Promotion Effect Of Scaffolds Combined With Exosomes Derived From HIF-1? Modified BMSCs In Repairing Advanced Cartilage Defects

ObjectiveTo explore the protective effect of exosomes(BMSCs-Exo^MU)secreted from bone mesenchymal stem cells?BMSCs?modified by hypoxia inducible factor-1??HIF-1??on the chondrocytes,and to elucidate the possible mechanism of its joint with cartilage regenerated scaffold in promoting the repairment of the advanced cartilage defects.MethodsThe exosomes(BMSCs-Exo^WT and BMSCs-Exo^MU)were extracted from the BMSCs modified by wild type of HIF-1?and mutant type of HIF-1?by ultracentrifugation method and identified in the meantime.In vitro,the inflammatoryresponseofchondrocyteswereinducedby interleukin-1??IL-1??,the same amount of PBS,BMSCs-Exo^WT?80?g/mL?,BMSCs-Exo^MU?80?g/mL?were respectively cultivated with the chondrocytes cells under the inflammatory reaction and Hoechst 33342 dye was used to study the effect of BMSCs-Exo^MU on the apoptosis of chondrocytes mediated by IL-1?.The Western blotting method was used to detect the expression levels of AKT/p-AKT,ERK/p-ERK and p38/p-p38.12 New Zealand white rabbits were randomized into 4 groups to construct the models of rabbit knee cartilage defects,and the equal volume of physiological saline,physiological scaffold+saline,scaffold+BMSCs-Exo^WT,scaffold+BMSCs-Exo^MU were respectively injected into the cartilage defects of rabbits.6 weeks after operation,gross conference,HE and safranin O staining were used to observe and compare the repair effect of cartilage defects in each group.ResultsBMSCs-Exo^WT and BMSCs-Exo^MU were successfully extracted and identified,and the exosomes were observed to be nearly circular with diameter of about 40-100nm.The Western blotting results showed that they expressed special proteins CD63 and CD81 respectively.In vitro,the number of apoptosis bodies of chondrocytes in BMSCs-Exo^MU was lower than those in inflammation group and BMSCs-Exo^WT group.The Western blotting revealed results that the expression levels of p-ERK1/2 in BMSCs-Exo^WT and BMSCs-Exo^MUU groups were lower than those in inflammation group?p<0.05?;the expression levels of p-AKT,p-p38 were obviously elevated;and the effect in BMSCs-Exo^MU group was stronger than BMSCs-Exo^WT group,the difference was statistically significant.In the advanced cartilage defect models of rabbit knee joint,the repair effect in scaffold+BMSCs-Exo^MU group wasbetterthanthatinblankgroup,scaffoldgroupand scaffold+BMSCs-Exo^WT group,and the difference between groups was statistically significant?P<0.05?.ConclusionsCartilage scaffold combined with BMSCs-Exo^MU can promote the repair of cartilage defects.