Polyunsaturated fatty acid metabolism of human skin fibroblasts during cellular aging.

The linoleic acid metabolism was studied in serially cultured human skin fibroblasts during 30 passages. Confluent cells were incubated with [U-14C]linoleic acid in serum free medium for 4 h after 3, 6, 12, 18, 24 and 30 passages. The labeled linoleic acid was rapidly incorporated in cell lipids, preferentially into phospholipids (80%), and the distribution within the lipid classes remained constant during the cell cycles. The rate of conversion of [14C]linoleic acid into long chain fatty acids varied with the number of passages. The formation of dihomo-gamma-linolenic acid and of arachidonic acid decreased significantly from 12% to 5% (as % of incorporated linoleic acid) between 3 and 30 serial passages whereas the linoleic acid content increased in the cells from 68% to 83%. The results indicate that the desaturase activities decreased significantly during cellular aging of human skin fibroblasts.