title: Operating curves to characterize the contraction of fibroblast-seeded collagen gel/collagen fiber composite biomaterials: effect of fiber mass.
abstract: BACKGROUND
  Collagen is a well-established and important biomaterial that could be used to help meet significant medical needs for various soft-tissue replacements. Many efforts to create engineered soft-tissue constructs by seeding cells within collagen gels have been hampered because constituent cells contract collagen gels over time, resulting in a construct that is only a fraction of the original size and that contains a cell population that has suffered a large degree of cell death. However, the presence of embedded short collagen fibers has been shown to significantly limit contraction and dramatically enhance permeability in fibroblast-seeded collagen gels.
  
  
  METHODS
  Five volume fractions of short collagen fibers were embedded in fibroblast-seeded collagen gels. Collagen gel contraction (n > or = 4 for all groups) and cell viability (n > or = 3 for all groups) were examined after up to 2 weeks in culture.
  
  
  RESULTS
  The present study demonstrated that increasing the volume fraction of short collagen fibers in fibroblast-seeded collagen gels correspondingly reduced the amount of gel contraction without negatively impacting cell viability after 2 weeks of culture. Furthermore, operating curves that describe the quantitative relationships between the contraction of fibroblast-seeded collagen gel/collagen fiber composite biomaterials, time in culture, and volume fraction of embedded fibers were obtained.
  
  
  CONCLUSIONS
  The resulting operating curves enable investigators to tailor initial fabrication procedures to ultimately yield cell-seeded collagen composites of specifically desired sizes-a critical step toward developing clinically useful engineered soft-tissue constructs.
authors.affiliation: Department of Biomedical Engineering, Tulane University, USA.
authors.forename: Eileen
authors.initials: E
authors.lastname: Gentleman
authors.forename: Kay C
authors.initials: KC
authors.lastname: Dee
authors.forename: Glen A
authors.initials: GA
authors.lastname: Livesay
authors.forename: Eric A
authors.initials: EA
authors.lastname: Nauman
mesh_terms: D000818:Animals; D001672:Biocompatible Materials / Q000494:pharmacology*; D002470:Cell Survival; D003094:Collagen / Q000494:pharmacology*; D005347:Fibroblasts / Q000502:physiology*; D005782:Gels; D008422:Materials Testing; D051381:Rats; D012867:Skin; D023822:Tissue Engineering; D014945:Wound Healing
chemical_list: D001672:Biocompatible Materials; D005782:Gels; D003094:Collagen