The adult hippocampus hosts a population of neural stem and progenitor cells (NSPCs) that proliferates throughout the mammalian life span. To date, the new neurons derived from NSPCs have been the primary measure of their functional relevance. However, recent studies show that undifferentiated cells may shape their environment through secreted growth factors. Whether endogenous adult NSPCs secrete functionally relevant growth factors remains unclear. We show that adult hippocampal NSPCs secrete surprisingly large quantities of the essential growth factor VEGF in vitro and in vivo. This self-derived VEGF is functionally relevant for maintaining the neurogenic niche as inducible, NSPC-specific loss of VEGF results in impaired stem cell maintenance despite the presence of VEGF produced from other niche cell types. These findings reveal adult hippocampal NSPCs as an unanticipated source of an essential growth factor and imply an exciting functional role for adult brain NSPCs as secretory cells.adult neurogenesis | vascular endothelial growth factor | stem cell | hippocampus | neural precursor

Youth partnerships are a promising but understudied strategy for prevention and health promotion. Specifically, little is known about how the functioning of youth partnerships differs from that of adult partnerships. Accordingly, this study compared the functioning of youth partnerships with that of adult partnerships. Several aspects of partnership functioning, including leadership, task focus, cohesion, participation costs and benefits, and community support, were examined. Standardized partnership functioning surveys were administered to participants in three smoke-free youth coalitions (n = 44; 45% female; 43% non-Hispanic white; mean age = 13) and in 53 Communities That Care adult coalitions (n = 673; 69% female; 88% non-Hispanic white; mean age = 49). Multilevel regression analyses showed that most aspects of partnership functioning did not differ significantly between youth and adult partnerships. These findings are encouraging given the success of the adult partnerships in reducing community-level rates of substance use and delinquency. Although youth partnership functioning appears to be strong enough to support effective prevention strategies, youth partnerships faced substantially more participation difficulties than adult partnerships. Strategies that youth partnerships can use to manage these challenges, such as creative scheduling and increasing opportunities for youth to help others directly, are discussed.