Effects On Mandible And Condylar Bone Marrow Derived Mesenchymal Stem Cells In Young Rats Induced By Nasal Obstruction

Background&Purpose:The fact that long-term mouth breathing would lead to mandibular deficiency has been confirmed by numerous clinical studies.However the specific mechanism still remains unknown.This study aims to utilize the animal model of mouth breathing,to discuss its influence on the growth and development of mandible and condyle,and also its effect on the chondrogenic differentiation of Bone Marrow derived Mesenchymal Stem Cells(BMSCs)derived from condyleMethods:Forty 4-week-old Sprague Dawley(SD)rats were randomly divided into two groups.The experiment group contains 28 rats,referring to the mouth-breathing group,while the control group contains 12 rats The experiment group had both nostrils occluded by nose plugs,from 8:00 a.m.to 4:00 p.m.every day.The control group had no processing The animal experiment lasted for 4 weeks.During modeling daily weight of each rat was monitored,different growth period of the mandibles were scanned by CT and reconstructed.Bilateral condylar BMSCs were cultured in vitro,CCK-8 was used to compare the difference of cell proliferation,RT-PCR was used to detect the difference of gene expression of BMSCs chondrogenic marker genes(Agg,COL-Ⅱ,Sox-9)Results:There was a significant decrease of weight in the obstruction group than the control group after 4 weeks.CT results showed that the mandible and condyle in the experiment group grew much slower than the control ones.During modeling,different growth period of condylar BMSCs cell proliferation ability,as well as the expression of chondrogenic marker genes(Agg,COL-Ⅱ,Sox-9)were all significantly lower in the experiment group than the control group.Conclusion:Long-term mouth breathing caused by bilateral intermittent nasal obstruction,would result in the deficiency of the mandible and condyle of the rats.The mechanism might be closely related to the inhibition of condylar BMSCs cartilage differentiation.