[Reconstruction of segmental bone defect by gene modified tissue engineering bone combined with vascularized periosteum].
OBJECTIVE
To evaluate the therapeutic effect of bone morphogenetic protein 2 (BMP-2) gene modified tissue engineering bone (GMB) combined with vascularized periosteum in the reconstruction of segmental bone defect.


METHODS
Adenovirus carrying BMP-2 gene (Ad-BMP-2) was transfected into the isolated and cultured rabbit bone marrow stromal cells (MSCs). The transfected MSCs were seeded on bovine cancellous bone scaffolds (BCB) to construct gene modified tissue engineering bone (GMB). The bilateral rabbits radial defects (2.5 cm long) were created as animal model. The rabbits were divided into five groups to reconstruct the defects with CMB combined with vascularized periosteum (group A); or GMB combined with vascular bundle implantation (group B); or GMB combined with free periosteum (group C); or GMB only (group D); or BCB scaffolds only (group E). Angiogenesis and osteogenesis were observed by X-ray, histological examination, biomechanical analysis and capillary ink infusion.


RESULTS
In group A, the grafted GMB was revascularized rapidly. The defect was completely reconstructed at 8 weeks. The mechanism included both intramemerbrane and endochondral ossification. In group B, the vascular bundle generated new blood vessels into the grafted GMB, but the osteogenesis process was slow in the central zone, which healed completely at 12 weeks. In group C, the free graft of periosteum took at 4 weeks with angiogenesis. The thin extremal callus was formed at 8 weeks and the repairing process almost finished at 12 weeks. Better osteogenesis was found in group D than in group E, due to the present of BMP2 gene-transfected MSCs. The defects in group D were partial repaired at 12 weeks with remaining central malunion zone. The defects in group E should nonunion at 12 weeks with only fibre tissue.


CONCLUSIONS
BMP-2 gene modified tissue engineering bone combined with vascularized periosteum which provides periosteum osteoblasts as well as blood supply, has favorable ability of osteogenesis, osteoinduction and osteoconduction. It is an ideal method for the treatment of segmental bone defect.
Li
Jian-jun
JJ
Department of Orthopaedics, Second Hospital of China Medical University, Shenyang.
Zhao
Qun
Q
Wang
Huan
H
Yang
Jun
J
Yuan
Quan
Q
Cui
Shao-qian
SQ
Li
Lei
L
D000818:Animals; D001854:Bone Marrow Cells / Q000166:cytology; D055396:Bone Morphogenetic Protein 2 / Q000235:genetics*; D001861:Bone Regeneration; D018786:Bone Substitutes; D016025:Bone Transplantation / Q000379:methods*; D001842:Bone and Bones / Q000473:pathology; D002417:Cattle; D059630:Mesenchymal Stem Cells / Q000166:cytology; D010521:Periosteum / Q000098:blood supply / Q000637:transplantation; D011817:Rabbits; D013524:Surgical Flaps / Q000098:blood supply; D023822:Tissue Engineering / Q000379:methods*; D054457:Tissue Scaffolds; D014162:Transfection
D055396:Bone Morphogenetic Protein 2; D018786:Bone Substitutes