Study On Immunoregulatory Effect Of Two Kinds Of Stem Cells Via Microtransplantation Following Inflammation Secondary To Traumatic Brain Injury

Part I : Study on effect of two different approaches for neural stem cell implantation in miceObjectiveTo study the effect of two different approaches for neural stem cell(NSC) implantation in mice.MethodsNSCs were separated from C57BL/6 mice embryo and labeled using BrdU. Two approaches were utilized to inject NSCs into the different sides of cerebral hemisphere of adult C57BL/6 mice: the skull on the left side was penetrated by a drill and the right side by a syringe. After transplantation, animals were randomly sacrificed and their brain sections were stained for the morphology analysis, the evaluation of immunocytes infiltration, sustain of grafts and distribution of neurons and astrocytes.Results1. When compared with that using a syringe penetration on the right side, the brain tissue was obviously broken by a drill on the left. From 1 to 3 day after transplantation, there were more necrosis of neurons, spillover of RBC and infiltration of immunocytes on the left side than that on the right. Besides, 7 days later, there was more visible scar tissue on the left side than that on the right.2. There were more inflammatory cells on the left side than that on the right. Microglia/macrophage infiltrated quickly within one week; T cells were detected early after transplantation; B cells were obviously detected after 21 days.3. The ratio of Brd U(+) cells on the right side of transplantation area was higher than that on the left, at every time point(P<0.05).4. The ratio of astrocytes on the left side of transplantation area was higher than that on the right, while the ratio of neurons was opposite, at every time point(P<0.05).ConclusionMicrotransplantation improves the function of graft via attenuating brain injury including mechanical damage and secondary injury following inflammation, reducing the spillover of graft and improving the efficiency of implantation.Part II : Study on immunoregulatory effect of two kinds of stem cells via microtransplantation following inflammation secondary to traumatic brain injuryObjectiveTo study the similarities and differences of immunoregulatory effect of grafted NSCs, MSCs via microtransplantation following inflammation secondary to TBI.MethodsAdult C57BL/6 mice(male) were assigned into sham group(n=54), TBI group(n=210). The free-falling weight drop device was utilized to establish TBI model. After 12 h, animals which got 3~7 points by NSS were collected into TBI group. After 24 h, NSCs and MSCs derived from C57BL/6 adult mice were separately injected into the brain of TBI model via microtransplantation and utilized PBS injection as the control. After 1 d, 3 d and 7 d, mice were randomly sacrificed and their brain tissues were stained for the morphology analysis and the evaluation of infiltrated immunocytes. The mRNA and protein of mice brain were extracted to analyze the expression of cytokine.Results1. After 7 d, brain injury was obviously limited in the NSCs group and MSCs group.2. After 3 d and 7 d, the number of microglia/macrophages in the NSCs group or MSCs group was obviously less than that in the control group(P<0.05). After 7 d, the number of T lymphocytes in the NSCs group was obviously less than that in the control group(P<0.05). 3. The expression of m RNA or protein of IL-6 or TNF-α in the MSCs group was obviously lower than that in the control group(P<0.05). The expression of m RNA or protein of IL-10 in the NSCs group was obviously higher than that in the control group(P<0.05). Conclusion NSCs and MSCs via microtransplantation can influence the immunocytes infiltration and the expression of cytokines so as to modulate the inflammation secondary to TBI.