Abstract: The present invention is related to the discovery of a novel class of neural progenitor cells, which proliferate in response to platelet derived growth factor (PDGF) and differentiate into neurons and oligodendrocytes but not astrocytes. Progeny of the progenitor cells can be obtained by culturing brain tissue in PDGF without serum, epidermal growth factor (EGF), fibroblast growth factor 2, or transforming growth factor alpha. Upon subculturing into EGF-containing media, these progeny cells can proliferate and form neurospheres, whereas PDGF has no such effect.

Abstract: This invention provides a method of increasing the number of neural stem cells by using ovarian hormones. Ovarian hormones induce an increase in the number of neural stem cells, resulting in a larger pool of neural stem cells, which may be used in the treatment or amelioration of neurodegenerative diseases or conditions. Another aspect of the invention provides a method for identifying genes that regulate the ovarian hormone-induced stem cell increase.

Abstract: This invention provides a method of increasing the number of neural stem cells by using estrogen. Estrogen induces an increase in the number of neural stem cells, resulting in a larger pool of neural stem cells, which may be used in the treatment or amelioration of neurodegenerative diseases or conditions. Another aspect of the invention provides a method for identifying genes that regulate the estrogen-induced stem cell increase.