Efficacy And Mechanism Of Umbilical Cord Mesenchymal Stem Cells In Treatment Of Traumatic Brain Injury

Mesenchymal stem cells(MSCs)is a kind of multipotent adult stem cells derived from early mesoderm of embryos.The main causes or pathogenesis of most central nervous system diseases,such as traumatic brain injury(TBI),spinal cord injury,stroke and neurodegenerative diseases,are degeneration,apoptosis,injury or death of nerve cells.It is particularly important that timely and effective replenishment of nerve cells can prevent and treat nervous system diseases.The current basic and clinical researches have shown that MSC which has the potential to differentiate into nervous system cells,can migrate,home,survival,proliferate,and differentiate into neuroid cells in damaged nerve tissues,thus the MSC can improve the neurological function,survival status and prognosis of patients because of providing "seed cells” for the treatment of TBI.MSC which can be used as an ideal "seed cell" to intervene in TBI,improves the quality of life of patients,because itself has very low immunogenicity and can be regarded as immune exemption in the nervous system.Umbilical cord which can turn waste into treasure,has a wide range of sources.The MSC selected by this research is human umbilical cord mesenchymal stem cells(hUC-MSC).The purpose of this study was to explore the therapeutic effect,mechanism,safety and proteomics changes of hUC-MSC transplantation in the treatment of TBI,so as to provide theoretical support and clinical experience for the clinical treatment of TBI with stem cells.In this study,45 male SD rats were randomly divided into 3 groups,including control group,TBI model group and TBI stem cell therapy group,with 15 rats in each group.The TBI rat model was established by using the electric cortical contusion impactor.Rats in TBI stem cell therapy group were injected with 0.1 ml hUC-MSCs suspension and 0.1 ml normal saline by tail wein,while rats in control group and TBI model group were injected with 0.2 ml normal saline.The gene expression of interleukin-12(IL-12)and superoxide dismutase(SOD)in brain tissue and serum were found out by PCR,Western Blot,immunohistochemistry and ELISA.By comparison,it was found that the mRNA and protein expression levels of IL-12 in brain tissues of the TBI stem cell therapy group were significantly down-regulated,while the mRNA and protein expression levels of SOD were significantly up-regulated,and the concentration of IL-12 in serum was significantly decreased.The immunohistochemical results also confirmed the up-regulated expression levels of SOD in brain tissues.In order to demonstrate the efficacy,cell transplantation mode and safety of hUC-MSCs transplantation in treatment of TBI,a total of 24 patients with severe TBI admitted to the department of neurological intensive care of the former affiliated hospital of logistics college of the Chinese people's armed police force from April 2015 to November 2015 were retrospectively analyzed and divided into 2 groups,including conventional treatment group and hUC-MSCs treatment group.Basic clinical data such as gender,age and cause of injury of patients in the conventional treatment group and the hUC-MSCs treatment group were compared.GCS scores of patients at admission,1 month and 3 months after injury,GOS scores at 6 months after injury duration of hospitalization of patients in the two groups were compared.Adverse events in the hUC-MSCs treatment group were observed.It was found that GCS score at 3 months after injury,GOS score at 6 months after injury,and duration of hospitalization in the hUC-MSCs treatment group were significantly superior to the conventional treatment group,and no significant adverse events occurred during the transplantation treatment and subsequent follow-up.In order to further explore molecular mechanism of hUC-MSCs in treating acute TBI,this study used Data Independent Acquisition(DIA)technology for Data collection.Bioinformatics processing was performed on patients' cerebrospinal fluid before and after hUC-MSCs treatment.A total of 722 proteins were identified by strict quantitative polypeptide and daughter ion screening,among which 633 were quantitatively analyzed,and 42 differentially expressed proteins mainly including interleukin(IL-6,IL-12),penetrin,peroxidase,nerve growth factor and so on,were screened before and after hUC-MSCs treatment,including 29 upregulated proteins and 13 down-regulated proteins.The changes of these differentially expressed proteins were mainly manifested in stress response regulation,immune regulation,axon remodeling and vascular reconstruction by using GO analysis,KEGG Pathway analysis,protein interaction network analysis and cluster analysis for screening differentially expressed proteins.This experimental study proved that hUC-MSCs after transplantation controlled inflammation by down-regulating IL-12 and effectively inhibited the oxidative stress reaction by effectively increasing expression of SOD which could reduce the secondary damage to the damaged brain tissue.hUC-MSCs transplantation for the treatment of severe TBI could improve the prognosis of patients and shorten the duration of hospitalization.Multiple,multi-pathway and sequential hUC-MSCs transplantation for TBI was an effective and safe treatment.The mechanism of hUC-MSCs transplantation for the treatment of TBI may be to improve stress response,regulate immune,improve microenvironment,promote axon regeneration and remodeling and vascular reconstruction.Cell replacement therapy and "pseudo bystander effect" worked together to repair the morphological structure to a certain extent,and at the same time substances with biological activity secreted through paracrine or autocrine action to promote the recovery of nervous system function.