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Updated: May 11, 2026
Polyelectrolyte Complex for Heparin Binding Domain Osteogenic Growth Factor Delivery
Published on: August 22, 2016
NELL-1 based demineralized bone graft promotes rat spine fusion as compared to commercially available BMP-2 product
Wei Yuan1, Aaron W James, Greg Asatrian
1Department of Orthopaedic Surgery, Zhongshan Hospital, FudanUniversity, 180 Fenglin Road, Shanghai 200032, China.e-mail: dong.jian@zs-hospital.sh.cn
Background:
Spinal fusion is among the most commonly performed orthopaedic procedures. Unfortunately, current treatments such as autologous bone grafting or recombinant proteins (BMP-2) have numerous clinical shortcomings. Here, we directly compare the efficacy of NELL-1, a novel osteoinductive growth factor, to two currently available treatments, (1) recombinant BMP-2 and (2) iliac crest bone grafting, in a spinal fusion model.
Methods:
Twenty-six skeletally mature athymic rats underwent posterolateral spine fusion of L4/L5 vertebrae. Treatment groups included NELL-1 (10 and 50 μg) in a demineralized bone matrix (DBX), as compared to BMP-2 (90 μg) in an absorbable collagen sponge (ACS) or morselized iliac crest bone. Scaffolds without recombinant protein were used as controls. Animals were sacrificed at 4 weeks post-operative and fusion was assessed by manual palpation, radiography [high-resolution X-ray, micro-computed tomography (microCT)], histology (hematoxylin and eosin, Masson's trichrome) and immunohistochemistry (osteocalcin).
Results:
Results showed 100 % fusion in all NELL-1- and BMP-2-treated samples. In contrast, lower rates of fusion were observed in scaffold-only and bone graft treatment groups. MicroCT scans revealed radiographic evidence of fusion among spines treated with NELL-1. Bone bridging was also observed with BMP-2 treatment, but was accompanied by inner radiolucency, suggesting cyst-like bone formation. Histologically, NELL-1-treated grafts showed increased bone formation, endochondral ossification and vascularization. Although BMP-2 treated grafts exhibited increased bone formation and angiogenesis, numerous adipocytes were also observed.
Conclusion:
NELL-1-based bone grafts are comparable to BMP-2 + ACS in spinal fusion efficacy. Histological differences were observed however, including robust endochondral ossification with NELL-1 treatment as compared to lipid-filled bone with BMP-2 treatment. These findings suggest NELL-1 based bone grafts show promise for future efforts in skeletal tissue engineering.
