An end effector assembly configured for use with a surgical instrument or surgical system includes first and second jaw members each including an outer jaw housing, a tissue-treating plate, and a longitudinally-extending channel therethrough. At least one of the first or second jaw members is pivotable relative to the other between a spaced-apart position and an approximated position. A cutting mechanism is configured to cut tissue grasped between the jaw members. The cutting mechanism may include an activation member coupled to a knife and configured to advance the knife transversely between the jaw members, a heat-activated elongated sheet configured to un-roll to advance a cutting edge thereof transversely between the jaw members, or a clutch and spring mechanism configured to deploy a knife longitudinally between the jaw members.