[NELL-1: a novel highly efficient and specific growth factor]

Regeneration of bone tissue, as well as other tissues, requires involvement and interaction of cells, scaffolds and relevant growth factors, among which growth factors play a crucial role in maintaining the stability of microenvironment. Nel-like-type 1 molecule (NELL-1), a novel growth factor in tissue engineering, has been studied intensively in recent years. Researches mainly covered gene and protein structure and their expression profiling, biological function, molecular mechanisms and disease relevance. NELL-1 expressed in embryonic tissue is essential for growth and development of bone tissue. NELL-1 presents excellent abilities of inducing bone and cartilage regeneration,especially with high specificity to chondrocyte lineage. Compared with classic osteogenic growth factor bone morphogenetic protein 2 (BMP-2), the process of osteogenesis interacted with NELL-1 exhibits stronger specificity, higher bone density and fewerside effects. Furthermore, a recent study shows synergistic effects of NELL-1 and BMP-2. NELL-1 enhances the osteogenic reaction induced by BMP-2 of cells and notably declines inflammation response caused by BMP-2. This review evaluates the current research progress of the function and application of NELL-1 by the systematic method of evidence-based medicine.