Human Urine-derived Stem Cells Promote The Repairment Of Tooth Movement Induced Root Resorption

Objective:To investigate the role of hUSCs in promoting the repairment of tooth movement induced root resorption by in vivo and vitro experiments.Materials and methods:In vitro experiments:hUSCs were isolated from six healthy adult males(age:25-27 years old).The mesenchymal stem cell characteristics of human urine-derived stem cells were identified by flow cytometry detection of cell surface markers and multilineage differentiation assay.The method of indirect co-culture was used to co-culture hUSCs and OCCM30 with the rate of 1:1 for osteogenesis induction.Alkaline phosphatase activity was measured and stained on day 7.Alizarin red stain was performed on day 21.RT-PCR and Western-blot were used to detect the expression of RUNX2,Osterix,OPN and ALP on day 7.CCK8 was used to detect the OCCM30 proliferation on days 1,3,5 and 7.In vivo experiments:Twelve 10-week-old SD rats were used to establish the root resorption model.100 force was loaded on the two maxillary first molars to move the teeth mesial.After 14 days force loading,the appliance was removed,the rats were divided into two groups,the experiment group contained 6 rats(10×10~4/mL hUSCs were injected into the mesio-vestibular and buccal-palatinal corners of upper first molar teeth,one time per three days),control group contained6 rats(no injection).After 10 days,all the rats were sacrificed and the alveolar bones contained first and second molar were obtained.Micro-CT and HE stain were used to observe the root resorption and alveolar bone trabecula parameters.The number of osteoclasts was observed by TRAP staining.The expression of OPN,OCN,CAP and MAB1281 were detected by immunohistochemistry.Results:1.Flow cytometer analysis showed positivity for CD90,CD146 and CD105,which represent mesenchymal stem cell surface markers.The result of multi-directional differentiation detection showed that hUSCs could differentiate into three lineages:osteoblasts,adipocytes and chondroblasts,indicating that human urinary stem cells have the characteristics of mesenchymal stem cells.2.CCK8 detective showed hUSCs could significantly promote the proliferation of OCCM30.3.RT-PCR and Western blot analysis revealed that human urine-derived stem cells could significantly promote the expression of RUNX2,Osterix,OPN,ALP in OCCM30.4.Micro-CT detection found that the root resorption lacuna volume in the experiment group was significantly smaller than that in the control group(P<0.05).5.The bone volume fraction(BV/TV)and trabecular thickness(Tb.Th.)was significantly higher in the experiment group than that in the control group(P<0.05),and the structure model index(SMI)and trabecular separation(Tb.Sp.)was no significant difference between two groups(P>0.05).6.The number of osteoclasts in the experiment group was less than that in the control group.7.The expression of OPN,OCN and CAP were higher in the experiment group than in the control group,and the MAB1281 expression was positive in the experiment group.Conclusions:hUSCs promoted the osteogenesis and proliferate of the cementoblasts significantly,and promote the repairment of tooth movement induced root resorption.These results indicate that hUSCs had the potential ability to promote the repairment of tooth movement induced root resorption.