Sealing or filling tissue defects using polyfunctional crosslinking agents and protein polymers

Abstract

Proteinaceous polymers having repetitive units from naturally occurring structural proteins are employed as backbones for functionalities for crosslinking to provide strongly adherent tissue adhesive compositions for bonding together separated tissue, and for sealing or filling tissue defects by injecting the compositions into the defects. Particularly, block copolymers having repeating units of elastin and fibroin are employed having lysine substitutions in spaced apart units, where the amino group can be crosslinked using difunctional crosslinking agents such as glutaraldehyde, activated diolefins, diisocyanates, acid anhydrides or diamines. The protein polymer contains at least 40 weight percent of repetitive units of 3 to 30 amino acids, preferably 3 to 15 amino acids, of at least one naturally occurring structural protein and at least two amino acids containing a functional group capable of reacting with the crosslinking agent. The protein polymer generally has a molecular weight of at least about 30 kD and not more than 250 kD. A preferred protein polymer contains at least 70 weight percent of repetitive units of Gly-Ala-Gly-Ala-Gly-Ser and Gly-Val-Gly-Val-Pro, where in at least two units an amino acid is substituted with one of lysine or arginine, and the protein polymer has a lysine and arginine equivalent weight in the range of 1 to 20 kD and contains at least two amino acids having a functional group capable of reacting with at least one of aldehyde, isocyanate, thioisocyanate and activated carboxy. The protein polymer is produced by recombinant DNA technology, and a kit may be formed containing the crosslinking agent and protein polymer.