粒细胞集落刺激因子对骨髓极小胚胎样干细胞的动员和募集

Effect of granulocyte-colony stimulating factor on mobilization and recruitment of very small embryonic-like stem cells

背景:极小胚胎样干细胞(very small embryonic-like stem cells,VSEL-SCs)是一种非造血干细胞,具有类似胚胎干细胞的生物学特性。目前,心肌梗死后 VSEL-SCs 的研究较多,而急性脑梗死后 VSEL-SCs 的动员及其修复受损组织的研究在国内外报道尚少。目的:观察小鼠急性脑梗死后粒细胞集落刺激因子对骨髓来源的 VSEL-SCs 动员、募集及其作用机制。方法:线栓法制备小鼠大脑中动脉栓塞模型,腹腔内分别注射粒细胞集落刺激因子和生理盐水,观察术后神经功能评分,流式细胞分析计数动员到外周血中的 VSEL-SCs 数量;ELISA 方法分析术后血浆及缺血侧脑组织中基质细胞衍生因子 1 水平的动态变化,免疫组化观察缺血边缘带的基质细胞衍生因子 1 阳性细胞表达。结果与结论:与生理盐水组相比,术后 108 h 粒细胞集落刺激因子组造模后神经功能评分明显降低(P < 0.05);术后 72,108 h粒细胞集落刺激因子组动员到外周血的 VSEL-SCs 含量高于生理盐水组(P < 0.05);粒细胞集落刺激因子组血浆和脑组织中基质细胞衍生因子 1 水平高于生理盐水组(P < 0.05),血浆基质细胞衍生因子 1 水平与动员到外周血的 VSEL-SCs 数量成正相关;脑组织免疫组化中,粒细胞集落刺激因子组基质细胞衍生因子 1 阳性细胞多于生理盐水组。结果显示粒细胞集落刺激因子能使更多的 VSEL-SCs 从骨髓动员到外周血中,粒细胞集落刺激因子对缺血脑组织的保护作用,可能在于其能够使缺血边缘带的基质细胞衍生因子 1 表达增加,并通过 CXCR4/SDF-1 轴的趋化作用,使募集到梗死区域的 CXCR4+细胞增多来实现的。

BACKGROUND：A population of very small embryonic-like stem cells（VSEL-SCs） is a kind of non-hemopoietic stem cells,which has similar biological characteristics to embryonic stem cells.Currently,most studies concerning VSEL-SCs after myocardial infarction,but mobilization of VSEL-SCs and its effect on repair damaged tissues after acute cerebral infarction remain poorly understood.OBJECTIVE：To investigate the effects of granulocyte-colony stimulating factor（G-CSF） on mobilization of bone marrow-derived VSEL-SCs,recruitment and mechanism after mouse acute cerebral infarction.METHODS：Mouse middle cerebral artery occlusion（MCAO） model was induced by using the filament occlusion method.G-CSF and normal saline were separately injected to MCAO model.Neurological scales were evaluated.The number of VSEL-SCs mobilized into peripheral blood was checked by fluorescence-activated cell sorting analysis.The level of stromal cell derived factor-1（SDF-1） in plasma and cerebral tissue were determined by ELISA assay.Positive expression of SDF-1 in ischemic regions was detected by immunohistochemistry.RESULTS AND CONCLUSION：Compared with the normal saline group,the neurological behavioral scale of G-CSF treated group was significantly lower at 108 hours after operation（P0.05）.G-CSF groups mobilized more VSEL-SCs into peripheral blood compared with the operated control group at 72 and 108 hours（P0.05）.The SDF-1 density significantly increased in the plasma and brain tissues of the G-CSF group than that of the normal saline group（P0.05）,and positive correlation can be seen between the number of VSEL-SCs mobilized into peripheral blood and the SDF-1 plasma concentration.The positive expression of SDF-1 in the G-CSF group was greater than that of the normal saline group.The results indicated that G-CSF mobilized VSEL-SCs in adult MCAO mouse bone marrow into peripheral blood.The mechanism of beneficial effects of G-CSF possibly related to increase of SDF-1 expression in the infracted tissues and recruitment of more VSEL-SCs through CXCR4/SDF-1 axis.