Effects of aminoguanidine on nitric oxide production induced by inflammatory cytokines and endotoxin in cultured rat hepatocytes

AIM: To study the effects of aminoguanidine (AG) and two L-arginine analogues N(omega)-nitro-L-arginine methyl ester (L-NAME) and N(omega)-nitro-L-arginine (L-NNA) on nitric oxide (NO) production induced by cytokines (TNF-alpha, IL-1 beta, and IFN-gamma) and bacterial lipopolysaccharide (LPS) mixture (CM) in the cultured rat hepatocytes, and examine their mechanisms action. METHODS: Rat hepatocytes were incubated with AG, L-NAME, L-NNA, Actinomycin D (ActD) and dexamethasone in a medium containing CM (LPS plus TNF-alpha, IL-1 beta, and IFN-gamma) for 24h. NO production in the cultured supernatant was measured with the Griess reaction. Intracellular cGMP level was detected with radioimmunoassy. RESULTS: NO production was markedly blocked by AG and L-NAME in a dose-dependent manner under inflammatory stimuli condition triggered by CM in vitro. The rate of the maximum inhibitory effects of L-NAME (38.9%) was less potent than that obtained with AG(53.7%, P 【 0.05). There was no significant difference between the inhibitory effects of AG and two L-arginine analogues on intracellular cGMP accumulation in rat cultured hepatocytes. Non-specific NOS expression inhibitor dexamethasone (DEX)and iNOS mRNA transcriptional inhibitor ActD also significantly inhibited CM-induced NO production. AG(0.1 mmol x L(-1)) and ActD (0.2 ng x L(-1)) were equipotent in decreasing NO production induced by inflammatory stimuli in vitro, and both effects were more potent than that induced by non-selectivity NOS activity inhibitor L-NAME (0.1 mmol x L(-1)) under similar stimuli conditions (P【0.01). CONCLUSION: AG is a potent selective inhibitor of inducible isoform of NOS,and the mechanism of action may be not only competitive inhibition in the substrate level, but also the gene expression level in rat hepatocytes.

Transplantation of human hepatocytes into tolerized genetically immunocompetent rats

AIM: To determine whether normal genetically immunocompetent rodent hosts could be manipulated to accept human hepatocyte transplants with long term survival without immunosuppression. METHODS: Tolerance towards human hepatocytes was established by injection of primary human hepatocytes or Huh7 human hepatoma cells into the peritoneal cavities of fetal rats. Corresponding cells were subsequently transplanted into newborn rats via intrasplenic injection within 24h after birth. RESULTS: Mixed lymphocyte assays showed that spleen cells from non-tolerized rats were stimulated to proliferate when exposed to human hepatocytes, while cells from tolerized rats were not. Injections made between 15 d and 17 d of gestation produced optimal tolerization. Transplanted human hepatocytes in rat livers were visualized by immunohistochemical staining of human albumin. By dot blotting of genomic DNA in livers of tolerized rats 16 weeks after hepatocyte transplantation, it was found that approximately 2.5 X 10(5) human hepatocytes survived per rat liver. Human albumin mRNA was detected in rat livers by RT-PCR for 15 wk, and human albumin protein was also detectable in rat serum. CONCLUSION: Tolerization of an immuno-competent rat can permit transplantation, and survival of functional human hepatocytes.

Effects of hypoxia,hyperoxia on the regulation of expression and activity of matrix metalloproteinase-2 in hepatic stellate cells

AIM: To study the effects of hypoxia, hyperoxia on the regulation of expression and activity of matrix metalloproteinase-2 (MMP-2) in hepatic stellate cells (HSC). METHODS: The expressions of MMP-2, tissue inhibitor of matrix metalloproteinase-2 (TIMP-2) and membrane type matrix metalloproteinase-1 (MT1-MMP) in cultured rat HSC were detected by immunocytochemistry (ICC) and in situ hybridization (ISH). The contents of MMP-2 and TIMP-2 in culture supernatant were detected with ELISA and the activity of MMP-2 in supernatant was revealed by zymography. RESULTS: In the situation of hypoxia for 12h, the expression of MMP-2 protein was enhanced (hypoxia group positive indexes: 5.7 +/- 2.0, n=10; control: 3.2 +/- 1.0, n = 7; P【0.05), while TIMP-2 protein was decreased in HSC (hypoxia group positive indexes: 2.5 +/- 0.7, n = 10; control: 3.6 +/- 1.0, n = 7; P 【 0.05), and the activity (total A) of MMP-2 in supernatant declined obviously (hypoxia group: 7.334 +/- 1.922, n = 9; control: 17.277 +/- 7.424, n = 11; P 【 0.01). Compared the varied duration of hypoxia, the changes of expressions including mRNA and protein level as well as activity of MMP-2 were most notable in 6h group. The highest value(A(hypoxia)-A(control)) of the protein and the most intense signal of mRNA were in the period of hypoxia for 6h, along with the lowest activity of MMP-2. In the situation of hyperoxia for 12h, the contents (A(450)) of MMP-2 and TIMP-2 in supernatant were both higher than those in the control, especially the TIMP-2 (hyperoxia group: 0.0499 +/- 0.0144, n = 16; control: 0.0219 +/- 0.0098, n = 14; P 【 0.01), and so was the activity of MMP-2 (hyperoxia group: 5.252 +/- 0.771, n = 14; control: 4.304 +/- 1.083, n = 12; P 【 0.05), and the expression of MT1-MMP was increased. CONCLUSION: HSC is sensitive to the oxygen, hypoxia enhances the expression of MMP-2 and the effect is more marked at the early stage; hyperoxia mainly raises the activity of MMP-2.

Establishment and characterization of a rat pancreatic stellate cell line by spontaneous immortalization

AIM: Activated pancreatic stellate cells (PSCs) have been implicated in the pathogenesis of pancreatic fibrosis and inflammation. Primary PSCs can be subcultured only several times because of their limited growth potential. A continuous cell line may therefore be valuable in studying molecular mechanisms of these pancreatic disorders. The aim of this study was to establish a cell line of rat PSCs by spontaneous immortalization.METHODS: PSCs were isolated from the pancreas of male Wistar rats, and conventional subcultivation was performed repeatedly. Telomerase activity was measured using the telomere repeat amplification protocol. Activation of transcription factors was assessed by electrophoretic mobility shift assay.Activation of mitogen-activated protein (MAP) kinases was examined by Western blotting using anti-phosphospecific antibodies. Expression of cytokine-induced neutrophil chemoattractant-1 was determined by enzyme immunoassay.RESULTS: Conventional subcultivation yielded actively growing cells. One clone was obtained after limiting dilution,and designated as SIPS. This cell line has been passaged repeatedly more than 2 years, and is thus likely immortalized.SIPS cells retained morphological characteristics of primary,culture-activated PSCs. SIPS expressed α-smooth muscle actin, glial acidic fibrillary protein, vimentin, desmin, type Ⅰ collagen, fibronectin, and prolyl hydroxylases. Telomerase activity and p53 expression were negative. Proliferation of SIPS cells was serum-dependent, and stimulated with platelet-derived growth factor-BB through the activation of extracellular signal-regulated kinase. Interleukin-1β activated nuclear factor-κB, activator protein-1, and MAP kinases.Interleukin-1β induced cytokine-induced neutrophil chemoattractant-1 expression through the activation of nuclear factor-κB and MAP kinases.CONCLUSION: SIPS cells can be useful for in vitro studies of cell biology and signal transduction of PSCs.

Influencing factors of rat small intestinal epithelial cell cultivation and effects of radiation on cell proliferation

INTRODUCTIONCrypt epithelial cells in normal small intestineproliferate at a high speed. But they are verydifficult to culture in vitro and passage stably. A lotof studies have been done[1-16]. Some domestic labsisolated and cultured crypt cells from embryonalintestines and aseptic animal intestine, but failed.We introduced normal rat epithelial cell line-IEC-6from the USA and its living condition for stablepassage was successfully established after trials. Thecell line was testified to be the small intestinalepithelial cell by electron microscopy,immunihistochemistry and enzymatic histoch-emistry. It has been applied to some relatedresearch work[17-21]. It was found that manyfactors were involved in the culture system. Ourpresent study focuses on the culture method and theinfluencing factors on IEC-6.

大鼠肝细胞的原代培养及鉴定

目的:探讨大鼠肝细胞原代培养的方法及细胞的鉴定。方法:采用胶原酶消化获取大鼠肝细胞进行纯化、培养,并采用免疫组织化学方法对其进行鉴定。结果:培养的肝细胞产量高、活力好,用相差显微镜对不同生长时期的肝细胞进行观察证实了细胞贴壁后变平变薄,双核细胞和多核细胞呈岛状连接的形态学特性,采用抗大鼠细胞角蛋白(ck18)的特异抗体进行免疫组化细胞爬片鉴定,经SP染色DAB显色后,阳性着色部位在胞浆呈棕黄色颗粒,阴性对照未见着色。结论:成功地体外培养了大鼠肝细胞并对其进行了鉴定,为进一步的实验研究奠定了基础。

SD大鼠骨髓间充质干细胞体外培养、表型鉴定及标记

目的:探讨SD大鼠骨髓间充质干细胞(MSCs)体外分离培养、表型鉴定和标记的方法,为进一步研究MSCs干预器官移植的免疫排斥奠定基础。方法:采用直接贴壁法分离培养MSCs;通过流式细胞术检测细胞表面标志抗原CD90、CD45的表达率对培养的MSCs进行表型鉴定;DAPI标记第3代MSCs,观察标记效率。结果:体外培养的原代MSCs48h内可见有少量贴壁细胞,7～10d达到90%汇合;流式细胞术检测,第3代MSCs表面标记物CD90、CD45的阳性率分别为99.8%、6.8%,提示MSCs表达CD90而不表达CD45;用DAPI进行细胞标记后,荧光显微镜下见所有MSCs均已被标记蓝色荧光,提示DAPI标记法敏感性好,标记效率高。结论:贴壁培养法是一种简便易行的培养MSCs方法,操作简单,成功率高,可以作为培养SD大鼠MSCs的常规方法;DAPI标记可作为标记MSCs的一种有效手段。

大鼠嗅球神经干细胞培养

目的 建立大鼠嗅球神经干细胞 (neuralstemcells,NSC)体外培养方法 ,研究其增殖和分化特性。方法 采用添加丝裂原的无血清培养基分离、培养新生第 1天和成年大鼠嗅球NSC ,应用免疫细胞化学方法鉴定培养的NSC及自然分化为特异性神经细胞的类型 ,四甲基偶氮唑盐 (MTT)法测定嗅球NSC的生长曲线。结果 从生后第 1天和成年大鼠嗅球分离、培养出表达巢蛋白(nestin) ,并能分化为神经元、星形胶质细胞和少突胶质细胞的NSC。生后第 1天和成年大鼠嗅球的神经球形成率分别为 2 0 %～ 30 %和 0 1%。嗅球NSC的增殖依赖表皮生长因子 (epidermalgrowthfactor,EGF)和碱性成纤维细胞生长因子 (fibroblastgrowthfactor basic,bFGF) ,其中EGF的促分裂增殖作用明显优于bFGF。结论 从生后第 1天和成年大鼠嗅球可以培养出具有自我增殖和多向分化潜能的NSC。

植块法与酶消化法结合培养原代大鼠雪旺细胞

目的:探讨利用植块法与酶消化法相结合培养大鼠原代雪旺细胞的可行性,并研究其增殖规律。方法:取10只新生2～3d的SD大鼠双侧坐骨神经,剥除神经外膜,剪成约1mm3大小的碎块,用0.03%胶原酶和0.25%胰蛋白酶按1∶2对神经碎块消化12min,加入少量含10%胎牛血清的DMED培养基小心吹打细胞及组织块,再植于培养皿中培养。用S-100免疫组化染色鉴定雪旺细胞,结合Hoechst3342染色计算其纯度,在显微镜下确定细胞数量。结果:在植块培养24h后即有大量细胞迁出,2～6d细胞生长迅速,10d以后生长较为缓慢,其倍增时间为2.3d。经S-100染色证实所培养细胞为雪旺细胞,结合Hoechst3342染色可得其培养8d时纯度为95.1%,传代后纯度可达96.3%。10只新生鼠培养12d后可得细胞数约为4.8×106个。结论:利用植块法与酶消化法相结合的方法可以迅速获得大量高纯度的雪旺细胞,其增殖速度在前6d最快,倍增时间为2.3d。

新生大鼠心肌细胞的原代培养

目的:探讨新生大鼠心肌细胞的分离和培养方法。方法:应用0.0625%的胰蛋白酶重复消化出生第2 d乳鼠的心肌组织多次,收集的细胞用含10%胎牛血清的DMEM培养基中和,用差速贴壁分离法分离,在以溴脱氧尿嘧啶(Brdu)纯化心肌细胞后置CO2培养箱孵育7 d。结果:分离1只乳鼠获得的心肌细胞产量约为140万个,且有活力心肌细胞占90%以上;培养4～6h的乳鼠心肌细胞开始贴壁生长,12～24h明显增殖,3～4 d后细胞融合成片;心肌细胞由圆形变为梭形、星形、多角形,并出现自发性节律性搏动。结论:本研究应用的心肌细胞原代培养方法可获得高产量、高活力的心肌细胞,是一种可靠的心肌细胞培养方法。

大鼠脂肪干细胞体外定向诱导分化为脂肪细胞和成骨细胞的研究

目的研究大鼠脂肪干细胞的基本生物学特性及其向脂肪细胞和成骨细胞诱导分化潜能。方法取6周龄SD大鼠腹股沟处脂肪组织,胶原酶消化法分离出脂肪干细胞,体外培养。取第3代细胞,免疫细胞化学测定其CD44、CD34抗原表达,分别用成脂和成骨诱导培养液诱导其向脂肪细胞及成骨细胞分化。油红染色、碱性磷酸酶染色和vonKossa染色鉴定其分化能力。结果大鼠脂肪干细胞生长能力旺盛,表达CD44,而不表达CD34;定向诱导后,油红染色、碱性磷酸酶染色和vonKossa染色阳性。结论大鼠脂肪组织可分离培养出脂肪干细胞,能向脂肪细胞和成骨细胞诱导分化,有可能成为组织工程理想的种子细胞来源之一。

大鼠剑突软骨细胞的体外分离与培养

目的探讨大鼠剑突软骨细胞的培养方法，以及多聚2一羟乙基甲基丙烯酸脂（poly-2-hydroxyethylmethacrylate，poly-HEMA）在培养过程中对软骨细胞生物学特性的影响。方法无菌条件下取Wistar大鼠的剑突。用剪刀将其剪成1mm。大小，加入0．25o．4的胰酶消化30min，然后用0．15％的胶原Ⅱ消化3～5h。将分离得到的细胞分别接种在预先用poly-HEMA包被的平皿和普通的平皿内，并将普通平皿的细胞进行差速贴壁。通过形态学及甲苯胺蓝染色对细胞进行鉴定。结果①从剑突软骨可获得大量软骨细胞，每克软骨可获得软骨细胞（3．1±0．5）×10^7个细胞，活性率为（95．2±0．3）％。②在普通平皿内经过两次差速贴壁得到的软骨细胞较纯，甲苯胺蓝染色阳性率达90％。③软骨细胞在poly-HEMA包被的平皿内始终悬浮生长，且能长期保持软骨细胞的特性。结论从剑突获得大量软骨细胞的方法是可行的，poly-HEMA能使体外培养的软骨细胞未经传代的情况下长期保持其生物学特性，为体外实验及组织工程研究提供优质种子细胞。

糖尿病视网膜Mǖller细胞病理改变的体内外研究

目的研究糖尿病视网膜M櫣ller细胞的病理改变。方法用链脲菌素(STZ)腹腔注射建立大鼠糖尿病模型,3个月后观察视网膜M櫣ller细胞超微结构的变化。行免疫组织化学染色,在激光共聚焦显微镜下观察视网膜M櫣ller细胞GFAP、VEGF表达的改变;纯化培养出生5～7d(SD)乳鼠的M櫣ller细胞,在其中加入糖基化终末产物(AGEs)2500μg/mL,培养24h后,用MTT方法检测细胞活性。结果3个月后电镜观察发现糖尿病鼠视网膜M櫣ller细胞突起有损伤表现,微血管内皮细胞、周细胞未见病理改变;正常鼠视网膜VEGF染色阴性,视网膜内界膜下、神经节细胞层有GFAP染色;糖尿病鼠除视网膜内界膜下、神经节细胞层有GFAP染色外,其余各层也可见丝条状贯穿于内外界膜之间的GFAP染色,在上述部位有VEGF及GFAP的共表达。培养24h后,2500μg/mL质量浓度的AGEs对M櫣ller细胞活性有显著促进作用。结论反应性胶质化增生可能是糖尿病早期M櫣ller细胞的主要病理改变,它所引起的M櫣ller细胞结构和功能改变应在糖尿病视网膜病变(DR)的发生发展中起重要作用。AGEs可能是DR中视网膜M櫣ller细胞反应性胶质化增生的重要致病因素。

鼠尾胶原为底物的人鼻腔纤毛上皮细胞培养模式的建立

目的建立以鼠尾胶原为贴附底物的人鼻腔纤毛上皮细胞的体外培养模式,为人鼻腔黏液纤毛运输系统的研究提供科学有效的方法。方法制备鼠尾胶原并铺片,以鼠尾胶原为贴附底物组织块培养法培养人鼻腔纤毛上皮细胞,培养7天时进行HE染色及扫描电镜和透射电镜观察细胞形态和结构,应用高速摄像技术测量纤毛摆动频率。结果鼠尾胶原要平坦均匀,平均厚度约为1mm;HE染色可见上皮细胞呈单层向周围爬开;扫描电镜下见纤毛上皮细胞呈不规则多角形,纤毛周围可见微绒毛;透射电镜下可见纤毛上皮细胞间为紧密连接;同一细胞任意两点纤毛摆动频率是相同的;同一来源体外培养的钩突和下鼻甲的纤毛摆动频率是相同的。结论以鼠尾胶原为贴附底物人鼻腔纤毛上皮细胞的体外培养模式的成功建立,为今后研究鼻内用药对纤毛清除功能的影响提供了良好的方法和途径。

高原现场大鼠肝细胞的体外长期培养

[目的]在高原环境条件下初步建立体外肝细胞长期培养的一种方法。[方法]将体外分离的大鼠肝细胞以3×105/孔接种于用胶原包被的12孔塑料培养板内,总体培养时间为30 d,动态观察培养细胞形态、细胞数量及培养上清中总蛋白、白蛋白和尿素水平变化。[结果]细胞接种4 h开始贴壁,8 h开始增殖,6 d生长满瓶,形成均匀的单层;4 d细胞数量明显增多,8 d最多,达35.2×105/孔,然后细胞数量渐减少;14 d培养细胞胞浆内开始出现颗粒状物质和空泡,20 d培养细胞开始出现细胞脱壁现象,培养液中漂浮细胞增多;培养上清中总蛋白、白蛋白和尿素水平均呈现显著升高,其达峰值时间分别为10、8和10 d,然后渐降低,培养结束时仍然高于培养2 d时的水平。[结论]在高原环境条件下,体外长期培养肝细胞生长、增殖及其生物学功能良好,可以应用于高原肝脏生理及病理生理等相关方面的研究。

大鼠关节软骨细胞的培养

目的探讨大鼠关节软骨细胞培养方法。方法采用胶原酶NB4消化法从1周龄SD大鼠的关节软骨中分离出软骨细胞并进行原代和传代培养,每日在倒置显微镜下观察细胞形态及其生长情况,并用HE、甲苯胺蓝染色和Ⅱ型胶原免疫组织化学染色进行鉴定。结果软骨细胞形成单层的时间在原代培养1周左右,5d左右即可传代。第5代后部分变为梭形,第7代后绝大部分变为长梭形,增殖能力减弱。结论采用此法可在短时间内获得大量纯化的大鼠软骨细胞。

新生大鼠成骨细胞原代培养与鉴定

背景:组织工程需要大量的种子细胞,成骨细胞是骨组织工程的重要种子细胞之一。但是成骨细胞培养难度大,不同培养方法得到的成骨细胞数量、纯度、增殖及分化活性各有区别。目的:验证及比较成骨细胞原代培养常用的3种方法,探索一种操作简便,既经济又高效的原代培养成骨细胞的方法,为进一步的实验研究奠定基础。方法:取新出生72 h内SD大鼠乳鼠颅骨,以胶原酶消化法、分段胶原酶消化法及组织块法分离成骨细胞,进行细胞形态观察、细胞化学染色、CCK-8法绘制生长曲线及锥虫蓝排斥法计数活细胞率。结果与结论:分离培养的成骨细胞增殖良好,具备典型成骨细胞特性,细胞化学染色结果明显。胶原酶消化法比分段胶原酶消化法提取的成骨细胞数量多,细胞存活率高(P<0.05);且比分段胶原酶消化法操作简单,耗时短。组织块法操作最为简单,对细胞损伤较小,但是细胞数量低、耗时长,很难用于大规模成骨细胞培养。胶原酶消化法是一种方便、高效、理想的原代成骨细胞分离培养方法。

大鼠肾小球系膜细胞原代培养与鉴定

目的:原代培养及鉴定大鼠肾小球系膜细胞(GMC),探索分离、培养GMC的最佳条件。方法:对大鼠双肾灌洗后,筛网滤过分离肾小球,并用Ⅳ型胶原酶消化处理,然后种植法体外培养大鼠肾小球。同时采用免疫细胞化学和免疫荧光技术,检测亚代GMC的α-平滑肌肌动蛋白(α-SMA)、波形蛋白(V im entin)、细胞角蛋白(Cytokeratin)、Ⅷ因子相关抗原抗体的表达,鉴定GMC,并绘制其生长曲线。结果:种植4 d后,约80%肾小球贴壁,可见卵圆形上皮细胞生长,18 d左右镜下细胞多呈星状或三角形并伴有不规则的突起,21 d后细胞生长密集,细胞团簇之间形成网络。免疫细胞化学和免疫荧光证实抗α-SMA及抗V im entin染色阳性,而抗Cytokera-tin、抗Ⅷ因子抗体染色为阴性。GMC亚代倍增时间为4 d。结论:结果表明,用改良的培养方法成功率高,培养的细胞为大鼠肾小球系膜细胞。

大鼠前脂肪细胞的原代培养分化

目的 建立一种简便的大鼠前脂肪细胞的原代培养方法.方法 无菌取成年Wistar大鼠的腹股沟纯脂肪颗粒,采用酶消化法进行原代培养.在倒置显微镜下观察细胞形态及生长情况,以油红O脂肪染色法进行原代培养细胞的鉴定.结果 培养细胞的形态学观察显示,脂肪细胞贴壁后初为类圆形,3 d后渐成梭形;7～8 d细胞增殖明显,形状由多角梭形变为椭圆形,并开始积聚脂肪颗粒;10 d后细胞呈椭圆形、圆形,胞内积聚大量脂肪颗粒.培养10 d的细胞经油红O染色后于普通光镜下观察,见细胞内出现红染颗粒,可以鉴定细胞分化为前脂肪细胞.结论 成功建立了大鼠前脂肪细胞的原代培养方法,为脂肪内分泌学研究提供了制备适用细胞模型的手段.

牛胎盘中肝细胞生长因子的生物学特性

实验研究来源于牛胎盘的肝细胞生长因子的生物学特性。将新鲜牛胎盘匀浆后经盐析、亲和层析、超滤和离子交换层析可以纯化到一种肝细胞生长因子。实验采用３Ｈ－ＴｄＲ掺入细胞ＤＮＡ的量来表示肝细胞生长因子促进细胞ＤＮＡ合成的作用，用液体闪烁计数来探测３Ｈ的放射性。结果表明：该因子对原代培养的大鼠肝细胞、肾细胞的ＤＮＡ合成都有刺激作用，而且也能刺激原代培养的人胎肝细胞的ＤＮＡ合成。但对传代培养的小鼠腹水Ｓ１８０细胞的ＤＮＡ合成则有抑制作用。另外，此因子对热不稳定，经热处理之后，其对大鼠肝细胞的刺激作用和对小鼠腹水Ｓ１８０细胞的抑制作用都降低了。