Effect of local gene delivery(Ad-BMP-2) on ectopic bone formation around the mandibular periosteum in rabbits

Objective To investigate the effect of Ad-BMP-2 on ectopic bone formation around the mandibular periosteum in rabbits.Methods Eighteen New Zealand White rabbits were used in the study.About 2×109pfu of Ad-BMP-2 vectors(0.2 milliliter lysate) were injected into the site around the lateral periosteum of the mandible on the right side of each rabbit to serve as the experimental group,and the left side had the same volume of phosphate buffered saline(PBS) injected into the periosteum to serve as the control group.Six animals were sacrificed at the time points of 2,5 and 10 weeks post-operation.All the samples were examined by X-ray and histological chemiscal observation to investigate the temporal and spatial characteristics of new bone formation.Results In vivo local delivery of Ad-BMP-2 resulted in a certain degree of immunologic rejection,which was decreased as time went on.At week 2,many native cells around the injection site began to proliferate and differentiate towards the cell line of osteoblast;at week 5,osteoid tissue was found and some new tissues began to be mineralized;at week 10,immature woven bone and marrow cavity-like structures were formed.There were some differences between animals in the ossification degree of new forming tissue.There was no osteoid tissue formed in the control groups.Conclusion Ad-BMP-2 could induce ectopic bone formation around the mandibular periosteum and could augment the thickness of cortex bone.