间充质干细胞外泌体改善脑脊液-间质液交换减轻慢性低灌注所致的脑白质损伤

Exosomes Derived from Mesenchymal Stem Cells Attenuate White Matter Injury Caused by Chronic Hypoperfusion via Improving Cerebrospinal Fluid-interstitial Fluid Exchange

目的 探究慢性脑低灌注背景下起源于间充质干细胞外泌体(MSC-Exos)对脑白质病变的影响及其可能原因。方法 提取并标记人脐带来源MSC-Exos,利用小动物活体成像和组织免疫荧光染色观察MSC-Exos滴鼻后2 h在脑内的分布。构建C57BL/6小鼠双侧颈总动脉狭窄(BCAS)模型,随机分为假手术组、BCAS组和治疗组,BCAS组和治疗组术后经鼻给予等量磷酸缓冲液和MSC-Exos溶液。采用侧脑室注射脑脊液示踪剂,检测术后3 d示踪剂在各组脑实质内的分布情况,免疫荧光染色和电镜检测术后28 d的髓鞘病变。结果 经鼻递送的MSC-Exos可在脑内富集,部分MSC-Exos被胼胝体、海马和纹状体等脑区的星形胶质细胞和内皮细胞摄取。BCAS组小鼠术后早期脑内出现脑脊液-间质液(CSF-ISF)交换障碍,MSC-Exos经鼻递送可改善低灌注下CSF-ISF交换障碍,减轻BCAS组小鼠的晚期脱髓鞘病变。结论 经鼻递送MSC-Exos可减轻慢性低灌注所致的脑白质损伤,可能与其改善低灌注早期CSF-ISF交换有关。

Aim To explore the effect of exosomes derived from mesenchymal stem cells(MSCExos)on white matter lesions in the context of chronic cerebral hypoperfusion and its underlying cause.Methods MSC-Exos derived from human umbilical cord were extracted and labeled,and cerebral distribution of MSC-Exos was observed 2 hours after intranasal administration by vivo imaging and immunofluorescence staining.The bilateral common carotid artery stenosis(BCAS)model was established.C57BL/6 mice were randomly divided into a sham group,a BCAS group and a treated group.The BCAS group and treated group were given the same amount of PBS and MSC-Exos solution intranasally after procedure.The exchange of cerebrospinal fluid(CSF)and interstitial fluid(ISF)in each group was detected by intracisternal CSF tracer injection 3 days after operation,and the myelin lesions were detected by immunofluorescence staining and electron microscope on 28 days post.Results MSC-Exos intranasally delivered were enriched in the brain and some of them were taken up by astrocytes and endothelial cells in the corpus callosum,hippocampus and striatum.Reduced CSF-ISF exchange occurred in the BCAS model early,and intranasal delivery of MSC-Exos can increase the exchange under hypoperfusion and attenuate advanced demyelinating lesions.Conclusion Intranasal delivery of MSCExos alleviated white matter injury caused by chronic hypoperfusion,probably in association with the improvement of CSF-ISF exchange in the early period of hypoperfusion.