Glycosaminoglycans Partially Substitute for Proteoglycans in Spheroid Formation of Adult Rat Hepatocytes in Primary Culture

Adult rat hepatocytes seeded in a noncoated plastic dish containing serum-free medium formed a monolayer within 24 h of culture. Those seeded in a dish coated with a proteoglycan fraction isolated from rat liver reticulin fibers attached to the dish but did not spread within 4 h, and then gradually assembled to form floating spherical aggregates (spheroids) with a diameter of 120 +/- 40 micron, within 72 h. The proteoglycan fraction appeared to contain dermatan sulfate, heparan sulfate and an unidentified glycosaminoglycan in its glycan moieties by glycosaminoglycan analysis after pronase digestion and high molecular weight proteoglycan molecules (mw: over 300,000 and about 200,000) by SDS-PAGE analysis. Cells seeded in dishes coated with these defined glycosaminoglycans and heparin assembled to form hemispheroids and multilayer islands, but not floating spheroids, within 72 h of culture. Dermatan sulfate had a stronger ability to induce hemispheroids than heparan sulfate or heparin. As the hemispheroid and multilayer islands were the intermediate form between monolayer and floating spheroids, the glycosaminoglycan moieties of the proteoglycan fraction were thought to participate in the formation of spheroid.