Prospective characterization of neural stem cells by flow cytometry analysis using a combination of surface markers

Neural stem cells (NSCs) with self‐renewal and multilineage differentiation properties can potentially repair degenerating or damaged neural tissue. Here, we have enriched NSCs from neurospheres, which make up a heterogeneous population, by fluorescence‐activated cell sorting (FACS) with antibodies against syndecan‐1, Notch‐1, and integrin‐β1, which were chosen as candidates for hematopoietic cell—or somatic stem cell—markers. Antigen‐positive cells readily initiated neurosphere formation, but cells lacking these markers did so less readily. Doubly positive cells expressing both syndecan‐1 and Notch‐1 underwent neurosphere formation more efficiently than did singly positive cells. The progeny of sorted cells could differentiate into neurons and glial cells both in vitro and in vivo. These antibodies were also useful for isolating cells from the murine embryonic day 14.5 brain that efficiently formed neurospheres. In contrast, there was no distinct difference in neurosphere formation efficiency between Hoechst 33342‐stained side population cells and main population cells, although the former are known to have a stem cell phenotype in various tissues. These results indicate the usefulness of syndecan‐1, Notch‐1, and integrin‐β1 as NSC markers. © 2005 Wiley‐Liss, Inc.