Growth Factor Delivery for the Repair of a Critical Size Tibia Defect using Acellular, Biodegradable PEG-Albumin Hydrogel Implant

Growth factor delivery using acellular matrices presents a promising alternative to current treatment options for bone repair in critical-sized injuries. However, supra-physiological doses of the factors can introduce safety concerns that must be alleviated, mainly by sustaining delivery of smaller doses using the matrix as a depot. We developed an acellular, biodegradable hydrogel implant composed of polyethylene glycol and denatured albumin to be used for sustained delivery of bone morphogenic protein-2 (BMP2). In this study, PEG-Albumin (PEG-Alb) hydrogels were produced and loaded with 7.7 µg/ml of recombinant human BMP2 (rhBMP2) to be tested for safety and performance in a critical-size long-bone defect, using a rodent model. The hydrogels were formed ex-situ in a 5mm long cylindrical mold of 3mm diameter, implanted into defects made in the tibia of sprague-dawley rats and compared to non-rhBMP2 control hydrogels at 13 weeks following surgery. The hydrogels were also compared to the more established P...