The existence of neural stem cells (NSCs) in the adult human brain provides impetus for investigating possible neuroreplacement therapies for neurodegenerative disease. Due to recent advances in techniques affording isolation and maintenance of NSCs using non-serum culture media, these cells have become exciting candidates for therapeutic strategies. We are able to expand NSCs by mitogenic growth factors in vitro and in defined conditions, NSCs differentiate into each of the diverse brain cell types: neurons, astrocytes and oligodendrocytes. This article addresses the involvement of amyloid-beta precursor protein and the presenilins in NSCs' biology and possible application of NSCs for therapeutic approaches in Alzheimer's disease. Ongoing studies in our laboratory, and recent findings by others using human neural progenitors, serve as the conceptual frame for this article.