Preparation And Application Of 3D Printed Degradable Tissue-engineered Auditory Bone Scaffolds

Objective Application of 3D printing technology and degradable composite materials to discuss the preparative method of tissue engineering ossicles for middle ear hearing reconstruction.Methods Domestic polymer（polylactic acid-glycolic acid copolymer,PLGA）and degradable ceramic material（β-tricalcium phosphate,β-TCP）were selected and prepared by low temperature deposition method according to the design ratio to Program according to the outline design code of the required scaffold to generate appropriate print files,and then use the self-developed low-temperature deposition printing device to prepare tissue-engineered osseous scaffolds in accordance with the print files in a low-temperature environment.The scaffolds is freeze-dried and sterilized for later use after printing.Light microscopy and scanning electron microscopy were used to observe the apparent characteristics and internal structure of the scaffolds and check its pore size,porosity and mechanical properties.scaffold were implanted into animals to observe their degradation and rejection.Results The degradable scaffold has a horizontal and vertical interlaced warp and weft structure,the wire spacing is 1.2mm,and the pores are connected to each other.The surface can see circular or quadrangular pores with a pore size of about 100-400um.The diameter of the inter-pore cross-linked channels is about 50um and the diameter of the surrounding circular micropores is about 10-40um.β-TCP particles with a size of about 700 nm are attached to the surface of the PLGA material.The average porosity of the whole scaffolds83.43%±0.01,and the content of BMP-2 loaded is about 0.7μg/mm^2.After freeze-drying,the mechanical strength of the scaffold is moderate,and there is no obvious deformation during stretching and compression,which meets the mechanical requirements of tissue engineering ossicles.The degradation time of the scaffold was 1.5 months after implantation,and no rejection occurred at the implantation site.Conclusions Using the low-temperature deposition printing method and strictly controlled processes and conditions,a polymer-degradable ceramic ossicle tissue engineering scaffold can be prepared for implantation experiments.The scaffold has suitable porosity and mechanical properties,and can be loaded with osteoinductive factors.The scaffold has good biocompatibility and can be implanted into cavity auditory vesicles.This study laid a foundation for later clinical application.