Astrocyte cultures were examined for their ability to support neuronal viability in culture. Human fetal neurons remained viable in culture for 8-10 weeks if co-cultivated with human fetal astrocytes. These cells produced nerve growth factor (NGF) as well as interleukin 6 (IL- 6). Investigations of their ability to produce other neurotrophins such as brain-derived neurotrophic factor (BDNF) and glial-derived neurotrophic factor (GDNF) are ongoing. Phenotypic characteristics of fetal neurons suggest that support from astrocytes contributes to their longevity and activity in culture. In vivo experiments are now underway in rodent and nonhuman primate studies. We have also identified aggregates of cells in culture that are testing positive and respond to epidermal growth factor (EGF). These cells may represent neural stem cells which can self-renew as well as give rise to progenitors.
