On the useful role of OH center dot free radicals in differentiation of cultured human fibroblasts

The working hypothesis assuming that oxygen free radicals cannot be conside red only as harmful by-products of the oxidative metabolism has been experi mentally tested. Human fibroblasts were grown in culture from the following five types of tissues: (1) normal orbital fat; (2) orbital fat of patients with endocrine ophtalmopathy (EOP); (3) normal orbital muscle; (4) orbital muscle of EOP patients; (5) skin. These fibroblasts (second to 12th passag es) were treated for 2 x 72 h with the Fenton reactants: ADP-Fe2+-complex ( 0.1 mM for iron) and H2O2 (0.055 mM), final concentrations. This treatment caused a slowing down of the cell proliferation, induced various morphologi cal signs of differentiation, and significantly increased (40-150%) the tot al superoxide dismutase (SOD) and catalase (CAT) activities of the fibrobla sts. Authors suggest that the increased expression of these enzymes may pla y a general role in the cell differentiation mechanisms, meaning that the g eneration of oxygen free radicals is an essential, useful factor even durin g the early phases of development, and may not be taken only as a harmful p rocess during aging. (C) 2000 Elsevier Science Ireland Ltd. All rights rese rved.