title: Differences in the mechanism for high- versus moderate-density fibroblast-populated collagen lattice contraction.
abstract: The free-floating fibroblast-populated collagen lattice (FPCL) model introduced by Bell contains 0.5 x 10(5) cell/ml and here is defined as a moderate-density FPCL (MD-FPCL). One modification of the model is to increase the cell density by a factor of 10, where 5 x 10(5) cells/ml defines a high-density FPCL (HD-FPCL). The initial detection of HD-FPCL contraction is 2 h, whereas MD-FPCL is later, 6 h. A contracted HD-FPCL has a doughnut-like appearance, due to the high density of cells accumulating at the periphery. A contracted MD-FPCL is a flattened disc. The compacted collagen of MD-FPCL lattice exhibits a strong birefringence pattern due to organized collagen fiber bundles. In contracted HD-FPCL, a minimal birefringence develops, indicating minimal organization of collagen fiber bundles. MD-FPCL contraction was reduced with less than 10% serum; the disruption of microtubules, uncoupling of gap junctions, inhibition of tyrosine kinases, and addition of a blocking antibody to alpha2beta1 collagen integrin. Making HD-FPCL with only 1% serum or including the inhibitory agents had only minimal affect on lattice contraction. On the other hand, platelet-derived growth factor stimulated HD-FPCL contraction but had no influence on MD-FPCL contraction. It is suggested that the mechanism for HD-FPCL contraction is limited to the process of cells spreading. HD-FPCL contraction is independent of collagen organization, microtubules, gap junctions, alpha2beta1 integrin, and tyrosine phosphorylation. MD-FPCL contraction involves collagen organization and is optimized by the involvement of microtubules, gap junctions, alpha2beta1 integrin, and tyrosine phosphorylation. When studying cell physiology in a collagen matrix, cell-density influences need to be considered.
authors.affiliation: Section of Plastic and Reconstructive Surgery, Milton S. Hershey Medical Center, Hershey, Pennsylvania, USA. pehrlich@psu.edu
authors.forename: H P
authors.initials: HP
authors.lastname: Ehrlich
authors.forename: T
authors.initials: T
authors.lastname: Rittenberg
mesh_terms: D002452:Cell Count; D002460:Cell Line; D003094:Collagen / Q000502:physiology*; D005109:Extracellular Matrix / Q000502:physiology*; D005347:Fibroblasts / Q000166:cytology* / Q000502:physiology*; D006801:Humans; D013314:Stress, Mechanical
chemical_list: D003094:Collagen