| The structure and morphology of biomaterial matrices and the deposition of extracellular matrix (ECM) are interdependent issues critical to the integration of bioengineered materials and tissues in vivo. To address the mechanistic basis for the relationships between matrices and cells, a model system was studied in vitro employing type I collagen and human fibroblasts. We hypothesized that collagen structure influences rate and extent of matrix remodeling and deposition due to differences in surface chemistry and enzymatic digestion. To evaluate this hypothesis, matrix trafficking was assessed quantitatively and fit to a model by tracking collagen and proline metabolic fluxes. Human fibroblasts (IMR-90) were used to study the effect of collagen matrix structure variations on cell phenotypic and genotypic outcomes. Cell proliferation, morphology, senescence-specific beta-galactosidase, transcript content for Collagen-1, Matrix Metal loproteinase-1, Matrix Metal loproteinase-2, Tissue Inhibitor of Matrix Metal loproteinase-1, and Tissue Inhibitor of Matrix Metalloproteinase-2, trafficking of radio labeled collagen and proline from cell substrate or media, matrix phagocytosis, and intracellular protein levels were determined. The collagen matrices were characterized as functions of helicity, chemical composition, and topology. Cells grown on denatured collagen exhibited: improved cell viability, morphology and lower beta-galactosidase, senescence associated, activity; a significantly higher level of collagen matrix incorporation; and significantly greater levels of matrix remodeling (indicated by transcript levels) when compared to cells grown on native collagen and tissue culture plastic. The data suggest that denatured collagen promotes more active remodeling toward new extracellular matrix. This is significant because remodeling of tissue engineering matrices is critical to the integration of in vivo implants, and remodeling is integral to the pathology of several collagen related diseases. The ability to quantitatively address issues related to matrix trafficking offers a more systemic approach to understanding the influence of biomaterial structure, morphology, chemistry, or extracellular matrix features, on tissue remodeling, wound repair and disease progression. The model presents a quantitative basis for cell-matrix interactions and provides a critical first step toward future studies in which modes to influence these physiological features can be rationally assessed. |
