Osteogenic protein-1 induced gene expression: evaluation in a posterolateral spinal pseudarthrosis model.

Abstract

Molecular study of gene expression in rabbit lumbar pseudarthrosis repairs using reverse transcriptase polymerase chain reaction. To evaluate differential gene expression of no graft, autograft, and osteogenic protein-1 treated pseudarthroses. Osteogenic protein-1 is a potential bone graft alternative that has achieved high fusion rates in a rabbit lumbar fusion model, including in the repair of nicotine-induced pseudarthroses. A previous study established a correlation between osteogenic protein-1 fusion outcomes and an enhanced level of cytokine gene expression. The expression of such cytokines is known to be decreased in nicotine-exposed rabbit fusion masses. Messenger ribonucleic acid was isolated from nicotine-exposed New Zealand white rabbit lumbar pseudarthroses following attempted no graft, autograft, and osteogenic protein-1 pseudarthrosis repairs. Reverse transcriptase polymerase chain reaction was used to assess the expression of angiogenin, angiopoietin, intercellular adhesion molecule, platelet-derived growth factor-beta, vascular endothelial growth factor, bone morphogenetic proteins 2 and 7, type I collagen, and osteonectin. Glyceraldehyde-3-phosphate dehydrogenase was used as a constitutively expressed control. Levels of gene expression in the osteogenic protein-1 group were higher than those of the autograft group, which were higher than the no graft group for the majority of the genes studied. In the rabbit pseudarthrosis model, gene expression data supported the hypothesis that successful pseudarthrosis repair is related to the induction of osteogenic and angiogenic cytokines by osteogenic protein-1.