Hideki Mori1,2,3,4, Kazuaki Ninomiya3,4, Masahiro Kino‐oka1, Tomoko Shofuda2,3, Mohammed Omedul Islam3, Mami Yamasaki2, Hideyuki Okano5, Masahito Taya1, Yonehiro Kanemura2,3
1Division of Chemical Engineering, Graduate School of Engineering Science, Osaka University, Osaka, Japan
2Institute for Clinical Research, Osaka National Hospital, National Hospital Organization, Osaka, Japan
3Research Institute for Cell Engineering, National Institute of Advanced Industrial Science and Technology, Hyogo, Japan
4The first two authors contributed equally to this work.
5Department of Physiology, Keio University School of Medicine, Tokyo, Japan
Tóm tắt
AbstractNeural stem/progenitor cells (NSPCs) proliferate as aggregates in vitro, but the mechanism of aggregation is not fully understood. Here, we report that aggregation promotes the proliferation of NSPCs. We found that the proliferation rate was linear and depended on the size of the aggregate; that is, the population doubling time of the NSPCs gradually decreased as the diameter approached 250 μm and flattened to a nearly constant value beyond this diameter. Given this finding, and with the intent of enhancing the efficiency of human NSPC expansion, we induced the NSPCs to form aggregates close to 250 μm in diameter quickly by culturing them in plates with U‐bottomed wells. The NSPCs formed aggregates effectively in the U‐bottomed wells, with cell numbers approximately 1.5 times greater than those in the aggregates that formed spontaneously in flat‐bottomed wells. In addition, this effect of aggregation involved cell–cell signaling molecules of the Notch1 pathway. In the U‐bottomed wells, Hes1 and Hes5, which are target genes of the Notch signal, were expressed at higher levels than in the control, flat‐bottomed wells. The amount of cleaved Notch1 was also higher in the cells cultured in the U‐bottomed wells. The addition of γ‐secretase inhibitor, which blocks Notch signaling, suppressed cell proliferation in the U‐bottomed wells. These results suggest that the three‐dimensional architecture of NSPC aggregates would create a microenvironment that promotes the proliferation of human NSPCs. © 2006 Wiley‐Liss, Inc.
