098 Cytokine Dynamics in Three-Dimensional Extracellular Matrices

Abstract

Fluorescence correlation spectroscopy was used to measure the binding and diffusion of growth factors in model extracellular matrices in order to investigate the importance of protein-matrix interactions in regulating signaling molecules within a three-dimensional matrix. Two important growth factors were studied, transforming growth factor β1 and basic fibroblast growth factor, which are known to have specific affinities for fibronectin and the heparan-sulfate-proteoglycan perlecan, respectively. Collagen-based matrices were prepared by polymerizing type I collagen in the presence of fibronectin or perlecan, and we measured diffusion constants and binding constants of the two growth factors. The binding constant measured for transforming growth factor β1 with fibronectin-containing matrices was in good agreement with that measured using affinity chromatography. However, the interactions measured between fibroblast growth factor and perlecan were significantly weaker than expected. Surprisingly, the strongest interactions by far were with monomeric collagen solutions and fibrillar collagen matrices. Our findings suggest a central role for the three-dimensional fibrillar collagen matrix in growth factor interactions, with modulatory roles for fibronectin or perlecan.