Minocycline-loading Multilayered Films On Titanium Substrates For Osteoimmunology Regulation Of MSCs And Macrophages

Titanium and its alloys were widely used as clinic joint implants and dental implants etc.,due to their good biocompatibility,corrosion resistance and mechanical properties.Nevertheless,the related implants are lack of osseointegration with surrounding bone tissue,resulting in poor stability at the early stage.Therefore,how to optimize the materials design and improve its bone formation,is one of focus in the related researches.The maintenance of normal bone microenvironment in a host relies on the dynamic balance of osteoblasts and osteoclasts,however,there are a large number of immune cells such as T lymphocyte,B lymphocyte,dendritic cells and macrophages etc.in the bone microenvironment in addition to the osteoblasts and osteoclasts.In recent years,researches verified that these immune cells also played an important role in the regulation of normal bone microenvironment balance.Thus,it is urgent to be extensively investigated.In this work,layer by layer(LBL)assembly technique was employed to construct multilayered films incorporating minocycline on titanium substrates,and further investigated the influence of the modified titanium on osteoimmunology behavior of immune cells.The research contents of the work are listed as follows:(1)Construction of minocycline loading multilayered film structure on titanium surface: LBL technique was employed to sequentially deposit gelatin(Gel),chitosan(Chi),gelatin,minocycline,chitosan,basing on the electrostatic interactions in between the components,and to form stable multilayered film structure on titanium surface.The successful construction of multilayered film structure on titanium surface was confirmed by atomic force microscopy and contact angle measurements;(2)Effects of minocycline loading multilayered film structure on titanium on the biological behavior of mesenchymal stem cells(MSCs): Considering the fact that MSCs have multi-directional differentiation potential and modulation of tissue immunity,we chose MSCs for related research.Except for its excellent antibacterial property,minocycline has certain effect on the differentiation of MSCs.In this work,cell compatibility of minocycline loading multilayered film structure on titanium were confirmed by lactate dehydrogenase(LDH)and cell activity(MTT)assays.Alkaline phosphatase(ALP)and mineralization tests proved that the modified titanium significantly promoted the osseo-differentiation of MSCs;(3)Osteoimmunology evaluation of minocycline loading multilayered film structure on titanium: The work mainly investigated on the effects of minocycline loading multilayered film structure on titanium on the biological functions of macrophages(RAW264.7),including M1 / M2 type conversion,the improved expressions of bone related genes and anti-inflammatory factors,the inhibition of the expression of inflammatory factor,and explored the modulation mechanism of the osteoimmunology.The results showed that the osteoimmunology modulation was realized by the inhibition of TLR signaling pathway.In summary,this work employed LBL technique to surface modify titanium substrates,in combination of the antibacterial and promoted bone formation functions of minocycline,and clarified the related cell behavior from the osteoimmunology point of view.The study has important scientific values for fundamental researches on regenerative medicine and development of high quality bone repairing implants.