[Study on repair of critical calvarial defects with nano-hydroxyapatite/collagen/polylactic acid material compounded recombinant human bone morphogenetic protein 2 in rabbits].
OBJECTIVE
To investigate the effect of tissue engineering bone compounded in vitro by nano-hydroxy-apatite/collagen/polylactic acid (nHAC/PLA) and recombinant human bone morphogenetic protein 2 (rhBMP-2) in repairing rabbit critical calvarial defects.


METHODS
Forty-eight New Zealand rabbits, weighting 2.0-2.5 kg, were made the models of critical cranial defects (15 mm in diameter) and divided into 4 groups randomly. Defects were repaired with auto-flank bone in the positive control group; with no implant in the blank control group; with nHAC/ PLA in the negative control; and with active nHAC/PLA(AnHAC/PLA) in the experimental group(the average quality of each AnHAC/PLA absorbed rhBMP-2 was 1.431 mg). The reapir results were observed through X-ray,HE dyeing and Masson's trichrism dyeing after 8 and 16 weeks.


RESULTS
The difference of bone formation was observed by X-ray block degree of skull defect area at 8 and 16 weeks. In the 8 th week and 16 th week, the radiopacities on cranial defect were 67.21%+/-2.06% and 86.48%+/-1.73% in the positive control group; 5.84%+/-1.92% and 9.48%+/-2.72% in the blank control group; 19.13%+/-2.51% and 35.67%+/-3.28% in the negative control group; and 58.84%+/-2.55% and 85.61%+/-3.36% in the experimental group. There were significant differences between the negative control and the positive control group, and between the experimental group and the positive control group at 8 weeks (P<0.05). There were significant differences between the negative control and blank group, and between the experiment and the blank group at 8 and 16 weeks (P<0.05). The histology observation showed that the width of bone trabecula at 16 weeks was more than that at 8 weeks and bone defect was full of bone tissue in positive control group. The bone defect was full of fibrous tissue at 8 and 16 weeks, and there was no new bone in the blank group. The bone defect was full of remnant material and fibrous tissue in the negative control group. The implanted area was replaced by the new bone at 8 weeks and the new bone was lamellar at 16 weeks in the experimental group; the residual material was less in defect area and there were more osteoblasts surrounding.


CONCLUSIONS
The nHAC/PLA is a good scaffold material of rhBMP-2 and AnHAC/PLA has a good ability in repairing bone defect. So it is hopeful to be applied in the clinical repair of large bone defect.
Chen
Peng
P
Department of Stomatology, General Hospital of PLA, Beijing, 100853, PR China. chenpenglb@yahoo.com.cn
Liu
Bing
B
D000818:Animals; D001672:Biocompatible Materials; D019485:Bone Morphogenetic Proteins / Q000494:pharmacology*; D001861:Bone Regeneration / Q000187:drug effects; D016025:Bone Transplantation / Q000379:methods; D003094:Collagen / Q000737:chemistry / Q000494:pharmacology*; D004195:Disease Models, Animal; D005260:Female; D006801:Humans; D006882:Hydroxyapatites / Q000737:chemistry / Q000494:pharmacology*; D007085:Ilium / Q000637:transplantation; D019344:Lactic Acid / Q000737:chemistry / Q000494:pharmacology*; D008297:Male; D049329:Nanostructures; D011091:Polyesters; D011108:Polymers / Q000737:chemistry / Q000494:pharmacology*; D011817:Rabbits; D011897:Random Allocation; D012886:Skull / Q000293:injuries / Q000601:surgery*; D023822:Tissue Engineering
D001672:Biocompatible Materials; D019485:Bone Morphogenetic Proteins; D006882:Hydroxyapatites; D011091:Polyesters; D011108:Polymers; D019344:Lactic Acid; C033616:poly(lactide); D003094:Collagen