Study On Low-temperature Deposition Manufacturing Of Tissue Engineering Scaffolds In Treating Spinal Cord Injury

With the modern social and economic development, the incidence of spinal cord injury also showed increasing trend. The emergence of tissue engineering technology has brought new hope to the treatment of spinal cord injury. It is a key point to the development of tissue engineering technology that the scaffold is manufactured with excellent properties. There are many manufacturing methods, each of which has separate advantages and disadvantages. The development of rapid prototyping (RP) technology provides a new way of scaffold manufacturing. As a novel RP technique, Low-temperature Deposition Manufacturing (LDM) not only has the common characteristics of RP, but also has the advantage of thermally induced phase separation process. So it has become the new daring of making tissue engineering scaffolds.In this thesis, the spinal cord tissue engineering scaffolds was modeled using LDM technique. Firstly, according to the performance requirements of spinal cord tissue engineering scaffold, PLGA was selected as the manufacturing material. Then based on the spinal cord physical structure, the spinal cord bionic scaffold was designed with an insulating layer to distinguish of porosity, pore size and material of gray matter and white matter, which could indu(?) oriented differentiation of cell after transplantation into the defect site and promote regeneration of the spinal cord tissues.LDM is essentially a process that the computer-aided 3D model is transformed into numerical control (NC) information to drive the LDM machine to extrude and deposit the material in low temperature environment. Macro-porous structure of the scaffold was made by extrusion and scanning of the nozzle. In this process, the temperature of the nozzle and that in the modeling room has direct impact on the macro-porous shape errors and adhesive strength. So it is the most important part in LDM to regulate the two temperatures and match the extruding speed and scanning speed. The impact to the modeling results was mainly studied through four aspects in this thesis:parameters setting in the software, property of the slurry, match of the velocity and regulation of temperature, and then 3D spinal cord bionic scaffolds with macro-porous and micro-porous structure were formed.The porosity, degradation rate and hydrophilic rate of the scaffold were measured. The results indicated that the average porosity of scaffold manufactured by LDM was 87.43% and degradation and hydrophilic can well meet the requirements of the spinal cord tissue engineering scaffolds. Then the cultured Schwann cells of purity of more than 95% were implanted in PLGA scaffold. The medium was changed every day and SCs were scanned after three days by electron microscopy. SEM examination confirmed that Schwann cell grow rapidly after inoculated in PLGA scaffolds, which shows that the PLGA scaffolds have excellent biocompatibility and bioactivity. Lastly, the spinal cord was set up and the complex of Schwann cells and PLGA scaffolds were transplanted into rats with spinal cord injury site. The result showed that each rat has different levels of paraplegia in the first week, but from the second week beginning, the BBB score of rats began to recover.