The middle cerebral artery occlusion (MCAO) model has been extensively applied to study ischaemic stroke. This study attempted to clarify effect of bone marrow stromal cells (BMSCs) on infarct injury of MCAO rats. BMSCs were isolated and identified by staining CD29/CD44 and CD31/CD45. CX3CL1 silencing vector (pLVX-shRNA-CX3CL1) was generated and infected to BMSCs. pLVX-shRNA-CX3CL1 infected BMSCs were transplanted into brain tissue of MCAO rats. Real-time PCR was used to determine CX3CL1 expression. Infarct areas were stained with TTC to evaluate infarct size. Double-staining immunofluorescence was conducted to determine anti-inflammatory type CD206 and pro-inflammatory type tumour necrosis factor a (TNF-a) microglia. Isolated BMSCs were positively presented for CD29/CD44, and negatively for CD31/CD45. CX3CL1 was significantly lower in the BMSC + pLVX-shRNA2-CX3-CL1 group compared to the BMSCs + pLVX group (p < 0.05). According to TTC and neurological scores, MCAO rats were successfully generated. BMSCs transplantation significantly increased CD206 microglia and decreased TNF-a microglia. However, shRNA-CX3CL1-infected BMSCs remarkably reduced CD206 microglia and enhanced TNF-a microglia compared to the MCAO + BMSCs group. In conclusion, BMSCs reverse microglia from pro-inflammatory type TNF-a microglia to anti-inflammatory type CD206 microglia in the infarct region of MCAO rats (3rd to 7th days post BMSC transplantation), through triggering of CX3CL1 secretion. Therefore, the potential effects of CX3CL1 secreted by BMSCs would provide an insight for stem cell-dependent therapeutic strategies in treating ischaemic stroke-associated disorders.

中文翻译：

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骨髓基质细胞通过触发CX3CL1的分泌逆转大脑中动脉闭塞大鼠的小胶质细胞类型从促炎性肿瘤坏死因子a小胶质细胞到抗炎CD206小胶质细胞

大脑中动脉闭塞 (MCAO) 模型已广泛应用于研究缺血性中风。本研究试图阐明骨髓基质细胞 (BMSCs) 对 MCAO 大鼠梗塞损伤的影响。通过染色 CD29/CD44 和 CD31/CD45 分离和鉴定 BMSC。生成 CX3CL1 沉默载体 (pLVX-shRNA-CX3CL1) 并感染 BMSCs。将 pLVX-shRNA-CX3CL1 感染的 BMSCs 移植到 MCAO 大鼠的脑组织中。实时 PCR 用于确定 CX3CL1 表达。梗塞区域用 TTC 染色以评估梗塞大小。进行双染色免疫荧光以确定抗炎型CD206和促炎型肿瘤坏死因子a（TNF-a）小胶质细胞。分离的 BMSC 对 CD29/CD44 呈阳性，对 CD31/CD45 呈阴性。与 BMSCs + pLVX 组相比，BMSC + pLVX-shRNA2-CX3-CL1 组的 CX3CL1 显着降低（p < 0.05）。根据 TTC 和神经系统评分，成功生成 MCAO 大鼠。BMSCs 移植显着增加 CD206 小胶质细胞并减少 TNF-a 小胶质细胞。然而，与 MCAO + BMSCs 组相比，shRNA-CX3CL1 感染的 BMSCs 显着减少了 CD206 小胶质细胞并增强了 TNF-a 小胶质细胞。总之，BMSCs 通过触发 CX3CL1 分泌，将 MCAO 大鼠梗塞区（BMSC 移植后第 3 天至第 7 天）的小胶质细胞从促炎型 TNF-a 小胶质细胞逆转为抗炎型 CD206 小胶质细胞。因此，BMSCs 分泌的 CX3CL1 的潜在作用将为治疗缺血性中风相关疾病的干细胞依赖性治疗策略提供见解。