Abstract: This invention encompasses new and substantially improved methods and compositions for delivery of therapeutic agents to specifically chosen body sites. Conjugation of fibronectin to bioactive agents or to lipids or to liposomes which entrap the bioactive agents permits immobilization of the bioactive agent when administered at collagen-, heparin-, hyaluronic acid-, fibrin/fibrinogen-, or ganglioside-rich sites. Covalent conjugation is achieved by two methods: (1) the enzymatically catalyzed cross-linkage of fibronectin to an amine containing compound, and (2) by a modified NHS method which permits formation of peptide bonds between fibronectin and lipid compounds.

Abstract: Compositions and methods for maintaining reservoirs of bioactive agents by sequestering the reservoir in a gel matrix are described. In particular, liposomes containing an entrapped bioactive agent are sequestered in a gel matrix. The resulting liposome-gel compositions may be used in vivo or in vitro to provide for sustained release of the bioactive agent. The gel matrix inhibits the dispersion and clearance of the sequestered liposomes without interfering with the ability of the liposomes to release the entrapped bioactive agent. Furthermore, the rate of release of the bioactive agent from the liposome-gel compositions may be varied by altering the composition of the liposomes and/or gels.