Surface-adsorbed α₁-microglobulin modulation of human fibroblasts spreading and matrix metalloproteinases release

The lipocalin α₁-microglobulin (α₁-m), an immunoregulatory protein produced by human hepatocytes and distributed in various organs and fluids, is physiologically adsorbed onto polymer surfaces from both serum and urine, and its adsorption correlated to the degree of surface hydrophobicity. Starting from the hypothesis that α₁-m holds a modulatory role at the biomaterials-tissue interface, we have observed a dose-dependent reduction in adhesion of human fibroblasts (cell line MRC-5) seeded onto polystyrene (PS) in a serum-free medium in the presence of adsorbed α₁-m (2.1±0.2×10⁴ cells/cm² at 200ng/ml α₁-m ) compared to cells seeded onto cell grade PS (2.9±0.05×10⁴ cells/cm²) after 72h. Moreover, in the presence of α₁-m, adherent MRC-5 cells exhibit an altered shape due to inhibition of cell spreading, and release of matrix metalloproteinase -2 (gelatinase A, MMP-2) by fibroblasts was also increased by 1.6-1.9-fold after 72h of incubation. These data extend the known spectrum of α₁-m activities, suggesting a possible role of this protein in the complex series of events occurring at the tissue-biomaterial interface.