The Effect Of Maimendong Decoction On The Directional Homing Of BMSCs In Pulmonary Fibrosis Rats Through The SDF-1/CXCR4 Axis

Objective: Bone marrow mesenchymal stem cells are an effective stem cell source for repairing tissue damage after pulmonary fibrosis,but the curative effect is limited,one of the reasons is that BMSCs,which live in the nests and survive in the lung,are few in number.Stromal cell derived factor 1(SDF-1)and its specific receptors of chemokine receptor 4(CXCR4)consisting of SDF-1 / CXCR4 axis in BMSCs homing and fixed value to participate in the repair of damaged parts play an important role in the process.Our previous studies showed that Maimendong Decoction effevtively improve pulmonary fibrosis in rats and which can promote BMSCs mobilization,homing as well as directional differentiation to alveolar epithelial cells.The purpose of this study is to explore BMSCs of Maimendong Decoction combined with Maimendong Decoction pretreatment to determine whether its role was performed through the sdf-1 /CXCR4 axis.Methods: In the first part,150 female SD rats aged 6-8 weeks were randomly divided into 3 groups: blank group(n=50),Pulmonary fibrosis control group(n=50)and Maimendong Decoction(n=50).The three subjects were respectively executed on 1 day,7 days,14 days,21 days and 28 days through dynamic changes of SDF-1-1 in fibrous lung tissue were detected by HE,MASSON staining,ELISA and RT-q PCR,so that SDF-1 expression peak was selected as the time point for BMSCs transplantation or MMD-BMSCs transplantation in the second part.The second part randomly divided the rats into five groups: sham-operated group,which was injected into the the same dose of normal saline at 5mg/kg through trachea;Those who was injected into the model group tail vein PBS(PBS group);Those who was injected into untreated BMSCs(BMSCs group);Those who was injected into BMSCs pretreated Maimendong Decoction(MMD-BMSCs group);Those who was injected into AMD3100 intervention(AMD3100 group);First of all,MTT colorimetry was used to determine the optimal dose of BMSCs cell survival rate pretreated with MMD decoction.Secondly,the pulmonary fibrosis model rats were prepared by injecting bleomycin solution into exposed trachea at 5mg/kg.Thirdly,after successful modeling,BMSCs labeled with GFP were injected via tail vein 14 days after lung tissue injury.Finally,each group was executed on the 1st day,7th day,14 th day and 28 th day respectively.The infiltration and fibrosis of BMSCs inflammatory cells were detected by histopathology was detected by immunofluorescence and in small animal vivo imager.Results: Compared to the model group,the m RNA and protein expression of SDF-1 were significantly increased by oral administration of MMD decoction,and reached the peak on the 14 th day,which was selected as the point of BMSCs transplantation.Compared with BMSCs group,MMD-BMSCs can significantly control the infiltration and fibrosis degree of inflammatory cells,and the improvement effect of MMD-BMSCs was significantly inhibited after the addition of AMD3100 to block the SDF-1/CXCR4 axis.Histological analysis showed that the pulmonary fibrosis area and inflammatory cell infiltration of MMD-BMSCs were significantly reduced compared with the BMSCs group,and the above effects could be partially blocked by AMD3100.In terms of directional homing,immunofluorescence and the directional homing of small animals showed that the number of homing BMSCs of MMD-BMSCs was further increased compared with that of BMSCs group.The tests verified that the above indexes were significantly transplanted after AMD3100.Compared with that of model group,the number of GFP-BMSCs in lung tissues of BMSCs group was significantly increased.Conclusion: MMD pretreatment can enhance the directional homing of BMSCs to damaged tissues,and the combination of which can further increase the number of BMSCs homing through SDF-1 /CXCR4 axis,promoting tissue regeneration and development,inhibiting cellular inflammatory response,reducing the area of fibrosis,and improveing pulmonary function after pulmonary fibrosis.To sum up,maimendong decoction pretreatment of BMSCs may be an effective method to improve the efficacy of stem cells.