FIBRONECTIN PRODUCTION BY CULTURED HUMAN LUNG FIBROBLASTS IN 3-DIMENSIONAL COLLAGEN GEL CULTURE

In vivo, fibroblasts are distributed in a three-dimensional (3-D) conn ective tissue matrix. Fibronectin is a major product of fibroblasts in routine cell culture and is thought to regulate many aspects of fibro blast biology. In this context, we sought to determine if the interact ion of fibroblasts with a 3-D matrix might affect fibronectin producti on. To examine this hypothesis, fibronectin production by fibroblasts cultured in a 3-D collagen gel or on plastic dishes was measured by EL ISA. Fibroblasts in 3-D gel culture produced more fibronectin than tho se in monolayer culture. Fibroblasts in 3-D culture produced increasin g amounts of fibronectin when the collagen concentration of the gel wa s increased. The 3-D nature of the matrix appeared to be crucial becau se plating the fibroblasts on the surface of a plastic dish underneath a collagen gel was not different from plating them on a plastic dish in the absence of collagen. In addition to increased fibronectin produ ction, the distribution of the fibronectin produced in 3-D culture was different from that of monolayer culture. In monolayer culture, more than half of the fibronectin was released into the culture medium. In 3-D culture, however, approximately two-thirds remained in the collage n gel. In summary, the presence of a 3-D collagen matrix increases fib roblast fibronectin production and results in greater retention of fib ronectin in the vicinity of the producing cells.