Hydrogel systems for barriers and local drug delivery in the control of wound healing

Many wound healing outcomes are determined by local cell-tissue interactions. The use of tissue-adherent hydrogels as barriers to prevent cell attachment and migration and as local release depots for macromolecular drugs in controlling healing is reviewed and discussed. Terminally diacrylated ABA block copolymers of lactic acid oligomers (A) and polyethylene glycol (B) have been used to form barriers directly upon tissue surfaces by photopolymerization of aqueous precursor solutions. Bulk photoinitiation has been performed to result in macroscopic gels, and interfacial photoinitiation has been used to form gels with thickness on the order of single cell diameters. These materials have been explored to reduce postoperative adhesions and to block post-balloon angioplasty thrombosis and reduce thickening of the arterial intima. Proteins have been released in vitro and in vivo, and locally released urokinase and tissue plasminogen activator have been demonstrated to further reduce postoperative adhesions relative to the gel barrier alone.