Maxillary sinus floor elevation using a tissue-engineered bone complex with beta-TCP and BMP-2 gene-modified bMSCs in rabbits.

摘要

OBJECTIVES: To study the effects of maxillary sinus floor elevation by a tissue-engineered bone complex with beta tricalcium phosphate (beta-TCP) and bone morphogenetic protein-2 (BMP-2) gene-modified bone marrow stromal cells (bMSCs) in rabbits. MATERIAL AND METHODS: bMSCs derived from New Zealand rabbit bone marrow were cultured and transduced with the adenovirus with BMP-2 (AdBMP-2), adenovirus with enhanced green fluorescent protein gene (AdEGFP) in vitro. Gene transfer efficiency was detected by EGFP expression. These gene-modified autologous bMSCs were then combined with a beta-TCP granule scaffold at a concentration of 2 x 10(7) cells/ml and used to elevate the maxillary sinus floor in rabbits. Twenty rabbits were randomly allocated into groups and sacrificed at weeks 2 and 8. For each time point, 20 maxillary sinus floor elevation surgeries were made bilaterally in 10 rabbits for the following groups (n=5 per group): group A (beta-TCP alone), group B (untransduced bMSCs/beta-TCP), group C (AdEGFP-bMSCs/beta-TCP), and group D (AdBMP-2-bMSCs/beta-TCP). All samples were evaluated by histology and histomorphometric analysis. The fate of implanted bMSCs was traced initially by a confocol fluorescent microscope in the AdEGFP group. RESULTS: Gene transfer efficiency reached up to 60-80% with 50 PFU/cell transduction as demonstrated by fluorescent microscopic analysis in the AdEGFP group. The augmented maxillary sinus height was maintained for the four groups till 8 weeks post-surgery, while new bone area increased over the time. At week 2, bone areas in groups B-D were significantly larger than those in group A, while at week 8, in group D, the BMP-2 gene-enhanced tissue-engineered bone had the largest bone area among the groups (P<0.05, ANOVA). In that group, a mature bone structure was detected in the center of the elevated space. Under a confocal microscope, green fluorescence in newly formed bone was observed for the EGFP group, which suggested that those implanted bMSCs might have contributed to the new bone formation. CONCLUSION: bMSCs modified with the AdBMP-2 gene can promote new bone formation and maturation in the rabbit maxillary sinus. BMP-2 regional gene therapy and a tissue engineering technique could be effectively used in maxillary sinus elevation and bone regeneration.