FIG. 1.

EC-conditioned medium reduces neurosphere formation in favor of adherent NPC cultures. Schematic representation of the experimental design (A) for cells isolated from the adult SVZ and expanded in neurosphere cultures using a base medium of DMEM (control) (B1-3), static EC-conditioned (C1-3), or dynamic EC-conditioned (D1-3) medium for 14 days. Neurospheres developed in control and dynamic EC-conditioned medium-treated cultures; however, the static EC-conditioned medium formed only adherent cultures. Dynamic EC-conditioned medium also supported adherent cultures. Control medium supports greater neurosphere numbers (E) compared with dynamic EC-conditioned medium. The average neurosphere size (F) was not significantly different for cells expanded in either the control or dynamic EC-conditioned medium. (G) Evaluation of the total cell number shows that control medium generated significantly (*P < 0.05, n = 6) more cells than those cultured in EC-conditioned medium. Mixed cultures in dynamic EC-conditioned medium generated significantly more cells than those expanded as adherent cells in static EC-conditioned medium (*P < 0.05, n = 6). (H) Cells expanded for 14 days in experimental and control conditions were dissociated and subsequently cultured for an additional 21 days in an NCFC assay to assess potency. Cells preconditioned in EC-conditioned medium (dynamic and static, P < 0.05, n = 6) generate larger and more numerous colonies. Colonies greater than 2 mm are considered to be indicative of NSC colonies, rather than NPC colonies. Only SVZ cells preconditioned with EC-conditioned medium collected under dynamic culture generated the largest >2-mm neurospheres at the end of 21 days; however, this result was not statistically significant as so few colonies were detected. Data are represented as mean ± standard deviation. Scale bar = 0.5 mm. EC, endothelial cell; NCFC, neural colony-forming cell; NPC, neural progenitor cell; SVZ, subventricular zone.