ASTROGLIOSIS IN CULTURE .4. EFFECTS OF BASIC FIBROBLAST GROWTH-FACTOR

Previous studies have shown that the mechanical wounding of 3-week-old cultured rat astrocytes results in cell proliferation and hypertrophy resembling astrocyte responses to a brain injury in vivo. We now repo rt the effects of basic fibroblast growth factor (bFGF) and an anti-bF GF antibody on astrocyte morphology, proliferation, and migration foll owing in vitro wounding of confluent secondary cultures. Addition of b FGF (20 ng/ml) to wounded cultures induced morphological changes chara cteristic of differentiation in wounded and nonwounded areas of the cu lture. Combined treatment with bFGF and an anti-bFGF antibody (100 mu g/ml) prevented this effect. Astrocyte proliferation along the edges o f a scratch wound was at maximum 24 hr after wounding in cells growing in Eagle's minimum essential medium (EMEM) containing 10% serum. Low serum concentration and treatment with dibutyryl cyclic adenosine mono phosphate (dbc-AMP) reduced injury-associated astrocyte proliferation, Addition of bFGF to cultures in EMEM with serum increased astrocyte p roliferation at 18 and 24 hr after wounding. This effect was reduced c onsiderably by treatment of cultures with bFGF in combination with an anti-bFGF antibody. The combined treatment and the antibody alone redu ced cell division to a level lower than in control cultures. Twenty-fo ur hr following wounding, astrocytes along the edges of the wound exhi bited extension of thick, flat processes into the wound area. At 3 and 5 days after wounding, a bodily migration of astrocytes into the woun ded area was observed. Addition of bFGF significantly increased astroc yte migration 1 day after wounding, with maximum effect on day 3 and n o subsequent increase on day 5. A combination of bFGF and anti-bFGF an tibody as well as the antibody alone reduced astrocyte migration to a level lower than in controls. Immunohistochemical localization and iso form pattern of bFGF in astrocytes did not change with dbc-AMP treatme nt or wounding. We conclude that mechanically wounded culture medium b y enhancing cell division, differentiation, and migration. In addition , the results of the antibody treatment also suggest a role for endoge nous bFGF in astrocyte proliferation and migration elicited by woundin g in vitro, These results support the notion that in vivo, both bFGF r eleased by injury and endogenous bFGF synthesized by astrocytes, contr ibute to the cellular responses that lead to astrogliosis. (C) 1995 Wi ley-Liss, Inc.