Regulation And Control Of Mechanical Properties And Specific Shape Tissue Engineering Cartilage

Tissue engineering provides a promising approach for complete repairment and functional reconstruction of cartilage defects and the construction in vitro is the key technology for translation to clinical application,in which lack of mechanical strength for engineered cartilage in vitro and accuracy of shape control are still two main bottlenecks.mechanical strength of engineered is mainly influenced by excellular matrix(ECM)assembly and structure and the main ingredients are collagen in ECM,therefore collagen cross-linking is the most important factor to influence cartilage mechanical function.Since lysyl oxidase(LOX)activation can increasing collagen cross-linking of engineered cartilage in vitro and Mechanical stimulation can also activate LOX and increase collagen cross-linking,based on above points,our research pose the following points:First,Is upregulation of LOX conducive to enhance cartilage mechanical strength?Which pattern of mechanical stimulus can enhance mechanical function in maxium and the mechanism is related to the upregulation of LOX? Is it a new approach for construction of ideal tissue engineered cartilage through combination of activation of LOX with mechanical stimuli ?On the second bottleneck question,tissue engineered cartilage common present?hollow?phenomenon because of some nutritional problem when tissue thickness and volume exceeding a certain value.How to regenerate cartilage with large size and specific shape ? In order to solve these problems,related experiments had been conducted.First,we systematically choose inhibitor and activator of LOX to intervene the cartilage construction in vitro,then qualitative and quantitative detection were analysed in 2-dimension(2D)and 3-dimension(3D)chondrocytes culture.The results indicated that mechanical strength get lower after inhibition of LOX,but higher after activitation of LOX.Second,we modulated three patterns of mechanical stimuli(hydrostatic pressure,shearing force of low velocity,centrifugal force)to intervene the construction process of cartilage,then detection analysis were performed from morpholy,molecule,protein and gene expression level.The results show that hydrostatic pressure can enhance mechanical function in maxium relating with activation of LOX.Furthermore we debugged dynamic hydrostatic pressure bioreactor.Third,Polycaprolactone(PCL)+hydroxylapatite(HA)were utilized to construct specific shape scaffold with inner core by 3D printing and CAM/CAD technique,then the chondrocytes were seeded on the Polyglycolic acid(PGA)coated on scaffolds and the cell-scaffolds were transplanted onto nude mouse after 4 weeks.The samples in vivo were analysed after 8 weeks.The over view of samples show that complete and integrated cartilage tissue coating the scaffold with higher mechanical strength and specific shape.In summary,LOX activation and mechanical stimulation can regulate mechanical function of tissue engineered cartilage in vitro,meanwhile,the mechanism of mechanical stimuli on biomechanical strength may be through LOX activation pathway and offer a new approach for optimizing in vitro culturing course of tissue engineered cartilage through combination of LOX activator and mechanical stimuli.the application of 3D printing technique and biomaterials such as PCL+HA simulating special shape cartilage will promote the development of specific shape construction of tissue engineered cartilage in future.