Stem cells in planarian

Abstract

The high regenerative power of planarian has fascinated scientists for a long time. Although many famous scientists, including Thomas Hunt Morgan, extensively devoted themselves to studying mechanisms underlying regeneration, the planarian regeneration still remains mysterious phenomenon. Recently, modern approaches have been developed and incorporated in planarian research, and several mysterious points were clarified. Here, I focus on old problems of planarian stem cells. Planarian stem cells were called neoblasts and considered to be the only cells maintaining proliferative activity and pluripotency. However, recent analyses using molecular markers and FACS sorting revealed their heterogeneity. Now we should change the old view of the planarian stem cell system to one closer to mammalian stem cell systems. These insights indicate the planarian regeneration studies may provide new ideas for handling mouse and human ES cells for therapeutic use in the near future. © 2008 Springer Netherlands.