3D Printed-bioceramic Scaffolds For Bone Tissue Regeneration And Therapy

Osteochondral defect and bone tumor are two common diseases in the bone tissue engineering.When articular cartilage suffers from focal and retrogressive diseases caused by lesion and disorder,it is difficult to self-heal because of its avascularity and low cellularity and ultimately can evolve into osteoarthritis?OA?which in turn results in articular hyaline cartilage degradation and subchondral bone structural remodeling.The bone tissue has high concentration of calcium,many different kinds of growth factors that can stimulate osteolysis,and acid pH,which can attract tumor cells in other body parts to form bone tumor.The exairesis is a common method of bone tumor therapy.However,the exairesis does not guarantee all bone tumor cells to be cleared,meanwhile,the large bone defect will be formed after exairesis.Therefore,aimed at osteochondral defect and bone tumor in the bone tissue engineering,it is quite significant to prepare bifunctional scaffolds to treat osteochondral defect and bone tumor.When applying bifunctional scaffolds to repairing osteochondral defect,scaffolds regenerate the articular cartilage,and at the same time help to repair subchondral bone.When using bifunctional scaffolds to treat bone tumor,the scaffolds can kill the remaining bone tumor cells after exairesis,and repair bone defects caused by exairesis.In this thesis,3D-printed traditional bioceramic scaffolds combining with some bioactive metal compounds were prepared and respectively applied to repairing osteochondral defect and curing bone tumor.The main research results were described as follows:1.The bioactive glass ceramic?BGC?scaffolds containing different content of Mo were prepared through combining sol-gel method with 3D printing technology and the Mo exists in the form of CaMoO₄ in the bioactive glass ceramic.Because of its low melting point,the CaMoO₄ significantly enhanced the density and compressive strength of scaffolds.The in vitro degradation experiment indicated that degradation mass of scaffolds decreased with the increase of Mo content in scaffolds under the same condition.Compared with the extraction solution of BGC,the extraction solution of 7.5Mo-BGC not only significantly promoted the expressions of osteogenesis-related genes of human bone mesenchyme stem cells?HBMSCs?,enhanced ALP activity and more calcium nodules formation,but also promoted expressions of chondrogenesis-related genes of rabbit chondrocytes?RCs?.The in vitro cell experiments showed that 7.5Mo-BGC scaffolds promoted the proliferation and attachment of HBMSCs and RCs.In the coculture system of MoO₄^2-ions,RCs and HBMSCs,MoO₄^2-ions finally stimulated chondrogenic differentiation of RCs and chondrogenesis of HBMSCs through upregulating anabolic responses of RCs and HBMSCs and inhibiting catabolic responses of RCs and HBMSCs.The in vivo study showed that 7.5Mo-BGC scaffolds distinctly promoted the formation of glycosaminoglycans?GAGs?which is the critical constituent of cartilage and forming of new bone tissues.Therefore,the bioactive glass ceramic scaffolds containing Mo are expected to cure osteoarthritis clinically through achieving the bifunction of synchronously repairing articular cartilage and subchondral bone.2.The CuFeSe₂ nanoparticles were successfully grown on the surfaces of bioactive glass?BG?ceramic scaffolds through a solvothermal method.The results showed that the CuFeSe₂ contents on the surface of BG scaffold could be regulated by changing the content of reactants.The prepared BG-CFS scaffolds had excellent photothermal property which was regulated by altering the CuFeSe₂ content,environmental humidity and laser power density of near infrared?NIR?light.In vitro,BG-5CFS scaffolds effectively killed the bone tumor cells under the irradiation of NIR light and this killing effect can be regulated by changing laser irradiation duration time,laser irradiation time and laser irradiation temperature.In vivo,BG-5CFS scaffolds ablated bone tumor tissues and inhibited their growth through released hyperpyrexia,whose ablation efficiency reached 96%.Meanwhile,the BG-5CFS scaffolds promoted the proliferation of rabbit bone mesenchyme stem cells?rBMSCs?,supported their attachment and stimulated the expressions of bone-related genes OPN and OCN in rBMSCs.The BG-5CFS scaffolds induced the formation of new bone tissues in vivo,which presented the similar osteogenesis capacity to BG scaffolds.Therefore,3D-printed bioactive glass ceramic scaffolds with in situ growth of CuFeSe₂ could firstly kill bone tumor cells under the irradiation of NIR light,and subsequently repaired bone defects,showing the potential in treating bone tumor disease.3.Poly-DL-lactic acid?PDLLA?has excellent viscosity and acts as glue.The LaB₆ micro-nanoparticles after high energy ball milling were coated on the surfaces of?-tricalcium phosphate?TCP?scaffolds to prepare TCP-PDLLA-LB scaffolds.The TCP-PDLLA-5LB scaffolds possess higher compression resistant capacity than TCP scaffolds owing to the strong adhesive PDLLA that bound the LaB₆micro-nanoparticles and scaffolds tightly and enhanced compactness of TCP-PDLLA-5LB scaffolds through filling micropores with PDLLA and LaB₆micro-nanoparticles.In addition,the compression resistant capacity was regulated by altering the coating frequency.Because of localized surface plasmon resonance,the LaB₆ micro-nanoparticles endowed the TCP-PDLLA-LB scaffolds with excellent photothermal property that can be regulated by LaB₆ content,environmental humidity and power density of NIR light.The ability of killing bone tumor cells of TCP-PDLLA-5LB scaffolds was regulated by changing power density of NIR light,irradiation duration time of NIR light and irradiation frequency of NIR light.The TCP-PDLLA-5LB ablated bone tumor tissues via hyperpyrexia in vivo.The in vitro osteogenesis results showed that TCP-PDLLA-5LB scaffolds supported the attachment and proliferation of rabbit bone mesenchyme stem cells?rBMSCs?and promoted expressions of osteogenesis-related genes BMP2,RUNX2 and COL I through releasing a series of bioactive ions Ca²⁺,PO₄^3-,La³⁺,BO₃^3-.TCP-PDLLA-5LB scaffolds promoted the new bone generation in the rabbit femoral defect model.Therefore,LaB₆ and PDLLA modified TCP scaffolds with a series of advantages such as high strength,tumor treatment and bioactivity of repairing bone can be used to repair the bone defects resulting from bone tumors possibly in load-bearing bones.4.The copper coordinated tetrakis?4-carboxyphenyl?porphyrin?Cu-TCPP?belongs to a member of MOFs family.Because of the structural feature of two-dimensional?2D?nanosheets,the Cu-TCPP can response to the external NIR light fast and meanwhile transform it to heat energy.The Cu-TCPP nanosheets were in situ grown on the surfaces of TCP scaffolds via a solvothermal method to fabricate Cu-TCPP-TCP scaffolds.The Cu-TCPP-TCP scaffolds had excellent photothermal property which was ascribed to the Cu-TCPP and it could be regulated by Cu-TCPP content,environmental humidity and NIR light power density.Under the irradiation of NIR light,20Cu-TCPP-TCP scaffolds killed bone tumor cells through hyperpyrexia in vitro and ablated the bone tumor tissues and inhibited their growth in vivo.Additionally,the 20Cu-TCPP-TCP scaffolds supported the attachment and growth of human bone mesenchyme stem cells?HBMSCs?and human umbilical vein endothelial cells?HUVECs?in vitro,activated the expressions of osteogenesis-related and angiogenesis-related genes and promoted the formation of new bone tissues in vivo.Therefore,copper metal organic framework material combining with TCP bioceramic scaffolds own some clinical application potentials through achieving cure for bone tumor and regeneration of vascularized bone.In conclusion,through combining the metal compounds with traditional bioceramic scaffolds,we successfully prepared the bioactive ceramic scaffolds and characterized their physico-chemical properties.On the one hand,bioactive ceramic scaffolds significantly stimulated the regeneration of osteochondral tissues through releasing some bioactive metal ions.On the other hand,bioactive ceramic scaffolds cured bone tumors through transforming light into heat energy by photothermal agents on the surfaces of them and meanwhile repaired the bone defects caused by bone tumors through releasing a series of bioactive ions.These functional scaffolds can offer the basis of selecting novel bone materials in bone tissue engineering and promote the combination of bone tissue engineering and tumor treatment,which shows important clinical significance.