Osteoinductive potential of freeze-dried, biodegradable, poly(glycolic acid-co lactic acid) disks incorporated with bone morphogenetic protein in skull defects of rats

Biodegradable, porous, polymer implant disks with an osteoinductive potential were prepared by a freeze-drying technique by incorporating bovine bone morphogenetic protein (BMP) in poly(glycolic acid-co-lactic acid) (PGLA). The PGLA disks with and without BMP were implanted in rat skull defects, and the defect sites were studied radiographically and histologically for 2 and 4 weeks after implantation. A quantitative radiographic analysis showed significantly thicker radiopacity for the disks with BMP than those without BMP (P<0.01). After 2 weeks, chondrogenesis and new bone formation were observed on the BMP-incorporated disks. After 4 weeks, PGLA was completely replaced by new bone in the defects with implantation of the BMP-incorporated disks, whereas the defects implanted with PGLA alone were filled with fibrous connective tissue. The results suggest that BMP-incorporated PGLA is an idea bone substitute with osteoinductive potential.