The Research Of Tissue Engineering Scaffold For Spinal Cord Injury Repair

The rapid development of tissue engineering brings new hope to the neurological function recovery after spinal cord injury. The three-dimensional structure of scaffold is a key factor to treat spinal cord injury in tissue engineering method. A new forming process named low-temperature deposition manufacturing (LDM) was used to fabricate gradient scaffolds by accurately controlling the assembly of biomaterials and the pore structures throughout the scaffolds. It integrated the extrusion/jetting process and the thermally induced phase seperation process of the materials. The spinal cord scaffold will be fabricated by this method.The study includes two parts: research on low-temperature deposition craft and design and manufacture on spinal cord biomimetic scaffold.The physiological structure and biological environment in vivo was regarded as an important basis in the design of scaffolds. In the functional region/separate interface pathway, the scaffold was separated by a compact layer. Therefore the scaffold would not destroy the environments in vivo. And the articulate gray matter and white matter could be constructed simultaneously by differentiation of stem cells in the different environments. Through the analysis of various biological materials, PLGA was selected as scaffold materials and the pores were researched and fabricated to meet the requirements of different regions.There are some problems in fabricated scaffold process. Through improving the nozzle device, the extruding speed can already match with scanning speed. Based on the analysis of the modeling room and slurry's cooling principle, air-flow refrigeration design was proposed. It speed up slurry's solidification rate in the modeling room and improve the efficiency of refrigeration. And it solves the problem that a small area of scaffold can not form too high.Through integrated low-temperature deposition manufacturing and particle leaching, the three level pore structure scaffold be fabricated, which solve the problem that the scaffold is lack of pore structures in 10～100μm. The influences of process parameters on the porous structures and mechanical properties of the scaffolds were also lucubrated. The key point in LDM which is the match of the extruding speed, scanning speed and solidification time are discussed. Then through continuous experiments, the minimum interval between scaffolds is found. The experiment results show that the big pores of scaffold were round and regular. The scaffold included a large number of irregular pore structure, good penetrating and good mechanical property. The scaffold porosity of 89.92% could well meet the needs of the high porosity.In this paper, it is tested that scaffold degradation and modified the surface of the scaffold pores. Little 5% mass loss was observed for the first 16 weeks, which could well meet the needs of the spinal cord repair requirement a longer repair period. Through the prewetting process to modify the surface of the scaffold pores, it showed that the scaffolds were with good hydrophilic properties. These results indicate that the scaffold in spinal cord tissue engineering will have a good prospect.