突变型α-核突触蛋白的自噬性降解途径及可能机制

目的 观察突变型α-核突触蛋白对PC12细胞增殖的影响和可能的降解途径,探讨其在帕金森病发病机制中的作用.方法 对转染了α-核突触蛋白(A30P)的PC12细胞进行药物干预,检测细胞的增殖活性,并采用透射电镜观察细胞超微结构改变以及自噬的特征性改变,同时检测α-核突触蛋白的表达和超氧化物歧化酶(SOD)的水平.结果 (1)Western Blot法检测α-核突触蛋白的表达:A30P+渥曼青霉素组(A30P+W组)、A30P+1-甲基4-苯基吡啶组(A30P+MPP+组)较A30P组明显增高,以A30P+W组最为明显;而A30P+雷帕霉素组(A30P+R组)条带较A30P组减低(P＜0.01);(2)不同时间点细胞培养液中SOD水平(U/ml)的测定:用MPP+处理转染了突变型α-核突触蛋白的PC12细胞后,培养液中SOD水平(A30P+MPP+组:3 h:97.49±13.8;12 h:102.7±12.7:24 h:101.5±11.8;48 h:104.3±12.4)较A30P组在各时间点显著下调(t=3.7721,P=0.0017);A30P+R组在给药12 h以后,培养液中SOD水平逐渐升高,其中在24 h(121.2±13.0)、48 h(124.3±14.1)和72 h(127.7±13.7)时与A30P+W组比较差异有统计学意义(t=2.9746,P=0.0083);突变型α-核突触蛋白激活了自噬途径,并介导了MPP+的毒性作用,自噬抑制剂渥曼青霉素可通过抑制自噬而加剧α-核突触蛋白积聚,导致细胞死亡;而自噬诱导剂雷帕霉素则可以通过诱导自噬的发生而促进α-核突触蛋白的降解和细胞生长.结论 α-核突触蛋白的异常积聚导致PC12细胞的自噬性细胞死亡,促进自噬有助于突变型α-核突触蛋白降解,对细胞具有保护作用.     

Overexpression of microRNA-124 promotes the neuronal differentiation of bone marrow-derived mesenchymal stem cells

microRNAs(miRNAs) play an important regulatory role in the self-renewal and differentiation of stem cells. In this study, we examined the effects of miRNA-124(miR-124) overexpression in bone marrow-derived mesenchymal stem cells. In particular, we focused on the effect of overexpression on the differentiation of bone marrow-derived mesenchymal stem cells into neurons. First, we used GeneChip technology to analyze the expression of miRNAs in bone marrow-derived mesenchymal stem cells, neural stem cells and neurons. miR-124 expression was substantially reduced in bone marrow-derived mesenchymal stem cells compared with the other cell types. We constructed a lentiviral vector overexpressing miR-124 and transfected it into bone marrow-derived mesenchymal stem cells. Intracellular expression levels of the neuronal early markers β-III tubulin and microtubule-associated protein-2 were significantly increased, and apoptosis induced by oxygen and glucose deprivation was reduced in transfected cells. After miR-124-transfected bone marrow-derived mesenchymal stem cells were transplanted into the injured rat spinal cord, a large number of cells positive for the neuronal marker neurofilament-200 were observed in the transplanted region. The Basso-Beattie-Bresnahan locomotion scores showed that the motor function of the hind limb of rats with spinal cord injury was substantially improved. These results suggest that miR-124 plays an important role in the differentiation of bone marrow-derived mesenchymal stem cells into neurons. Our findings should facilitate the development of novel strategies for enhancing the therapeutic efficacy of bone marrow-derived mesenchymal stem cell transplantation for spinal cord injury.     

姜黄素通过诱导热休克蛋白70保护多巴胺能细胞

目的 探讨姜黄素通过诱导热休克蛋白70(Hsp70)高表达,抑制α-突触核蛋白的异常表达和聚集,促进蛋白酶体系统降解异常α-突触核蛋白对多巴胺能细胞的保护作用.方法 选用大鼠嗜铬细胞瘤细胞株(PCI2细胞),鱼藤酮诱导其损伤建立帕金森病细胞模型,利用姜黄素进行干预:采用MTT法检测细胞活力,荧光酶标仪检测蛋白酶体水解酶活性,Western blot检测Hsp70和α-突触核蛋白的表达,免疫荧光法检测细胞内Hsp70的表达和α-突触核蛋白的聚集.结果 鱼藤酮组PC12细胞活力及蛋白酶体水解酶活性明显降低,Hsp70的表达轻度增加,α-突触核蛋白表达和聚集明显增加,与对照组比较差异有统计学意义(P<0.05).经不同浓度姜黄素预处理4h后与0.1 μmol/L鱼藤酮共同孵育PC12细胞24 h,与鱼藤酮组比较,0.5 μmol/L和1.0 μmol/L姜黄素使细胞活力以及蛋白酶体水解酶活性明显升高,Hsp70表达明显升高,α-突触核蛋白的表达和聚集明显减少,差异有统计学意义(P<0.05);5.0 μmol/L和10 μmol/L姜黄素对鱼藤酮的拮抗作用明显减弱,细胞活力与鱼藤酮组比较差异均无统计学意义(P>0.05),胰蛋白酶、多肽-谷氨酰-多肽水解酶活性与鱼藤酮组比较差异均无统计学意义(P>0.05);10 μmol/L姜黄素组糜蛋白酶样水解酶活性进一步降低,与鱼藤酮组比较差异有统计学意义(P<0.05).结论 低浓度姜黄素能够通过诱导PC12细胞表达Hsp70,诱导蛋白酶体水解酶活性表达,进而抑制α-突触核蛋白的表达和聚集,从而拮抗鱼藤酮诱导的PC12细胞的损伤.     

成人骨髓源性神经干细胞的致瘤性研究

目的研究体外培养的成人骨髓源性神经干细胞的致瘤性。方法对骨髓源性神经干细胞分别进行细胞形态学观察、刀豆球蛋白A凝集试验和双层软琼脂培养以探明其是否具有恶性转化细胞的形态特征、表面结构及生长特性的变化：利用免疫细胞化学的方法检测骨髓源性神经干细胞的端粒酶和肿瘤相关基因的表达：将骨髓源性神经干细胞接种到裸鼠体内观察其成瘤性。结果骨髓源性神经干细胞不具有恶性转化细胞的形态特征，在不同刀豆球蛋白A浓度下均未见明显的凝集反应，在双层软琼脂不能形成细胞克隆；骨髓源性神经干细胞的c-myc、c-fos和p53基因均呈阴性表达，而端粒酶逆转录酶呈弱阳性表达：将骨髓源性神经干细胞接种于裸鼠皮下6个月未见肿瘤形成，亦未见其它组织形成。结论骨髓源性神经干细胞保持了正常细胞的生物学特征．体内和体外的各项指标均未提示其具有致瘤性．体外的培养条件没有使其发生恶性转化．从致瘤性方面证实了骨髓源性神经干细胞临床移植的安全性。     

异基因间充质干细胞在体内免疫调节作用的时间及剂量依赖性

背景：异基因间充质干细胞移植时,发挥作用需要的剂量、持续的时间及是否具有不良反应是目前研究的热点。 目的：观察异基因的骨髓间充质干细胞在体内免疫调节作用的时间、剂量依赖性。 方法：免疫系统正常的BALB/c小鼠模型,制备骨髓来源间充质干细胞,24只BALB/c小鼠随机分为4组,实验组每只小鼠分别通过尾静脉注射0.3 mL细胞悬液,分别含5×105,5×104,5×103骨髓间充质干细胞,对照组小鼠仅注射0.3 mL生理盐水。进行淋巴细胞增殖检测、混合淋巴细胞反应、间充质干细胞移植对异基因小鼠免疫系统的影响等实验。 结果与结论：不同剂量的C57BL/6骨髓来源间充质干细胞经尾静脉注射给BALB/c受体小鼠后,骨髓间充质干细胞体内对免疫系统的调节呈剂量依赖性。间充质干细胞促进异基因移植物的植入,同时这种免疫下调作用在2周时最强,1个月逐渐减弱,2个月基本消失,提示间充质干细胞的免疫调节作用具有剂量依赖性,并且只能维持一段时间。     

1-甲基-4-苯基吡啶离子诱导嗜铬细胞瘤细胞自噬应激并导致α-突触核蛋白的自噬性清除障碍

目的 探讨1-甲基-4-苯基吡啶离子(MPP+)所诱导的自噬应激在嗜铬细胞瘤(PC12)细胞损伤中的作用以及MPP+导致α-突触核蛋白自噬性清除障碍及其异常聚集的可能机制.方法 在MPP+处理细胞24 h后,采用四甲基偶氮盐法检测细胞活力,Western blot检测α-突触核蛋白及微管相关蛋白1轻链3-Ⅱ(LC3-Ⅱ)在蛋白水平表达的变化,并用MDC染色和免疫荧光标记观察自噬水平的变化及α-突触核蛋白、LC3-Ⅱ和溶酶体相关膜蛋白-1(LAMP-1)在细胞内的共定位情况.结果 MPP+处理后细胞的活力明显下降;与未处理组相比(PC12组:0.20±0.08;A30P组:0.76±0.09),PC12+MPP+组(0.66±0.07,t=5.7271,P=0.0023)和A30P+MPP+组(1.71 4±0.40,t=8.6100,P=0.0005)α-突触核蛋白表达增加;LC3-Ⅱ蛋白的表达水平及自噬泡的平均数目均增高.另外,MPP+处理后,α-突触核蛋白和LC3-Ⅱ的荧光信号及其共定位增加,尽管LAMP-1标记的溶酶体荧光信号增加,但与LC3-Ⅱ标记的自噬体共定位程度却减小.结论 MPP+导致自噬体与溶酶体的融合出现障碍,引起α-突触核蛋白的自噬性清除障碍与自噬应激的出现,最终导致细胞的损伤甚至死亡.     

骨髓间充质干细胞对局灶脑缺血再灌注损伤的超早期干预

摘要：目的　探讨骨髓间充质干细胞(BMSCs) 对大鼠脑缺血再灌注损伤保护作用及机制。方法　雄性SD大鼠72只,以线栓法制成缺血再灌注模型,随机分为2组：溶剂对照组;BMSCs移植组。在缺血再灌注后1天、3天、6天分别行神经功能检测、TTC染色、免疫组化法检测Survivin、caspase-3表达,TUNEL法检测凋亡细胞表达。结果　与溶剂对照组比较,在梗死脑组织中移植骨髓间充质干细胞BMSCs后,可使大鼠神经功能有所恢复,在大鼠大脑中动脉局灶脑缺血90分钟再灌注3天及6天神经功能评分比较高,有统计学意义;TTC染色脑梗死体积百分比在缺血再灌注第3天、第6天较溶剂对照组分别减少2.13%和2.10%,有统计学意义。单纯BMSCs移植组比较对照组在缺血再灌注后1天、3天、6天缺血侧皮层Survivin表达增高、caspase-3表达降低,凋亡细胞减少,均有统计学意义。结论　脑缺血部位脑实质单纯 BMSCs 移植能够改善缺血后神经功能,减少脑缺血后梗死体积,可能通过增加脑缺血再灌注损伤部位Survivin蛋白的表达,降低凋亡相关蛋白Caspase-3表达,减少凋亡细胞数量发挥作用     

Transplantation of autologous bone marrow-derived mesenchymal stem cells for traumatic brain injury

Results from the present study demonstrated that transplantation of autologous bone marrow-derived mesenchymal stem cells into the lesion site in rat brain significantly ameliorated brain tissue pathological changes and brain edema, attenuated glial cell proliferation, and increased brain-derived neurotrophic factor expression. In addition, the number of cells double-labeled for 5-bromodeoxyuridine/glial fibrillary acidic protein and cells expressing nestin increased. Finally, blood vessels were newly generated, and the rats exhibited improved motor and cognitive functions. These results suggested that transplantation of autologous bone marrow-derived mesenchymal stem cells promoted brain remodeling and improved neurological functions following traumatic brain injury.     

Myogenic cells derived from rat bone marrow mesenchymal stem cells exposed to 5-azacytidine

The compound 5-azacytidine has been previously shown to convert cells of the rat embryonic fibroblastic cell line, C3H/10T1/2, into myoblasts, adipocytes, and chondrocytes. Rare, resident cells of bone marrow and periosteum, referred to as mesenchymal stem cells, have been shown to differentiate into a number of mesenchymal phenotypes including bone, cartilage, and adipocytes. Rat bone marrow-derived mesenchymal stem cells were exposed to 5-azacytidine beginning 24 h after seeding twice-passaged cells into culture dishes. After an exposure of 24 h, long, multinucleated myotubes were observed in some of the dishes 7–11 days later. Cells containing Sudan black-positive droplets in their cytoplasm were also observed. Thus, culture-propagated rat bone marrow mesenchymal stem cells appear to have the capacity to be induced to differentiate in vitro into myogenic and adipocytic phenotypes, although nonmesenchymal cells (rat brain fibroblasts) cannot be so induced. Taken together, these observations provide support for the suggestion that mesenchymal stem cells in the bone marrow of postnatal organisms may provide a source for myoprogenitor cells which could function in clinically relevant myogenic regeneration. © 1995 John Wiley & Sons, Inc.     

慢性粒细胞白血病肿瘤干细胞的免疫功能

背景：研究认为间充质干细胞可能是骨髓造血微环境的免疫保护位点。由于慢性粒细胞白血病存在造血微环境异常和免疫异常,所以推测间充质干细胞可能在慢性粒细胞白血病的病理过程中扮演了一个重要角色。 目的：观察慢性粒细胞白血病骨髓来源的肿瘤干细胞的免疫学特征,比较其与正常人来源的间充质干细胞是否存在免疫功能的异常。 方法：分离正常人和慢性粒细胞白血病患者的骨髓间充质干细胞,分别检测它们对T细胞周期、活化、抑制和增殖的作用。 结果与结论：慢性粒细胞白血病和正常志愿者骨髓来源的间充质干细胞形态和表型没有差异,慢性粒细胞白血病患者来源的间充质干细胞抑制T细胞增殖的作用减弱,抑制T细胞周期及活化的能力减弱,慢性粒细胞白血病患者抑制T细胞凋亡的作用增强。提示慢性粒细胞白血病患者骨髓来源的间充质干细胞存在明显的免疫调节功能缺陷,如果使用慢性粒细胞白血病患者自体的间充质干细胞移植治疗可能不是一种很好的选择,对于骨髓增生异常综合征患者最好是选用异基因的间充质干细胞移植。     

引产儿与正常成人骨髓间充质干细胞的比较*

背景：骨髓间充质干细胞是多能干细胞,同时可参与免疫调节反应,而成人及引产胎儿骨髓均是间充质干细胞的重要来源。 目的：通过引产儿与正常成人骨髓间充质干细胞的细胞形态、免疫表型、增殖活性及分泌细胞因子的比较,揭示二者生物学特点的差异。 方法：采用密度梯度离心法分离引产儿与正常成人骨髓单个核细胞,通过贴壁法培养骨髓间充质干细胞,收集传3代后的骨髓间充质干细胞,流式细胞术鉴定其免疫表型、MTT比色法检测其增殖活性以及用ELISA法检测细胞培养上清液中白细胞介素6、血小板源性生长因子和表皮生长因子的水平。 结果与结论：引产儿组和正常成人组骨髓间充质干细胞形态相似、表型相同,分泌细胞因子水平无显著差异,但引产儿细胞增殖活性显著高于正常成人。提示引产儿与正常成人骨髓间充质干细胞除增殖活性有差异外,其余生物学特点相似,引产儿可以为间充质干细胞研究提供新的骨髓来源。     

骨髓源性神经干细胞体外培养体系的安全性评价

目的评价成人骨髓源性神经干细胞体外培养体系的安全性。方法对骨髓源性神经干细胞的培养上清分别进行无菌试验、支原体检测、热原质检测和异常毒性试验。结果骨髓源性神经干细胞的培养上清经培养无细菌和真菌生长，PCR检测未扩增出支原体的特异性片断，培养上清的热原质含量符合规定的限度，进行异常毒性试验的动物在观察期内未出现局部和全身异常反应，结论骨髓源性神经干细胞的培养体系中不含有对人体移植具有潜在危害的因素，整个培养流程和培养体系是安全可靠的。     

Magnet-targeted delivery of bone marrow-derived mesenchymal stem cells improves therapeutic efficacy following hypoxic-ischemic brain injury

hypoxicischemic brain injury;however,the therapeutic efficacy of bone marrow-derived mesenchymal stem cells largely depends on the number of cells that are successfully transferred to the target.Magnet-targeted drug delivery systems can use a specific magnetic field to attract the drug to the target site,increasing the drug concentration.In this study,we found that the double-labeling using superparamagnetic iron oxide nanoparticle and poly-L-lysine(SPIO-PLL)of bone marrow-derived mesenchymal stem cells had no effect on cell survival but decreased cell proliferation 48 hours after labeling.Rat models of hypoxic-ischemic brain injury were established by ligating the left common carotid artery.One day after modeling,intraventricular and caudal vein injections of 1×105 SPIO-PLL-labeled bone marrow-derived mesenchymal stem cells were performed.Twenty-four hours after the intraventricular injection,magnets were fixed to the left side of the rats’heads for 2 hours.Intravoxel incoherent motion magnetic resonance imaging revealed that the perfusion fraction and the diffusion coefficient of rat brain tissue were significantly increased in rats treated with SPIO-PLL-labeled cells through intraventricular injection combined with magnetic guidance,compared with those treated with SPIO-PLL-labeled cells through intraventricular or tail vein injections without magnetic guidance.Hematoxylin-eosin and terminal deoxynucleotidyl transferase dUTP nick-end labeling(TUNEL)staining revealed that in rats treated with SPIO-PLL-labeled cells through intraventricular injection under magnetic guidance,cerebral edema was alleviated,and apoptosis was decreased.These findings suggest that targeted magnetic guidance can be used to improve the therapeutic efficacy of bone marrow-derived mesenchymal stem cell transplantation for hypoxic-ischemic brain injury.This study was approved by the Animal Care and Use Committee of The Second Hospital of Dalian Medical University,China(approval No.2016-060)on March 2,2016.     

Bone marrow-derived mesenchymal stem cells increase dopamine synthesis in the injured striatum

Previous studies showed that tyrosine hydroxylase or neurturin gene-modified cells transplanted into rats with Parkinson’s disease significantly improved behavior and increased striatal dopamine content. In the present study, we transplanted tyrosine hydroxylase and neurturin gene-modified bone marrow-derived mesenchymal stem cells into the damaged striatum of Parkinson’s disease model rats. Several weeks after cell transplantation, in addition to an improvement of motor function, tyrosine hydroxylase and neurturin proteins were up-regulated in the injured striatum, and importantly, levels of dopamine and its metabolite 3,4-dihydroxyphenylacetic acid increased significantly. Furthermore, the density of the D2 dopamine receptor in the postsynaptic membranes of dopaminergic neurons was decreased. These results indicate that transplantation of tyrosine hydroxylase and neurturin gene-modified bone marrow-derived mesenchymal stem cells increases dopamine synthesis and significantly improves the behavior of rats with Parkinson’s disease.     

Effects of lateral ventricular transplantation of bone marrow-derived mesenchymal stem cells modified with brain-derived neurotrophic factor gene on cognition in a rat model of Alzheimer's disease

In the present study, transplantation of bone marrow-derived mesenchymal stem cells modified with brain-derived neurotrophic factor gene into the lateral ventricle of a rat model of Alzheimer’s disease, resulted in significant attenuation of nerve cell damage in the hippocampal CA1 region. Furthermore, brain-derived neurotrophic factor and tyrosine kinase B mRNA and protein levels were significantly increased, and learning and memory were significantly improved. Results indicate that transplantation of bone marrow-derived mesenchymal stem cells modified with brain-derived neurotrophic factor gene can significantly improve cognitive function in a rat model of Alzheimer’s disease, possibly by increasing the levels of brain-derived neurotrophic factor and tyrosine kinase B in the hippocampus.     

骨髓间充质干细胞移植治疗脑梗死及存在问题

骨髓间充质干细胞（BMSCs）已成为21世纪干细胞工程的热点和前沿,是最有前途的组织工程种子之一。大量的动物实验证实BMSCs移植治疗脑梗死能明显改善受损的神经功能,具有极大临床应用价值。但是在临床前期实验研究方面存在着众多的困惑性问题。本文就临床移植BM—SCs移植治疗脑梗死及存在的问题做一综述。     

Lactacystin诱导PC12细胞胞内嗜酸性包涵体动态变化的研究

目的 研究蛋白酶体抑制剂lactacystin诱导PC12细胞胞浆内嗜酸性包涵体的动态变化过程.方法 PC12细胞中加入不同浓度lactacystin(0、5、10、20μmol/L),孵育24 h后行HE染色及α-synuclein免疫组织化学染色,光镜观察包涵体变化;其中10 μmol/L lactacystin组分别于加入lactacystin后24、36、48、72、96和120 h行上述染色法,光镜观察包涵体变化.结果 lacatacystin作用于PC12细胞24 h后,HE染色显示随着浓度增加.胞浆中嗜伊红包涵体数量逐渐增多.0 μmol/L组胞浆中未看到包涵体,5 μmol/L组胞浆中有少量包涵体出现(3.33%±1.15%),10μmol/L组多数细胞胞浆出现典型球状包涵体(71.33%±4.16%),20μmol/L组几乎每个细胞胞浆中均出现嗜伊红包涵体(90.33%±3.21%),个别包涵体游离于细胞外;10 μmol/L组随着时间延长,包涵体逐渐从胞浆中游离至细胞外,其后胞浆逐渐缺失,在96 h和120 h时仅剩余胞核和球状包涵体.免疫组化染色显示:lactacystin作用24 h时,胞浆中α-synuclein免疫反应阳性物质逐渐由散在颗粒逐渐聚集成球状包涵体;随着浓度的增加和时间延长,α-synuclein染色阳性的球状包涵体游走于细胞外,胞浆逐渐缺失,至96 h和120 h时仅剩余胞核和包涵体.结论 lactacystin作用于PC12细胞后,早期在胞浆中出现散在的嗜酸性和α-synuclein免疫反应阳性的颗粒,随着浓度增加和时间延长,颗粒状物质在核旁聚集,最终形成固缩的包涵体,细胞外包涵体可独立存在.这种包涵体的动态变化过程与以人类帕金森病为代表的神经变性疾病中的包涵体非常相似,可以作为研究包涵体相关问题的有力工具.     

Gender difference in the neuroprotective effect of rat bone marrow mesenchymal cells against hypoxia-induced apoptosis of retinal ganglion cells

Bone marrow mesenchymal stem cells can reduce retinal ganglion cell death and effectively prevent vision loss. Previously, we found that during differentiation, female rhesus monkey bone marrow mesenchymal stem cells acquire a higher neurogenic potential compared with male rhesus monkey bone marrow mesenchymal stem cells. This suggests that female bone marrow mesenchymal stem cells have a stron-ger neuroprotective effect than male bone marrow mesenchymal stem cells. Here, we ifrst isolated and cultured bone marrow mesenchymal stem cells from female and male rats by density gradient centrifugation. Retinal tissue from newborn rats was prepared by enzymatic digestion to obtain primary retinal ganglion cells. Using the transwell system, retinal ganglion cells were co-cultured with bone marrow mesenchymal stem cells under hypoxia. Cell apoptosis was detected by lfow cytometry and caspase-3 activity assay. We found a marked increase in apoptotic rate and caspase-3 activity of retinal ganglion cells after 24 hours of hypoxia compared with normoxia. Moreover, apoptotic rate and caspase-3 activity of retinal ganglion cells signiifcantly decreased with both female and male bone marrow mesenchymal stem cell co-culture under hypoxia compared with culture alone, with more signiifcant effects from female bone marrow mesenchymal stem cells. Our results indicate that bone marrow mesenchymal stem cells exert a neuroprotective effect against hypoxia-induced apoptosis of retinal ganglion cells, and also that female cells have greater neuroprotective ability compared with male cells.