Abstract: The invention provides a method of inhibiting cell death in a mammal. The method comprises administering to a mammal an effective amount of a composition comprising a cell protection factor covalently linked to a bone targeting agent via a linkage that is cleaved under physiological conditions, whereby the cell protection factor is released from the bone targeting agent in vivo to inhibit cell death. The invention further provides a compound comprising a cell protection factor covalently attached to a bone targeting agent via a linker that is cleaved under physiological conditions.

Abstract: This invention provides a method of modifying a cellular response in a mammal. The method comprises administering to the mammal an effective amount of biodegradable nanoparticles, each of said nanoparticles comprising an active agent, a biodegradable polymer, and a bone targeting agent administering to a mammal an effective amount of a composition comprising a compound absorbed in a biodegradable nanoparticle which is attached to a bone targeting agent. The invention also provides a method for modifying a cellular response in a mammalian cell comprising contacting the mammalian cell with biodegradable nanoparticles. The invention further provides a method of delivering an exogenous substance to a mammal. The method comprises administering to the mammal a composition comprising the exogenous substance absorbed into a biodegradable nanoparticle, wherein the biodegradable nanoparticle is covalently attached to a bone targeting agent.

Abstract: The invention provides a method of inhibiting cell death in a mammal. The method comprises administering to a mammal an effective amount of a composition comprising a cell protection factor covalently linked to a bone targeting agent via a linkage that is cleaved under physiological conditions, whereby the cell protection factor is released from the bone targeting agent in vivo to inhibit cell death. The invention further provides a compound comprising a cell protection factor covalently attached to a bone targeting agent via a linker that is cleaved under physiological conditions.