Jie Wu^∗,†, Yan Cai^‡, Shixiong Xu^§, Quan Long^¶, Zurong Ding^*, Cheng Dong^∗,||

Molecular & Cellular Biomechanics, Vol.9, No.2, pp. 95-126, 2012, DOI:10.3970/mcb.2012.009.095

Abstract The effects of vascular-disrupting treatments on normalization of tumor microvasculature and its microenvironmental flow were investigated, by mathematical modeling and numerical simulation of tumor vascular-disrupting and tumor haemodynamics. Four disrupting approaches were designed according to the abnormal characteristics of tumor microvasculature compared with the normal one. The results predict that the vascular-disrupting therapies could improve tumor microenvironment, eliminate drug barrier and inhibit metastasis of tumor cells to some extent. Disrupting certain types of vessels may get better effects. In this study, the flow condition on the networks with "vascular-disrupting according to flowrate" is the best comparing with the other three… More >

Molecular & Cellular Biomechanics, Vol.9, No.1, pp. 77-94, 2012, DOI:10.3970/mcb.2012.009.077

Abstract Image-based computational modeling has been introduced for vulnerable atherosclerotic plaques to identify critical mechanical conditions which may be used for better plaque assessment and rupture predictions. In vivo patient-specific coronary plaque models are lagging due to limitations on non-invasive image resolution, flow data, and vessel material properties. A framework is proposed to combine intravascular ultrasound (IVUS) imaging, biaxial mechanical testing and computational modeling with fluid-structure interactions and anisotropic material properties to acquire better and more complete plaque data and make more accurate plaque vulnerability assessment and predictions. Impact of pre-shrink-stretch process, vessel curvature and high blood pressure on stress, strain,… More >

Ricky Martinez^†, Hai-Chao Han^‡

Molecular & Cellular Biomechanics, Vol.9, No.1, pp. 55-76, 2012, DOI:10.3970/mcb.2012.009.055

Abstract The stability of arteries is essential to normal arterial functions and loss of stability can lead to arterial tortuosity and kinking. Collagen is a main extracellular matrix component that modulates the mechanical properties of arteries and collagen degradation at pathological conditions weakens the mechanical strength of arteries. However, the effects of collagen degradation on the mechanical stability of arteries are unclear. The objective of this study was to investigate the effects of collagen degradation on the critical buckling pressure of arteries. Arterial specimens were subjected to pressurized inflation testing and fitted with nonlinear thick-walled cylindrical model equations to determine their… More >

Ze-Wei Zhang^*, Hui Wang^†, Qing-Hua Qin^∗,‡

Molecular & Cellular Biomechanics, Vol.9, No.1, pp. 31-54, 2012, DOI:10.3970/mcb.2012.009.031

Abstract This paper presents a hybrid finite element model for describing quantitatively the thermal responses of skin tissue under laser irradiation. The model is based on the boundary integral-based finite element method and the Pennes bioheat transfer equation. In this study, temporal discretization of the bioheat system is first performed and leads to the well-known modified Helmholtz equation. A radial basis function approach and the boundary integral based finite element method are employed to obtain particular and homogeneous solutions of the laser-tissue interaction problem. In the boundary integral based finite element formulation, two independent fields are assumed: intra-element field and frame… More >

Hong Qian^∗, Hao Ge^†

Molecular & Cellular Biomechanics, Vol.9, No.1, pp. 1-30, 2012, DOI:10.3970/mcb.2012.009.001

Abstract Biochemical reaction systems in mesoscopic volume, under sustained environmental chemical gradient(s), can have multiple stochastic attractors. Two distinct mechanisms are known for their origins: (a) Stochastic single-molecule events, such as gene expression, with slow gene on-off dynamics; and (b) nonlinear networks with feedbacks. These two mechanisms yield different volume dependence for the sojourn time of an attractor. As in the classic Arrhenius theory for temperature dependent transition rates, a landscape perspective provides a natural framework for the system's behavior. However, due to the nonequilibrium nature of the open chemical systems, the landscape, and the attractors it represents, are all themselves… More >

Shu Q. Liu^∗,†, Brandon J. Tefft^*, Di Zhang^*, Derek Roberts^*, Daniel J. Schuster^*, Allison Wu^*

Molecular & Cellular Biomechanics, Vol.8, No.4, pp. 319-338, 2011, DOI:10.3970/mcb.2011.008.319

Abstract Myocardial ischemia, a disorder causing myocardial infarction and malfunction, can activate various adaptive mechanisms that protect cardiomyocytes from ischemic injury. During the early hours post myocardial ischemia, injured cardiac cells can release several molecules, including adenosine, opioids, and bradykinin, which promote myocardial survival by activating the G protein signaling pathways. During a later phase about several days, myocardial ischemia induces upregulation of growth factors and cytokines, including VEGF, ILGF, HGF, and SDF-1, in the injured myocardium, contributing to cardioprotection. In addition to the injured heart, the liver participates in cardioprotection. In response to myocardial ischemia, the liver upregulates and releases… More >

Hana Chang^*, Melissa L. Knothe Tate^∗,†,‡

Molecular & Cellular Biomechanics, Vol.8, No.4, pp. 297-318, 2011, DOI:10.3970/mcb.2011.008.297

Abstract In the preceding study (Part A), we showed that prescribed seeding conditions as well as seeding density can be used to subject multipotent stem cells (MSCs) to volume changing stresses and that changes in volume of the cell are associated with changes in shape, but not volume, of the cell nucleus. In the current study, we aim to control the mechanical milieu of live cells using these prescribed seeding conditions concomitant to delivery of shape changing stresses via fluid flow, while observing adaptation of the cytoskeleton, a major cellular transducer that modulates cell shape, stiffness and remodeling. We hypothesize that… More >

Joshua A. Zimmermann^*, Melissa L. Knothe Tate^∗,†,‡

Molecular & Cellular Biomechanics, Vol.8, No.4, pp. 275-296, 2011, DOI:10.3970/mcb.2011.008.275

Abstract Shape and fate are intrinsic manifestations of form and function at the cell scale. Here we hypothesize that seeding density and protocol affect the form and function of live embryonic murine mesenchymal stem cells (MSCs) and their nuclei. First, the imperative for study of live cells was demonstrated in studies showing changes in cell nucleus shape that were attributable to fixation per se. Hence, we compared live cell and nuclear volume and shape between groups of a model MSC line (C3H10T1/2) seeded at, or proliferated from 5,000 cells/cm2 to one of three target densities to achieve targeted development contexts. Cell… More >

Wangping Duan^∗, Lei Wei^†, Juntao Zhang^∗, Yongzhuang Hao^∗, Chunjiang Li^∗, Hao Li^∗, Qi Li^∗, Quanyou Zhang^‡, Weiyi Chen^‡, Xiaochun Wei^∗,§

Molecular & Cellular Biomechanics, Vol.8, No.4, pp. 253-274, 2011, DOI:10.3970/mcb.2011.008.253

Abstract The cytoskeleton network is believed to play an important role in the biomechanical properties of the chondrocyte. Ours and other laboratories have demonstrated that chondrocytes exhibit a viscoelastic solid creep behavior in vitro and that viscoelastic properties decrease in osteoarthritic chondrocytes. In this study, we aimed to understand whether the alteration of viscoelastic properties is associated with changes in cytoskeleton components of ageing chondrocytes from rabbit knee articular cartilage. Three age groups were used for this study: young (2-months-old, N=23), adult (8-months-old, N=23), and old (31-months-old, N=23) rabbit groups. Cartilage structure and proteoglycan and type II collagen content were determined… More >

Di Pan^*, Yuhua Song^∗,†

Molecular & Cellular Biomechanics, Vol.8, No.3, pp. 233-252, 2011, DOI:10.3970/mcb.2011.008.233

Abstract Cytoskeletal restraints affect force-regulated integrin function in cell adhesion. However, the structural and molecular basis underlying the effect of cytoskeletal restraints on b1 integrin binding to fibronectin is still largely unknown. In this study, we used steered molecular dynamics simulations to investigate the changes in glycosylated b1 integrin-fibronectin binding and in conformation and structure of the glycosylated b1 I-like domain-FN-III9 - 10 complex caused by altered restraints applied to b1 I-like domain. The results revealed that imposition of the increased constraints on b1 integrin increased resistance to force-induced dissociation of the b1 I-like domain-fibronectin complex. Specifically, the increased constraints enhanced… More >