How dose nicotine affect bone regeneration?

Abstract

OBJECTIVE: To study the effect of nicotine on bone regeneration and neo-angiogenesis using a rabbit model of madibular lengthening and evaluate the influence of nicotine on the expression of osteogenesis and angiogenesis related growth factors in distraction regenerate. METHODS: 50 adult New Zealand white rabbits were randomly assigned to two equal groups: placebo control and 1.5g nicotine. 60-day time release nicotine pellets or placebo pellets were implanted in the neck subcutaneous tissue of the rabbits. Total nicotine exposure time was seven weeks. After nicotine implantation, a standard procedure of mandibular body osteotomy and distraction were performed. The animals were sacrificed at day 5 of distraction, day 1, week 1, week 2 and week 4 of consolidation. The madibles were harvested for the analysis of plain X-ray, micro-CT, Histological staining and real-time PCR. RESULTS: Nicotine exposure increased microvessel density, whereas inhibited blood flow and bone formation. Frequent appearance of cartilage islands suggested ischemia and low oxygen tension in the distraction regenerate. The expression of bone morphogenetic protein was decreased. The expression of vascular endothelial growth factor was increased. CONCLUSIONS: Nicotine compromises bone regeneration by causing ischemia and directly inhibitory effect on osteoblastic cells. Nicotine exposure enhances angiogenesis but can not compensate for the adverse effect of vasoconstriction.