Described are medical graft materials and devices which can be usefully modified with liquid additives such as cell suspensions, bioactive agents, or combinations of these. The medical graft materials and devices can have a first outer surface and a second outer surface and can define an internal chamber between the first outer surface and the second outer surface. The medical graft materials and devices can also have at least one region of the graft material interrupting the chamber and surrounded by the chamber. Also described are methods for making and using these medical graft materials and devices.