title: The development of structural and mechanical anisotropy in fibroblast populated collagen gels.
abstract: An in vitro model system was developed to study structure-function relationships and the development of structural and mechanical anisotropy in collagenous tissues. Fibroblast-populated collagen gels were constrained either biaxially or uniaxially. Gel remodeling, biaxial mechanical properties, and collagen orientation were determined after 72 h of culture. Collagen gels contracted spontaneously in the unconstrained direction, uniaxial mechanical constraints produced structural anisotropy, and this structural anisotropy was associated with mechanical anisotropy. Cardiac and tendon fibroblasts were compared to test the hypothesis that tendon fibroblasts should generate greater anisotropy in vitro. However, no differences were seen in either structure or mechanics of collagen gels populated with these two cell types, or between fibroblast populated gels and acellular gels. This study demonstrates our ability to control and measure the development of structural and mechanical anisotropy due to imposed mechanical constraints in a fibroblast-populated collagen gel model system. While imposed constraints were required for the development of anisotropy in this system, active remodeling of the gel by fibroblasts was not. This model system will provide a basis for investigating structure-function relationships in engineered constructs and for studying mechanisms underlying the development of anisotropy in collagenous tissues.
authors.affiliation: Department of Orthopaedic Surgery, Washington University School of Medicine, 1 Barnes-Jewish Hospital Plaza, Suite 11300, Campus Box 8233, St, Louis, MO 63110, USA. thomopoulosS@msnotes.wustl.edu
authors.forename: Stavros
authors.initials: S
authors.lastname: Thomopoulos
authors.forename: Gregory M
authors.initials: GM
authors.lastname: Fomovsky
authors.forename: Jeffrey W
authors.initials: JW
authors.lastname: Holmes
mesh_terms: D000818:Animals; D016880:Anisotropy; D001672:Biocompatible Materials / Q000032:analysis / Q000737:chemistry; D001696:Biomechanical Phenomena / Q000379:methods; D018929:Cell Culture Techniques / Q000379:methods*; D016764:Cell Polarity; D002478:Cells, Cultured; D024042:Collagen Type I / Q000032:analysis / Q000737:chemistry*; D003198:Computer Simulation; D004548:Elasticity; D005347:Fibroblasts / Q000166:cytology* / Q000502:physiology*; D005782:Gels / Q000032:analysis / Q000737:chemistry; D040542:Mechanotransduction, Cellular / Q000502:physiology*; D008954:Models, Biological; D051381:Rats; D017207:Rats, Sprague-Dawley; D013314:Stress, Mechanical; D023822:Tissue Engineering / Q000379:methods
chemical_list: D001672:Biocompatible Materials; D024042:Collagen Type I; D005782:Gels