Methods of inhibiting proliferation of a plurality of proliferating cells are disclosed. Methods of inhibiting cell overgrowth on compositions that are in an animal's body are disclosed. Methods of inhibiting cell overgrowth on a device that is in an animal's body are disclosed. Devices that have on their exterior surface an alginate matrix that comprises Strontium are disclosed. Compositions comprising an alginate body and alginate sheets that each comprise a single layer of cells coating the exterior surface of the alginate body are disclosed. Methods of preparing an artificial tissue are disclosed. Devices comprising cells encapsulated within an alginate matrix and/or maintained as a monolayer on an alginate body, and methods of making and using the same are disclosed. Methods of coating compositions and devices are disclosed.