A tissue-manipulating system including a tissue-manipulating device having shaft and a tissue grasper assembly. The tissue grasper assembly has at least one grasper arm resiliently expandable from a closed configuration, within and extending along the longitudinal axis of a shaft, to an open configuration outside the shaft with the grasper arm expanded in a direction transverse to the longitudinal axis of the shaft. In the open configuration, the at least one grasper arm may be engaged with tissue wall to manipulate or move the tissue wall, such as to move a distal tissue wall closer to a proximal tissue wall. The tissue grasper assembly may be deployable (such as by being separated from the shaft), such as to remain in place holding two tissue walls in apposition.