Presentation Abstract

Program#/Poster#: 1528/A484
Abstract Title: Continuous Measurement Of Physical Forces During Human Primary Corneal Fibroblast Migration
Presentation Start/End Time: Monday, May 07, 2012, 8:30 AM -10:15 AM
Session Number: 229
Session Title: Corneal Biomechanics I
Location: Hall B/C
Reviewing Code: 149 corneal biomechanics - CO
Author Block: Dhananjay Tambe1, Ramin Zareian2, Dimitrios Karamichos3, James D. Zieske3, Jeffrey W. Ruberti2. 1Department of Environmental Health, Harvard school of public health, Boston, MA; 2Mechanical Engineering, Northeastern University, Boston, MA; 3Department of Ophthalmology, Schepens Eye Research Institute, Harvard medical school, Boston, MA.
Keywords: 447 cell-cell communication, 518 extracellular matrix, 550 imaging/image analysis: non-clinical
Abstract Body: Purpose: : Little is known about the mechanobiology of matrix production by corneal fibroblasts which have been shown to self organize and produce extracellular matrix in vitro. During coordinated migration, epithelial and endothelial cells apply forces to the substrate as well as to their neighbors [Trepat et al 2009 Tambe et al 2011]. If such forces are generated by fibroblasts during matrix production, they may influence the deposition and retention of collagenous matrix [Zareian et al 2010]. However it is very difficult to follow fibroblast behavior while measuring forces on time scales long enough to permit matrix production. Here we present an in vitro mechanobiological assay capable of directly observing the behavior of PHCF over relatively long time scales while simultaneously measuring intrinsic (cell-cell and cell-substrate) physical forces.
Methods: We combine the mechanobioreactor described in [Paten et al 2011] with a 100um thick, collagen coated, calibrated polyacrylamide gel [E=1250 Pa Yeung et al 2005] to observe the mechanobiology of PHCF culture. Forces applied to the substrate are interrogated continuously via embedded 0.5um fluorescent beads. Using Fourier transform traction microscopy the gel deformation is transformed into a continuous traction vector field applied by the cells to the substrate. Using monolayer stress microscopy the traction field is transformed into stresses applied by the cells to their neighbors.
Results: Over the time course of this experiment, the corneal fibroblasts actively migrate over the gel surface and begin to form a confluent monolayer. We observe that cells gradually build up tractions. When they self organize, the traction at a point has contributions from two sources, contraction generated by cells attached at that location, and contractions generated by cells far from that location but transmitted through cell-cell contacts. Magnitude of this traction is on the order of 150Pa.
Conclusions: The combination of the mechanobioreactor with the traction force microscopy method permits direct measurement PHCF physical forces during migration and growth to confluence. The system will ultimately enable dynamic, continuous and quantitative observation of the mechanobiology of matrix production.
CommercialRelationships:  Dhananjay Tambe, None; Ramin Zareian, None; Dimitrios Karamichos, None; James D. Zieske, None; Jeffrey W. Ruberti, None
Support: NIH NIAMS R21 AR053551-01



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