Immune response of traumatic brain injury rats regulated by transplantation of human umbilical cord blood mesenchymal stem cells

Object To study the immune effects of intravenous administration of human umbilical cord blood mesenchymal stem cells (HUCBMSCs) on TBI rats,and to explore the mechanisms of neurological recovery.Methods HUCBMSCs were labelled by Brdu before transplantation,the TBI model was established by using modified Feeney free-falling method,and the TBI rats were injected with HUCBMSCs via tail vein.The rats were killed at corresponding time points after evaluating the neurological severity scores (NSS).On the first,second,third,fifth and seventh days after the rats were traumaed,we detected the values of plasma IL-6,IL-8,IL-10 and TNF-α ex vivo synthesis among the shamed group,the trauma group and the transplanted group,at the same time we compared and analyse the dynamic changes.Results In the transplanted group HUCBM-SCs were found obviously gather around the injured areas.From the NSS scores,we can detect that neurological function of the transplanted group was significantly improved compared with that of trauma group,except the first day (t =3.35,5.70,5.40,4.93,P ＜ 0.05).In the transplanted group,the amounts of plasma IL-6 were obviously lower than those in trauma group at each time point after trauma (t =4.72,3.53,3.77,2.32,2.43,P ＜ 0.05).The amounts of plasma IL-8 were obviously lower than those in trauma group on the first day (t =2.26,P ＜0.05).In the transplanted group both the IL-10 and TNFα decreased for a short period,and then showed an obvious upward trend.In the fifth and seventh days,the amounts of IL-10 were even higher than those in shamed group (t =2.61,2.81,P ＜ 0.05).And the TNFα exceeded those in trauma group at each time point after trauma (t =2.12,2.53,2.77,4.32,7.43,P ＜ 0.05).Conclusion With no immuno-suppressants,intravenous-injected HUCBMSCs can migrate to peripheral zone of traumatic brain injury areas of heterogeneous rats,HUCBMSCs can combat hyperinflammation and reverse effectively immunosuppression after trauma and can promote the functional recovery of neurons. Key words: Human umbilical cord blood mesenchymal stem cells;  Traumatic brain injury;  Inflammatory reaction ;  Immunosuppression