Biofunctionalized Structure And Component-mimicking Scaffolds Achieving In Situ Articular Cartilage Regeneration

Objective: Due to the lack of blood supply and low cell density,articular cartilage has poor self-healing ability.Once it is damaged,often secondary to the formation of osteoarthritis,resulting in poor prognosis of patients.In recent years,tissue engineering therapy strategies based on specific and effective recruitment of host cells and prochondrogenic differentiation have brought new hope for in situ regeneration of articular cartilage.This study aims to construct tissue engineering scaffolds that can not only recruit endogenous stem cells,but also mimic the natural microenvironment and microstructure of cartilage,and facilitate the maturation of new tissues,so as to achieve in situ repair of articular cartilage.Method: In this study,on the one hand,the physical perfusion method was used to construct the demineralized cancellous bone(DCB)/cartilage extracellular matrix(ECM)-derived composite scaffold loaded with transforming growth factor β3(TGF-β3)(denoted as DCB/ECM/TGF-β3 scaffold).On the other hand,the drug-loading technology of microspheres was optimized,the printable bioink based on ECM was prepared,and a new type of cartilage biomimetic scaffold(PE-μS scaffold)loaded with TGF-β3 microspheres and polycaprolactone(PCL)was constructed by 3D bio-printing technology.Characteristics of physical,chemical,histological,biological mechanics properties of scaffolds were evaluated in vitro,in the same time the cytocompatibility and immune rejection,stem cell recruitment and prochondrogenesis potential of scaffolds were also detected.Finally,in situ repair experiments were performed in animals,and the in-situ cartilage regeneration of scaffolds was evaluated through the evaluation of gross view,imageological,biomechanics,molecular biology and histology examination.Results: Both scaffolds possessed good gross structure and microstructure,could release factors for more than 4 weeks,and provide adequate biomechanical support.Furthermore,both scaffolds showed good cytocompatibility and low immunogenicity,and had the ability to recruit stem cells and promote chondrogenesis in vitro and in vivo.Post-implantation in rabbits and sheep for a period of time,the two scaffolds had good in situ regeneration and repair effects on cartilage injury.Conclusion: DCB/ECM/TGF-β3 composite scaffold and 3D bioprinting cartilage biomimetic scaffold can recruit stem cells and promote chondrogenic differentiation,which show a good repair capacity in the in-situ repair of articular cartilage in small and large animals.These results indicate that endogenous cell recruitment and prochondrogensis strategy is a promising strategy for in situ articular cartilage regeneration.