Experimental Study Of Repair Of Cranial Bone Defects Using BMP-2 Derived Bioactive Peptide Combined With Nano-hydroxyapatite And Collagen Ⅰ

Objective: To investigate the osteogenetic capacity of bone repair in rat cranial bone defects by nHAC loading with a BMP-2-derived peptide P24 biomimetic scaffold materials.Methods:19 male Sprague–Dawley rats were divided into four groups. Five-millimeter critical-size cranial bone defects were created in each one. The defects were treated with P24/nHAC scaffold (A group), rhBMP-2/ nHAC scaffold (B group), nHAC scaffold (C group)and only bone defect(D group). Up to the 6th and 12th weeks, the rats were sacrificed in batch respectively. Defects were evaluated by X-ray,three-dimensional reconctruction of computer tomography,histology and the percentage of bone formation areas.Results:①Radiological examination indicated that there were some flaky radiodense areas in A and B gruoups of each rat, but the density of the radiodense areas of C group were obviously lower than the density of A and B groups at the 6th week.At the 12 week,the radiodense areas of C group were denser than the 6th week,but defects not repaired. The defects nearly healed at the 12th week in the A and B groups. A trifle of radiodense areas were discovered in the margin of defects in the D group.②Three-dimensional reconstruction of computed tomography indicated that there were fewer radiodense areas and not saw bone bridge in the C group, but the density of the radiodense areas of A and B groups were obviously denser than the density of C group and bone brige was discovered at the 6th week. The defects completely healed in B group and nearly reparied in A group that was treated with BMP-2- derived peptide loaded nHAC at the 12th week ,while not saw defects were connected by bone bridge in C group and D group. The percentages of the regenerated areas in C and D group were significantly lower than A group and B group at 6 and 12 weeks (p<0.05),but no significant difference between A group and B group(p>0.05).③Histological examination: At 6 weeks post-surgery, Small amount of composite in group C degraded, few of inflammation; and A group and B group showed some new bone tissue and osteoblasts. At 12 weeks, in the A group and B group, the bony-union between new bone and host bone was observed. Meanwhile, the composite was almost completely degraded. In the C group, there were still slight amounts of new bone, the scaffolds were only partly degraded and the residual materials were surrounded by areas of new bone formation.Conclusion:①The osteogenic capability of BMP-2- derived peptide loaded nHAC is obviously superior to nHAC alone.②nHAC is an ideal scaffold and a sustained release carrier.③It is suggested that P24/ n nHAC biomimetic scaffold material can be a ideal and steady repairing material for bone defects.