Fibroblast-Mediated Fiber Realignment in Fibrin Gels

2013 ◽  
Author(s):  
Aribet M. De Jesus ◽  
Maziar Aghvami ◽  
Edward A. Sander
Keyword(s):  
Time Lapse ◽  
Dermal Fibroblasts ◽  
Initial Alignment ◽  
Fibrin Gel ◽  
Traction Forces ◽  
Fiber Alignment ◽  
Fibrin Gels ◽  
Mechanical Constraints ◽  
Ecm Proteins ◽  
Cell Traction

When fibroblasts are added to a fibrin gel, the cells rapidly compact the gel and produce a fiber alignment pattern that depends in part on the cell traction forces, gel geometry, and gel mechanical constraints [1]. Over time the fibrin is digested and replaced with cell synthesized collagen and other extracellular matrix (ECM) proteins that follow the initial alignment pattern of the gel [2]. This remodeling process proceeds in a complex and integrated manner that is influenced by the mechanical environment [3]. In order to better understand fibroblast-fibrin interactions and the remodeling process, we obtained time-lapse images of the development of fiber alignment between clusters of dermal fibroblasts (i.e., explants) in a fibrin gel. The experimental results were then compared to a model that incorporated the effects of traction forces on ECM reorganization.

Remodeling in Cell-Seeded Fibrin Gels: Changes in Composition, Organization, and Planar Biaxial Mechanical Behavior

2009 ◽  
Author(s):  
Edward A. Sander ◽  
Sandra L. Johnson ◽  
Victor H. Barocas ◽  
Robert T. Tranquillo
Keyword(s):  
Aspect Ratio ◽  
Stress Field ◽  
Mechanical Behavior ◽  
The Other ◽  
Fibrin Gel ◽  
Fiber Alignment ◽  
Mechanical Environment ◽  
Heterogeneous Sample ◽  
Fibrin Gels ◽  
Stress Environment

Engineered tissues are necessary to replace diseased and damaged tissues incapable of healing on their own. One method employed to produce them involves cell entrapment in a fibrin gel constrained by specially designed molds [1]. As the cells compact and remodel the gel, the combination of mold constraints and cell tractions produces fiber alignment similar to native tissues [2]. One potentially important factor in the remodeling outcome is the local mechanical environment that develops during the compaction and remodeling process. It is well established that the global stress environment leads to changes in remodeling in an isotropic sample [3], but we do not know the effect of local variations in stress field in a heterogeneous sample. To begin to assess the local mechanical environment’s role, we examined the remodeling process in cross-shaped Teflon molds (cruciforms). In this experiment, two mold geometries with differing channel widths were examined: a 1:1 aspect ratio in which the both axes possessed 8 mm wide channels, and a 1:0.5 aspect ratio in which one axis had 8 mm wide channels and the other 4 mm wide channels (fig. 1).

Video-microscopic measurement of cell-substratum traction forces generated by locomoting keratocytes

1993 ◽  
Vol 51 ◽  
pp. 188-189
Author(s):  
Tim Oliver ◽  
Michelle Leonard ◽  
Juliet Lee ◽  
Akira Ishihara ◽  
Ken Jacobson
Keyword(s):  
Silicone Rubber ◽  
Molecular Motors ◽  
Video Frame ◽  
Traction Forces ◽  
Cell Traction Forces ◽  
Latex Beads ◽  
Cell Traction ◽  
Local Cell ◽  
Microscopic Measurement ◽  
Kinetics Of

We are using video-enhanced light microscopy to investigate the pattern and magnitude of forces that fish keratocytes exert on flexible silicone rubber substrata. Our goal is a clearer understanding of the way molecular motors acting through the cytoskeleton co-ordinate their efforts into locomotion at cell velocities up to 1 μm/sec. Cell traction forces were previously observed as wrinkles(Fig.l) in strong silicone rubber films by Harris.(l) These forces are now measureable by two independant means.In the first of these assays, weakly crosslinked films are made, into which latex beads have been embedded.(Fig.2) These films report local cell-mediated traction forces as bead displacements in the plane of the film(Fig.3), which recover when the applied force is released. Calibrated flexible glass microneedles are then used to reproduce the translation of individual beads. We estimate the force required to distort these films to be 0.5 mdyne/μm of bead movement. Video-frame analysis of bead trajectories is providing data on the relative localisation, dissipation and kinetics of traction forces.

scholarly journals Cell Traction Forces Direct Fibronectin Matrix Assembly

2009 ◽  
Vol 96 (2) ◽  
pp. 729-738 ◽  
Author(s):  
Christopher A. Lemmon ◽  
Christopher S. Chen ◽  
Lewis H. Romer
Keyword(s):  
Matrix Assembly ◽  
Traction Forces ◽  
Cell Traction Forces ◽  
Fibronectin Matrix ◽  
Cell Traction

scholarly journals Dissipation of contractile forces: the missing piece in cell mechanics

2017 ◽  
Vol 28 (14) ◽  
pp. 1825-1832 ◽  
Author(s):  
Laetitia Kurzawa ◽  
Benoit Vianay ◽  
Fabrice Senger ◽  
Timothée Vignaud ◽  
Laurent Blanchoin ◽  
...  
Keyword(s):  
Cell Mechanics ◽  
Force Production ◽  
Traction Force ◽  
Structural Rearrangements ◽  
Force Transmission ◽  
Traction Forces ◽  
Cell Traction Forces ◽  
Cell Traction ◽  
Contractile Forces ◽  
Fiber Contraction

Mechanical forces are key regulators of cell and tissue physiology. The basic molecular mechanism of fiber contraction by the sliding of actin filament upon myosin leading to conformational change has been known for decades. The regulation of force generation at the level of the cell, however, is still far from elucidated. Indeed, the magnitude of cell traction forces on the underlying extracellular matrix in culture is almost impossible to predict or experimentally control. The considerable variability in measurements of cell-traction forces indicates that they may not be the optimal readout to properly characterize cell contractile state and that a significant part of the contractile energy is not transferred to cell anchorage but instead is involved in actin network dynamics. Here we discuss the experimental, numerical, and biological parameters that may be responsible for the variability in traction force production. We argue that limiting these sources of variability and investigating the dissipation of mechanical work that occurs with structural rearrangements and the disengagement of force transmission is key for further understanding of cell mechanics.

scholarly journals Fibrin regulates neutrophil migration in response to interleukin 8, leukotriene B4, tumor necrosis factor, and formyl-methionyl-leucyl-phenylalanine.

1995 ◽  
Vol 181 (5) ◽  
pp. 1763-1772 ◽  
Author(s):  
J D Loike ◽  
J el Khoury ◽  
L Cao ◽  
C P Richards ◽  
H Rascoff ◽  
...  
Keyword(s):  
Extracellular Matrix ◽  
Polyethylene Glycol ◽  
Tumor Necrosis Factor ◽  
Tumor Necrosis ◽  
Leukotriene B4 ◽  
Interleukin 8 ◽  
Matrix Proteins ◽  
Fibrin Gel ◽  
Fibrin Gels ◽  
Necrosis Factor

We have examined the capacity of four different chemoattractants/cytokines to promote directed migration of polymorphonuclear leukocytes (PMN) through three-dimensional gels composed of extracellular matrix proteins. About 20% of PMN migrated through fibrin gels and plasma clots in response to a gradient of interleukin 8 (IL-8) or leukotriene B4 (LTB4). In contrast, < 0.3% of PMN migrated through fibrin gels in response to a gradient of tumor necrosis factor alpha (TNF) or formyl-methionyl-leucyl-phenylalanine (FMLP). All four chemoattractants stimulated PMN to migrate through gels composed of collagen IV or of basement membrane proteins (Matrigel), or through filters to which fibronectin or fibrinogen had been adsorbed. PMN stimulated with TNF or FMLP adhered and formed zones of close apposition to fibrin, as measured by the exclusion of a 10-kD rhodamine-polyethylene glycol probe from the contact zones between PMN and the underlying fibrin gel. By this measure, IL-8- or LTB4-treated PMN adhered loosely to fibrin, since 10 kD rhodamine-polyethylene glycol permeated into the contact zones between these cells and the underlying fibrin gel. PMN stimulated with FMLP and IL-8, or FMLP and LTB4, exhibited very little migration through fibrin gels, and three times as many of these cells excluded 10 kD rhodamine-polyethylene glycol from their zones of contact with fibrin as PMN stimulated with IL-8 or LTB4 alone. These results show that PMN chemotaxis is regulated by both the nature of the chemoattractant and the composition of the extracellular matrix; they suggest that certain combinations of chemoattractants and matrix proteins may limit leukocyte movements and promote their localization in specific tissues in vivo.

Collagen Network Architecture Varies Between Pure Collagen and Collagen-Fibrin Co-Gels

2012 ◽  
Author(s):  
Victor K. Lai ◽  
Allan M. Kerandi ◽  
Spencer P. Lake ◽  
Robert T. Tranquillo ◽  
Victor H. Barocas
Keyword(s):  
Mechanical Behavior ◽  
Network Architecture ◽  
Rational Design ◽  
Structural Integrity ◽  
Collagen Network ◽  
Fibrin Gel ◽  
Ecm Proteins ◽  
Fibrin Networks ◽  
Pure Collagen ◽  
Function Relationship

Naturally-occurring extracellular matrix (ECM) proteins, e.g. collagen I and fibrin, play an important role in tissues, conferring structural integrity and providing a biochemical environment for eliciting important cellular responses (e.g. migration). Tissue engineers use a variety of matrix polymers as initial scaffolds for seeding cells, sometimes in combination with one another (e.g. collagen-fibrin [1]). For example, our group fabricates arterial tissue equivalents (TEs) by seeding cells in a fibrin gel, which is gradually degraded over time and replaced by cell-produced collagen [2]. While the structure and mechanics of individual ECM proteins have been studied extensively, how multiple fibrillar networks interact to confer overall mechanical behavior remains poorly understood. Narrowing this gap in knowledge of scaffolds comprising multiple fibril networks is crucial in allowing for more rational design in tissue engineering, as cells react differently according to their mechanical environments. For collagen-fibrin networks in particular, early efforts in elucidating interactions between these two fibril networks in co-gels have proven inconclusive due to inconsistent findings from various groups. Recent modeling efforts by our group have shown that simple “series” and “parallel” type interactions provide bounds for the mechanical behavior of collagen-fibrin co-gels [3]. In addition, experiments on pure collagen and fibrin vs. their respective networks from collagen-fibrin co-gels after digestion showed slight differences in mechanical behavior [4]. These previous studies have focused on the composition-function relationship between collagen and fibrin. The objective of the current work is to explore how collagen network architecture changes in the presence of the fibrin network in collagen-fibrin co-gels, thereby providing an added dimension to our understanding of collagen-fibrin systems by elucidating structure-composition-function relationships between collagen and fibrin.

Development of micropost force sensor array with culture experiments for determination of cell traction forces

2007 ◽  
Vol 64 (7) ◽  
pp. 509-518 ◽  
Author(s):  
Bin Li ◽  
Luke Xie ◽  
Zane C. Starr ◽  
Zhaochun Yang ◽  
Jeen-Shang Lin ◽  
...  
Keyword(s):  
Sensor Array ◽  
Force Sensor ◽  
Traction Forces ◽  
Cell Traction Forces ◽  
Cell Traction
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