The Study Of 3D-printed Scaffold Loaded With Neural Stem Cells Repairs Neurological Damage After Traumatic Brain Injury

Objective:To explore the neuro-reparative effect of 3D printing hydrogel scaffolds loaded with neural stem cells in transplantation after traumatic brain injury.Methods:1.We use MRI to test the velocity of cerebrospinal fluid in four parts of 5patients with traumatic brain injury as the basic data of the experiment,and design and build a cylindrical model as the impact site of cerebrospinal fluid through computer software.The cube model of the stent is placed in the central groove of the cylindrical model,and then the fluid mechanic’s simulation analysis is used to calculate the size and distribution of the force on the inner surface of the lumen representing the small cube of the 3D printed stent.The planting distribution provides a theoretical basis for future cell planting;2.Referring to the previous literature,we printed three kinds of scaffolds: 1)10% gelatin + 1% sodium alginate,2)2.8% gelatin + 2% sodium alginate,3)10%GelMA(acrylic anhydride gelatin)+ 1% sodium alginate;we demonstrated the microscopic morphology of the three scaffolds by electron microscopy;evaluated the mechanical properties of the three scaffolds by mechanical testing;observed the adhesion between neural stem cells and the three scaffolds by optical microscopy Adherence;immunofluorescence antibody staining was used to detect the growth and differentiation of neural stem cells on the scaffolds;3.After the above experiments were combined,we selected a scaffold with better biocompatibility among the three groups for planting a large number of neural stem cells.In vitro culture to observe whether the scaffold can withstand a large number of cells loading;4.In the in vivo experiment part,we used adult SD rats to establish a brain trauma model.After modeling,scaffolds loaded with neural stem cells of different degrees of differentiation were implanted in situ.Nissl staining was used to detect the degree of brain tissue loss in the chronic phase of traumatic brain injury,and behavioral tests were used to evaluate the recovery of long-term neurological function after traumatic brain injury.Results:1.Collection of cerebrospinal fluid flow velocity data in patients with traumatic brain injury: MRI detection of cerebrospinal fluid in patients with traumatic brain injury 1.968 cm/s 3.The flow rate of cerebrospinal fluid at the midline of the frontal cortex is 0.397(0.342-1.021)cm/s 4.The flow rate of cerebrospinal fluid at the frontal lobe far from the midline is 0.343(0.265-0.669)cm/s.2.Hydrodynamic force analysis: According to the fluid pressure analysis diagram on the inner surface of the lumen,cerebrospinal fluid mainly causes two different force regions on the surface of the cube.and the surrounding force is smaller,which means that the fluid has less influence on the scaffold and the cells on the scaffold.3.Mechanical analysis,electron microscope images and physical properties of the three scaffolds: H-type hydrogel scaffolds,W-type hydrogel scaffolds and G-type hydrogel scaffolds can withstand 69.29 n,80N and 77.75 n pressure respectively.The results of electron microscope showed that the surfaces of Htype hydrogel scaffolds and W-type hydrogel scaffolds were smooth,while the surfaces of G-type hydrogel scaffolds were rough,suitable for cell attachment.Pore diameter and column changes: the pore diameter and column of three different hydrogel scaffolds changed greatly before and after hydration;G-type hydrogel scaffold has the smallest pore diameter and the largest column width,which is suitable for cell adhesion.4.Biocompatibility of scaffolds,the effect of different scaffolds on cell adhesion,growth and differentiation: the three scaffolds in this experiment,Htype hydrogel scaffolds,W-type hydrogel scaffolds,and the adhesion to neural stem cells are all crossed.G-type hydrogel scaffolds have good biocompatibility.After neural stem cells are planted on the scaffolds,they will gradually fit with the scaffolds and grow on the scaffolds.5.Validation of cerebrospinal fluid shock model: Using the cerebrospinal fluid shock model in vitro,it was verified that cerebrospinal fluid has an effect on the three kinds of GelMA scaffolds carrying neural stem cells.Among them,the low-promoting differentiation group had more cell residues after cerebrospinal fluid shock than the other two groups.6.Animal experimental results: The results of the balance beam experiment in rats showed that the neural function recovery of the rats in the scaffold group loaded with neural stem cells was better than that in the blank scaffold group,among which the recovery of the rats in the low-promoted differentiation group and the non-promoted differentiation group was better.quick.The results of the cylinder experiment showed that the neurological function of the low-promoted differentiation group recovered better than the empty scaffold group.If the Nissl staining result is not put,it should be deleted in the previous method.If it is put,it needs to be added here.Conclusion:1.The GelMA scaffold has good biocompatibility with neural stem cells,which can not only allow a small number of neural stem cells to grow,but also allow a large number of neural stem cells to attach to it for growth without destroying the scaffold。2.The flow of cerebrospinal fluid can affect the retention of neural stem cells on the GelMA scaffold,and the residual rate of the low differentiation group is higher than that of the other two groups.GelMA scaffolds loaded with neural stem cells and then undergo a certain degree of pro-differentiation treatment can effectively promote the recovery of neural function after brain trauma...