The present disclosure provides a device, method and assembly for use in wound treatment. Specifically disclosed is a wound dressing device； an assembly, e.g. in the form of a kit-of-parts, which comprises the device as one of its components； and a method of wound dressing and a use wherein said device is a key component. The device comprises a cavity defined by concave walls surrounded by lips configured for attachment to skin in a fluid tight manner and a closure removably fixed to the lips and sealing the cavity. The assembly also comprises, as other of its components a device for introducing blood into the cavity after it is fixed over a wound to permit the blood to clot over the wound within said cavity. In use, the clotting mold device is fixed on top of a wound, and blood is introduced into the mold space to permit the blood to clot within the mold space to thereby form a blood clot over the wound.
