[Experimental study on spinal fusion induced by hBMP-4 gene modified tissue engineered bone].
OBJECTIVE
To evaluate the efficacy of hBMP-4 gene modified tissue engineered bone graft in the enhancement of rabbit spinal fusion and find an ideal kind of substitute for the autograft bone.


METHODS
Rabbit BMSCs were cultured and transfected with AAV-hBMP-4 using different MOI value. The optimal MOI value were determined by observing cell's morphology change. BMSCs were then transfected with AAV-hBMP4 and AAV-EGFP respectively, following which the transfected cells were evenly suspended in a collagen sponge I, and implanted to either side of the L5,6 intertransverse spaces posterolateral in the New Zealand rabbits to induce spinal fusion. Fourteen rabbits were randomly divided into 2 groups. Group 1: AAV-hBMP-4 transfected BMSCs in the right side (hBMP-4 side) and autograft bone in the left side. Group 2: AAV-hBMP-4 transfected BMSCs in the right side (hBMP-4 side) and AAV-EGFP transfected BMSCs in the left side (EGFP side). Radiographs and three-dimensional CT of the spine, manual palpation, gross and histological examination of the fusion masses for all the animals were performed subsequent to animals having been sacrificed at 12 weeks after surgery.


RESULTS
Evaluation has been taken in 12 New Zealand rabbits delivered into 2 groups which meet the criterion after operation. Eleven in 12 implemented sides involved hBMP-4 achieved bony fusion, to which 5 in 6 autografted sides was similar. But only 2 in 6 sides in EGFP-group achieved bony fusion meanwhile. Three-dimensional CT scan and palpation also evidenced the results. Bone formation was observed obviously on specimen both in hBMP4 sides and autografted ones. EGFP-group also got bony integration, but the quantity was small.


CONCLUSIONS
Tissue-engineered bone graft constructed from application of hBMP4 is a fine substitute for autograft. Effective enhancement of bony integration in spinal fusion surgery has been evidenced in vivo.
Zheng
Zhao-Min
ZM
Department of Orthopedics, First Affiliated Hospital, Sun Yat-Sen University, Guangzhou 510080, China. zhengzm1@163.com
Dong
Zhi-Yong
ZY
Kuang
Guan-Ming
GM
Chen
Hui
H
Lü
You
Y
Zhang
Kui-Bo
KB
Liu
Hui
H
Li
Fo-Bao
FB
D000818:Animals; D055415:Bone Morphogenetic Protein 4 / Q000235:genetics*; D001861:Bone Regeneration; D018786:Bone Substitutes; D016025:Bone Transplantation / Q000379:methods; D005822:Genetic Vectors; D016086:Lentivirus / Q000235:genetics; D008297:Male; D023461:Myeloid Progenitor Cells; D011817:Rabbits; D011897:Random Allocation; D013123:Spinal Fusion / Q000379:methods*; D017154:Stromal Cells; D023822:Tissue Engineering; D014162:Transfection
D055415:Bone Morphogenetic Protein 4; D018786:Bone Substitutes