Delayed NGF infusion fails to reverse axotomy-induced degeneration of basal forebrain cholinergic neurons in adult p75(LNTR)-deficient mice

The p75 low-affinity neurotrophin receptor (p75^LNTR) appears to have various functions that include enhancing nerve growth factor (NGF)-mediated survival by increasing TrkA (high-affinity NGF receptor) efficiency, and mediating apoptosis by acting as a ligand-regulated pro-apoptotic receptor. Here, we investigated the role of p75^LNTR for adult cholinergic basal forebrain neurons by comparing neuronal responses to injury in control and p75^LNTR-deficient mice. In both types of mice, 70% of the cholinergic neurons in the ipsilateral medial septum had lost their markers choline acetyltransferase and tyrosine kinase A by 28 days following unilateral transection of the dorsal septohippocampal pathway (fimbria fornix). A 7-day delayed infusion of NGF that started 28 days after the injury resulted in reversal of choline acetyltransferase expression and cell atrophy in control, but not in p75^LNTR-deficient, mice. This lack of response to delayed NGF treatment in p75^LNTR-deficient mice was most likely not due to cell death, as all of the septohippocampal neurons, labeled with Fluorogold before the lesion, were present at 28 days post-lesion, similar to control mice. p75^LNTR-deficient cholinergic neurons can respond to NGF as they were protected by NGF infusions that started immediately after the injury. These observations, the fact that lesioned p75^LNTR-deficient neurons atrophy faster, and that non-lesioned neurons hypertrophy in response to NGF in control but not in p75^LNTR-deficient mice, suggest that p75^LNTR is needed for tyrosine kinase A and NGF signaling efficiency.

In conclusion, during adulthood p75^LNTR appears to play a beneficial role in the response of cholinergic neurons to injury, consistent with the proposed role of p75^LNTR in the enhancement of TrkA signaling and the transport of neurotrophins by these neurons.     

人β-NGF基因修饰的骨髓间充质干细胞对帕金森病大鼠行为学的影响

 目的：探讨脑内移植人β-神经生长因子(β-NGF)基因修饰的骨髓间充质干细胞(MSCs)对帕金森病(PD)模型大鼠行为学的影响。方法：将成功制备的PD大鼠模型按随机数字法分为β-NGF基因修饰的MSCs移植组(β-NGF-MSCs组)、MSCs移植组(MSCs组)、DMEM/F12培养液纹状体内注射组(DMEM/F12组)和非移植组(PD模型组)。细胞移植后,动态观察PD模型大鼠行为学变化及脑组织形态学的变化。结果：β-NGF基因修饰的MSCs脑内移植能有效改善PD模型大鼠的行为学表现。细胞移植术后第2周、第4周和第6周,β-NGF-MSCs组在阿朴吗啡诱发下30 min内的平均旋转圈数均明显低于MSCs组和PD模型组(P<0.05)。DMEM/F12组和PD模型组的旋转行为手术前后比较无明显变化(P>0.05)。免疫组织化学染色结果显示,移植细胞在PD模型大鼠脑内均能存活,并能够与宿主组织产生整合,具有良好的组织相容性;宿主的脑组织结构无破坏,无胶质瘢痕形成。PD模型大鼠纹状体内移植β-NGF基因修饰的MSCs后,可持续稳定表达β-NGF,其对PD模型大鼠旋转行为的改善明显优于单纯应用MSCs移植治疗。结论:β-NGF基因修饰的MSCs脑内移植能明显改善PD模型大鼠行为学症状,具有潜在的临床应用价值。     

重组质粒pcDNA3-β-NGF的构建及其转染小鼠骨髓间充质干细胞生物学活性的研究*

 目的：构建人神经生长因子β亚基(β-NGF)真核表达载体,转染荧光小鼠骨髓间充质干细胞(MSCs)并研究其生物学活性。方法：全骨髓贴壁培养法分离、培养和纯化荧光小鼠MSCs,构建真核表达载体pcDNA3-β-NGF,并转染MSCs;免疫组织化学染色检测β-NGF的表达,观察β-NGF阳性的MSCs对小鼠海马神经元生长的作用。结果：荧光小鼠MSCs可发出明亮的绿色荧光,且荧光不随培养时间延长和传代次数增加而衰减。重组质粒pcDNA3-β-NGF转染MSCs后β-NGF阳性率为(37.12±2.14)%,高于MSCs组［(2.36±0.62)%］和空白对照组［(1.43±0.76)%］,差异有统计学意义(P<0.05)。pcDNA3-β-NGF转染MSCs上清液培养的新生小鼠海马神经元的突起长度［(31±3)μm］较pcDNA3转染MSCs组［(23±4)μm］明显增加,差异有统计学意义(P<0.05),表明β-NGF基因转染MSCs培养上清液中的产物能促进小鼠海马神经元的突起生长,具有明显的生物学活性。结论：成功构建了pcDNA3-β-NGF真核表达载体,其转染的荧光小鼠MSCs能正确、稳定表达和分泌有生物学活性的β-NGF。     

EGF培养条件下NGF与BDNF对大鼠海马神经干细胞向神经元分化的差异

目的探讨在表皮生长因子(EGF)培养条件下,相同浓度神经生长因子(NGF)与脑源性神经生长因子(BDNF)对成年大鼠海马神经干细胞向神经元分化比例的差异。方法用含碱性成纤维生长因子(bFGF)、EGF、B27的无血清细胞培养技术体外培养成年大鼠海马神经干细胞,单细胞克隆后行Nestin免疫细胞化学染色,诱导分化1周,行GFAP和NSE免疫细胞化学染色;根据培养液中所加营养因子的不同将单细胞克隆传代细胞分为5组培养:EGF组、NGF组、BDNF组、EGF+NGF组、EGF+BDNF组,此5组细胞培养1周,进行NSE免疫细胞化学染色,计数阳性细胞比例后进行统计学分析。结果:单细胞克隆培养后克隆球细胞表达Nestin,诱导分化1周,细胞表达NSE、GFAP;与EGF组、NGF组、BDNF组相比,EGF+NGF组和EGF+BDNF组细胞分化为神经元的比例较高(P<0.05),其中EGF+BDNF组细胞的比例最高。结论在EGF培养条件下,BDNF促进成年大鼠海马神经干细胞向神经元分化的能力高于NGF。     

慢病毒介导沉默P75神经营养因子受体联合神经生长因子过表达促进大鼠骨髓间充质干细胞的增殖

文题释义：P75神经营养因子受体(P75 Neurotrophin receptor,P75^NTR)：属于一种Ⅰ型糖蛋白,在非神经系统组织及多种肿瘤细胞中表达。p75^NTR与Trk受体通过不同的信号传递对细胞增殖与凋亡发挥着双重的生物效应。神经生长因子：在神经生长因子信号通路中,p75^NTR可以与神经生长因子相结合,引起神经酰胺的释放而激活JNK通路来调节细胞的增殖和凋亡。  摘要背景：P75神经营养因子受体(P75 Neurotrophin receptor,P75^NTR)是神经生长因子(nerve growth factor,NGF)的受体之一。在各种细胞组织中发挥着促进增殖或凋亡的双重作用,且P75^NTR在骨折不愈合处存在高表达,而过量的NGF可关闭P75^NTR受体,从而挽救受损的细胞。因此研究沉默P75^NTR联合NGF过表达共转染对骨髓间充质干细胞增殖的影响,可为临床治疗骨折不愈合提供新思路。目的：观察慢病毒介导沉默P75^NTR联合NGF过表达共转染对SD大鼠骨髓间充质干细胞增殖的影响。方法：体外培养至第3代SD大鼠骨髓间充质干细胞分为空白对照组、阴性对照组、沉默p75^NTR组、NGF过表达组、沉默p75^NTR联合NGF过表达组。将慢病毒介导沉默P75^NTR、过表达NGF转染至大鼠骨髓间充质干细胞,倒置荧光学显微镜观察慢病毒转染第3天细胞形态变化,流式细胞仪检测转染效率及Western blot方法检测P75^NTR和NGF的表达,最后用MTT法和CCK-8法检测各组细胞增殖活性。结果与结论：①共转染慢病毒后的细胞生长、分布良好;双基因慢病毒载体的转染效率已超过70%;②与空白对照组和阴性对照组比较,沉默P75^NTR联合NGF过表达组P75^NTR蛋白表达明显下调,NGF蛋白表达明显增加;③与空白对照组与阴性对照组相比,沉默P75^NTR联合NGF过表达组、沉默P75^NTR组、NGF过表达组细胞增殖明显加快,差异有显著性意义(P < 0.05),其中沉默P75^NTR联合NGF过表达组增殖最快;④结果显示：沉默P75^NTR联合NGF过表达共转染可促进SD大鼠骨髓间充质干细胞的增殖。ORCID: 0000-0003-3826-7213(王宁) 中国组织工程研究杂志出版内容重点：干细胞;骨髓干细胞;造血干细胞;脂肪干细胞;肿瘤干细胞;胚胎干细胞;脐带脐血干细胞;干细胞诱导;干细胞分化;组织工程     

通过基因转染诱导骨髓间充质干细胞为胰岛样细胞的进展

随着器官和组织移植技术的进步,胰腺和胰岛移植已开始用于治疗糖尿病并成为热点,但是关于胰岛细胞的来源问题还是存在着许多不足和改进之处。其中骨髓间充质干细胞(BMSCs)因为具有获取简单、易于培养和免疫抑制等优点成为被诱导为胰岛样细胞的热点。近几年来人工构建类胰岛细胞（即利用基因重组及基因转染再造胰岛样细胞）的技术提高了单...     

PNGF导管复合骨髓间充质干细胞修复大鼠12 mm坐骨神经缺损

目的　观察RGD多肽接枝聚（乳酸-羟基乙酸-L-赖氨酸）/聚乳酸/β-磷酸三钙/神经生长因子（PRGD/PDLLA/β-TCP/NGF,PNGF）缓释导管复合骨髓间充质干细胞(Bone marrow derived mesenchymal stem cells, BMSCs)构建组织工程化人工神经,修复大鼠12 mm坐骨神经缺损的效果。  方法    雄性Wistar大鼠30只, 随机分为3组,每组10只,左后肢制作12 mm坐骨神经缺损模型,分别行单纯PNGF导管桥接（A）、PNGF导管复合BMSCs桥接（B）、自体神经移植（C）,所有大鼠左侧为实验侧,右侧为正常自身对照侧。术后3个月行大体观察、坐骨神经功能指数、电生理检测、小腿三头肌湿重恢复率测量、新生神经及靶肌肉组织学观察等检测坐骨神经功能恢复情况。  结果　术后3个月取材时见导管管壁变薄,表面血管化良好,管内有再生神经通过,直径较正常神经细。坐骨神经功能指数的检测结果显示PNGF导管复合BMSCs高于单纯PNGF导管组（P＜0.05）,PNGF导管复合BMSCs组神经传导速度恢复率、小腿三头肌湿重恢复率、有髓神经纤维数量和直径均优于单纯PNGF导管组（P＜0.01）,取得与自体神经移植组相似的效果。  结论　PNGF缓释导管复合BMSCs桥接修复大鼠坐骨神经缺损, 能够有效促进神经再生, 效果接近自体神经移植。     

大鼠骨髓间充质干细胞来源HGF对肝星状细胞DR5及Caspase-8表达的影响*

 目的:观察大鼠骨髓间充质干细胞(BMSCs)来源的肝细胞生长因子（HGF）对原代肝星状细胞(HSCs)死亡受体-5(DR5)及Caspase-8的影响,初步探讨BMSCs来源HGF在促进HSCs凋亡中的部分作用机制。方法:贴壁法培养及纯化SD大鼠BMSCs,使用第3-4代细胞进行实验;复苏大鼠原代HSCs及传代,应用6孔培养板,每孔使用(Transwell insert)半透膜建立双层细胞共培养体系,常规培养24h、48h、72h。实验分为4组:A组:空白对照组; B组:BMSCs+HSCs共培养组; C组: TNF-a预处理组及D组:HGF-ShRNA干扰组。酶联免疫吸附法（Elisa）检测各组上清液中HGF及TRAIL的浓度;用流式细胞仪Annexin V-FITC/PI双染法检测细胞凋亡;分别使用荧光定量PCR(FQ-PCR)、Western blot检测各组HSCs内DR5、Caspase-8mRNA和蛋白的表达。结果：1. Elisa法检测结果示:TNF-a预处理组的HGF浓度明显高于BMSCs组及空白对照组（P<0.01）;BMSCs组中TRAIL的浓度明显高于空白对照组及TNF-a预处理组（P<0.01）;2. Annexin-V-FITC/PI双染法检测凋亡结果示：TNF-a预处理组HSCs的凋亡率明显高于其它3组（P<0.01）且呈时间依赖性;HGF-ShRNA干扰组中HSCs的凋亡率低于共培养组,较空白对照组高二者比较有统计学意义（P<0.05）。3. FQ-PCR、Western blotting结果示共培养组及TNF-a预处理组HSCs的DR5、Caspase-8mRNA及蛋白表达量明显高于空白对照组及HGF-ShRNA干扰组（P<0.01）。 结论： BMSCs与HSCs共培养后促进HSCs的凋亡,其可能与BMSCs来源HGF能上调HSCs的DR5及Caspase-8的表达有关。     

The great migration of bone marrow-derived stem cells toward the ischemic brain: therapeutic implications for stroke and other neurological disorders

Accumulating laboratory studies have implicated the mobilization of bone marrow (BM)-derived stem cells in brain plasticity and stroke therapy. This mobilization of bone cells to the brain is an essential concept in regenerative medicine. Over the past ten years, mounting data have shown the ability of bone marrow-derived stem cells to mobilize from BM to the peripheral blood (PB) and eventually enter the injured brain. This homing action is exemplified in BM stem cell mobilization following ischemic brain injury. Various BM-derived cells, such as hematopoietic stem cells (HSCs), mesenchymal stem cells (MSCs), endothelial progenitor cells (EPCs) and very small embryonic-like cells (VSELs) have been demonstrated to exert therapeutic benefits in stroke. Here, we discuss the current status of these BM-derived stem cells in stroke therapy, with emphasis on possible cellular and molecular mechanisms of action that mediate the cells' beneficial effects in the ischemic brain. When possible, we also discuss the relevance of this therapeutic regimen in other central nervous system (CNS) disorders.