Wound dressing assembly including (i) blood-clotting mold device having an enclosure defined between walls of a main body and a removable closure over an opening and configured for introduction of blood thereinto, and (ii) coagulation initiator in amount sufficient to coagulate blood introduced into the enclosure to form a blood clot. The formed blood clot is transferable onto a wound. Method for preparing a wound dressing by introducing a volume of blood into the enclosure of the blood-clotting mold device, maintaining the blood within the enclosure for time sufficient to permit clotting of the blood to obtain a blood clot； removing said the closure to open the enclosure； and extracting the blood clot from the enclosure. The formed blood clot may be used in a method for dressing a wound by fixation of the clot onto the wound.
