Construction And Evaluation Of Metformin Slow-Release System And The Mechanism Of Analgesic Action Of Metformin In Osteoarthritis

Objective: Construct and evaluate the slow-release-system of metformin and investigate its the mechanism of analgesic action in osteoarthritis(OA).Methods:(1)We developed an injectable slow-release formulation of F127-DOPA-HRP-metformin and evaluated its’ quality;(2)Using Intra-articular injection of monosodium iodoacetate(MIA)to develop OA rat model and single intra-articular injection of the F127-DOPA-HRP-metformin was conducted to investigate the effect of pain relief in OA rat.Knee joint tissue section of OA rat were analyzed through hematoxylin and eosin(HE)staining to examine the effect of F127-DOPA-HRP-metformin hydrogel in relieving synovitis;(3)We extracted bone marrow derived macrophage(BMDMs)from C57/BL6 mice and analyzed the cell cytotoxicity of metformin on BMDMs by CCK-8 tests.Immunofluorescence and Western Blot were performed to explore the influence of metformin on macrophage polarization.Knee joint tissue section of OA rat were analyzed through immunofluorescence to examine the effect of F127-DOPA-HRP-metformin hydrogel in regulating synovial macrophage.Results:(1)Successful construction a F127-DOPA-HRP-metformin hydrogel slow-release system with a long-acting release useful which has excellent rheological properties and biological security;(2)Single intra-articular injection of the F127-DOPA-HRP-metformin hydrogel relieved knee pain in OA rats and HE staining results showed that F127-DOPA-HRP-metformin hydrogel could reduce synovitis;(3)CCK-8 tests showed metformin below 20 m M had no obvious cytotoxicity on BMDMs.Immunofluorescence and Western Blot showed that metformin inhibited BMDMs polarized toward an M1 phenotype and stimulated BMDMs polarized toward an M2 phenotype.Immunofluorescence showed that metformin inhibited synovitis by diminishing M1 macrophage polarization and promoting M2 macrophage polarization.Conclusion: Intra-articular injection F127-DOPA-HRP-metformin hydrogel slow-release-system could obviously relieve knee pain in OA rats and reduced synovial inflammation.Metformin could reduce synovitis through regulated macrophage polarization.