大鼠胰岛分离纯化新方法“两步过筛法”的建立及评估

目的：建立胆管内灌注胶原酶分离胰岛与适宜孔径滤网过筛相结合的快速纯化胰岛细胞的方法并评估这种方法的效果。方法：清洁级8～12周龄Sprague Dawley大鼠胆总管内灌注胶原酶消化、分离胰岛,分别采用Ficoll不连续密度梯度离心法和两次经不同孔径滤网过滤的两步过筛法纯化胰岛细胞,行双硫腙（dithizone,DTZ）染色、吖啶橙/碘丙啶(acridine orange / propidium iodide, AO/PI)双色荧光染色法分析分离胰岛的纯度与活率;行葡萄糖刺激-胰岛素释放试验检测细胞活性;采用免疫组化荧光染色法观察胰岛细胞胰岛素的合成功能。结果：大鼠两步过筛法和胰岛密度梯度离心法胰岛细胞收获量分别782±115 胰岛当量（IEQ）和598±135 IEQ,差异有统计学意义（P<0.01）;纯度分别为90％～100％和65％～85%,活率分别为>95％和85%～95%。两步过筛法分离的胰岛葡萄糖刺激-胰岛素释放试验显示培养24 h后,高糖实验组胰岛素浓度（76.9±6.1 μg/L）显著高于刚分离纯化后即加入高糖刺激时的浓度（49.4±3.9 μg/L）,差异有统计学意义（P<0.01）。结论：两步过筛法分离纯化大鼠胰岛可获得纯度高、活率高且活性好的大鼠胰岛细胞。     

Survival of encapsulated islets: More than a membrane story

At present, proven clinical treatments but no cures are available for diabetes, a global epidemic with a huge economic burden. Transplantation of islets of Langerhans by their infusion into vascularized organs is an experimental clinical protocol, the first approach to attain cure. However, it is associated with lifelong use of immunosuppressants. To overcome the need for immunosuppression, islets are encapsulated and separated from the host immune system by a permselective membrane. The lead material for this application is alginate which was tested in many animal models and a few clinical trials. This review discusses all aspects related to the function of transplanted encapsulated islets such as the basic requirements from a permselective membrane (e.g., allowable hydrodynamic radii, implications of the thickness of the membrane and relative electrical charge). Another aspect involves adequate oxygen supply, which is essential for survival/performance of transplanted islets, especially when using large retrievable macro-capsules implanted in poorly oxygenated sites like the subcutis. Notably, islets can survive under low oxygen tension and are physiologically active at > 40 Torr. Surprisingly, when densely crowded, islets are fully functional under hyperoxic pressure of up to 500 Torr (> 300% of atmospheric oxygen tension). The review also addresses an additional category of requirements for optimal performance of transplanted islets, named auxiliary technologies. These include control of inflammation, apoptosis, angiogenesis, and the intra-capsular environment. The review highlights that curing diabetes with a functional bio-artificial pancreas requires optimizing all of these aspects, and that significant advances have already been made in many of them.     

联合转染A20、HO-1基因对大鼠胰岛抗凋亡能力影响的研究

目的 研究A20基因、血红素加氧酶1基因(heme oxygenase 1 gene,HO-1)转染在大鼠胰岛细胞中的表达情况及对体外培养条件下胰岛活性、拮抗放线菌酮(CHX)和肿瘤坏死因子-α(TNF-α)诱导的胰岛细胞凋亡作用的影响.方法 构建A20、HO-1和增强绿色荧光蛋白(EGFP)慢病毒转移载体,荧光显微镜连续观察EGFP表达情况,评估转基因效率、确定诱导凋亡时机.Western印迹测定A20和HO-I蛋白表达.超敏ELISA试剂盒检测胰岛素浓度.胰岛经CHX+ TNF-α处理48 h进行TUNEL、流式细胞仪检测凋亡率.Western印迹检测半胱氨酸蛋白酶-3的活化.结果 (1)分别以A20和HO-1慢病毒转染胰岛检测表明A20和HO-1蛋白均呈高表达.(2)胰岛细胞经培养48h和96 h,转基因各组胰岛素浓度高于空白对照组(P＜0.01).(3)CHX+ TNF-α诱导胰岛细胞凋亡后,转A20组胰岛素浓度为(93.58 ±4.12) μg/ml、转HO-1组胰岛素浓度为(88.98±4.77) μg/ml,联合转A20和HO-1组胰岛素浓度(103.33 ±3.16) μg/ml,均高于转EGFP组[(9.03±0.65) μg/ml]和空白对照组[(8.86±0.38) μg/ml,P＜0.001].Western印迹法检测显示联合转A20/HO-1基因组活化型半胱氨酸蛋白酶-3表达水平最低.结论 原代胰岛细胞中高效表达的A20和HO-1蛋白具有抗CHX+ TNF-α诱导的胰岛凋亡作用,联合转A20和HO-1基因有协同抗凋亡效应.     

Retinoids in the pancreas

Retinoids (vitamin A and its natural and synthetic analogs) are required by most tissues for maintaining the normal health of the tissue. This is certainly true for the pancreas. The recent literature is convincing that retinoids are needed by the adult to assure normal pancreatic endocrine functions, especially those of the α- and β-cells. It is also well established that retinoids are required to insure normal pancreas development in utero, including the development of the endocrine pancreas. The actions of retinoids for maintaining normal pancreatic islet functions has drawn considerable research interest from investigators interested in understanding and treating metabolic disease. Pancreatic retinoids are also of interest to investigators studying the origins of pancreatic disease, including the development of pancreatic fibrosis and its sequelae. This research interest is focused on pancreatic stellate cells (PSCs) which store retinoids and possess the metabolic machinery needed to metabolize retinoids. The literature on pancreatic disease and retinoids suggests that there is an association between impairments in pancreatic retinoid storage and metabolism and the development of pancreatic disease. These topics will be considered in this review.     

女性腹型肥胖患者低脂联素血症与胰岛β细胞功能关系探讨

目的：探讨女性腹型肥胖患者脂联素水平与胰岛β细胞功能之间的关系。方法：应用高葡萄糖钳夹技术检测了9例女性腹型肥胖、9例健康女性对照和7例女性2型糖尿病患者的胰岛G细胞功能和胰岛素敏感性，用MRI测定局部体脂和酶联免疫法测定脂联素水平。结果：对照组胰岛素分泌第一时相（FPIR）、葡萄糖代谢清除率（GDR）、胰岛素敏感性指数（ISI）和脂联素水平高于腹型肥胖组和2型糖尿病组；内脏脂肪面积（VA）低于腹型肥胖组和2型糖尿病组（P〈0．05）。腹型肥胖组脂联素、FPIR、胰岛素分泌第二时相（SPIR）和胰岛素分泌最大量（INSmax）高于2型糖尿病组（P〈0．05）。多元逐步回归分析显示，年龄、FPIR和GDR与脂联素呈独立正相关（B分别为0．145、0．194、0．277，均P〈0．05）；腰臀比（WHR）与脂联素呈独立负相关（B为-7．424，P〈0．05）。砖论：腹型肥胖女性脂联素水平降低，可能与胰岛素分泌密切相关。     

小鼠胰岛的分离及胰岛移植

目的研究小鼠胰岛分离和移植的方法。方法在Gotoh等所介绍的小鼠胰岛分离方法的基础上作了一些改进,由原来经胆总管注入胶原酶消化液改为由胆囊注入,并在消化液和Ficoll分离液中加入了胰酶抑制剂和BSA。结果使分离纯化后的胰岛产量由原来方法的41.7±13.2个提高到了266.5±32.1个(P<0.01),活性在95%以上,除了少量导管外几乎不含腺泡组织。结论改进后的方法可以在肉眼条件下注入消化液,而不需要解剖显微镜,既方便了操作又提高了成功率;避免了整个消化和分离过程中胰酶对胰岛的消化作用,提高了得率,且具有很好的重复性。     

大鼠胰岛细胞的体外和体内MR成像方法

目的探讨MRI对SPIO标记的大鼠胰岛细胞在体外及体内的扫描参数及序列的选用。方法联合应用SPIO和多聚左旋赖氨酸(PLL),通过受体介导的内吞作用标记胰岛细胞。采用GE3.0T Signa Excite磁共振扫描仪,配合3英寸小动物线圈作GRE序列T2*W成像,比较SPIO标记的胰岛细胞与未标记的细胞,再分别采用两种具有不同分辨率的扫描方案进行扫描,比较图像的差异。而后将两种细胞分别移植入大鼠体内,比较在体内的差异。对标记后的大鼠分别用FSET2W序列和GRET2*W序列扫描,比较各序列的敏感性。结果无论是体外还是体内,只有SPIO标记后的胰岛细胞可以被MRI监测到,表现为较明显的低信号点。采用更高分辨率的参数扫描后所得到的胰岛图像更为清晰。GRET2*WI较FSET2WI序列对SPIO的监测更敏感。结论MRI能对SPIO标记的胰岛细胞进行成像,可用于活体,实时监测胰岛细胞移植术后移植物的存活及排异情况。     

成人胰岛细胞的分离

目的　探讨成人胰岛细胞的分离及胰腺冷缺血时间与胰岛细胞活率的关系。方法　采取胰、肾联合切取 ,经腹主动脉插管 ,用自制的灌注器以高渗枸橼酸盐嘌呤溶液 (HC A液 ) 15 0 0～2 0 0 0ml进行原位灌洗。将肾与胰腺、十二肠、脾分离 ,采用胶原酶P消化胰腺 ,分离并纯化胰岛细胞 ,以双硫腙及丫腚橙染色 ,测定所得到的胰岛细胞的纯度及活率。结果　胰腺的冷缺血时间为 2 .5～ 8h ,温缺血时间为 0～ 3min。胰岛收获量为 (2 .38± 0 .6 7)× 10 3 IEQ/g ,纯化后胰岛细胞的活率为 19%～ 83% ,冷保存指数 (或输注指数 )为 9.8～ 6 6 .4。胰岛细胞的活率与胰腺的冷缺血时间呈负相关 ,冷保存指数和胰岛细胞活率呈负相关。结论　以高渗枸橼酸盐嘌呤溶液灌洗、胶原酶P消化胰腺所得到的胰岛细胞活率高 ,但胰腺的冷缺血时间不宜超过 5h。     

Presence of extrapancreatic islets of Langerhans in the duodenal wall of the rat

Summary In the present study we report the existence of typical islets of Langerhans in the duodenal wall of the rat. The nature of the cells and of their corresponding secretory granules were assessed by morpho-cytochemical techniques. The insulin cells formed the core of the islets while the glucagon, the somatostatin and the pancreatic polypeptide cells were located at the periphery. These islets were located in the connective tissue between the duodenal crypts and the muscle layer, neighbouring the last portion of the bile duct. The morphological features of these endocrine cells indicate the presence of high secretory activities which may play an important role in the maintenance of glucose homeostasis, particularly during absorption of nutrients.     

Effects of a 7-day infusion of glucose on insulin secretion in vivo and in vitro in ventromedial hypothalamic-lesioned obese rats

Excessive stimulation of insulin secretion may be one cause of the beta-cell dysfunction induced by hyperglycemia. We investigated a possible link between the prior endogenous hypersecretion of insulin and this dysfunction by performing a 7-day glucose infusion (50% wt/vol, 1.2 ml/h) on ventromedial hypothalamic VMH-lesioned hyperinsulinemic rats. Intravenous glucose tolerance tests (IVGTT 1.0 g/kg) revealed that a 3-day glucose infusion enhanced the insulin responses in both the sham- and VMH-lesioned rats compared with saline infusions. A similar 7-day glucose infusion enhanced the insulin response to glucose in sham-lesioned rats but not in VMH-lesioned rats. Batch-incubation of islets isolated from sham-lesioned rats showed an enhanced insulin response to glucose after 7 days of glucose treatment compared with the saline infusions. Conversely, the glucose infusion in VMH-lesioned rats markedly suppressed the in vitro insulin response. In sham- and VMH-lesioned rats, similar islet insulin contents were produced by saline and glucose treatments. Electron microscopy revealed that glucose infusions impaired the granule-releasing function of the beta-cells in VMH-lesioned rats, while insulin synthesis was accelerated in either group. These findings support the notion that excessive secretion is partly responsible for the beta-cell dysfunction induced by hyperglycemia without signs of exhaustion. Received: 13 June 1997 / Accepted in revised form: 14 November 1997