Changes of the glycosaminoglycan metabolism in human lung fibroblasts and porcine aortic endothelium cells influenced by the number of subcultures in vitro and by lipids in the medium.

In vitro aging fibroblasts and porcine aortic endothelium cells were treated with a commercial soy-bean lipid emulsion and incubated in 35S-sulfate or 3H-glucosamine respectively. The glycosaminoglycans (GAGs) were characterized by enzyme digestion following proteolysis. Uronic acid concentrations were determined in fibroblast cultures. The GAG content is lower in the last possible passage than in the foregoing ones. Lipid treatment leads to an increase, especially in early passages. The incorporation of radiolabeled precursors decreases with increasing in vitro age in both cell types. By lipid treatment the heparansulfate (HS) radioactivity of fibroblasts is increased insignificantly, while the GAG radioactivity of endothelium cells and the chondroitinsulfate (CS) radioactivity of fibroblasts are decreased. The in vitro age-related reduction of the precursor incorporation is more pronounced in CS as compared to HS, whereby the HS radioactivity shows a percentual increase, especially following lipid treatment. The effect of lipids shows changes related to in vitro aging. The role of cellular GAG metabolism and lipid loads in arteriosclerosis is discussed. Even in the arterial wall different cell types may react differentially.