Study On The Treatment Of Spinal Cord Injury Using Collagen-chistan Bionic Scaffolds Fabricated By Three Dimensional Printing Technology

ObjectiveThree dimensional printing technology combined with vacuum freeze-drying technology was applied to construct biomimetic spinal scaffolds with good biocompatibility and mechanical properties.The effect of collagen-chitosan scaffolds fabricated by 3D printing technology was explored for the repair of spinal cord injury in rats.Material and method1.The preparation of spinal cord bionic scaffolds: the collagen and chitosan materials were mixed at a low temperature and then took out part of it directly to the vacuum freeze drying;another part of the complex use 3D printing technology to fabricate scaffold with vesicular structure,-80 ℃ preservation ovacuum refrigerating machine.To observe apparent characteristics of the scaffolds after molding and its filament size;gravimetric detemination was used to detect the ratio of porosity and water absorption;after 24 h immersion,mechanical testing machine testing support compression mechanical properties.2.The operation groups of spinal cord injury model: 40 adult female SD rats weighed 250-300 g and T8 spinal cord transection injury model was prepared by hanging line method.After the hemostasis completely stopped,collagen-chitosan scaffolds were immediately implanted in the section.According to the different types of scaffolds,rats were divided into 4 groups: after exposure to the spinal cord,directly suture the muscle and skin,blank control group(sham);no transplant group(SCI),transplantation of direct freeze-dried scaffold group(SCI+S),3D printing scaffold group(SCI+3D-S).3.The repair effect of bionic scaffold: 8 weeks after operation,the data of MRI and DTI in spinal cord of rats was collected to evaluate the changes of microstructure and morphology of spinal cord injury;8 weeks after operation,we gathered the data of electrophysiological activity of hind limbs;once a week after injury,the BBB score and inclined climbing test were performed to evaluate the functional recovery of hind limbs by double blind method;after sacrificed,the recovery of spinal cord was observed;after slicing,HE staining,silver staining and NF immunofluorescence was used to observe the repair of damage cavity and promotion of regeneration effect of nerve fiber.Result1.The water absorption of 3D printed bionic spinal cord scaffold(3D-S)was 804.65±16.3%;the porosity ratio was 86.36±2.9% and elastic modulus 26.68±1.89 kPa.While the direct freeze-dried scaffolds(S)had water absorption of 1025.54±20.5%,the porosity ratio 64.74±1.5% and the elastic modulus 14.38±1.36 kPa.It was suggested that 3D printing biomimetic scaffold has good mechanical properties and was more suitable for spinal grafts.2.The hanging line method ensures the transaction of spinal cord.At the moment of injury,the severe convulsions of the hind limbs and the weakness of the muscles was observed with no reflection after pain stimulus,suggesting that the model of spinal cord injury was made successfully.3.The results of MRI and DTI,electrophysiological activity,BBB score and inclined climbing test in SCI+3D-S group were significantly better than those in the SCI and SCI+S group 8 weeks after operation.HE staining was found that the formation of the cavity was significantly decreased in scaffold group.Silver staining and NF immunofluorescence results showed that the scaffold group promoting nerve regeneration after spinal cord injury and 3D-S group best.Conclusion3D printing porous collagen-chitosan bionic scaffold improves microstructure,sensation and movement function of hind limb,fills cavity and promotes regeneration of nerve fibers and axons.It is a promising scaffold for spinal cord injury.