Research On Silk Composite Scaffolds And Polymeric Porous Microspheres In Promoting Ear Cartilage Repair

Microtia is not only a psychological and physiological burden for patients,but also affects the life quality of patients.Cartilage tissue engineering was proposed and expected to make breakthroughs for external ear reconstruction.It is widely recognized that the physicochemical features of polymeric scaffolds such as biochemical stimuli and mechanical properties exert profound influences on the adhesion,proliferation and differentiation of cells for tissue regeneration by providing similar microenvironments as the intrinsic extra-cellular matrix.Especially,the adequate mechanical strength which matches the elastic modulus of native tissue plays an important role in maintaining cellular morphology and the integrity of neo-tissues.Therefore,it is necessary to construct polymeric composite scaffolds with adequate mechanical strength to meet the requirements for auricular cartilage regeneration.In addition,polymer porous microspheres have attracted great interests because of their excellent properties,such as superior repairing abilitiy.In recent years,porous microspheres have made a great progress in a variety of tissue engineering.However,there is few study in auricular tissue engineering.Therefore,it is improtant to construct polymer porous microspheres as cell carriers for auricular reconstruction.The main research in this dissertation was divided into two parts as following:1.Based on the excellent biomechanical properties of Antheraea pernyi silk fibers,inspired by "steel bars reinforced concrete" structure in architecture,the composite scaffolds co-reinforced by silk fibers and PLLA porous microspheres were prepared to meet the mechanical requirements for auricular cartilage regeneration.Based on the result of physicochemical investigation,the composite scaffolds possessing superior physicochemical properties were selected to further explore the difference in biological performance in vitro.The chondrogenic potential evaluation in vitro showed that the composite scaffold co-reinforced by Antheraea pernyi silk fibers and PLLA porous microspheres possessed good biomechanical properties in comparison with Bombyx mori silk fiber-based scaffolds and are promising in auricular cartilage tissue engineering.2.Based on the study of PLLA porous microspheres,the particle sizes of PLLA and PLGA porous microspheres were compared and PLGA porous microspheres with smaller particle size was chosen to further explore.To meet the size requirements(no more than 100 μm)of 3D printing nozzle,the preparation conditions of the PLGA porous microspheres were optimized.Porous microsphere carrying cells were observed and the observations showed the trend of cellular migration to the inside of the porous microspheres.To some extent,it can protect the cells inside the microspheres from the damage of shear force,which can be beneficial to the fabrication of high quality bioink for auricle reconstruction.In summary,based on the excellent biomechanical properties of Antheraea pernyi silk fibers and the adjustability of particle size of polymer porous microspheres,the Antheraea pernyi silk fiber-based scaffolds and the cell-loaded PLGA porous microspheres in this dissertation are promising in auricular cartilage repair and can provide an idea for the future design of auricular cartilage tissue engineering scaffolds.