Sit P Sidney, Kohn Joachim
Department of Chemistry and Chemical Biology, Rutgers University and New Jersey Center for Biomaterials, Piscataway, NJ 08854, USA.
Acta Biomater. 2009 Oct;5(8):2823-31. doi: 10.1016/j.actbio.2009.05.022. Epub 2009 May 27.
The membrane stiffness (epsilon) of rat lung fibroblasts (RLFs) adhered on different polymeric surfaces was probed by atomic force microscopy. The corresponding cell morphology was also analyzed to probe its interrelationship with epsilon. Two tyrosine-derived polymer families, poly(DTR glutarate)s and poly(DTE-co-PEG(1000) carbonate)s with systematic variations in the chemical composition and physical properties, notably surface hydrophilicity, were used. The cell membrane of adhered RLFs was indented by a probe tip. epsilon was obtained by best-fitting the relationship of applied tip forces and the indentation depth with the Hertz model. Excluding tissue culture polystyrene, non-PEG-containing polymers are generally hydrophobic and the changes in chemical composition do not elicit significant changes in epsilon. In contrast, polymers containing as little as 2mol.% PEG display a major increase in surface hydrophilicity and invoke a substantial decrease in epsilon. Additionally, RLFs show a high degree of spreading and fibroblastic appearance on non-PEG-containing polymers, but much less spreading and axial morphology when PEG is present. A mechanism is proposed to explain how a cell maintains its structural integrity on different polymeric surfaces: the degree of cell spreading is higher on non-PEG-containing surfaces than on PEG-containing ones, resulting in more extended cytoskeletal filaments and hence a stiffer cell membrane. Our studies shed light on the use of cellular micromechanics, and in particular membrane stiffness, to characterize cell response as a function of the chemical composition of the underlying substrata.
采用原子力显微镜探测黏附在不同聚合物表面的大鼠肺成纤维细胞（RLFs）的膜刚度（ε）。同时分析相应的细胞形态，以探究其与ε的相互关系。使用了两个酪氨酸衍生的聚合物家族，即聚（DTR戊二酸酯）和聚（DTE-co-PEG(1000)碳酸酯），它们在化学组成和物理性质（特别是表面亲水性）上有系统变化。用探针尖端压入黏附的RLFs的细胞膜。通过将施加的尖端力与压痕深度的关系与赫兹模型进行最佳拟合来获得ε。除了组织培养聚苯乙烯外，不含PEG的聚合物通常是疏水的，化学组成的变化不会引起ε的显著变化。相反，含有低至2mol.%PEG的聚合物表面亲水性大幅增加，ε显著降低。此外，RLFs在不含PEG的聚合物上表现出高度铺展和成纤维细胞外观，但当存在PEG时铺展程度和轴向形态要小得多。提出了一种机制来解释细胞如何在不同聚合物表面维持其结构完整性：细胞在不含PEG的表面上的铺展程度高于含PEG的表面，导致细胞骨架丝更伸展，从而细胞膜更硬。我们的研究揭示了利用细胞微力学，特别是膜刚度，来表征细胞对底层基质化学成分的响应。
