Objective    To explore the effect of bone marrow stromal cells (BMSC) transferred by Nell-1 gene combined with biomaterial fibrin glue (FG) to enhance segmental bone defect healing in dog mandible.     Methods    Nell-1 gene vector was reconstructed in retroviral vector and then transfected BMSC. The protein of Nell-1 gene in transferred cells was determined by immunohistochemistry. Segmental defects were created surgically in the dog’s mandible. The defect was repaired with BMSC transfected by Nell-1 retroviral granules in presence of FG

untransfected BMSC in combination with FG

and FG alone. The cont

rol group was left untreated. The defect-repairing capability for each treatment were assessed by gross observation

radiography

and histology at 8

th

week and 16

th

week.     Results    Cells transfected by Nell-1 retroviral granules expressed abundant Nell-1 mRNA and protein in the cytoplasm. Positive results were not found in those cells that were not transferred. The use of BMSC transferred by Nell-1 retroviral granules combined with FG materials exhibited the strongest defect-repairing ability. Gross observation，radiographical and histomorphometric analyses revealed a significantly greater total area of bone formation

increased amount of the new bone in the defects than in those treated with the untransfected BMSC.     Conclusion    Nell-1 gene transfection may be used to promote the osteogenic ability of BMSC.