The Research Of Functional Magnetic Resonance Imaging In Neural Stem Cells Combined With Peptide Hydrogel For Treating Rat Brain Injury

Background:Traumatic brain injury(TBI)is a complex condition that causes high disability and mortality on a global scale,and creates a huge social and economic burden.After brain injury,a series of clinical symptoms are emerged[J].These symptoms are caused by external forces and are caused by external mechanical forces on the skull and brain tissue.The pathophysiological mechanisms of traumatic brain injury include destruction of the blood-brain barrier,extensive neuroinflammation,axonal damage,and subsequent neurodegenerative diseases.So far,the treatment methods for brain trauma include reducing intracranial pressure,nutritional nerves and correcting electrolyte acid-base imbalance,surgical intracranial hematoma removal,decompressive craniectomy,etc.The rehabilitation treatment options for brain trauma include hyperbaric oxygen therapy,non-invasive brain stimulation,task-oriented functional electrical stimulation and behavioral therapy,but can not effectively repair the missing nerve tissue and effectively restore nerve function.Transplantation of neural stem cells(NSCs)is an emerging therapeutic option for brain injury.In recent years,exogenous stem cell transplantation has been shown to increase endogenous cell proliferation and promote neural differentiation in the injured area of the brain,and studies have shown that local transplantation of neural stem cells in brain lesions can repair defective nerve tissue[2].The preliminary work of our group through pathological examination and motor function test showed that the transplanted neural stem cells could survive in the injured area and further differentiate into neurons and astrocytes,and the motor function of the rats was improved to some extent.However,it is unclear whether the specific improvement mechanism is that the transplanted cells replace the function of the damaged cells,or whether the neurological function is replaced by the other parts of the cortex.OBJECT:Using manganese-enhanced magnetic resonance imaging(ME-MRI)to observe the therapeutic effect of NSCs combined with hydrogel transplantation on TBI rat.The MRI T2 sequence was used to observe the repair of the tissue structure of the brain injury after NSCs combined with hydrogel transplantation.And further the application of manganese ion-enhanced magnetic resonance imaging to show the active brain area and speculate the recovery of brain function.METHODS:We selected healthy male Sprague Dawley(SD)rats as the study subjects.The TBI model of 2.0 mm indentation of the right sensory motor cortex(SMC)in rats was induced by the head trauma contusion device according to the previous method[3].Always maintaining the integrity of the endocranium during the modeling process.The asymmetrical movement of the forelimbs on both sides of the rats after operation was considered successfully.Rats in the transplantation group received a combination of neural stem cells and hydrogels 7 days after TBI.MRI was performed by electric stimulator of the contralateral forepaws and venous injection of MnC12·4H2O(Sigma,USA)before magnetic resonance imaging.Rats in the control group received an equal amount saline transplantation 7 days after TBI.Rats in the only injury group received TBI surgery without any transplantation.RESULTS:In this study,we obtained the following results:(1)The magnetic resonance T2 sequence was used to find that the lesions of NSCs combined with hydrogel transplantation group were significantly reduced at 1 week after transplantation,and entered the plateau at the second week after transplantation.While hydrogel transplantation group and injury only group had no significant changes were observed in the lesions of the brain lesions.(2)Using the ME-MRI T1 sequence to find that the ROI signal increased after NSCs combined with hydrogel transplantation(indicating neuronal activity),the signal intensity increased significantly in the first week after transplantation,and then gradually decreased.While the hydrogel transplantation group and injury only group had no significant increase in T1 sequence.(3)The motor function evaluation of NSCs combined with hydrogel transplantation group showed that the motor function of the contralateral forelimb had significantly improved in the first week after transplantation,and gradually improved in the second week and the third week.While the hydrogel transplantation group and injury only group had no significant changes.(4)The decrease of the lesion size of the injured lesions in the NSCs combined with hydrogel transplantation group and the signal enhancement of ROI(indicating that the neuronal function is active)corresponded generally at the observed time nodes.CONCLUSION:(1)Dynamic observation of magnetic resonance T2 sequence scanning revealed that the NSCs combined with hydrogel co-transplantation treatment of TBI rats had a narrower range of brain tissue defects,suggesting that the brain damage structure was repaired;(2)ME-MRI T1 sequence scanning dynamic found that NSCs combined with hydrogel co-transplantation in the treatment of TBI rats had local signal enhancement in ROI,reflecting the active metabolism of the brain,combined with animal behavioral evaluation results,suggesting that the neural function has been fixed to some extent.