瓦勒变性坐骨神经段对大鼠BMSCs向SCs分化的影响

 目的:通过观察瓦勒变性坐骨神经段对大鼠骨髓间充质干细胞（bone marrow mesenchymal stem cells, BMSCs）增殖、分泌功能以及向施万细胞（Schwann cells, SCs）分化的影响,探讨其在BMSCs向SCs分化中的作用及可能的机制。方法:采用全骨髓贴壁法分离、培养SD大鼠BMSCs,并采用免疫荧光法鉴定。应用Transwell建立坐骨神经段与BMSCs双层培养体系,将实验分为瓦勒变性坐骨神经段与BMSCs联合培养组（A组）、正常坐骨神经段与BMSCs联合培养组（B组）和BMSCs单独培养组（C组）。倒置相差显微镜观察联合培养过程中BMSCs 形态变化;免疫荧光染色检测联合培养第7天各组BMSCs表达S-100情况;联合培养第0、1、4、7、11、14天,利用细胞计数法绘制各组BMSCs生长曲线,ELISA法检测各组培养液上清中神经生长因子（nerve growth factor, NGF）含量,实时荧光定量PCR检测各组BMSCs中S-100 mRNA表达情况。结果:成功分离培养BMSCs,免疫荧光鉴定BMSCs呈CD29、CD44和CD90表达阳性。联合培养第7天倒置相差显微镜观察可见,A组BMSCs胞体回缩,呈梭形,并带有突起,形态类似SCs;B、C 组大部分BMSCs 形态无明显变化。联合培养第7天免疫荧光染色示,A、B、C 组 BMSCs S-100阳性表达率分别为31.1%±2.9%、16.2%±1.7%和0.42%±0.07%,A组阳性表达率明显增高（P<0.05）。各组BMSCs生长曲线均近似“S”形,从第4天开始,A组BMSCs增殖速度明显快于B、C组（P<0.05）;ELISA 法检测示,A 组NGF含量呈时间依赖性增加,于联合培养第7天达高峰,随后呈下降趋势。B、C 组NGF含量随共培养时间延长有所增加,但显著低于A组（P<0.05）;实时荧光定量PCR检测示,联合培养第4、7、11、14天,A组S-100 mRNA表达明显高于B、C组（P<0.05）。结论: 瓦勒变性坐骨神经段能有效促进大鼠BMSCs增殖并诱导BMSCs向SCs样细胞分化,联合培养过程中NGF可能参与BMSCs向SCs分化的调控。     

TOLL样受体4拮抗剂干预周围神经损伤后的瓦勒变性

BACKGROUND: The mechanism underlying Wallerian degeneration following peripheral nerve injury is complex. Immune regulation on Wallerian degeneration is beneficial for early repair of perpheral nerve injury. OBJECTIVE: To investigate the effects of Toll-like receptor 4 (TLR4) antagonist on Wallerian degeneration and axonal regeneration after early peripheral nerve injury in rats. METHODS: Fifty male Wistar rats were recruited and randomly divided into treatment group (n=20), model group (n=20) and sham group (n=10). The right sciatic nerves of rats in treatment and model groups were cut and sutured end-to-end, while the sciatic nerves of rats in sham group were only exposed. In the treatment group rats were intravenously injected with 0.15 mg/kg TAK-242 via tail vein 1 hour preoperatively and 7 days postoperatively, and the rats in the other two groups were given intravenous injection of the same volume of normal saline. The sciatic nerves were removed at 24 hours, 3, 4 and 7 days after surgery. RESULTS AND CONCLUSION: Real-time PCR indicated that the mRNA expressions of interleukin-1β and monocyte chemoattractant-1 were significantly increased in the model group compared with the sham group at 24 hours after surgery (both P < 0.001), while the expressions were significantly decreased after TAK-242 injection (both P < 0.001). Immunofluorescence showed that compared with the model group, down-regulated expression of CD68+ and iba1+ cells appeared in the treatment group at 3 days after surgery (P < 0.01, P < 0.05). Luxol fast blue staining revealed that demyelination at the sciatic nerve stump appeared in both model and treatment groups at postoperative 7 days, but myelin debris clearance in the treatment group was significantly reduced compared with the model group (P < 0.05). Hematoxylin-eosin staining showed that a lot of inflammatory cells, Schwann cells and regenerated nerve fibers at the sciatic nerve stump were found in the model group, while there were few inflammatory cells, Schwann cells and regenerated nerve fibers in the treatment group at 7 days after surgery. Immunohistochemistry found that the expression of growth-associated protein-43 in the treatment group was significantly lower than that in the model group at 4 days postoperatively (P < 0.05). Besides, compared with the model group, a significantly decreased sciatic functional index was found in the treatment group at 20, 30 and 40 days after surgery (P < 0.05). These results show that TLR4 antagonists delay early nerve regeneration in rats after sciatic nerve injury probably by inhibiting the TLR4 signaling pathway. 中国组织工程研究杂志出版内容重点：组织构建;骨细胞;软骨细胞;细胞培养;成纤维细胞;血管内皮细胞;骨质疏松;组织工程     

一定强度静磁场可促进许旺细胞快速分泌神经生长因子

背景：国内外对静磁场加载许旺细胞的研究较少,对其产生的生物学效应尚不清楚。目的：探索静磁场对许旺细胞分泌神经生长因子水平的影响。方法：将传代良好的许旺细胞随机分为3组,分别为0.05 mT静磁场组、0.1 mT静磁场组、空白对照组。从接种第2天即开始静磁场加载,每天曝磁12 h,空白对照组不进行静磁场加载。加载6 d后利用RT-PCR技术检测许旺细胞中神经生长因子mRNA的表达,ELISA技术检测许旺细胞分泌神经生长因子水平。结果与结论：静磁场组培养上清中神经生长因子mRNA的表达和分泌神经生长因子水平显著高于空白对照组(P < 0.05);0.1 mT静磁场组神经生长因子mRNA的表达和分泌神经生长因子水平虽高于0.05 mT静磁场组,但是差异无显著性意义(P >0.05)。结果表明一定强度的静磁场可以促进许旺细胞快速分泌神经生长因子。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     

高压氧联合许旺细胞移植脊髓损伤大鼠电生理及后肢功能的变化

背景：高压氧治疗可以改善脊髓损伤区微环境,联合许旺细胞移植有望提高大鼠脊髓损伤疗效。目的：观察高压氧联合许旺细胞移植对脊髓损伤大鼠神经功能恢复的影响。方法：80只雌性SD大鼠建立脊髓损伤模型后随机分成4组,每组20只,空白对照组和细胞移植组分别在建模6 h后尾静脉注射L-DMEM培养液和许旺细胞(3×10⁶个)悬液,高压氧组建模1 h后开始高压氧治疗,联合组进行高压氧和许旺细胞移植联合治疗。于移植后1,3 d以及1,2,3,4周进行斜板试验、改良Tarlov 评分,BBB评分评定大鼠后肢运动功能恢复情况;移植第4周PCR检测各组脊髓组织中SRY基因表达;移植第8周行辣根过氧化物酶示踪及神经电生理检测。结果与结论：联合组下肢运动功能优于细胞移植组和高压氧组,细胞移植组和高压氧组优于空白对照组。细胞移植组和联合组有SRY基因表达,对照组和高压氧组未检测到SRY基因。辣根过氧化物酶阳性神经纤维数：联合组>细胞移植组和高压氧组>空白对照组,差异有显著性意义(P < 0.01)。联合组大鼠体感诱发电位及运动诱发电位的潜伏期、波幅明显优于其他3组(P < 0.05或P < 0.01)。结果提示高压氧与许旺细胞移植联合应用可促进脊髓损伤大鼠神经突触的再生,改善肢体运动功能和电生理功能,其治疗效果优于单独应用高压氧或许旺细胞。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;组织工程全文链接：     

人端粒酶反转录酶转染大鼠许旺细胞的生物学特性

背景：研究表明,基因修饰许旺细胞可使许旺细胞在体内存活时间延长,促进神经再生和功能的恢复。目的：以反转录病毒PLXSN 为载体,将hTERT 基因转染入体外培养的大鼠许旺细胞,检测许旺细胞端粒酶活性及细胞生物学特性。方法：体外培养Wistar大鼠许旺细胞,经反转录病毒PLXSN为载体介导人端粒酶反转录酶基因转染,在同等条件下进行空载病毒转染,以正常培养的许旺细胞为对照组。采用RT-PCR,Western blot检测许旺细胞人端粒酶反转录酶基因和蛋白的表达,流式细胞仪测定细胞周期分布的变化。以细胞生长曲线、MTT比色法观察细胞生长的优化作用。结果与结论：人端粒酶反转录酶基因转染许旺细胞48 h后,检测到人端粒酶反转录酶mRNA和蛋白水平表达明显。与对照组和空载病毒组比较,细胞的生长速度明显增快,G₀/G₁期细胞数减少,S期细胞数增多,差异有显著性意义(P < 0.05)。结果表明通过反转录病毒PLXSN 为载体介导人端粒酶反转录酶基因转染使许旺细胞端粒酶活性明显升高,能够促进体外培养的大鼠许旺细胞增殖。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;组织工程全文链接：     

不同浓度人羊膜匀浆上清液培养大鼠许旺细胞的增殖

背景：许旺细胞是周围神经修复过程的重要细胞,而研究发现人羊膜细胞分泌的多种细胞因子能够促进许旺细胞增殖。 目的：观察不同浓度人羊膜匀浆上清液对鼠许旺细胞(RSC96)生长的影响。 方法：使用含体积分数20%胎牛血清的高糖DMEM培养基原代培养RSC96细胞株,传代至第2代用于实验研究。根据人羊膜匀浆上清液在培养基中的不同体积分数(0,10,15,20,25%)分组。 结果与结论：人羊膜匀浆上清液的总蛋白浓度为675 mg/L,表皮生长因子、碱性成纤维生长因子和血管内皮生长因子浓度分别为(470.625±2.546),(4.121±0.026)和(0.172±0.002) ng/L。在培养第1-7天,10%和15%人羊膜匀浆上清液组的增殖率大于20%和25%人羊膜匀浆上清液组(P < 0.05);10%、15%人羊膜匀浆上清液组显示出促进细胞增殖的作用,而20%、25%人羊膜匀浆上清液组显示出抑制细胞增殖的作用;各实验组的细胞活力与对照组接近(P > 0.05)。提示人羊膜匀浆上清液低浓度时(10%和15%)具有促进RSC96增殖作用,高浓度时(20%和25%)抑制RSC96增殖。 中国组织工程研究杂志出版内容重点：组织构建;骨细胞;软骨细胞;细胞培养;成纤维细胞;血管内皮细胞;骨质疏松;组织工程全文链接：     

用于组织工程构建的表皮角质形成细胞的生物学特性

目的　研究体外培养的人表皮角质形成细胞的生物学特性 ,为构建组织工程皮肤提供技术参数。方法　用Dispase/胰蛋白酶法消化分离人表皮角质形成细胞 ,进行原代及传代培养。计算原代细胞获得率 ,观察各代细胞形态学改变 ,描记细胞生长曲线 ,计算群体倍增时间 (PDT) ,免疫组织化学方法检测细胞角蛋白表达。结果　原代表皮角质形成细胞获得率为 ( 0 .72 6± 0 .3 48)× 10 6 /cm2 ,表皮角质形成细胞体外可培养至第 7代 ,第 2代的PDT最短 ,为( 46.5 7± 2 .2 5 )h ,第 4代的细胞角蛋白表达仍为阳性。结论　综合细胞增殖速率、细胞数量及细胞功能的维持各因素 ,考虑第 3、4代的表皮角质形成细胞是构建组织工程皮肤最佳的种子细胞     

许旺细胞联合C5a受体拮抗剂移植脊髓损伤大鼠的电生理及后肢功能变化

背景：C5a通过增强脊髓损伤后早期炎症反应参与了脊髓损伤后的继发性损伤,C5a受体拮抗剂能有效阻断这一过程。 目的：观察许旺细胞移植联合C5a受体拮抗剂对脊髓损伤大鼠神经功能恢复的影响。 方法：Wistar大鼠80只建立脊髓损伤动物模型后随机分成4组。①空白对照组尾静脉注射培养液组+腹腔注射生理盐水。②细胞移植组尾静脉注射许旺细胞。③C5a受体拮抗剂组腹腔注入C5a受体拮抗剂。④联合组尾静脉注射许旺细胞,同时腹腔注入C5a受体拮抗剂。 结果与结论：下肢运动功能评价联合移植组优于细胞移植组和C5a受体拮抗剂组,细胞移植组和C5a受体拮抗剂组优于对照组。细胞移植组和联合组有SRY基因表达。HRP阳性神经纤维数：联合组>胞移植组与C5a受体拮抗剂组>空白对照组,且各组之间差异有显著性意义(P < 0.01)。联合组大鼠体感诱发电位及运动诱发电位的潜伏期、波幅明显优于其他3组(P < 0.05或P < 0.01)。提示许旺细胞移植和C5a受体拮抗剂联合应用可促进脊髓损伤大鼠神经突触的再生,改善其肢体运动功能和电生理功能。     

许旺细胞在不同孔径丝素蛋白支架上的生长

背景：细胞在生物支架上的生长行为受到支架表面形貌、润湿性、孔径及孔隙率等多种因素影响。 目的：观察许旺细胞在不同孔径丝素蛋白支架上的生长情况。 方法：制备大孔径50~60 µm、小孔径10~   20 µm两种多孔丝素材料。选用许旺细胞永生化细胞R3 [33-10ras3]为种子细胞,当细胞在培养瓶底形成致密单层时即可消化细胞并进行接种实验,将许旺细胞悬液种于不同形貌的多孔丝素材料表面。复合培养1周后,扫描电镜观察许旺细胞的生长形态及增殖等情况。 结果与结论：不同孔径丝素材料的表面可见许旺细胞生长情况不一。在10~20 µm孔径材料支架上,细胞浓度较低,细胞表现为特异的双极性形态,细胞与细胞之间或平行排列,或首尾相连成细胞链;细胞与细胞之间或平行排列,或首尾相连成细胞链;在50~ 60 µm孔径丝素材料支架上,细胞浓度较高,细胞多为球形,单个分散在多孔支架表面,或呈现成团成串葡萄样聚集在孔的底部,未延展成双极性形态,只有极少量生长在孔与孔之间嵴上的细胞呈双极样。说明多孔丝素蛋白支架的孔径对许旺细胞的黏附、生长有一定的影响,许旺细胞更适合生长在孔径略大于胞体直径的支架材料上。     

树突状细胞的生物学特性及临床应用

1 引言肿瘤的免疫治疗是目前肿瘤临床治疗的重要趋势，其中主动免疫的方法之一是通过注射抗原提呈细胞刺激淋巴细胞产生抗肿瘤效应。树突状细胞(Dendritic Cell, DC)被认为是最佳的抗原提呈细胞。树突状细胞在非淋巴组织内吞噬抗原物质，与MHC抗原结合，将抗原信息表达于细胞表面，通过血液或淋巴液迁徒至淋巴组织，激活初始淋巴细胞，产生免疫反应[1]。另一方面树突状细胞又具有免疫耐受功能，可用于控制免疫损伤反应。近些年，从骨髓或外周血体外诱导生成一定数量的树突状细胞供生物学研究乃至临床应用已成为现实[2，3]。树突状细胞生…     

成年大鼠雪旺细胞增殖和纯化研究

目的：探索成年大鼠雪旺细胞的体外培养和纯化方法。方法：取成年大鼠背根神经节采用植块法培养，坐骨神经采用酶消化法分散培养。各分三组，第一组为阿糖胞苷处理组；第二组为免疫溶解处理后加垂体浸出液组；第三组为对照组。以活细胞计数和S-100标记相结合判断雪旺细胞增殖和纯化程度。结果：采用植块培养法至第2周末，雪旺细胞纯度在第一、二和三组分别为90％、97％和50％。分散培养至第18天，雪旺细胞纯度第一组94％，第二组大于97％，第三组80％。细胞数量第一组增加1．4倍，第二组增加5．1倍，第三组增加2．4倍。结论：采用免疫溶解处理后加垂体浸出液方法培养成年大鼠来源的雪旺细胞，可得到数量多纯度高的雪旺细胞。     

联合应用神经生长因子和神经节苷脂1对坐骨神经损伤大鼠脊髓神经元的保护作用

目的：了解联合应用神经生长因子(NGF)和神经节苷脂1(GMl)对大鼠周围神经损伤后脊髓神经元的保护作用。方法：选用SD大鼠,分为生理盐水(NS)组、NGF组、GM1组和NGF GM1组,将大鼠坐骨神经造成5mm缺损,术中硅胶管内局部加药、术后大鼠损伤侧小腿肌注药物。术后定期光、电镜观察L4～I6脊髓前角神经元结构变化,测定损伤远段和近段神经传导速度。结果：脊髓运动神经元数目以及神经传导速度4周时,NGF组和GM1组均多于或快于NS组,NGF GM1组则多于或快于NS组、NGF组和GM1组,8周时NGF GM1组、NGF组、GM1组组间无显著性差异但均多于或快于NS组。结论：NGF GM1对周围神经损伤后脊髓运动神经元退变的保护作用与单用NGF或GM1相比,能更早期地发挥作用,并且效果优于单用NGF或GM1。     

长时间坐骨神经横断伤后远侧端雪旺氏细胞活性变化

目的:研究坐骨神经长时间损伤不同时间后远侧端雪旺氏细胞(Schwann cells,SCs)的活性变化。方法:根据坐骨神经横断时间,SD大鼠分4组:正常对照组(A组)、损伤1月组(B组)、损伤2月组(C组)和损伤3月组(D组)。取坐骨神经损伤远侧端和正常坐骨神经进行SCs培养;S-100免疫细胞化学染色等形态学观察细胞形态;应用CCK8试剂检测SCs活力;ELISA定量检测SCs分泌的神经生长因子(nerve growth factor,NGF);以神经元的突起长度为指标来检测各组SCs来源的条件培养液对运动神经元的营养作用。结果:坐骨神经损伤后,其远侧端SCs形态发生改变,其中B组最明显;B组SCs活力最强,C、D组与B组相比均明显下降(P<0.05);SCs分泌的NGF量随着损伤时间的延长而逐渐下降(P<0.05);B组SCs来源的条件培养基中生长的神经元突起长度最长,C、D组与B组相比均短(P<0.05)。结论:周围神经长时间损伤后远侧端SCs发生了形态的改变;其细胞活力,分泌NGF以及促进神经元突起生长方面的能力都发生下降,但并未完全随着损伤时间延长而进一步下降。     

体外培养的大鼠Schwann细胞神经生长因子和脑源性神经营养因子的表达

目的：研究体外培养的Schwann细胞神经生长因子(NGF)和脑源性神经营养因子(BDNF)的表达。方法：用细胞培养技术，培养新生SD大鼠Schwann细胞，传代后用ABC免疫细胞化学法检测Schwann细胞的NGF、BDNF反应。结果：体外培养的Schwann细胞立体感强、折光性好，细胞为梭形、椭圆形或三角形，NGF、BDNF免疫反应为阳性。结论：体外培养的Schwann细胞能表达NGF、BDNF。     

Saturated fatty acids activate the inflammatory signalling pathway in Schwann cells: Implication in sciatic nerve injury

Sciatic nerve injury affects quality of life. Many immune cells and inflammatory cytokines have been reported to be involved in sciatic nerve injury, but little is known about the ligands and receptors that trigger inflammatory responses. By using a modified sciatic nerve clamp injury method, we found that the recruitment of Schwann cells and the inflammatory response were enhanced after sciatic nerve injury. Toll-like receptor 4 (TLR4), one of the major members of the TLR family, is highly expressed in Schwann cells. Under certain conditions, myeloid differentiation protein 2 (MD2) binds to TLR4 on the membrane and plays important roles in the inflammatory response. The reductions in the recruitment of Schwann cells and the inflammatory response induced by the blockade of TLR4 or MD2 suggest that TLR4 and MD2 are involved in sciatic nerve injury. What are the endogenous signals that activate the inflammatory response? A large number of free saturated fatty acids (SFAs) are released from Schwann cells, adipocytes and the blood after sciatic nerve injury. Liang et al reported that Schwann cells can be stimulated by palmitic acid (PA). Here, we found that the expression and secretion of TNF-α and IL-6 were enhanced by PA treatment. Moreover, PA activated TLR4 signalling pathway-related proteins and stimulated a strong association between TLR4 and MD2. Blocking TLR4 or MD2 reversed the PA-induced inflammatory response and TLR4 downstream signalling pathway. Thus, we speculated that SFAs act as endogenous ligands that activate TLR4/MD2, thus triggering Schwann cell inflammation during sciatic nerve injury.     

脱细胞异种神经桥接体联合经血源性间充质干细胞对大鼠坐骨神经缺损的影响

目的:研究脱细胞异种神经桥接体(ANX)联合经血源性间充质干细胞(MenSCs)对大鼠坐骨神经缺损的影响。方法:将SD大鼠随机分为自体移植组、单纯ANX组和ANX+MenSCs共培养组,制备SD大鼠右侧坐骨神经缺损模型,将不同组的桥接体移植到SD大鼠右侧坐骨神经缺损处,移植术后8周,用热板实验检测大鼠感觉功能的恢复,斜坡实验来检测运动功能的恢复,通过坐骨神经功能指数(SFI)检测大鼠坐骨神经功能,通过胫骨前肌湿重比率检测神经肌肉的功能,用透射电镜来观察髓鞘的恢复情况。结果:扫描电镜显示ANX组内原有的细胞及结构基本去除,完整保留了神经的基膜及外膜,ANX+MenSCs组可见圆形的细胞在基膜间稳定黏附生长;免疫荧光染色显示神经生长因子(NGF)在ANX+MenSCs共培养组中有阳性表达;移植术后8周,ANX+MenSCs组的患肢回缩时间显著短于单纯ANX组(P<0.05),爬坡坡度、SFI值以及胫骨前肌湿重比率均显著高于单纯ANX组(P<0.05),ANX+MenSCs组与自体组相比,两组的患肢回缩时间、爬坡坡度以及胫骨前肌湿重比均无显著差异(P>0.05),但自体组的SFI值显著增高(P<0.05);透射电镜显示与单纯ANX组相比,ANX+MenSCs组和自体组的髓鞘结构更完整,虽有水肿,但形状小而均匀致密。结论:ANX联合MenSCs修复SD大鼠坐骨神经缺损的效果良好,MenSCs可能成为外周神经系统疾病细胞治疗的潜在候选种子细胞。     

重组水蛭素对大鼠坐骨神经损伤后神经功能的影响及可能机制

目的探讨重组水蛭素对大鼠坐骨神经损伤后神经功能的影响及对坐骨神经微管相关蛋白-2(MAP-2)、神经丝蛋白(NF-M)与生长相关蛋白43(GAP-43)蛋白表达的影响。方法 60只SD大鼠,雌雄不限,随机分为随机分为假手术组、实验组与重组水蛭素处理组。通过钳夹大鼠坐骨神经制备周围神经损伤大鼠模型,对各组大鼠进行坐骨神经指数与小腿三头肌湿重比测定,western blot方法检测坐骨神经MAP-2、NF-M与GAP-43的表达,Real time-PCR方法检测坐骨神经MAP-2 mRNA、NF-M mRNA与GAP-43 mRNA的表达水平。结果给予重组水蛭素处理后,坐骨神经损伤大鼠的坐骨神经指数明显升高,小腿三头肌湿重比减小(P<0.05);坐骨神经MAP-2、NF-M与GAP-43蛋白与mRNA的表达升高(P<0.05)。结论重组水蛭素能促进周围神经损伤后再生和功能恢复,其机制可能与上调MAP-2、NF-M与GAP-43表达相关。     

miR-21在周围神经损伤时调控雪旺细胞凋亡

目的:探讨周围神经损伤时,微小RNA-21(microRNA-21,miR-21)与雪旺细胞(SC)凋亡的关系及相关分子机制。方法:采用实时荧光定量PCR(real-time PCR)检测动物模型中miR-21以及人第10号染色体缺失的磷酸酶及张力蛋白同源基因(phosphatase and tensin homologue deleted on chromosome 10,PTEN)的表达情况;通过将miR-21类似物(miR-21-mimic)、miR-21抑制物(miR-21-inhibitor)和阴性对照miRNA(negative control miRNA,NC-miRNA)转染入RSC96细胞中,构建出过表达miR-21的雪旺细胞株(MI-SC)、抑制miR-21表达的雪旺细胞株(IN-SC)及表达对照miRNA的雪旺细胞株(NC-SC);采用流式细胞仪检测3组细胞的凋亡情况;real-time PCR检测3组细胞中miR-21以及PTEN的表达情况;Western blot检测3组细胞中PTEN及凋亡相关蛋白激活型caspase-3(cleaved caspase-3)的表达情况。结果:神经损伤组miR-21的表达量与对照组相比明显升高,神经损伤组PTEN mRNA的表达水平与对照组相比明显降低;与NC-SC相比,上调miR-21组细胞的凋亡比例减少,PTEN mRNA及蛋白的表达水平降低,cleaved caspase-3的表达水平降低,下调miR-21组细胞的凋亡比例增加,PTEN mRNA及蛋白的表达水平升高,cleaved caspase-3的表达水平升高(P0.05)。结论:miR-21可能通过下调PTEN的表达抑制雪旺细胞的凋亡,从而可能在周围神经的损伤修复中发挥作用。     

Non-myelin-forming Schwann cells proliferate rapidly during Wallerian degeneration in the rat sciatic nerve

Summary Transection of a mixed peripheral nerve results in the degeneration of axons and breakdown of myelin in the distal stump. These events are accompanied by a sharp but transient Schwann cell proliferation. The present study seeks to determine whether both myelin-forming and non-myelin-forming Schwann cells enter a proliferative phase under these conditions, or whether the dividing cells are chiefly recruited from one or other of the Schwann cell populations. The macrophage recruitment into the transected distal stumps has also been timed and quantitated, since it has been suggested that macrophages are an important source of Schwann cell mitogens in degenerating peripheral nerves.Incorporation of [³H]-thymidine and autoradiography was used as a measure of cell proliferation, and cell type markers and immunohistochemistry were used to identify myelin-forming and non-myelin-forming Schwann cells. The cells were removed from the distal stump of the rat sciatic nerve and sympathetic trunk at various times after transection and proliferation measured during the first 24 h in culture. It was found that in the sciatic nerve, which contains a mixture of myelinated and unmyelinated fibres, both myelin-forming cells, identified by presence of the myelin protein P_o, and non-myelin-forming cells (P_o ^– cells) showed a substantial elevation in [³H]-thymidine labelling index at day 2 postoperatively, which was similar in magnitude for the two categories of cell. The proliferation rate of both P_o ⁺ and P_o ^– cells remained elevated for up to 8 days after transection. In the largely unmyelinated sympathetic trunk, the peak rate of P_o ^– Schwann cell division reached less than half the peak rate for P_o ^– cells in the sciatic nerve, and cell division fell to a level barely above the control value by postoperative day 4. In the sciatic nerve the number of macrophages, which were identified by monoclonal antibody ED1, rose sharply during the first postoperative day and peaked at day 2.These results provide strong evidence that non-myelin-forming and myelin-forming Schwann cells contribute approximately equally to the initial burst of Schwann cell proliferation seen in the distal stump of the transected rat sciatic nerve. They also indicate that the proliferative response of non-myelin-forming cells is substantially greater in nerves containing many myelinated fibres than in essentially unmyelinated nerves. The timing of macrophage recruitment in the sciatic nerve is consistent with the hypothesis that macrophages are an important source of Schwann cell mitogens during nerve degeneration.     

MicroRNA-21促进大鼠雪旺细胞增殖的实验研究

目的:探讨神经损伤后microRNA-21(miR-21)促进雪旺细胞增殖的分子机制。方法:通过实时荧光定量PCR检测miR-21的表达。通过脂质体介导将人工合成的miR-21模拟物(mimic)及其阴性对照转染大鼠雪旺细胞,CCK-8法检测转染miR-21的雪旺细胞的增殖。流式细胞术分析miR-21对雪旺细胞细胞周期的影响。使用Western blotting实验分析转化生长因子β诱导蛋白(TGFBI)和cyclin D1的表达水平。结果:miR-21在损伤模型组中的表达分别为假手术组和正常神经组织的(7.87±0.75)和(7.75±0.80)倍(P0.01)。miR-21 mimic组miR-21的表达分别为对照组和空白组的(2.21±0.14)和(2.29±0.21)倍(P0.05)。转染48 h后miR-21 mimic组CCK-8实验的A450值较阴性对照组和空白对照组增高(P0.05)。实验组细胞增殖指数高于阴性对照组和空白对照组(P0.01)。同时与对照组相比,转染miR-21后48 h实验组细胞TGFBI明显降低,cyclin D1表达增多(P0.05)。结论:miR-21可促进雪旺细胞增殖,其机制可能与其下调TGFBI的表达有关。