A method is provided for the localized intravascular administration of a fibrinolytic metalloproteinase to a human subject in amounts that are both safe and effective to lyse an occluding fibrin-containing blood clot, while also avoiding the neutralizing effects of .alpha..sub.2-macroglobulin in the circulating blood. A method is also provided for the treatment of a blood clot in, around or attached to an indwelling vascular access device. A method for restoring patency and function of an indwelling vascular access device is also provided.