胰岛素瘤动物模型的建立及特性研究

 目的：建立胰岛素瘤的动物模型并分析其特性,为胰岛素瘤的深入研究奠定实验基础。方法：首先检测体外培养的大鼠胰岛素瘤细胞株INS-1的激素释放能力,然后将INS-1细胞移植到裸鼠左肾包膜下,或在移植后18 d或在移植前3 d联合腹腔注射链脲佐菌素(STZ)破坏动物自身胰岛。尾静脉采血检测血糖,当血糖＜2.8 mmol/L认为胰岛素瘤模型建立。对各种条件建立的模型,观察给予不同刺激物对血糖的影响以及动物血清中胰岛素含量;并对动物胰腺组织和移植细胞的肾脏组织标本进行免疫组化染色检测胰岛素和胰高血糖素。结果：胰岛素瘤细胞既表达胰岛素,同时也表达胰高血糖素。裸鼠接种INS-1细胞后3~4周血糖＜2.8 mmol/L;移植肾脏明显增大,形成明显肿瘤,直径≥1 cm。细胞移植后腹腔注射STZ的动物,血糖短暂回升,超过正常血糖水平,之后又逐渐下降,约2周后血糖＜2.8 mmol/L。正常裸鼠给予STZ后血糖明显升高,移植INS-1细胞后动物血糖逐渐下降,约4周后血糖降至2.8 mmol/L。与正常对照组相比,3种方法建立的胰岛素瘤模型给予高糖后,动物血糖峰值低。高糖加精氨酸或乙酰胆碱刺激后,正常动物血糖峰值较单纯高糖刺激降低,并较快降至正常水平,但3种胰岛素瘤模型组血糖升高均明显超过单纯高糖刺激者。高糖加去甲肾上腺素刺激后,正常动物血糖达到峰值时间延迟,血糖水平下降缓慢,3种胰岛素瘤模型组血糖较单纯高糖刺激组有所升高。与正常对照组相比,3种胰岛素瘤模型血浆基础胰岛素的水平明显升高。结论：通过给裸鼠肾包膜下移植INS-1细胞,可建立胰岛素瘤动物模型,且瘤细胞同时表达胰岛素和胰高血糖素,不易被STZ破坏。该模型为进一步探讨胰岛素瘤的发病机制奠定实验基础。     

人AAT基因在糖尿病细胞治疗中对β细胞的免疫保护作用

目的:建立稳定表达人α1-抗胰蛋白酶(hAAT)基因的NIT-hAAT细胞系,观察hAAT基因在糖尿病细胞治疗中对β细胞的免疫保护作用。方法:构建hAAT的真核表达载体,转染并筛选得到NIT-hAAT细胞系。将该细胞系移植到糖尿病模型小鼠左肾包膜下,通过检测不同移植组小鼠的血糖、血清胰岛素水平和生存期,观察不同移植细胞对糖尿病的治疗效果;RFPCR检测移植部位的hAAT表达情况以及对小鼠左肾进行石蜡切片和苏木素-伊红(HE)染色,鉴定hAAT对NIT-1细胞的免疫保护作用。结果:糖尿病小鼠接受NIT-hAAT细胞移植后,hAAT可有效延长NIT-1细胞的存活时间,使血糖明显降低并维持至正常血糖水平,小鼠的生存率也明显提高(P<0.05);移植部位的病理HE染色结果证实hAAT可明显减轻小鼠对移植物炎症反应。但RT-PCR结果显示hAAT在体内的表达量随时间增长而出现逐渐下降,NIT-hAAT细胞最终因免疫排斥反应而失去功能。结论:NIT-hAAT细胞具有明显抑制体内免疫排斥反应,可有效延长β细胞存活时间,对胰岛细胞移植具有免疫保护作用。     

胰岛淀粉样多肽对高糖刺激下INS-1细胞凋亡及其相关基因表达的影响

目的探讨高糖刺激下转染过表达人胰岛淀粉样多肽基因的大鼠胰岛素瘤细胞(INS-1)细胞凋亡的影响及其相关基因表达。方法应用酶联免疫吸附法(ELISA)检测高糖刺激后INS-1及转染人胰岛淀粉样多肽的INS-1细胞(h IAPP/INS-1)上清液的胰岛素水平;利用Hoechst33258染色检测细胞凋亡百分率;采用RTPCR方法检测高糖刺激培养后的Bcl2、Bax m RNA的水平。结果高糖刺激下,与未转染人胰岛淀粉样多肽INS-1细胞相比较,h IAPP/INS-1细胞胰岛素分泌功能显著下降,凋亡细胞比例明显增加,抗凋亡基因Bcl2 m RNA表达水平下调,促凋亡基因Bax m RNA表达水平上调,Bcl2/Bax比例明显降低。结论人胰岛淀粉样多肽上调促凋亡基因表达和抑制抗凋亡基因表达可能与糖尿病的发生发展相关。     

移植途径对人脐带间充质干细胞治疗小鼠糖尿病效果的影响

目的:观察不同途径移植人脐带间充质干细胞(hUCMSCs)对小鼠糖尿病的治疗效果。方法:利用增强绿色荧光蛋白和萤光素酶报告系统(EGFP/Luc)标记hUCMSCs,通过胰腺包膜下途径或尾静脉途径将携带萤光标记的hUCMSCs移植到链脲霉素诱导的糖尿病模型小鼠体内。移植后利用萤光素酶报告基因追踪hUCMSCs在活体内的迁移和定位;组织学检测小鼠胰岛形态变化;功能学实验动态检测小鼠血糖、血清胰岛素水平和糖耐量。结果:活体生物发光成像显示胰腺包膜下途径移植的hUCMSCs主要定位于胰腺,尾静脉途径移植的hUCMSCs主要定位于肺,仅少量细胞向胰腺部位迁移。组织学检测发现,胰腺包膜下途径移植的小鼠胰岛边界清晰,无炎症细胞浸润;而尾静脉途径移植的小鼠胰腺组织有少量炎症细胞浸润和纤维化形成。功能学检测发现胰腺包膜下移植较尾静脉移植降低小鼠血糖作用显著,血糖可降至接近正常水平,且血清胰岛素水平明显升高,葡萄糖的调节能力显著增强。结论:移植途径对hUCMSCs治疗糖尿病的效果有影响。胰腺包膜下移植在降低小鼠血糖、升高胰岛素水平及改善胰岛功能方面均优于尾静脉移植。     

R6/2型亨廷顿病转基因小鼠胰岛β细胞功能损伤

目的：研究R6/2型亨廷顿病(HD) 转基因小鼠胰岛β细胞的功能,揭示HD转基因小鼠继发糖尿病的机制。方法：利用R6/2 型HD转基因小鼠模型,检测正常和HD小鼠空腹血糖以及血清胰岛素水平;并应用HE染色和免疫荧光技术分析正常和HD小鼠胰岛形态学差异。结果：与正常小鼠相比,R6/2 型HD小鼠空腹血糖显著增高,血清胰岛素水平明显降低,胰岛萎缩,β细胞数量减少,细胞功能指数降低,而胰岛素抵抗指数正常。结论：胰岛β细胞功能损伤是引起R6/2 HD转基因小鼠继发糖尿病发生的主要因素。     

人骨髓源干细胞向胰岛素分泌细胞分化(英文)

目的：探讨人骨髓源干细胞向具有功能的胰岛素分泌细胞分化的可能性。方法：从人骨髓分离间充质干细胞。采用表皮生长因子、β-巯基乙醇和高糖培养基诱导其向胰岛素分泌细胞分化。经诱导后,用RT-PCR检测胰岛β细胞相关基因的表达,并采用免疫细胞化学染色检测胞浆胰岛素的表达。此外,诱导后细胞分泌的胰岛素定量及胰岛素释放实验将采用化学发光法进行检测。将经诱导后的细胞移植到糖尿病小鼠的右侧肾被膜下。在移植后16 d持续检测小鼠的血糖水平,最后对右侧肾脏进行免疫组化检测。结果：经诱导后,细胞能表达胰岛β细胞相关基因;免疫细胞化学染色也能检测到胞浆有胰岛素的表达;而且这些细胞能对糖刺激有所反应。细胞被移植到糖尿病小鼠的肾被膜下,能起降血糖作用。其肾脏的免疫组化显示：肾被膜下有胰岛素阳性细胞。结论：人骨髓源干细胞具有向胰岛素分泌细胞分化的潜能,这将为糖尿病细胞治疗提供丰富的细胞来源。     

人α1-抗胰蛋白酶在胰岛β细胞移植中免疫抑制和保护作用的研究

 目的：探讨人α1-抗胰蛋白酶（hAAT）蛋白在胰岛β细胞移植中的免疫抑制和保护作用。方法：构建稳定表达hAAT蛋白的NIT-hAAT细胞系。将NIT-1细胞系和NIT-hAAT细胞系分别2次腹腔注射正常BALB/c小鼠,诱导细胞毒性T淋巴细胞(CTL)产生,将丝裂霉素处理后的2种细胞系与CTL混合培养,流式细胞术检测NIT-hAAT细胞凋亡情况;ELISA检测细胞因子表达;实时荧光定量PCR检测炎症因子mRNA表达。将2种细胞系分别植入糖尿病模型小鼠左肾包膜内,动态观察血糖和体重变化、血清中胰岛素和C肽水平以及移植部位的病理学变化。结果：CTL实验中,NIT-hAAT细胞受体鼠淋巴细胞的细胞毒作用较NIT-1细胞受体鼠明显减轻。hAAT具有减轻细胞凋亡、抑制炎症因子IL-1β、IL-6 mRNA的表达以及调节Th1/Th2细胞因子平衡的作用。NIT-hAAT细胞移植到糖尿病模型小鼠后,血糖明显下降并维持至28 d,血清中胰岛素和C肽含量明显升高,移植部位炎症细胞浸润明显减轻。结论：hAAT蛋白可减轻CTL对β细胞的杀伤作用,抑制炎症因子的表达,短期内可以抑制移植物免疫排斥反应,对胰岛β细胞移植治疗糖尿病具有明显的免疫抑制和保护作用。     

脐带源间充质干细胞与大鼠胰腺细胞共培养向胰岛样细胞分化及移植治疗1型糖尿病

背景：脐带Wharton’s Jelly中间充质干细胞可以向胰岛样细胞诱导分化。 目的：验证脐带源间充质干细胞与大鼠胰腺细胞共培养向胰岛样细胞诱导分化的可能性,并观察移植后对糖尿病大鼠血糖的影响。 方法：分离、诱导、传代脐带Wharton’s Jelly中间充质干细胞,再与大鼠胰腺细胞共培养,诱导成胰岛细胞团样组织。将大鼠分为3组,正常对照组不进行移植及造模;模型组仅制备糖尿病大鼠模型;实验组造模后将胰岛样细胞移植入糖尿病大鼠肾脏包膜。 结果与结论：脐带Wharton’s Jelly细胞培养中有细胞从组织块中爬出,第7天形态发生变化,贴壁细胞部分变成梭形。分离培养的细胞表达具有间充质干细胞表面特有标志CD44、CD29、CD105,不表达CD34、CD45、CD14。诱导第7,10天PDX-1及人胰岛素强染色;胰岛素及C-肽浓度较单纯培养组明显升高;PDX-1及人胰岛素mRNA诱导第7、10天较高表达。移植第1周大鼠尾尖血糖链脲佐菌素实验组明显低于模型组(P < 0.01),但明显高于正常照组(P < 0.01)。8周链脲佐菌素实验组肾脏被膜下发现胞核染棕色染色的Brdu阳性、胞浆棕色染色的胰岛素阳性细胞。结果表明,脐带Wharton’s Jelly中存在脐带源间充质干细胞,与大鼠胰腺细胞共培养可促进间充质干细胞向胰岛样细胞诱导分化,移植入糖尿病大鼠肾脏被膜下,可显著降低糖尿病大鼠血糖。     

小鼠iPSCs诱导分化为胰岛素分泌细胞及治疗糖尿病的实验研究

 目的: 利用3步法诱导方案,使小鼠诱导多能干细胞(induced pluripotent stem cells,iPSCs)分化为胰岛素分泌细胞(insulin-producing cells,IPCs),观察诱导效率和成熟度,并观察其对糖尿病小鼠治疗效果。方法: 本实验室通过piggyBac转座子将C57/C雄性小鼠来源胚胎成纤维细胞(mouse embryonic fibroblasts,MEFs)构建为小鼠iPSCs,利用3步法诱导方案分化为IPCs,观察细胞分化过程中的形态变化;RT-PCR和免疫荧光检测其胰岛β细胞发育相关基因和蛋白的表达;流式细胞术分析分化效率;葡萄糖刺激实验检测胰岛素和C肽分泌水平。将IPCs移植入C57/C雄性糖尿病小鼠模型左肾包膜下,监测血糖和血清中胰岛素含量28 d,观察逆转高糖血症的效果。结果: 建立的3步诱导方案可以将小鼠iPSCs诱导分化为IPCs,其表达胰岛β细胞的标志性基因(Pdx1、Ngn3、Pax6和Ins2)和蛋白(Pdx1、Nkx6.1和胰岛素),在葡萄糖刺激下可分泌胰岛素和C肽。流式细胞术结果表明诱导分化的效率达28%。移植后3 d糖尿病小鼠血糖即降低至接近正常水平,血清胰岛素含量明显升高,对葡萄糖的调控能力明显增强。病理学观察IPCs细胞移植28 d后仍存活。结论: 建立的3步诱导法可将iPSCs高效定向诱导分化为IPCs,明显缩短了诱导分化的时间,移植至近交系同性别小鼠体内可逆转糖尿病的高糖血症。     

PDX1联合NKX6.1促进骨髓间充质干细胞分化为胰岛β样细胞

目的： 为提高骨髓间充质干细胞(BMSCs)向胰腺β样细胞的分化效率,以产生足够用于移植的胰岛样细胞。方法: 构建含PDX1与NKX6.1双基因的重组腺病毒载体,用重组腺病毒感染并联合多种细胞因子分步诱导BMSCs。用RT-PCR、Western blotting等多种方法分别检测PDX1、NKX6.1、胰岛素及C-肽表达情况;观测植入鼠肾包膜下的细胞形态与胰岛素、C-肽等相应分子表达情况以及检测植入细胞对糖尿病模型大鼠的血糖水平的调节能力。结果: BMSCs经重组腺病毒pAdxsi-CMV-PDX1/CMV-NKX6.1联合相应细胞因子分步诱导,双硫腙染色细胞质呈亮红色,RT-PCR显示诱导后的细胞持续稳定表达胰岛素、葡萄糖转运蛋白2(GLUT2)等β细胞相关分子;Western blotting、免疫细胞化学与间接荧光结果亦相似。所诱导的实验组细胞经5.5和25mmol/L葡萄糖刺激后胰岛素分泌水平分别为(1 240.4±109.3) mU/L和(3 539.8±245.1) mU/L, 并显著高于对照组的分泌量。移植实验组细胞可恢复STZ糖尿病小鼠血糖正常水平。结论: PDX1与NKX6.1联合细胞因子在体外能有效地诱导BMSCs分化为胰岛β样细胞;这种胰岛β样细胞移植能有效恢复STZ糖尿病小鼠的血糖正常水平,维持小鼠良好的生存状态,这将为治疗糖尿病带来新的希望。     

A strategy for the engineering of insulin producing cells with a broad spectrum of defense properties

Insulin-producing pancreatic beta cells are known to be extremely susceptible to the oxidative stress and hypoxia generated following islet transplantation in diabetic patients. We hereby present a novel in vivo selection strategy based on the isolation of insulin-producing cells with enhanced protection after repeated rounds of encapsulation and xenotransplantation. Rat insulinoma INS-1 cells were encapsulated in alginate macrobeads and transplanted in the peritoneal cavity of mice. After 2 days the beads were retrieved and cells were recovered from alginate and propagated in vitro until submitted to a second round of encapsulation and transplantation. Three days later, the surviving cells, named INS-1m2, were isolated from the alginate beads and their protection and functional activity examined. Compared to parental INS-1 cells, the selected INS-1m2 cells were more resistant to hydrogen peroxide, nitric oxide, alloxan and hypoxia. This enhanced protection of the selected cells correlated with the increased level of catalase and poly (ADP-ribose) polymerase expression. Although selected cells expressed more insulin than parental cells, no change in their insulin response to glucose was observed. We conclude that the in vivo selection strategy is a powerful tool for the engineering of insulin producing cells with a broad spectrum of defense properties.     

Long-term isografts of cultured fetal mouse pancreatic islets. The oncogenic effects of streptozotocin and the prevention of diabetic renal complications

Female CBA mice made diabetic with a single intravenous dose of streptozotocin (STZ) were either grafted with cultured fetal mouse pancreatic islets onto the splenic capsule, treated with insulin, or left untreated. An age- and sex-matched group of nondiabetic mice served as normal controls. All islets-grafted and most insulin-treated mice survived and had normal fasting blood glucose levels. By contrast, of the untreated diabetic mice, one died and the survivors showed poor weight gain. Light-microscopic examination of the islet isografts showed a progressive increase in graft size and beta-cell granulation over the 9-month study period. Quantitative electron-microscopic examination of the kidney showed that, whereas the islet-grafted and nondiabetic control mice had similar glomerular capillary basement membrane (GCBM) thickness, the untreated diabetic and insulin-treated mice had markedly thickened GCBM. All STZ-treated mice develop diffuse hepatic dysplasia and, at later time points, some showed biliary hyperplasia, intrahepatic cysts, and occasionally nodular dysplasia. With increasing time after STZ, most mice developed renal adenomas. One untreated diabetic mouse also developed a solitary functional pancreatic beta-cell adenoma. STZ effects were not affected by treatment of diabetes.     

体外培养人胰岛素瘤细胞的特性

目的分离培养人胰岛素瘤细胞,并研究它的功能特性。方法原代分离人胰岛素瘤细胞,经多次筛选培养进行纯化。通过荧光显微镜观察细胞特有的自发荧光;RT-PCR方法检测胰岛素mRNA的表达和胰岛细胞自身抗原IA-2、IAR和ICAp69的表达;应用MTT方法检测抗人IA-2抗体对胰岛素瘤细胞的杀伤。结果分离的人胰岛素瘤细胞经传40代,在悬浮培养条件下可自发聚集成胰岛样结构,并有自发荧光。该细胞表达胰岛素mRNA并合成胰岛素,但明显低于大鼠胰岛素瘤细胞INS-1。该细胞也表达人胰岛细胞自身抗原IA-2、IAR和ICAp69,并且用抗人IA-2抗体与之孵育后可出现抗体剂量依赖性的细胞杀伤。结论此分离培养的人胰岛素瘤细胞表达人胰岛素和人胰岛细胞自身抗原,因此可以作为研究人Ⅰ型糖尿病发病机制的细胞模型。     

Bone marrow transplantation reverses new-onset immunoinflammatory diabetes in a mouse model

Bone marrow transplantation might be an effective method to cure type 1 diabetes mellitus. This study aimed to investigate whether bone marrow transplantation could reverse hyperglycemia in diabetic mice and whether high-dose total body irradiation followed by high-dose bone marrow mononuclear cell infusion could improve the efficiency of bone marrow transplantation in treating diabetic mice. Diabetic mice after multiple low doses of streptozotocin injection were irradiated followed by infusion with approximately 1×10⁷ bone marrow mononuclear cells intravenously. Before and after bone marrow transplantation, fasting blood glucose, intraperitoneal glucose tolerance test, serum insulin, pancreatic histology, and the examination of insulin and glucagon in islets were processed. All recipients returned to near euglycemic within 1 week after undergoing bone marrow transplantation. No mice became hyperglycemia again during investigation period. The change of serum insulin, glucose tolerance test, pancreatic histology and the expression of insulin and glucagon in recipient islets after bone marrow transplantation all revealed islets regeneration and significant amelioration when compared respectively with those of diabetic mice without bone marrow transplantation. Bone marrow transplantation contributed to reduce blood glucose, prevent further blood glucose hike in diabetic recipients, and promote islets regeneration. High-dose total body irradiation in combination with high-dose bone marrow monoclear cell infusion could improve the efficiency of bone marrow transplantation in treating streptozotocin-induced diabetes.     

Fibrin improves beta (INS-1) cell function,proliferation and survival through integrin αvβ3

Extracellular matrix (ECM)–integrin stimulation can promote beta cell differentiation, proliferation and function. However, beta cells lose their insulin secretion function in response to glucose stimulation, and senesce when cultured with ECM proteins for a long time. Fibrin is a provisional ECM protein that is capable of maintaining beta cell function, yet the mechanisms by which this occurs is unknown. The present study examined how fibrin interacts with integrin receptors to promote beta cell cluster formation, proliferation and function. The rat insulinoma cell line, INS-1, was cultured on tissue-culture polystyrene, or with 2-D or 3-D fibrin gels for up to 4 weeks. Cells cultured with fibrin formed islet-like clusters and showed direct contacts with fibrin determined by scanning electron microscopy. Fibrin-cultured INS-1 cells also had significantly increased glucose-stimulated insulin secretion. A significant increase in integrin αvβ3 protein and phosphorylated FAK, Erk1/2 and Akt levels was observed in fibrin-cultured INS-1 cells, which was associated with significantly increased cell proliferation and decreased cell apoptosis. Integrin αvβ3 blockade affected INS-1 cell spreading on fibrin gels, and resulted in significantly decreased FAK phosphorylation and increased cleaved caspase-3 levels. These results show that fibrin promotes beta cell function, proliferation and survival via integrin αvβ3 interactions.     

Interaction between Plasmodium chabaudi and C57Bl mice with particular reference to the immune response.

The direct immunosuppressant effects of streptozotocin (STZ) have been examined using C3H/HeN mice. Evidence is presented that bone marrow cells and important precursors of T lymphocytes obtained from STZ-diabetic mice are damaged or impaired by the diabetogenic agent. First, insulin treatment (0.2 units, twice daily) for 13 days only partially reversed the fall in number of nucleated cells in the thymus and spleen of STZ-diabetic mice. Second, bone marrow cells from STZ-diabetic mice are unable to reconstitute gamma-irradiated normal syngeneic mice. The survival rate of normal mice given lethal doses of gamma radiation is 100% if they receive bone marrow cells that are injected from untreated syngeneic normal mice. In contrast, irradiated normal mice given donor cells from STZ-treated mice (50-55 days post-STZ) have survival rates of 30% over a 4-week period of observation. These effects are not believed to involve simply a deficiency of insulin because normal syngeneic bone marrow cells completely reconstituted the spleen and thymus of control mice within 29-33 days. STZ-treated mice also have impaired contact sensitivity responses that are not reversed by insulin treatment. These observations suggest that insulin does influence the proliferation of lymphoid cell subpopulations in diabetic animals. However, direct effects of STZ may also occur that irreversibly damage bone marrow cell subpopulations or other important T-cell precursor populations in susceptible strains of mice.     

Glutamine metabolism, interorgan transport and glucogenicity in the sheep

[U-14C]glutamine and [6-3H]glucose were infused into four groups of sheep: fed, NH4Cl acidotic, fasted, and dexamethasone treated. Net and unidirectional plasma glutamine fluxes in the portal-drained viscera (PDV), liver, kidneys, and hindquarters were measured by multiplying venoarterial concentration differences and 14C extraction ratios by the rate of blood flow. In fed sheep, glutamine was released by kidneys and muscle but removed by PDV and liver. In all other sheep, renal glutamine release either decreased or switched over to net removal largely due to increased unidirectional renal utilization. This increased renal glutamine demand was compensated for, during acidosis, by a decreased net hepatic glutamine removal but, during fasting and dexamethasone treatment, by an increased muscle glutamine release. Plasma glutamine and glucose turnover rates averaged 11-12 and 19-24 mmol/h but the percentage of glutamine converted to glucose was higher during fasting and dexamethasone treatment (21%) than in normal fed sheep (17%) perhaps reflecting the increased glutamine removal by the kidneys. Since renal glutamine utilization increases with acidosis and fasting and, since glutamine turnover remains unchanged, glutamine metabolism by other body tissues must be altered to compensate for renal changes.