DIFFERENTIATION OF MESENCEPHALIC PROGENITOR CELLS INTO DOPAMINERGIC-NEURONS BY CYTOKINES

Rat progenitor cells from the germinal region of the fetal mesencephal on were isolated and expanded in media containing the mitogen epiderma l growth factor. These cells remained mitotically active (up to 8 mont hs), were immunoreactive for the progenitor cell marker nestin, and we re readily infected with the BAG alpha retrovirus. When incubated in c omplete media containing serum in poly-L-lysine-coated plates, these c ells spontaneously converted to neurons and glia but rarely expressed the dopamine (DA) neuron phenotype. Nineteen different cytokines were screened for their ability to induce the DA phenotype and only interle ukin (IL)-1 was found to induce the expression of the DA neuron marker tyrosine hydroxylase (TH). The addition of IL-1, IL-11, leukemia inhi bitory factor (LIF), and glial cell line-derived neurotrophic factor ( GDNF) were found to further increase the number of TH immunoreactive ( TH-ir) cells. The addition of mesencephalic membrane fragments and str iatal culture-conditioned media along with the cytokine mixture induce d the expression of morphologically mature TH-ir cells that were also immunoreactive for dopadecarboxylase, the DA transporter, and DA itsel f. The DA neuron cell counts were approximately 20-25% of the overall cell population and 50% of the neurofilament population. Astrocytes an d oligodendrocytes were also present. These data suggest that hematopo ietic cytokines participate in the development of the DA neuron phenot ype. Parallels between the function of hematopoietic cytokines in bone marrow and the central nervous system may exist and be useful in unde rstanding the factors which regulate the differentiation Of neurons in the brain. (C) 1998 Academic Press.