Expression of extracellular matrix receptors in 3-dimensional collagen gels.

Interactions between cells and their extracellular matrix (ECM) environment are important in regulating numerous cellular functions. Within the heart, fibroblasts secrete most of the extracellular matrix proteins, particularly collagen, and modify the overall matrix environment. While many studies have examined expression of ECM receptors, most use 2-dimensional models of cell culture instead of a 3-dimensional approach which more closely mimics the in vivo cellular environment. The goal of this study was to examine ECM receptor expression in a 3-dimensional environment. Protein isolated from rat cardiac fibroblasts and tubular 3-dimensional collagen gels was tested for the expression of Discoidin Domain Receptors 1 and 2 (DDR1 and DDR2 respectively) and [a.sub.1] integrin at various times in 3-dimensional collagen gels. Mechanically loaded gels and tubes were compared to determine if receptor expression changed in response to a mechanical environment. Protein samples were collected at t0, 24 and 72 hours and for tubes an additional time point was collected at 1 week. SDS-PAGE and western blotting was performed for DDR1, DDR2, and [a.sub.1] integrin using various antibodies. Overall, very little change in receptor expression was observed with either model except after 72 hours when significant changes were detected.