Abstract:

Abstract:Objective To compare the interbody fusion effects of  bone morphogenetic protein 2-9  (Adv-BMP 2-9) with single expression of Adv-BMP9 or adv-BMP2 mediated by co-expressing recombinant adenovirus combined with nano-hydroxyapatite/polyamide 66 (nHA/PA66) cage on   lumbar interbody fusion of goats,and to clarify the collaborative osteogenesis effects of BMP2 and BMP9.Methods Interbody fusion was performed at L2-3,L3-4 and L4-5 in 40 Chinese green goats,included a total of 120 interspace of lumbar vertebrae.Each interspace of lumbar vertebra was randomly implanted with a nHA/PA66 cage combined with one of the following four adenovirus, Adv-BMP9 (Adv-BMP9 group,n=30),Adv-BMP2 (Adv-BMP2 group,n=30),Adv-BMP2-9 (Adv-BMP2-9 group,n=30),and Adv-GFP (Adv-GFP group,n=30).The goats were euthanized 24 weeks after operation,and the fusion segment speciments were obtained;radiographic inspection and biomechanical analysis were performed on the segment speciments.Results The X-ray results showed there was no significant dirence of disc space height(DSH) before and after operation  between various groups.The interbody fusion rates were 70% (21/30) in Adv-BMP2-9 group and 53% (16/30) in Adv-BMP9 group and 31% (5/16) in Adv-BMP2 group and 30% (9/30) in Adv-GFP group.CT fusion degree tests  showed that CT fusion scores  in Adv-hBMP2-9 group,Adv-hBMP9 group,Adv-hBMP2 group and Adv-GFP group were 52.29±0.72,44.02±0.67,38.83±0.86,and 28.65±0.47,respectively; there were significant differences between various  groups(P<0.05 or P<0.01).Biomechanical analysis showed that the  stiffness of the fusion segment in Adv-BMP2-9 group was higher than that in Adv-BMP9 group(P<0.05),and stiffness in the fusion segment in   Adv-BMP9 group was higher  than that in Adv-BMP2 group,but there was no significant difference(P>0.05).During the experiment,no local or distant infection,fever,and foreign body rejection were observed in all goats.Conclusion The interbody fusion effect of co-expressing Adv-BMP2-9 combined with nHA/PA66 cage is superior to Adv-MP9 or Adv-BMP2  on goat lumbar,and BMP2 and BMP9 have collaborative osteogenesis.

Key words: bone morphogenetic protein')">

bone morphogenetic protein, recombinant adenovirus,  nano-hydroxyapatite')">interbody fusion; nano-hydroxyapatite, polyamide