Mallinckrodt plc, of Chesterfield, U.K., said it entered a merger agreement with Stratatech Corp., of Madison, Wis., a privately held regenerative medicine company focused on the development of skin substitute products. Its developmental products include Stratagraft regenerative skin tissue and a technology platform for genetically enhanced skin tissues. If approved, Stratagraft could be the first biological off-the-shelf skin substitute product for treatment of severe burns.