大量人胰岛分离技术的改进及相应胰岛功能的检测

目的 通过对人胰岛分离技术的改进以获得大量高活力胰岛并检测其功能。方法采用经典及改良技术分离、纯化28例人胰岛。胰岛收获量以胰岛当量(IEQ)表示。胰岛功能测定分别为体外测定胰岛素/DNA比率、静止葡萄糖刺激试验(SGS)及将胰岛移植至糖尿病裸小鼠的体内功能鉴定并行糖耐量试验,连续测血糖水平及其体内C肽浓度。结果 前13例采用经典方法,平均每个胰腺收获49123 IEQs,平均846 IEQs/g胰腺组织,平均纯度为87％。改进技术后15例的分离结果则分别为:501813 IEQs/胰腺,7003 IEQ/g胰腺组织及纯度89％。体外胰岛素刺激试验结果表明分离纯化后的人胰岛有正常功能,将12次分离得到的胰岛分别移植至34只糖尿病裸鼠肾包膜下,其中29只糖尿病裸鼠于12h内血糖恢复正常且糖耐量试验接近正常鼠,血中C肽水平亦接近正常。结论 采用改进的人胰岛分离方法,可以获得大量高活力的具有正常功能的胰岛,为同种异体胰岛移植用于临床奠定了必要的基础。     

胰岛分离、纯化制备的改进

目的 探讨大型哺乳动物胰岛机械化大量分离、纯化的方法,为人类胰岛移植物的大量制备摸索创造条件.方法 应用改进的机械化胰岛分离、纯化系统,用HCA和UW液顺序原位灌洗犬胰腺,主副胰管插管,4℃胶原酶-V(1.5 g/L)+胰酶抑制剂pefabloc(0.4 mmol/L)灌注后,Ricordi-Chamber消化罐消化,4℃COBE2991连续密度梯度离心纯化,测定胰岛当量(IEQ)、胰岛纯度及存活率、胰岛素及C-肽的释放量、培养24 h后光镜及电镜观察.结果 胰腺消化时间为(25.0±6.0)min,胰岛外分泌腺包裹率为(9.4±2.4)%,消化后胰岛收获量为(17.2±3.6)×104IEQ/每个胰腺,纯化后胰岛收获量为(8.3±2.0)×104IEQ/每个胰腺,胰岛纯度为(89.7±3.5)%.纯化胰岛体外低糖与高糖刺激下胰岛索分泌量及C-肽的释放量良好,培养24 h后形态结构及功能正常.结论 本实验室改进的胰岛机械分离方法及各设备运行可靠,获得的胰岛形态功能良好,可望用于临床人类胰岛的大量制备.     

正常成人胰岛移植治疗糖尿病的实验研究

目的探讨正常成人胰岛移植治疗糖尿病的作用。方法 2012年1月至2013年1月健康成人胰腺供体共13例。获取胰腺后经胶原酶消化并进行胰岛提取纯化,将纯化后的胰岛移植到糖尿病裸鼠肾包膜下为实验组,生理盐水代替胰岛移植为对照组,各13只。术后通过检测糖尿病裸鼠的血糖变化和组织学检查来判定胰岛移植后的存活情况和纠正血糖的效果。结果成人胰腺消化后胰岛产量为纯化前（3608±403）IEQ/g,纯化后（2820±318）IEQ/g,纯度为85%。实验组84.6%（11/13）糖尿病裸鼠在移植术后第1天,血糖降至正常,对照组血糖无明显变化。两组糖尿病裸鼠存活时间：实验组存活时间35～57d,中位存活时间46d。对照组存活时间5～12d,中位存活时间7d。两组比较差异具有统计学意义,Log-rank（Mantel-Cox）值为8.74,P值为0.0012。结论成人胰腺消化后,可得到高纯度活力正常的胰岛,并能纠正糖尿病裸鼠的高血糖。正常成人胰岛移植可能成为临床糖尿病患者的一种有效治疗方法。     

经脾实质胰岛移植治疗糖尿病小鼠的实验研究

目的介绍一种经脾实质内胰岛移植治疗糖尿病小鼠的方法并对移植前后小鼠的血糖、口服糖耐量和组织学进行评价。方法将分离纯化的Balb/c小鼠胰岛培养6 h后,用自制的移植工具进行同种糖尿病小鼠的脾实质内胰岛输注,移植当量为(500±30)IEQ。对移植前后的小鼠血糖进行测定,并在移植后第10天进行糖耐量试验;取受体小鼠脾脏,进行HE染色和免疫组化染色,观察胰岛细胞团在脾内的存活情况。结果受体小鼠移植胰岛后均能维持正常血糖时间达1个月以上,糖耐量试验结果显示与正常小鼠统计学无差异(P=0.69),组织学结果显示胰岛细胞团在小鼠脾实质内存活良好,胰岛有功能,但结构略有松散。结论本研究探索了胰岛在脾实质内移植后的特点,为研究脾实质作为胰岛移植的位点提供了参考。     

大鼠胰岛的分离纯化方法改进与功能鉴定

目的 通过改进胰腺消化和分离的技术条件,提高成年大鼠胰岛分离纯化产率和质量. 方法 用胶原酶Ⅺ液灌注消化成年SD大鼠胰腺,对胰岛分离纯化方法加以改进:以 4 种比重的 Euro- Ficoll (F1∶D=1.132,F2∶D=1.108,F4∶D=1.069) 和 Hank's 液(F5∶D=1.023) 不连续密度梯度离心,以离心半径 15 cm,2 000 r/min 于4℃缓慢升降离心 20 min,收集位于F1 和 F2界面的胰岛.双硫腙特异染色法鉴定胰岛纯度;二醋酸酯荧光素/碘化丙啶染色法计算胰岛成活率;放射免疫分析法检测葡萄糖刺激的胰岛素分泌量,计算刺激指数.将胰岛当量(islets equivalent quantity,IEQ) 为 1000 的胰岛移植于同品系糖尿病大鼠肾包膜下,9d 内隔日观察动物血糖的变化,评价胰岛功能.比较分离条件优化前后收获胰岛的产率和质量. 结果 改进纯化方法后每只大鼠胰岛收获量为(920±122) IEQ,胰岛纯度> 90%,胰岛细胞成活率为 91%±2%.胰岛细胞功能良好,在低糖和高糖刺激后培养液中胰岛素浓度分别为(18.25±0.32) mU/L 和(36.70±3.57)mU/L,刺激指数为 2.01±0.15.1000 IEQ 胰岛移植于糖尿病大鼠肾包膜下,观察期内可维持动物血糖水平正常. 结论 改进后的胶原酶灌注消化和不连续梯度离心方法提高了胰岛的产率,保证了胰岛的高纯度及高成活率.     

成人胰岛细胞移植治疗1型糖尿病

目的 探讨新型成人胰岛细胞分离、纯化技术分离的成人胰岛细胞移植治疗1型糖尿病的安全性与有效性.方法 采用全氟化碳液(PFC)和UW液双层冷藏胰腺,Liberase酶消化,COBE 2991型专用胰岛细胞分离机分离及连续密度梯度纯化,获取高纯度与高活性的胰岛细胞.通过上腹部小切口,胃右静脉或脐静脉插管,将经短期培养的胰岛细胞经门静脉移植到11例1型糖尿病患者肝脏内.采用达利珠单抗或阿来佐单抗进行诱导,西罗莫司和他克莫司联用的方案预防排斥反应,术后观察胰岛素使用情况,监测血糖、G-肽与糖化血红蛋白水平以及肝功能、肾功能.结果 45个胰腺中,42个成功分离出胰岛细胞,其数量平均为28.5×104胰岛当量(IEQ)/个,纯度为95.7%,活率为93.2%,胰岛素释放试验刺激指数为2.43.11例1型糖尿病患者共行胰岛细胞移植20次,其中移植1次4例,2次5例,3次2例,每次移植胰岛细胞数平均为11 200 IEQ/kg.术后随访6个月至4年,6例完全撤除胰岛素,2例胰岛素用量较术前减少80%,3例减少50%.术后血糖稳定维持在正常水平,C-肽均超过0.166 nmol/L,糖化血红蛋白基本正常,肝、肾功能正常,未发生与胰岛细胞输注相关的并发症.结论 新型成人胰岛细胞分离、纯化方法可靠,采用该技术分离、纯化的成人胰岛细胞移植治疗1型糖尿病临床效果较好.     

肾移植联合成人胰岛细胞移植治疗糖尿病肾病七例报告

目的 建立新型成人胰岛细胞分离纯化方法和无激素免疫抑制方案.观察.肾移植联合胰岛细胞移植治疗1型糖尿病肾病的安全性与有效性.方法 全氟化碳液与威斯康星大学器官保存液双层冷藏胰腺,Liberase酶消化,COBE 2991型专用胰岛细胞分离机分离及连续密度梯度纯化,获取高纯度与高活性的胰岛细胞.常规方法行尸体肾移植,次El采用外科方法将短期培养的胰岛细胞经门静脉移植到肝脏内,采用无激素免疫抑制治疗.术后定期监测血糖与胰岛素用量、C肽与糖化血红蛋白水平以及肝肾功能.结果 23个胰腺均成功分离胰岛细胞,平均数量30万胰岛当量(IEQ)、纯度92%、活率95%、刺激指数3.16,病原学结果均阴性.7例1型糖尿病肾病患者共行胰岛细胞移植12次(移植1次3例、2次3例、3次1例).每次移植胰岛数量平均为11 820 IEQ/kg.采用阿来佐单抗诱导、西罗莫司和小剂量他克莫司、无激素免疫抑制治疗.随访1.5～3.0年,4例完全撤除胰岛素,3例胰岛素用量较术前减少＞70%.术后血糖稳定维持在正常水平,C肽均＞0.166nmol/L,糖化血红蛋白正常,肝肾功能正常.结论 新型成人胰岛细胞分离纯化方法可靠,胰岛细胞联合肾移植治疗1型糖尿病肾病安全、有效.     

同种异体胰岛及胰腺干细胞来源的胰岛样结构序贯移植治疗糖尿病

目的 观察同种异体大鼠胰岛及胰腺干细胞来源的胰岛样结构序贯移植在糖尿病治疗中的作用.方法 分离胰腺组织获得胰岛及胰腺导管上皮细胞,将具有干细胞潜能的胰腺导管上皮细胞在体外培养27d.将新鲜分离的胰岛(200±50)个及诱导分化2周的胰腺干细胞来源的胰岛样结构(2×106)个序贯移植到糖尿病大鼠的肾被膜下观察大鼠的血糖及生存情况.结果 将胰岛及胰腺干细胞来源的胰岛样结构序贯移植到同一糖尿病大鼠3周后血糖仍在5 mmol/L水平,对照组血糖无明显下降.结论 胰腺干细胞可诱导分化为分泌胰岛素的胰岛样结构,胰岛及胰腺干细胞来源的胰岛样结构序贯移植对大鼠糖尿病有治疗作用.     

采用改良的胰腺三管插管法分离成人胰岛的实验研究

目的 探讨胰腺插管方式对成人胰岛分离及纯化的影响.方法 共对17例成人胰腺进行了胰岛的分离和纯化.采用改进的腹部器官联合快速切取技术获取胰腺,分别采用标准法(3例)、单管法(11例)和三管法(3例)对胰腺进行灌注.标准法是将胰腺从胰颈处完全切断,沿主胰管分别向胰头和胰尾插管,主胰管人十二指肠处予以结扎.单管法为采用加长插管自主胰管插入,直至胰尾.三管法是在胰颈背侧切开胰腺至主胰管,经主胰管分别向胰头和胰尾方向插管,在主胰管进入十二指肠处插第3根插管.采用胶原酶LibarseHI消化,Ficoll连续密度梯度离心法纯化.双硫腙染色,鉴定胰岛的纯度,并计算胰岛当量(IEQ).丫啶橙/溴乙啶荧光染色,计数活细胞百分率.体外葡萄糖刺激试验鉴定胰岛功能.结果 标准法的灌注量平均为0.71 ml/g胰腺,单管法的灌注量平均为0.96 ml/g胰腺,三管法的灌注量平均为1.24 ml/g胰腺,明显多于前两种方法(P＜0.05).标准法的胰岛收获量平均为1914 IEQ/g胰腺,单管法为2270 IEQ/g胰腺,三管法为2514 IEQ/g胰腺,单管法和三管法明显高于标准法(P＜0.05);其胰岛纯度/活性分别为74 ％/79.3％、75.6 ％/79.4％和78.3 ％/84.0％,三者间的差异无统计学意义.标准法所获得的胰岛胰岛素释放指数平均为3.46,单管法为4.74,三管法为5.27,单管法和三管法明显高于标准法(P＜0.05).结论不同的插管灌注方式对成人的胰岛分离有一定影响,三管法有利于提高胰腺灌注量,增加胰岛的收获量.     

大鼠胰岛移植物制备与异种移植

增加胰岛收获量，提高胰岛纯度一直是胰岛移植中面临的重要问题，本实验经胰管注射胶原酶，胰静止消化分离成年大鼠胰岛纯度一直是胰岛葡聚糖离心纯化。纯化后胰岛收获量为６１０－８２０个／胰纯度达９２％；胰岛形态结构完整，内分泌细胞超微结构保持良好，对葡萄糖刺激反应胰岛素释放量是基本分泌水平的８倍；异种移植可逆转实验性糖尿病小鼠的高血糖达一周。     

大鼠胰岛细胞转染Wee1Hu基因延长异种胰岛细胞移植后存活时间

目的 探讨大鼠胰岛细胞转染Wee1Hu基因对异种胰岛细胞移植后存活时间的影响。方法 以Wistar大鼠为供者，Balb／c糖尿病小鼠为受者，进行异种胰岛细胞移植。实验分为2组，每组20只。实验组：将转染Wee1Hu基因的1×10^6个供者胰岛细胞悬于0．5ml无菌生理盐水中，注射至受者的腹腔；空白对照组：将1×10^6个空载体胰岛细胞用与实验组相同的方法注射至受者腹腔。实验组和空白对照组的部分受者在移植前1周腹腔注射降植烷0．5ml，并于胰岛细胞移植后开始口服环孢素A30mg／kg，直至实验结束。监测2组胰岛细胞移植后的胰岛素释放功能及存活时间。结果 胰岛细胞移植后，空白对照组的受者均维持高血糖，且体重持续下降，平均生存时间为（18±2．5）d；实验组的受者血糖在2d内均降至正常，且体重增加，生存时间延长（38±3．5）d；两组相比较，差异有统计学意义（P〈0．05）。空白对照组维持正常血糖时间为（8±2．3）d，而实验组为（10±2．5）d。实验组中采用免疫抑制剂治疗的受者，长期维持正常血糖，平均维持时间超过30d，与空白对照组中采用免疫抑制剂治疗的受者比较，差异有统计学意义（P〈0．05）。结论 大鼠胰岛细胞转染Wee1Hu基因可延长异种胰岛细胞移植后的存活时间，与免疫抑制剂协同作用时效果更佳。     

Isolation of the elusive pig islet

This study describes a procedure for large scale isolation of swine islets. The reported results are from 15 consecutive isolations. The glands were removed from live animals with no warm ischemia, and the pancreata were digested by a modification of the automated method for human islet isolation. It was possible to separate an average of 690,000 +/- 279,429 islets per pancreas corresponding to 10,360 +/- 4034 islets per gram of pancreas with a volume of 714 +/- 480 mm3. After purification the recovery was 255,000 +/- 32,407 islets corresponding to 4,000 +/- 567 islets per gram of pancreas. Purity of the final preparation was 80% to 95% islets. Insulin content resulted in an average of 146.8 +/- 78 U before purification and 71 +/- 53 U after purification. After a 10 mm3 aliquot of the final preparation was transplanted under the renal subcapsular space of seven nude mice with diabetes, normoglycemia occurred in six of the mice. Thirty days after transplantation, nephrectomy of the kidneys bearing the grafts produced a rapid return to the diabetic state in all cases. This method makes it possible to provide large numbers of intact swine islets for preliminary studies of prevention of the rejection of pig islet xenograft by immunoalteration and immunoisolation procedures.     

Structural and functional abnormalities in the islets isolated from type 2 diabetic subjects

Type 2 diabetic subjects manifest both disordered insulin action and abnormalities in their pancreatic islet cells. Whether the latter represents a primary defect or is a consequence of the former is unknown. To examine the beta-cell mass and function of islets from type 2 diabetic patients directly, we isolated islets from pancreata of type 2 diabetic cadaveric donors (n = 14) and compared them with islets from normal donors (n = 14) matched for age, BMI, and cold ischemia time. The total recovered islet mass from type 2 diabetic pancreata was significantly less than that from nondiabetic control subjects (256,260 islet equivalents [2,588 IEq/g pancreas] versus 597,569 islet equivalents [6,037 IEq/g pancreas]). Type 2 diabetic islets were also noted to be smaller on average, and histologically, islets from diabetic patients contained a higher proportion of glucagon-producing alpha-cells. In vitro study of islet function from diabetic patients revealed an abnormal glucose-stimulated insulin release response in perifusion assays. In addition, in comparison with normal islets, an equivalent number of type 2 diabetic islets failed to reverse hyperglycemia when transplanted to immunodeficient diabetic mice. These results provide direct evidence for abnormalities in the islets of type 2 diabetic patients that may contribute to the pathogenesis of the disease.     

Porcine Pancreatic Islets: Isolation, Microencapsulation, and Xenotransplantation

Abstract: To provide a plentiful source of pancreatic islets for future clinical transplants into diabetic patients, we have developed a simple and reliable method to isolate porcine islets of a high degree of purity. Porcine pancreata were perfused and digested with collagenase, and the islets were then purified on dextran density gradients. In order to avoid any damage to the islets, no mechanical devices nor any strenuous treatment was employed. As many as 5 times 10⁵ islets were isolated from a single porcine pancreas. Islets were encapsulated in alginate-polylysine-alginate membranes with the aid of an electrostatic droplet generator. In vitro studies demonstrated that the isolated islets secreted insulin in response to glucose and 3-isobutyl-L-methylxanthine (IBMX) challenge for at least 4 weeks. Perifusion studies showed that the kinetics of insulin release from the encapsulated islets was similar to that exhibited by free islets. In in vivo studies, 18 diabetic BALB-c mice were transplanted with 1,500-2,500 encapsulated islets each. In 13 recipients, the diabetic condition was reversed for at least 85 days. When capsules were removed from 2 transplant recipients, their diabetic condition quickly recurred.     

Transplantation of porcine islets in nude mice: Implications for islet replacement therapy in humans

Abstract: Porcine islets obtained from adult donors were transplanted under the kidney capsule of streptozotocin diabetic nude mice. Over a period of 30 days or more, blood glucose levels fell to values lower than those of normal mice but comparable to those of normal pigs; this change in the mice was probably being driven by a lower set point for glucose-induced insulin secretion of porcine islets. Oral and intraperitoneal glucose tolerance tests had lower glucose profiles than those carried out in control mice. The mass of beta cell tissue in the porcine islet graft that cured the diabetes was about 1 mg, close to the normal beta cell mass of a mouse pancreas. When graft-bearing kidneys were perfused in situ, there was a marked increase of insulin secretion to challenges with glucose and arginine. These results suggest that porcine islets could be a good source of tissue for human islet replacement therapy. Some of the ramifications of this possibility are discussed.     

Gene transfer of constitutively active Akt markedly improves human islet transplant outcomes in diabetic severe combined immunodeficient mice

Akt is an important intracellular mediator of beta-cell growth and survival in rodents. However, whether constitutive activation of Akt in human beta-cells enhances the survival and function of transplanted islets is unknown. In the current study, we examined the efficacy of constitutive activation of Akt in improving human islet transplant outcomes using a marginal mass model in diabetic severe combined immunodeficient (SCID) mice. Human islets transduced with adenoviruses encoding constitutively active Akt1 (Adv-CA-Akt) displayed increased total and phosphorylated Akt and Akt kinase activity compared with control islets. Expression of CA-Akt in human islets induced a significant increase in beta-cell replication and a significant decrease in beta-cell death induced by serum and glucose deprivation or chronic hyperglycemia. Two control groups of islets (1,500 uninfected or adenovirus LacZ [Adv-LacZ]-transduced human islet equivalents [IEQs]) transplanted under the kidney capsule of streptozotocin-induced diabetic SCID mice were insufficient to correct hyperglycemia. Importantly and in marked contrast to these controls, 1,500 Adv-CA-Akt-transduced IEQs were capable of restoring euglycemia in diabetic SCID mice. Moreover, blood glucose normalization persisted for at least 6 months. Human plasma insulin at day 54 after transplant was 10-fold higher in Adv-CA-Akt islet recipients (2.4 +/- 0.4 ng/ml) compared with those receiving Adv-LacZ islets (0.25 +/- 0.08 ng/ml) (P < 0.05). In summary, expression of CA-Akt in human islets improves islet transplant outcomes in a subcapsular renal graft model in SCID mice. Akt is an attractive target for future strategies aimed at reducing the number of islets required for successful islet transplantation in humans.     

Histologic differentiation of human fetal pancreatic explants transplanted into nude mice

The transplantation of human fetal pancreas has been suggested as a means of treatment of insulin-dependent diabetes in man. We have obtained human fetal pancreata during the second trimester of pregnancy and transplanted 1-mm3 explants subcutaneously (s.c.) into both diabetic and nondiabetic nude mice, some of the tissue being cultured in vitro before implantation. These implants coalesced and grew. They were removed at intervals up to 37 wk later and showed selective differentiation of endocrine tissue that normally occurs in the fetus and neonate, with formation of bipolar, mantle, and mature islets. There was growth of this endocrine tissue with significantly more islets than in the freshly stained fetal pancreas assuming an average dimension larger than 150 micron, which is the reported mean diameter of a neonatal islet. Duct and fibrous tissue remained viable, but there was no definitive acinar tissue seen. The pancreata uncultured before implantation reached a larger size than that attained by those implants cultured before being transplanted, the difference probably being the amount of ductular and mesenchymal tissue still present. Of those glands cultured before transplantation, the longer the period of culture, the smaller the size the implants reached. Culture beyond 3 wk in vitro made it difficult to macroscopically locate the implant. These data show that, in human fetal pancreas removed from its usual environment, both selective differentiation of the endocrine component and growth of the islets can occur.     

Influence of pancreas preservation on human islet isolation outcomes: impact of the two-layer method

BACKGROUND: Human pancreas preservation for islet transplantation holds additional challenges and considerations compared with whole pancreas transplantation. The purpose of this study was to clarify the limitations of the University of Wisconsin (UW) solution and the potentials of the two-layer method (TLM) for pancreas preservation before human islet isolation. METHODS: We retrospectively evaluated human islet isolation records between January 2001 and February 2003. One hundred forty-two human pancreata were procured from cadaveric donors and preserved by means of the UW solution (n=112) or TLM (n=30). Human islet isolations were performed using a standard protocol and assessed by islet recovery and in vitro function of islets. RESULTS: Eight to ten hours of cold ischemia in the UW solution is a critical point for successful islet isolations. It is difficult to recover a sufficient number of viable islets for transplantation from human pancreata with more than 10 hours of cold storage in the UW solution. The overall islet recovery in the TLM group was significantly higher than in the UW group. With 10 to 16 hours of cold storage, the success rates of islet isolations remained at 62% in the TLM group but decreased to 22% in the UW group. Transplanted islets in the TLM group worked well in the recipients. CONCLUSIONS: There are time limitations for using the UW solution for pancreas preservation before human islet isolation. The TLM is a potential method to prolong the optimal cold storage time for successful islet isolations.