肽处理的 HaCaT 细胞的机械反应对应于 ACTN1 和 SOD2 转录水平的变化，预计其活性会受到 P2 处理的调节。