ESTABLISHMENT OF ADULT-RAT SCHWANN-CELL CULTURES - EFFECT OF B-FGF, ALPHA-MSH, NGF, PDGF, AND TGF-BETA ON CELL-CYCLE

Mitotically active Schwann cells isolated from adult rat sciatic nerve segments were cultivated, using a bivariate BrdU/DNA flow cytometry a nalysis, to test the effect of b-FGF (10 ng/ml), alpha-MSH (10 ng/ml), NGF (10 ng/ml), PDGF-AB (10 ng/ml), and TGF-beta 1 (10 ng/ml) on the cell cycle. Compared to control or cholera toxin-treated cultures, no significant differences (P < 0.05; Newmann-Keuls test) were observed i n the proportion of G0G1 cells, S cells, G2M cells, and in the LI when alpha-MSH, NGF, PDGF-AB, or TGF-beta 1 were present. The S phase dura tion varied from 6.16 +/- 0.24 to 7.86 +/- 2.6 h, and the deduced pote ntial doubling time was estimated at between 46.70 +/- 7.09 and 56.05 +/- 7.55 h. In contrast, when b-FGF was added to the culture, the cell cycle was significantly modified, and the proportion of G0G1 cells de creased from 68-77% to 59-64%, while the proportion of S cells increas ed from 14-16% to 24.0-26.4%. Although S phase duration was not signif icantly changed (6.02 +/- 0.36 h), the 1.7- to 2.8-fold LI increase re duced the potential doubling time to 25.99 +/- 6.13 h. We conclude fro m these results that only b-FGF-induced adult rat Schwann cells dramat ically reenter in cell cycle and that this growth factor may be an axo nally derived signal-promoting mitogenesis after nerve injury. (c) 199 4 Academic Press, Inc.