X. Edward Guo^∗,†,‡, Erica Takai^∗,‡, Xingyu Jiang^§, Qiaobing Xu^§, George M. Whitesides^§, James T. Yardley^¶, Clark T. Hung^*, Eugene M. Chow^||, Thomas Hantschel^∗∗, Kevin D. Costa^∗

Molecular & Cellular Biomechanics, Vol.3, No.3, pp. 95-108, 2006, DOI:10.3970/mcb.2006.003.095

Abstract In this study, bone cells were successfully cultured into a micropatterned network with dimensions close to that of in vivo osteocyte networks using microcontact printing and self-assembled monolyers (SAMs). The optimal geometric parameters for the formation of these networks were determined in terms of circle diameters and line widths. Bone cells patterned in these networks were also able to form gap junctions with each other, shown by immunofluorescent staining for the gap junction protein connexin 43, as well as the transfer of gap-junction permeable calcein-AM dye. We have demonstrated for the first time, that the intracellular calcium response of a… More >

Yong Gan^*, Zhen Chen^∗,†

Molecular & Cellular Biomechanics, Vol.3, No.3, pp. 89-94, 2006, DOI:10.3970/mcb.2006.003.089

Abstract Due to their nanoscale size and special features, carbon nanotubes could enter the human body via certain way. The growing use of carbon nanotubes in practical applications, hence, prompts a necessity to study the potential health risks of carbon nanotubes. A numerical study is performed in this paper to investigate the size effect of carbon nanotubes on the bulk modulus of a lipid bilayer by using the constant surface tension molecular dynamics simulation procedure. It is found that the size effect is not monotonic with the increase of nanotube length. An explanation is given on the basis of the atomic… More >

Meghan H. Hoskins^*, Cheng Dong^∗,†

Molecular & Cellular Biomechanics, Vol.3, No.2, pp. 79-88, 2006, DOI:10.3970/mcb.2006.003.079

Abstract It has been determined previously that polymorphonuclear leukocytes, or PMNs, can facilitate melanoma cell extravasation through the endothelium under shear conditions [1,2]. The interactions between melanoma cells and PMNs are mediated by the β₂-integrins expressed by PMNs and intercellular adhesion molecules (ICAM-1) expressed on melanoma cells. In this study, the kinetics of these interactions was studied using a parallel plate flow chamber. The dissociation rates were calculated under low force conditions for ICAM-1 interactions with both β₂-integrins, LFA-1 (CD11a/CD18) and Mac-1 (CD11b/CD18), together and separately by using functional blocking antibodies on PMNs. The kinetics of PMNs stimulated with IL-8 was… More >

Jui-Ming Yang^*, Philip R. LeDuc^∗,†

Molecular & Cellular Biomechanics, Vol.3, No.2, pp. 69-78, 2006, DOI:10.3970/mcb.2006.003.069

Abstract Inorganic and organic integrated systems detect, process, and respond to signals from solid media. Advances in fluidic systems have offered an alternative to traditional signaling methods through the development of aqueous signaling systems. Here, we show an experimentally simple mechanically governed fluidic system that creates three-dimensional molecular multiphase separation in a combination of discrete and continuous gradients analogous to digital and analog signals that can be used for controlled spatiotemporal cellular stimulation. We accomplish the pattern formation by fabricating a compartmentalized multi-level fluidics device where a network of capillaries converges into a main channel. Simultaneous control of the fluid streams… More >

Guanbin Song^∗,†, Toshiro Ohashi^†, Naoya Sakamoto^†, Masaaki Sato^†

Molecular & Cellular Biomechanics, Vol.3, No.2, pp. 61-68, 2006, DOI:10.3970/mcb.2006.003.061

Abstract Expression of adhesion molecules may play an important role in the interaction of tumor cells with vascular endothelial cells during tumor invasion and metastasis. In this study, the adhesive force of human hepatoma HepG2 cells to human umbilical vein endothelial cells (HUVECs) was investigated using a micropipette aspiration technique. Expression of an adhesion molecule, E-selectin, was also observed by immunofluorescence microscopy. In particular, the adhesive force after stimulation of HUVECs with recombinant human interleukin-1β (rhIL-1β) was examined. The results demonstrated that the adhesive force of HepG2 cells to stimulated HUVECs is significantly higher than that of unstimulated control cells, and… More >

Shaohua Hu^*, Ning Wang^†

Molecular & Cellular Biomechanics, Vol.3, No.2, pp. 49-60, 2006, DOI:10.3970/mcb.2006.003.049

Abstract One fundamental question in cell biology is how mechanical stresses are distributed inside the cytoplasm. Recently we have developed a synchronous detection approach to map cytoplasmic displacements and stresses using yellow fluorescent protein tagged mitochondria as fiducial markers of the cytoskeleton (CSK) in response to a localized load applied via an RGD-coated magnetic bead (7). We have shown that stresses are propagated to remote sites in the cytoplasm, a finding that contradicts continuum model predictions. Here we show that long distance force propagation in the cytoplasm was abolished when the contractile prestress in the CSK was lowered by relaxing agents… More >

Konstantinos A. Lazopoulos¹, Dimitrije Stamenović²

Molecular & Cellular Biomechanics, Vol.3, No.1, pp. 43-48, 2006, DOI:10.3970/mcb.2006.003.043

Abstract It is well documented that in response to substrate stretching adhering cells alter their orientation. Generally, the cells reorient away from the direction of the maximum substrate strain, depending upon the magnitude of the substrate strain and the state of cell contractility. Theoretical models from the literature can describe only some aspects of this phenomenon. In the present study, we developed a more comprehensive mathematical model of cell reorientation than the current models. Using the framework of theory of non-linear elasticity, we found that the problem of cell reorientation was a stability problem, with the global (Maxwell's) criterion for stability.… More >

K.Y. Volokh¹

Molecular & Cellular Biomechanics, Vol.3, No.1, pp. 35-42, 2006, DOI:10.3970/mcb.2006.003.035

Abstract It is common practice in the arterial wall modeling to assume material incompressibility. This assumption is driven by the observation of the global volume preservation of the artery specimens in some mechanical loading experiments. The global volume preservation, however, does not necessarily imply the local volume preservation -- incompressibility. In this work, we suggest to use the arterial ring- cutting experiments for the assessment of the local incompressibility assumption. The idea is to track the local stretches of the marked segments of the arterial ring after the stress-relieving cut. In the particular case of the rabbit thoracic artery, considered in… More >

Kyle Kurpinski^1,2,3, Jennifer Park^1,2,3, Rahul G. Thakar^1,2,3, Song Li^1,2

Molecular & Cellular Biomechanics, Vol.3, No.1, pp. 21-34, 2006, DOI:10.3970/mcb.2006.003.021

Abstract Vascular smooth muscle cells (SMCs) populate in the media of the blood vessel, and play an important role in the control of vasoactivity and the remodeling of the vessel wall. Blood vessels are constantly subjected to hemodynamic stresses, and the pulsatile nature of the blood flow results in a cyclic mechanical strain in the vessel walls. Accumulating evidence in the past two decades indicates that mechanical strain regulates vascular SMC phenotype, function and matrix remodeling. Bone marrow mesenchymal stem cell (MSC) is a potential cell source for vascular regeneration therapy, and may be used to generate SMCs to construct tissue-engineered… More >

Jizeng Wang^1,2, Xiaojun Fan², Huajian Gao²

Molecular & Cellular Biomechanics, Vol.3, No.1, pp. 13-20, 2006, DOI:10.3970/mcb.2006.003.013

Abstract This paper is aimed at a combined theoretical and numerical study of the force-extension relation of a short DNA molecule stretched in an electrolyte. A theoretical formula based on a recent discrete wormlike chain (WLC) model of Kierfeld et al. (Eur. Phys. J. E, Vol. 14, pp.17-34, 2004) and the classical OSF mean-field theory on electrostatic stiffening of a charged polymer is numerically verified by a set of Brownian dynamics simulations based on a generalized bead-rod (GBR) model incorporating long-ranged electrostatic interactions via the Debye-Hueckel potential (DH). The analysis indicates that the stretching of a short DNA can be well… More >