Compositions and methods for the culturing, propagation, cryopreservation andmanipulation of neural progenitor cells (NPC) and pluripotent stem cells (PSC)are provided. The cells exhibit rapid doubling times and can be maintained invitro for extended periods. Also provided is a method of propagating neuralprogenitor cells, and a method of transplanting human NPC and/or PSC to ahost. The cells can be genetically modified to express a therapeutic agentprior to the transplanting.