Adhesion, proliferation, and adipogenesis in primary rat cell cultures: effects of collagenous substrata, fibronectin, and serum

The effects of collagenous substrata, fibronectin, and fetal bovine serum on the adhesion, proliferation, and adipogenesis of rat stromal-vascular cells are reported. There was no effect on initial stromal-vascular cell-attachment by fetal bovine serum or fibronectin. The number of cells attached to a hydrated collagen-gel was almost twice (P<0.04) the number attached to dried collagen-gel or dried denatured collagen-gel. Total number of cells after 5 days in culture was similar among the collagenous substrata and among the treatments with or without fibronectin in the growth media. Total number of cells increased significantly (P<0.02) with 10% FBS. Adipocytic formation was inhibited by hydrated collagen-gel (P<0.02) compared to dried collagen-gel or dried, denatured collagenous substrata. An interaction occurred between dried, denatured gel and fetal bovine serum so that total formation of adipocytes increased by increasing the level of fetal bovine serum (P<0.07). Adipocytic formation was inhibited by hydrated collagen-gel at all levels of fetal bovine serum. The percentage of cells that converted to adipocytes was significantly lower (P<0.01) on hydrated collagen-gel compared to dried, denatured or dried collagen-gel. Percentage of conversion was not significantly different among levels of fetal bovine serum, although this percentage increased as fetal bovine serum level increased. Adipocytic conversion was not different between fibronectin-treated or untreated cells. Morphology of stromal vascular cells was similar on dried collagen and dried, denatured collagen-gel, but tended to remain bipolar on hydrated collagen-gel. These studies indicate that fetal bovine serum in combination with the extracellular matrix (dried, denatured collagen) increased the differentiation of rat stromal-vascular cells into adipocytes, and that hydrated collagen inhibited differentiation.