The present invention relates to devices and related methods for treating fistulas such as anal or recto-vaginal fistulas, in particular by the use of a seton to secure a tissue growth promoter such as a growth factor and/or fibrin. The various devices are particularly suitable for positioning tissue growth promoters securely within a fistula. Thus, one device comprises a seton and a tissue growth promoter. Further related aspects of the invention include devices comprising an enclosure provided inbetween portions of a seton, devices comprising a seton and a plurality of holes for enabling the device to be sutured to tissue, devices comprising a probe and a seton that are releasably connectable end-to-end, devices comprising an attachment device to secure the ends of a seton, and devices comprising a fistula plug adapted to be secured to a seton.