Graft materials containing bioactive substances, and methods for their manufacture

Described are packaged, sterile medical graft products containing controlled levels of a growth factor such as Fibrob-last Growth Factor-2 (FGF-2). Also described are methods of manufacturing medical graft products wherein processing, including sterilization, is controlled and monitored to provide medical graft products having modulated, known levels of a extracellular matrix factor, such as a growth factor, e.g. FGF-2. Preferred graft materials are extracellular matrix materials isolated from human or animal donors, particularly submucosa containing extracellular matrix materials. Further described are ECM compositions that are or are useful for preparing gels, and related methods for preparation and use.