Common myofibroblastic features of newborn rat astrocytes and cirrhotic rat liver stellate cells in early cultures and in vivo

Double-immunolabelling techniques were employed to investigate the distribu tion of smooth muscle alpha-actin (actin) in glial fibrillary acidic protei n (GFAP)-positive cells in rat brain during early postnatal development and maturation and in glial primary culture derived from newborn rat brain. In addition the expression of desmin was studied in the glial primary culture s as a function of the differentiation of the cells. Comparison of the cult ured astroglial cells at an early age with hepatic stellate cells derived f rom CCl4-induced cirrhotic rat liver, revealed features of the astrocytic c ytoskeleton characteristic of myofibroblastic cells, i.e., strong expressio n of both myofibroblastic markers, actin and desmin. In astroglial cells wi th an initial morphology reminiscent of fibroblasts the non-filamentous per inuclear immunoreaction of GFAP increased with time at the expense of actin and, partially, desmin, GFAP filaments were spread throughout the cytoplas m of the cells which acquired stellate morphology. The alterations in the m orphology of the cells acid the distribution and intensity of staining for GFAP and actin during the differentiation of astrocytes in culture were sim ilar to those observed in astrocytes during the maturation of the brain. In astrocytes from a newborn brain as well as in cirrhotic hepatic stellate c ells, the area of immunoreaction of GFAP was reduced and confined mainly to the nuclear region. In contrast, the cells expressed actin throughout the cytoplasm, These findings may hint at a similar function of these regionall y specialized perivascular myofibroblastic cells in a normal brain and dise ased liver and at inverse organ-specific functions which the cells fulfill under non-pathological conditions in vivo. (C) 1999 Elsevier Science Ltd. A ll rights reserved.