cultures 4 days after removal of the permeable membrane inserts stem cell clones ranged up to 4350 cells and on average only 9 were neurons similarly e11 cortical cells cultured as neurospheres for 7 days then differentiated in adherent culture for 4 days produced only 7 neurons many more stem cell clones growing in bpae co cultures contained a higher percentage of neurons up to 64 compared to ctx co culture fig2 d e and neuron production was prolonged increased neurogenesis from endothelial co cultured neural stem cells does not occur at the expense of gliogenesis the percentage of gfap astrocytes generated was similar and although oligodendrocyte differentiation indicated by o4 staining was reduced in bpae co cultures compared to ctx the difference could not account for the enhancement of neuron generation fig2 c e nih3t3 cells enhanced oligodendrocyte generation co culture with vsm or nih3t3 cells reduced neurogenesis compared to ctx fig2 e showing that the endothelial effect is cell type specific endothelial cells stimulate proliferation and neurogenesis of neural stem cells from a variety of embryonic cns regions not shown and from different stages e15 5 cortical and adult svz stem cells grown in endothelial co culture generated sheets of lex nestin cells after differentiation e15 5 endothelial expanded cortical cells and adult svz cells produce more neurons compared to control fig2 f 2 h neurosphere expanded stem cells respond to endothelial factors e15 5 cortical cells grown as neurospheres in fgf2 for 7 days were plated in adherent conditions and co cultured for 3 days with endothelial cells or with age matched cortical cells then differentiated by withdrawing feeder cells for 4 days stem cells exposed.