Human neural stem cells can be effectively isolated, expanded, differentiated in vitro, and therefore, characterized during development as a drug. However, depending on the expansion capacity of individual stem cell lines and their differentiation potentials in vivo (as well as the targeted indication), strategy for developing a stem cell–based drug development can vary widely. We have isolated, expanded, and characterized neural stem cells from several regions of the human fetal central nervous system. Some of these can be expanded up to approximately 60 cell doublings, representing in proximity to the mammalian senescence point, with enough cells to treat all current and future patients for certain indications. Others can be expanded for only up to approximately 20 cell doublings, which means having to recruit new cell lines periodically and retest each preparation. Such differences in the cells' expansion capacity, as well as differentiation capacity, seem to roughly correlate with in vivo neurogenesis during central nervous system development. We are testing these cell lines in various animal models of neurological diseases.
Johe KK. Development of Neural Stem Cells for Treatment of Neurological Diseases. Arch Neurol. 2003;60(2):297. doi:10.1001/archneur.60.2.297-a