| Some stimulations (such as caries, abrasion, trauma, etc. on teeth) couldresult in dentin defects which will lead to inflammation of pulp if it is serious,therefore, the pulp tissue will produce reparative dentin itself in response to thestimulation.At present, it thought that dental pulp stem cells play an importantrole in the repair of dentin-pulp injury; however, it is difficult to obtain andexpend the dental pulp stem cells. Many studies have indicated that bonemarrow mesenchymal stem cells (BMMSCs) could differentiate into multiplecells, such as osteoblast, chondrocytes，myocytes，neurocytes，skin cells etc.，which are important in the repair of injuries in bone, cartilage, muscle, nerveand skin etc.. BMMSCs are deemed to be the priority option in the cells torealize regeneration and repair on tissues. What’s more, many studies haveproved that the canonical wnt signaling plays an important role in the process.Tooth is one of the important organs of the body. No report shows whetherbone marrow mesenchymal stem cells in vivo will involve in the repair and the role of wnt signalling when the pulp is damaged. The experiment will explorethe role of BMMSCs in repair of injured pulp and the effect of the wnt signalingin this process.The study is divided into two parts:1. The compound of BMMSCs and Apical bud transplant to renal capsuleObjective: To explore the role of canonical wnt signaling in dentin-likedifferentiation of BMMSCs.Methods: BMMSCs are divided into three groups：（1）Control groups：Normal BMMSCs without any pretreatment;（2）Wnt3a groups： BMMSCswhich have been stimulated by Wnt3a(100ng/ml) for48h;（3）DKK-1groups：BMMSCs which have been stimulated by DKK-1(100ng/ml) for48h. TheseBMMSCs compound with the Apical bud，respectively, and then transplant torenal capsule， two weeks later, sliced and observed by HE andimmunohistochemistry staining.Results: Recombined BMSSCs/Apical bud developed into atypicaldentin-pulp complexes. Compared to control groups, more formation ofmineralized tissue appear and more DMP-1+/DSP+cells in DKK1groups，while fewer mineralized tissues are formed and fewer DMP-1+/DSP+cells inWnt3a groups.Conclusion: Canonical Wnt signaling may inhibit the odontogenicdifferentiation and mineralization of BMMSCs.2. The role of BMMSCs in the repair of pulp injury and the regulation ofcanonical Wnt in the processObjective: To investigate whether bone marrow mesenchymal stem cells(BMMSCs) take part in the repair of pulp injury and the role of wntsignaling in the process.Methods: The SD rat model jointed with GFP-BMMSCs, which werepretreated with Wnt3a/DKK1, was established by tail intravenous injection, theexperience groups comprised:(1)Control groups: injected GFP-BMMSCs werenormal without any stimulation;(2)Wnt3a groups: injected BMMSCs whichhave been stimulated for48h by Wnt3a(100ng/ml);(3)DKK-1groups: injectedBMMSCs which have been stimulated for48h by DKK1(100ng/ml). And thenthe rat model of pulp injury was established by making dentin defects. Atdifferent time after dentin defects, HE and immunofluorescence staining areused to observe the pathological change of dental pulp and distribution ofGFP-BMMSCs.Results:（1）At the beginning of dentin defects, pulp is with hyperaemia，and then forming reparative dentin. GFP-BMMSCs could be observed in pulp,moreover, more GFP-BMMSCs were observed in dentin defect groups than thecontrol groups.（2）Compared to control groups, more reparative dentin areformed and more GFP-BMMSCs appear in the DKK-1groups. On the contrary,fewer reparative dentin are formed and fewer GFP-BMMSCs appear in theWnt3a groups.Conclusion:（1）Bone marrow mesenchymal stem cells could migrate intothe site of pulp injury and involve in repair of damaged pulp in case of anyinjury in the pulp.（2）It could promote the repair process of pulp injury throughinhibiting canonical wnt signaling. |
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