The aims of the present study were to fabricate a novel porous polylactic acid (PLLA) composite scaffold and evaluate the capacity of the scaffold in carrying recombinant bone morphogenetic protein 2 (rhBMP2) for engineering bone formation. The structures of the PLLA scaffolds were evaluated by SEM and the controlled release of rhBMP2 from the composite scaffolds was assayed by ELISA. Bone induction by the scaffolds loaded with or without rhBMP2 was performed in the calf muscle of twenty Wistar rats for 3, 7, 10, 14, and 28 days. Tissue specimens were examined by Masson's trichrome and von Kossa stainings, and immunohistochemistry of bone proteins. Our results indicated that a moderate foreign body reaction was found in control scaffolds, which lasted for 4 weeks. The addition of rhBMP2 to this novel scaffold dramatically alleviated the adverse responses to PLLA. Enhanced deposition of collagen matrix and endochondral formation were observed in rhBMP2-PLLA scaffolds at 7-10 days, compatible with an early release of rhBMP2 in the composite scaffolds. Bone sialoprotein and osteopontin were demonstrated simultaneously. Von Kossa staining was observed in the test group at 10-14 days. In conclusion, the PLLA scaffolds exhibited the capability of carrying rhBMP2 for inducing bone formation within 2 weeks. These results suggest that rhBMP2-PLLA scaffold may be applicable in tissue engineering.
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