Mechanism of action and side effects of colchicine based on biomechanical properties of cells.

Many diseases are related to changes in the biomechanical properties of cells; their study can provide a theoretical basis for drug screening and can explain the internal working of living cells. In this study, the biomechanical properties of nephrocytes (VERO cells), hepatocytes (HL-7702 cells), and hepatoma cells (SMCC-7721 cells) in culture were detected by atomic force microscopy (AFM) to analyse the side effects of colchicine at different concentrations (0.1 µg/mL (A) and 0.2 µg/mL (B)) at the nanoscale for 2, 4 and 6 h. Compared with the corresponding control cells, the damage to the treated cells increased in a dose-dependent manner. Among normal cells, the injury of nephrocytes (VERO cells) was markedly worse than that of hepatocytes (HL-7702 cells) in both colchicine solutions A and B. Based on the analyses of biomechanical properties, the colchicine solution reduced the rate of division and inhibited metastasis of SMCC-7721 cells. By comparing these two concentrations, we found that the anticancer effect of colchicine solution A was greater than that of solution B. Studying the mechanical properties of biological cells can help understand the mechanism of drug action at the molecular level and provide a theoretical basis for preventing the emergence and diagnosis of diseases at the nanoscale.

Electrical conductivity measurement ofλDNA molecules by conductive atomic force microscopy.

Conductive atomic force microscopy (C-AFM) is a powerful tool used in the microelectronics analysis by applying a certain bias voltage between the conducting probe and the sample and obtaining the electrical information of sample. In this work, the surface morphological information and current images of the lambda DNA (λDNA) molecules with different distributions were obtained by C-AFM. The 1 and 10 ngµl-1DNA solutions were dripped onto mica sheets for making randomly distributed DNA and DNA network samples, and another 1 ngµl-1DNA sample was placed in a DC electric field with a voltage of 2 V before being dried for stretching the DNA sample. The results show that the current flowing through DNA networks was significantly higher than the stretched and random distribution of DNA in the experiment. TheI-Vcurve of DNA networks was obtained by changing the bias voltage of C-AFM from -9 to 9 V. The currents flowing through stretched DNA at different pH values were studied. When the pH was 7, the current was the smallest, and the current was gradually increased as the solution became acidic or alkaline.

Analysis of Colchicine-Induced Effects on Hepatoma and Hepatocyte Cells by Atomic Force Microscopy.

Biomechanical properties of cells are altered by many diseases. Cancer cell metastasis is related to the properties such as the cell stiffness that influences cell proliferation, differentiation and migration. In this paper, we used an atomic force microscope to analyze the colchicine-induced effects on the mechanical properties of hepatocyte (HL-7702 cells) and hepatoma cells (SMCC-7721 cells) in culture at the nanoscale. The cells were exposed to a solution with a normal dose of colchicine for two, four and six hours. Surface topographic images showed that colchicine decreased the stability of the cytoskeleton. After the same six-hour treatment in a solution with a normal dose of colchicine, the biomechanical properties of HL-7702 cells were almost unchanged. However, the stiffness and the adhesion force of the SMCC-7721 cells were clearly increased (more than twofold of the normal values), especially after four hours. The deformability of SMCC-7721 cancer cells was significantly decreased within the six-hour treatment in the solution with a normal dose of colchicine. Analysis of the biomechanical properties of post-treatment hepatoma cells provided a complementary explanation for the mechanism of action of colchicine on cells at the nanoscale. This method is expected to allow the monitoring of potential metastatic cancer cell changes, thus preventing the emergence and the transmission of disease, and improving the diagnosis of cancer.

Biomechanical measurement and analysis of colchicine-induced effects on cells by nanoindentation using an atomic force microscope.

Colchicine is a drug commonly used for the treatment of gout, however, patients may sometimes encounter side-effects induced by taking colchicine, such as nausea, vomiting, diarrhea and kidney failure. In this regard, it is imperative to investigate the mechanism effects of colchicine on biological cells. In this paper, we present a method for the detection of mechanical properties of nephrocytes (VERO cells), hepatocytes (HL-7702 cells) and hepatoma cells (SMCC-7721 cells) in culture by atomic force microscope (AFM) to analyze the 0.1 µg/mL colchicine-induced effects on the nanoscale for two, four and six hours. Compared to the corresponding control cells, the biomechanical properties of the VERO and SMCC-7721 cells changed significantly and the HL-7702 cells did not considerably change after the treatment when considering the same time period. Based on biomechanical property analyses, the colchicine solution made the VERO and SMCC-7721 cells harder. We conclude that it is possible to reduce the division rate of the VERO cells and inhibit the metastasis of the SMCC-7721 cells. The method described here can be applied to study biomechanics of many other types of cells with different drugs. Therefore, this work provides an accurate and rapid method for drug screening and mechanical analysis of cells in medical research.

Axisymmetric Contact Problem for a Flattened Cell: Contributions of Substrate Effect and Cell Thickness to the Determination of Viscoelastic Properties by Using AFM Indentation.

Nanoindentation technology has proven to be an effective method to investigate the viscoelastic properties of biological cells. The experimental data obtained by nanoindentation are frequently interpreted by Hertz contact model. However, in order to validate Hertz contact model, some studies assume that cells have infinite thickness which does not necessarily represent the real situation. In this study, a rigorous contact model based upon linear elasticity is developed for the interpretation of indentation tests of flattened cells. The cell, normally bonded to the Petri dish, is initially treated as an elastic layer of finite thickness perfectly fixed to a rigid substrate. The theory of linear elasticity is utilized to solve this contact issue and then the solutions are extended to viscoelastic situation which is regarded as a good indicator for mechanical properties of biological cells. To test the present model, AFM-based creep test has been conducted on living human hepatocellular carcinoma cell (SMMC-7721 cell) and its fullerenol-treated counterpart. The results indicate that the present model could not only describe very well the creep behavior of SMMC-7721 cells, but also curb overestimation of the mechanical properties due to substrate effect.