| The essence of tooth extraction healing is the process of bone restoration and remolding.Bone tissue is highly vascularized,in which angiogenesis is through the whole process of bone formation.Differentiation and proliferation of vascular endothelial cells and local regulation of angiogenic growth factors serve as two important factors of angiogenesis,and vascular endothelial growth factor(VEGF)perform a significant role in the process of angiogenesis.In early stage of bone formation,VEGF is secreted by vascular endothelial cells and osteoblasts in,inducing endothelial progenitor cells differentiation into vascular endothelial cells,and vascular endothelial cell aggregation and the formation of capillary network.Besides the role of promoting vascularization,VEGF affects osteogenesis activities of osteoblast.Osteoblasts exhibit chemotaxis for VEGF which binds to specific receptors on the surface of osteoblasts.Consequently,it promotes the recruitment of osteoblasts and improves the quality of new bone.VEGF promotes the secretion of IGF-I by vascular endothelial cells and fibroblasts,and promotes the growth and aggregation of osteoblasts.In addition,VEGF and BMP-2 are in the presence of synergistic,regulating local bone formation.When VEGF and BMP-2 intervene on the local bone defect at the same time,the treatment was significantly better than utilizing BMP-2 along.Chitosan is extensively detected in nature.It is widely used in drug delivery system for its advantages of easy access,good biocompatibility and low cost.Under suitable conditions,the complex of such two substances is formed as a result of the ionic interaction between the surface of chitosan solution and the theβ-glycerophosphate.Such complex is thermo-sensitive--it is fluid state at room temperature and become solid state when the temperature is approximate to 37℃.Consequently,the advantage of this feature is that it can be evenly distributed locally after injection,especially for small and irregularly shaped bone defects.The process of tooth extraction healing is related to the etiology,surgical trauma,patient compliance and health conditions of patients.These factors often influence the process as well as its quality.Therefore,drugs with the ablity to promote local bone healing can be loaded into the chitosan thermo-sensitive hydrogel system in order to make the drug evenly and fully in the various parts,thus improving the quality of bone healing.Panax notoginseng total saponins are the main active components of panax notoginseng andare able to increase the activity of bone formation by affecting the expression of bone morphogenetic growth factor such as BMP-2 IGF and VEGF.Moreover,Panax notoginseng saponins can induce differentiation of rat bone marrow mesenchymal stem cells and human periodontal ligament stem cells into osteoblasts.However,whether Panax notoginseng saponins can promote the healing of extraction and how to promote the expression of VEGF has not yet been confirmed.Objective:To further study the effect of panax notoginseng total saponins on tooth extraction wound healing and a rational way of drug loading,three different drug concentrations were analysis in this experiment,and panax notoginseng saponins chitosan thermo-sensitive gel was prepared and applied to the tooth extraction wounds of rat right middle incisors.Paraffin sections are made to HE staining and VEGF immunehistochemical staining to observe the formation of bone,the determination of VEGF positive cell count and the measurement of average optical density value.Materials and Mehtod:The chitosan thermo-sensitive hydrogel were prepared according to three different concentrations of panax notoginseng saponins.Forty-five male SD rats were selected and injections of chitosan thermosensitive hydrogel were initiated after the right incisor extraction,then these subjects were divided into five groups at random.The rats were killed at 1,2,4 weeks respectively after surgery,and then obtained the specimens in the operation area.HE staining and VEGF immunohistochemical staining were used to observe the healing of the tooth extraction and to determine the number of VEGF positive cells and the average optical density.Result:HE staining histology observation1.At first week,there was a significant number of migrations and accumulations of vascular endothelial cells and new blood vessels in the drug groups.Capillary expansion and a high degree of vascularization could be observed as well.2.At the second week,there were obvious osteoblast migrations and aggregations around the margins of trabecular bone,and the morphology was mature and the bone formation was active.The number of new capillaries increased and the morphology was more mature.The degree of vascularization peaked,especially in 1.0mg/ml group.3.At the fourth week,the number of new blood vessels was decreased but the pattern was inclined to be more mature.The pattern of trabecular bone was more mature as well and arranged regularly.Vascularization along with osteogenesis was more active in the drug groups than that in the control grup.Immunohistochemical analysis of VEGF and statistical analysis of the positive cell count and the value of average opticaldensity1.At the first weeks,the positive expression of VEGF was mainly concentrated in the vascular endothelial cells migrated around the blood vessels,the 1.0mg/ml group was the most conspicuous and positive,0.5mg/ml group and 1.5mg/ml group showed weak positive compared with the O.Omg/ml group and the control group.The drug groups were more evident than the O.Omg/ml group and the control group.The determination of VEGF positive cells count and the value of average optical density showed that O.Omg/ml group and control group were no significant differences(P>0.05);drug groups(0.5mg/ml group,1.0mg/ml group,1.5mg/ml group)and model group were statistically significant differences(p<0.05).What is remarkable was that 1.0mg/ml group was the highest.2.At the second week,the positive expression of VEGF in vascular endothelial cells and osteoblasts in each group enhanced significantly,and the positive expression of VEGF in each group reached the peak.The 1.0mg/ml group was strongly positive,which was significantly higher than that of 0.5mg/ml group and 1.5mg/ml group.The positive expression of VEGF in drug group was significantly higher than that in O.Omg/ml group and control group.The determination of VEGF positive cells count and the value of average optical density showed that the O.Omg/ml group and the control group were no significant differences(P>0.05);drug groups(0.5mg/ml group,1.0mg/ml group,1.5mg/ml group)and control group were statistically significant difference(p<0.05)and 1.Omg/ml group was the highest.3.At the fourth week,due to the reduction of vascularization degree,the expression of VEGF was weaker than in the second week and VEGF was mainly expressed in endothelial cells.The expression of VEGF in drug groupswas more obvious than the blank group and the model group.The number of VEGF positive cells and the average optical density value showed that the 0.0mg/ml group and control group were no significant differences(P>0.05);drug groupsand control group were statistically significant differences(p<0.05)and 1.0mg/ml group was the highest.Conclusions:1.Panax notoginseng saponins regulate VEGF expression positively.It can induced the differentiation and proliferation of vascular endothelial cell.Such effects play a significant role angiogenesis.2.Panax notoginseng saponins may promote the osteoblast aggregation by advancing high degree expression of VEGF,thus improving osteogenic activity.3.When drug concentration is 1.0mg/ml,vascularizationdegree is the highest and osteogenesis is the most active in each period of tooth extraction wound healing in rats in the experiment. |
PDF Full Text Request