Extracellular Matrix Expression and Production in Fibroblast-Collagen Gels: Towards an In Vitro Model for Ligament Wound Healing
Ligament wound healing involves the proliferation of a dense and disorganized fibrous matrix that slowly remodels into scar tissue at the injury site. This remodeling process does not fully restore the highly aligned collagen network that exists in native tissue, and consequently repaired ligament has decreased strength and durability. In order to identify treatments that stimulate collagen alignment and strengthen ligament repair, there is a need to develop in vitro models to study fibroblast activation during ligament wound healing. The objective of this study was to measure gene expression and matrix protein accumulation in fibroblast-collagen gels that were subjected to different static stress conditions (stress-free, biaxial stress, and uniaxial stress) for three time points (1, 2 or 3 weeks). By comparing our in vitro results to prior in vivo studies, we found that stress-free gels had time-dependent changes in gene expression (col3a1, TnC) corresponding to early scar formation, and biaxial stress gels had protein levels (collagen type III, decorin) corresponding to early scar formation. This is the first study to conduct a targeted evaluation of ligament healing biomarkers in fibroblast-collagen gels, and the results suggest that biomimetic in-vitro models of early scar formation should be initially cultured under biaxial stress conditions.
KeywordsCellular collagen gels Mouse embryonic fibroblasts Proteomics Gene expression Biaxial stress Uniaxial stress Confocal microscopy
Authors wish to thank John Everingham for designing and assembling the cruciform, Laura Bond for statistical analysis, and Peter Martin for analysis of Alcian blue stained images. Authors acknowledge support by the Institutional Development Award (IDeA) Program from the National Institute of General Medical Sciences of the National Institutes of Health under Grants #P20GM103408 and P20GM109095. We also acknowledge support from The Biomolecular Research Center at Boise State with funding from the National Science Foundation, Grants #0619793 and #0923535; the MJ Murdock Charitable Trust; Lori and Duane Steuckle, and the Idaho State Board of Education. Authors have no competing financial interests.
Conflict of interest
Authors have no competing financial interests.
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