Bone regeneration induced by an in situ gel-forming poloxamine, bone morphogenetic protein-2 system.

The aim of this study was to confirm previously shown, in vitro osteogenic induction by the Tetronics T908 and T1307 in a critical-size, rat calvaria defect. In vivo, the osteogenic activity of the hydrogels was comparable to in vitro, but less pronounced. However, similar to in vitro, the system was strongly potentiated by incorporating 6.5 microg of bone morphogenetic protein-2 in solution or pre-encapsulated in poly(lactic-co-glycolic) acid microspheres. These two systems extended the in vivo release of bone morphogenetic protein-2, determined with 125I- bone morphogenetic protein-2, for one and two additional weeks, respectively, time enough to fill approximately 40% and 90% of the defect with well-organized bone. Furthermore, the structural characteristics of Tetronic hydrogels together with their biocompatibility, injectability, and adaptability to multiple defect sizes and shapes suggest their role as new, potential bone morphogenetic protein-2 delivery, low-cost scaffolds for minor as well as critical bone defects.