Hou Y-J [a]. Yu A C H. Garcia J M R Z. Aotaki-Keen A. Lee Y-L. Eng L F.
Hjelmeland L J. Menon V K [a].
Astrogliosis in culture: IV. Effects of basic fibroblast growth factor, Journal of Neuroscience Research 40(3) :359-370, 1995.
Abstract
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 report the effects of basic fibroblast growth factor (bFGF)
and an anti-bFGF antibody on astrocyte morphology,
proliferation, and migration following in vitro wounding of
confluent secondary cultures. Addition of bFGF (20 ng/ml) to wounded cultures
induced morphological changes characteristic of differentiation in wounded
and nonwounded areas of the culture. Combined treatment with bFGF and an
antibFGF antibody (100 mu-g/ml) prevented this effect.
Astrocyte proliferation along the edges of 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 monophosphate (dbc-AMP) reduced
injury-associated astrocyte proliferation. Addition of bFGF
to cultures in EMEM with serum increased astrocyte
proliferation at 18 and 24 hr after wounding. This effect was reduced
considerably by treatment of cultures with bFGF in combination with an
anti-bFGF antibody. The combined treatment and the antibody alone reduced
cell division to a level lower than in control cultures. Twenty-four hr
following wounding, astrocytes along the edges of the wound
exhibited extension of thick, flat processes into the wound area. At 3 and 5
days after wounding, a bodily migration of
astrocytes into the wounded area was observed. Addition of
bFGF significantly increased astrocyte
migration 1 day after wounding, with maximum effect on day 3
and no subsequent increase on day 5. A combination of bFGF and anti-bFGF
antibody as well as the antibody alone reduced astrocyte
migration to a level lower than in controls.
Immunohistochemical localization and isoform pattern of bFGF in
astrocytes did not change with dbc-AMP treatment or
wounding. We conclude that mechanically wounded confluent
astrocytes respond to bFGF added to the culture medium by
enhancing cell division, differentiation, and migration. In
addition, the results of the antibody treatment also suggest a role for
endogenous bFGF in astrocyte proliferation and
migration elicited by wounding in vitro. These results
support the notion that in vivo, both bFGF released by injury and endogenous
bFGF synthesized by astrocytes, contribute to the cellular
responses that lead to astrogliosis.
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