Control of Healing with Photopolymerizable Biodegradable Hydrogels

Abstract

Post-surgical wound healing has been modified by the use of biodegradable hydrogel barriers to block cell adhesion to tissue surfaces, e.g. to the mesothelium in abdominopelvic surgery or to the subendothelium in angioplasty. These materials were formed in situ by photopolymerization of an aqueous precursor to obtain barriers that were conformai and adherent to the tissue. The precursor was comprised of a central chain of polyethylene glycol, with peripheral blocks of lactic acid oligomer, and with acrylate termini, the polyethylene glycol chain providing water solubility and biocompatibility, the lactic acid oligomer providing water lability, and the acrylate termini providing polymerizability to form a crosslinked hydrogel. Using these materials, it was possible to dramatically improve abdominal healing with less postoperative adhesions in rats and arterial healing with no thrombosis and less intimai thickening in rats. The hydrogel barriers were also employed as controlled release depots for protein drugs, the proteins being contained by entanglement. It was possible to further reduce postoperative abdominal adhesion formation in rats by releasing tissue plasminogen activator or urokinase plasminogen activator from the tissue-adherent barrier.