骨髓间充质干细胞来源外泌体对促进大鼠坐骨神经钳夹伤的修复作用

目的探讨骨髓间充质干细胞(BMSC)来源的外泌体对大鼠坐骨神经损伤的治疗效果。方法随机将24只SD大鼠平均分为3组。各组大鼠暴露出右侧坐骨神经后,在坐骨神经分叉处上方5 mm处用显微止血钳第二齿钳夹神经3次,每次10 s,中间间隔5 s。Exosome组在钳夹伤附近的神经外膜下注射5μl外泌体,Control组在相同部位注射等量PBS,Sham组仅分离出神经,不进行其他操作。术后4周,运用Catwalk检测大鼠运动功能的恢复情况;运用电生理检测神经传导功能的恢复情况;马松染色检测各组手术侧的腓肠肌肌纤维面积;透射电镜观察神经纤维直径等超微结构变化;对坐骨神经损伤的相应脊髓节段进行免疫荧光染色,观察小胶质细胞和星形胶质细胞的活化数量。结果 Catwalk示Exosome组大鼠坐骨神经功能指数优于Control组(P<0.05)。电生理示Exosome组大鼠的运动神经传导速度快于Control组(P<0.05),且复合肌肉动作电位的振幅高于Control组(P<0.05)。马松染色示Exosome组的腓肠肌肌纤维面积明显大于Control组(P<0.05)。透射电镜示Exosome组和Control组的有髓神经纤维直径小于Sham组(P<0.05),且Exosome组明显高于Control组(P<0.05),Exosome组的神经纤维排列也较Control整齐。免疫荧光示,Exosome组和Control组的腰段脊髓中的IBA-1和GFAP阳性区域面积百分比较Sham组明显上调(P<0.05),但Exosome组少于Control组(P<0.05)。结论坐骨神经损伤后,BMSC来源的外泌体促进了运动功能的恢复,其机制与促进轴突再生、缓解疼痛有关。

Minocycline reduces astrocytic reactivation and neuroinflammation in the hippocampus of a vascular cognitive impairment rat model

Objective To study the neuroprotective mechanism of minocycline against vascular cognitive impairment after cerebral ischemia. Methods The rat model with vascular cognitive impairment was established by permanent bilateral common carotid artery occlusion （BCCAO）. The observing time-points were determined at 4, 8 and 16 weeks after BCCAO. Animals were randomly divided into sham-operated group （n = 6）, model group （subdivided into 3 groups： 4 weeks after BCCAO, n = 6; 8 weeks after BCCAO, n = 6; and 16 weeks after BCCAO, n = 6）, and minocycline group （subdivided into 3 groups： 4 weeks after BCCAO, n = 6; 8 weeks after BCCAO, n = 6; and 16 weeks after BCCAO, n = 6）. Minocycline was administered by douche via stomach after BCCAO until sacrifice. Glial fibrillary acidic protein （GFAP） was examined by Western blotting and immunohistochemistry. Levels of cyclooxygenase-2 （COX-2） and nuclear factor-kappaB （NF-κB） were measured by immunohistochemistry. IL-1β and TNF-α levels were tested with ELISA method. Results Levels of GFAP, COX- 2, NF-κB, IL-1β and TNF-α were all up-regulated after permanent BCCAO, which could be significantly inhibited by minocycline. Conclusion Minocycline could ameliorate the inflammation and oxidative stress in the hippocampus of the vascular cognitive impairment rat model.

Life after the birth of the mitochondrial Na^+/Ca^(2+) exchanger,NCLX

Powered by the mitochondrial membrane potential,Ca2+ permeates the mitochondria via a Ca2+ channel termed Ca2+ uniporter and is pumped out by a Na+/Ca2+ exchanger,both of which are located on the inner mitochondrial membrane.Mitochondrial Ca2+ transients are critical for metabolic activity and regulating global Ca2+ responses.On the other hand,failure to control mitochondrial Ca2+ is a hallmark of ischemic and neurodegenerative diseases.Despite their importance,identifying the uniporter and exchanger remains elusive and their inhibitors are non-specific.This review will focus on the mitochondrial exchanger,initially describing how it was molecularly identified and linked to a novel member of the Na+/Ca2+ exchanger superfamily termed NCLX.Molecular control of NCLX expression provides a selective tool to determine its physiological role in a variety of cell types.In lymphocytes,NCLX is essential for refilling the endoplasmic reticulum Ca2+ stores required for antigen-dependent signaling.Communication of NCLX with the store-operated channel in astroglia controls Ca2+ influx and thereby neuro-transmitter release and cell proliferation.The refilling of the Ca2+ stores in the sarcoplasmic reticulum,which is controlled by NCLX,determines the frequency of action potential and Ca2+ transients in cardiomyocytes.NCLX is emerging as a hub for integrating glucose-dependent Na+ and Ca2+ signaling in pancreatic β cells,and the specific molecular control of NCLX expression resolved the controversy regarding its role in neurons and β cells.Future studies on an NCLX knockdown mouse model and identification of human NCLX mutations are expected to determine the role of mitochondrial Ca2+ efflux in organ activity and whether NCLX inactivation is linked to ischemic and/or neurodegenerative syndromes.Structure-function analysis and protein analysis will identify the NCLX mode of regulation and its partners in the inner membrane of the mitochondria.

Two-dimensional finite element model to study calcium distribution in astrocytes in presence of excess buffer

In this paper a finite element model is developed to study cytosolic calcium concen- tration distribution in astrocytes for a two-dimensional steady-state case in presence of excess buffer. The mathematical model of calcium diffusion in astrocytes leads to a boundary value problem involving elliptical partial differential equation. The model con- sists of reaction-diffusion phenomena, association and dissociation rates and buffer. A point source of calcium is incorporated in the model. Appropriate boundary conditions have been framed. Finite element method is employed to solve the problem. A MATLAB program has been developed for the entire problem and simulated to compute the numer- ical results. The numerical results have been used to plot calcium concentration profiles in astrocytes. The effect of ECTA, BAPTA and aCa influx on calcium concentration distribution in astrocytes is studied with the help of numerical results.

Effect of Tongluojiunao injection made from Sanqi(Radix Notoginseng) and Zhizi(Fructus Gardeniae) on brain microvascular endothelial cells and astrocytes in an in vitro ischemic model

OBJECTIVE: To explore the effect of Tongluojiunao injection(TLJN) prepared with Sanqi(Radix Notoginseng) and Zhizi(Fructus Gardeniae) on the interaction between brain microvascular endothelial cells(BMECs) and astrocytes in an in vitro ischemic model.METHODS: First, an in vitro model of cerebral ischemia in BMECs or astrocytes was established by oxygen-glucose deprivation(OGD). TLJN was used as a medicine of intervention. The OGD-injuredBMECs were cultured in various astrocyte-conditioned media. Cell activity, alkaline phosphatase(AKP) and γ-glutamyl transpeptidase(γ-GT) activity,interleukin-1 beta(IL-1β), and tumor necrosis factor alpha(TNF-α) content in BMECs were determined.Additionally, OGD-injured astrocytes were cultured in various BMEC-conditioned media. Cell activity, as well as expression of brain-derived neurotrophic factor(BDNF) and glial cell-derived neurotrophic factor(GDNF) in astrocytes, were detected.RESULTS: The results of paracrine signaling of normal BMECs or astrocytes showed a protective effect on each other: conditioned media from normal astrocytes improved cell viability, AKP, and γ-GT activity, and reduced IL-1β and TNF-α content of injured BMECs; conditioned media from normal BMECs improved cell viability and expression of BDNF and GDNF in injured astrocytes. However, once the BMECs or astrocytes were injured by OGD, the protective effect decreased or disappeared. The above-mentioned protective induction was effectively recovered by TLJN intervention.CONCLUSION: The therapeutic benefit of TLJN was achieved by recovering two-way induction between BMECs and astrocytes, enhancing activity of injured BMECs and astrocytes, stabilizing enzymatic barriers, promoting expression of neurotrophic factors, and inhibiting inflammatory cytokines.