Anti-VEGF therapy prevents Müller intracellular edema by decreasing VEGF-A in diabetic retinopathy

Background:Although vascular endothelial growth factor A(VEGF-A)is known to play a key role in causing retinal edema,whether and how VEGF-A induces intracellular edema in the retina still remains unclear.Methods:Sprague-Dawley rats were rendered diabetic with intraperitoneal injection of streptozotocin.Intravitreal injection of ranibizumab was performed 8 weeks after diabetes onset.rMC-1 cells(rat Müller cell line)were treated with glyoxal for 24 h with or without ranibizumab.The expression levels of inwardly rectifying K^(+)channel 4.1(Kir4.1),aquaporin 4(AQP4),Dystrophin 71(Dp71),VEGF-A,glutamine synthetase(GS)and sodium-potassium-ATPase(Na^(+)-K^(+)-ATPase)were examined using Western blot.VEGF-A in the supernatant of the cell culture was detected with ELISA.The intracellular potassium and sodium levels were detected with specific indicators.Results:Compared with normal control,protein expressions of Kir4.1 and AQP4 were down-regulated significantly in diabetic rat retinas,which were prevented by ranibizumab.The above changes were recapitulated in vitro.Similarly,the intracellular potassium level in glyoxal-treated rMC-1 cells was increased,while the intracellular sodium level and Na^(+)-K^(+)-ATPase protein level remained unchanged,compared with control.However,ranibizumab treatment decreased intracellular sodium,but not potassium.Conclusion:Ranibizumab protected Müller cells from diabetic intracellular edema through the up-regulation of Kir4.1 and AQP4 by directly binding VEGF-A.It also caused a reduction in intracellular osmotic pressure.

Therapeutic imaging window of cerebral infarction revealed by multisequence magnetic resonance imaging An animal and clinical study

In this study, we established a Wistar rat model of right middle cerebral artery occlusion and observed pathological imaging changes （T2-weighted imaging [T2WI], T2FLAIR, and diffusion-weighted imaging [DWI]） following cerebral infarction. The pathological changes were divided into three phases： early cerebral infarction, middle cerebral infarction, and late cerebral infarction. In the early cerebral infarction phase （less than 2 hours post-infarction）, there was evidence of intracellular edema, which improved after reperfusion. This improvement was defined as the ischemic penumbra. In this phase, a high DWI signal and a low apparent diffusion coefficient were observed in the right basal ganglia region. By contrast, there were no abnormal T2WI and T2FLAIR signals. For the middle cerebral infarction phase （2-4 hours post-infarction）, a mixed edema was observed. After reperfusion, there was a mild improvement in cell edema, while the angioedema became more serious. A high DWI signal and a low apparent diffusion coefficient signal were observed, and some rats showed high T2WI and T2FLAIR signals. For the late cerebral infarction phase （4-6 hours post-infarction）, significant angioedema was visible in the infarction site. After reperfusion, there was a significant increase in angioedema, while there was evidence of hemorrhage and necrosis. A mixed signal was observed on DWI, while a high apparent diffusion coefficient signal, a high T2WI signal, and a high T2FLAIR signal were also observed. All 86 cerebral infarction patients were subjected to T2WI, T2FLAIR, and DWI. MRI results of clinic data similar to the early infarction phase of animal experiments were found in 51 patients, for which 10 patients （10/51） had an onset time greater than 6 hours. A total of 35 patients had MRI results similar to the middle and late infarction phase of animal experiments, of which eight patients （8/35） had an onset time less than 6 hours. These data suggest that defining the ＂therapeutic time window＂ as the time 6 hours after infarction may not be suitable for all patients. Integrated application of MRI sequences including T2WI, T2FLAIR, DW-MRI, and apparent diffusion coefficient mapping should be used to examine the ischemic penumbra, which may provide valuable information for identifying the ＂therapeutic time window＂.

热休克预处理对感染性脑水肿时神经细胞内钙的影响及机制探讨

目的 探讨热休克预处理对感染性脑水肿时神经细胞内钙的影响及机制。方法 雄性 SD大鼠随机分为 (1)正常对照组 ;(2 )感染性脑水肿组 ;(3)生理盐水预处理组 ;(4 )热休克预处理组 ;(5 )内毒素预处理组。制备百日咳菌液脑水肿模型 ,Fura- 2 /AM荧光检测法测定突触体内游离钙浓度 ([Ca2 + ]i) ,同时测定脑含水量、伊文思蓝和 Na+含量 ;原位杂交和 Western印迹分析检测 HSP70的表达。结果 热休克预处理组和内毒素预处理组[Ca2 + ]i含量较感染性脑水肿组明显降低 (P<0 .0 1) ;[Ca2 + ]i含量的变化与脑含水量、伊文思蓝含量、Na+含量的改变呈直线正相关。热休克和内毒素预处理后 HSP70 m RNA和 HSP70明显增加。结论 热休克和内毒素预处理均可减少感染性脑水肿时 Ca2 +细胞内流 ,这种作用与其诱导 HSP70的基因表达增加有关。

人脐带间充质干细胞来源外泌体减轻大鼠脊髓星形胶质细胞氧糖剥夺/复氧损伤所致的水肿

背景:外泌体对神经细胞具有调控修复作用,从而促进神经细胞增生,减轻脊髓损伤,但外泌体对脊髓损伤水肿作用的相关研究较少。目的:探讨人脐带间充质干细胞来源外泌体减轻氧糖剥夺/复氧损伤大鼠脊髓星形胶质细胞水肿的作用及机制。方法:超高速离心法分离提取人脐带间充质干细胞外泌体,采用胰酶消化法提取新生SD大鼠脊髓星形胶质细胞。第一部分实验分组:①对照组,细胞正常培养,未进行氧糖剥夺/复氧处理;②模型组:氧糖剥夺6 h/复氧24 h;③人脐带间充质干细胞外泌体组:氧糖剥夺6 h/复氧24 h,在复氧过程的培养基中分别加入30,60,90μg人脐带间充质干细胞外泌体,作用24 h。Western blot检测细胞AQP4蛋白表达,活细胞工作站检测细胞体积,透射电镜观察细胞水肿超微结构变化。第二部分实验分组:①对照组:细胞正常培养,未进行氧糖剥夺/复氧处理;②模型组:氧糖剥夺6 h/复氧24 h;③人脐带间充质干细胞外泌体组:氧糖剥夺6 h/复氧24h,在复氧过程的培养基中加入90μg人脐带间充质干细胞外泌体,作用24h;④JNK受体抑制剂SP600125组:氧糖剥夺6 h/复氧24 h,在复氧过程的培养基中加入5μmol/L JNK受体抑制剂SP600125,作用24 h。Western blot检测细胞AQP4及p-JNK蛋白表达,活细胞工作站检测细胞体积。结果与结论:①与模型组比较,人脐带间充质干细胞外泌体干预24 h后,透射电镜可见线粒体、内质网水肿减轻,溶酶体数量减少,细胞水肿体积显著降低(P <0.05),AQP4蛋白的表达量减少(P <0.05);②与模型组比较,人脐带间充质干细胞外泌体与JNK抑制剂SP600125干预后,细胞中AQP4、p-JNK表达明显降低(P <0.05),细胞水肿体积显著降低(P <0.05);③结果表明,人脐带间充质干细胞外泌体可通过抑制JNK信号通路降低氧糖剥夺/复氧损伤后脊髓星形胶质细胞AQP4蛋白的表达,减轻细胞水肿。