Effect of human bone morphogenetic protein-7 gene transfection on proliferation of rabbit nucleus pulposus cells and synthesis of extracellular matrix / 中国组织工程研究

ABSTRACT

BACKGROUND: Previous studies demonstrated that recombinant human bone morphogenetic pretein-7 (hBMP-7) can effectively promote the synthesis of extracellular matrix, repair of damaged disc matrix, restore of degenerative disc height. It is hoped that BMP-7 can be used to control and reverse the intervertebral disc degeneration. However, because of the short half-life of recombinant protein and low biological activity, it is difficult to maintain BMP-7 high concentrations on degenerative disc. Gene therapy can prevent these defects effectively.OBJECTIVE: To study the effect of hBMP-7 gene transfeotion on biological activity of primary cultured rabbit nucleus pulposus cells in vitro, to determine the feasibility of hBMP-7 gene which will on gene therapy research of intervertebral disc degeneration,and to provide basis for further study.DESIGN, TIME AND SETTING: A randomized and controlled observation was performed at the Institute of Cardiothoracic Surgery of Changhai Hospital from December 2005 to September 2006.MATERIALS Six healthy New Zealand white rabbits of either gender, averaging 4 weeks old and weighing 500 g, were used in this study, and Ad-hBMP7 was constructed by the Cardiothoracic Surgery Institute of Changhai Hospital.METHODS: After rabbits sacrifice under aseptic condition, the nucleus pulposus was got. After digested with Pronase, type Ⅱcollagenase and type Ⅱ DNAase (4 hours, 37 "(2), the cells were seeded in the Petri dishes and were kept in the incubator. After 7 days and then twice a week, the media were refreshed. The nucleus pulposus cells were infected by adenovirus integrated with hBMP7 gene. The cells which were transfected by adenovirus vector for Lac-Z gene and which were not transfected were adopted as control.MAIN OUTCOME MEASURES: The expression of hBMP-7 was determined by RTopCR and Western blot. The effect of hBMP-7 on cell proliferation was surveyed by MTT. Furthermore, the effect of hBMP-7 gene on synthesis of proteoglycan and type Ⅱcollagen was detected by modified dimethylmethylene blue method and ELISA, respectively.RESULTS: Gene sequencing and PCR showed that hBMP-7 gene was inserted correctly and no mutation happened. The pdmary cultured rabbit nucleus pulposus cells were identical with those reported in literature. After Ad-hBMP7 transduct into the nucleus pulposus cells, high level of hBMP-7 expression was observed and lasted over 3 weeks. Also hBMP-7 gene can promote cell proliferation and synthesis of proteoglycan and type II collagen with significant difference compared with control groups (P < 0.05).CONCLUSION: hBMP-7 gene mediated by adenovirus can be the target gene for the further study on gene therapy of intervertebral disc degeneration.