['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.', "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 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.'] Does nELL-1 based demineralized bone graft promote rat spine fusion as compared to commercially available BMP-2 product?