There are provided compositions and methods for modulating stem cell division, in particular, division symmetry. It has been demonstrated that Wnt7a polypeptide fragments promoting symmetrical expansion of stem cells. The compositions and methods of the invention are useful, for example, in modulating stem cell division symmetry in vitro, ex vivo, and in vivo, in replenishing and expanding the stem cell pool, and in promoting the formation, maintenance, repair and regeneration of tissue.