Previous studies from this laboratory have demonstrated that fibroblast gro
wth factor 1 together with a number of co-activator molecules (dopamine, TP
A, IBMX/forskolin), will induce the expression of the catecholamine biosynt
hetic enzyme tyrosine hydroxylase (TH) in 10% of human neurons (hNTs) deriv
ed from the NT2 cell line [10]. In the present study, we found that TH indu
ction was increased to nearly 75% in hNTs when cells were permitted to age
2 weeks in culture prior to treatment with the differentiation cocktail. Th
is high level of TH expression was sustained 7 days after removal of the di
fferentiating agents from the media. Moreover, the induced TH present in th
ese cells was enzymatically active, resulting in the production of low leve
ls of dopamine (DA) and its metabolite DOPAC. These findings suggest that h
NTs may provide an important tissue culture model for the study of factors
regulating TH gene expression in human neurons. Moreover, hNTs may serve, i
n vivo, as a source of human DA neurons for use in transplantation therapie
s. (C) 2001 Elsevier Science B.V. All rights reserved.