成人胰腺干细胞分离及转分化为胰岛的研究

目的 通过对成人胰腺干细胞分离和转分化为胰岛过程的研究以便更进一步了解及改进胰腺干细胞分离、培养、鉴定方法。方法 成人胰腺组织以胶原酶消化，密度梯度离心法获得纯化的胰腺外分泌细胞、导管上皮细胞和胰岛。导管上皮细胞在体外共培养27d，观察细胞形态学变化及干细胞特异性转录基因PDX—1，CK—19蛋白等的表达。结果 上述方法可获得大量胰腺导管上皮细胞。体外培养第1天即可见PDX—1，CK—19阳性细胞，胰腺导管上皮细胞迅速分裂增殖并转变为有分化能力的干细胞继而转分化为三维结构的胰岛细胞。培养27d后，平均每克胰腺组织可生成760个胰岛。结论 用改进的方法可获得大量成人胰腺导管上皮细胞，并可在体外转分化为大量具有内分泌功能的胰岛，可能为克服胰岛移植的供体短缺提供一条新途径。     

胰岛发育和胰腺干细胞研究进展

胰腺移植手术可使糖尿病患者得到治愈,但供体不足成为制约其开展的瓶颈.胰腺干细胞移植治疗糖尿病是极具潜力的治疗方案,有希望克服尸体胰岛移植供体不足和需免疫抑制治疗的缺陷.众多研究者尝试利用不同来源的干细胞分化或转分化形成胰岛或β细胞,并努力寻找胰腺干细胞的特异性标志以确证和分离纯化胰腺干细胞.本文综述了近年胰岛发育和胰腺干细胞研究领域的一些研究进展.     

糖尿病小鼠胰腺干细胞转分化为胰岛样细胞

目的 观察链脲佐菌素所致糖尿病小鼠胰腺干细胞是否能转分化为胰岛样细胞.方法 以链脲佐菌素建立糖尿病小鼠模型,分离培养其胰腺导管上皮细胞,经体外扩增及诱导培养后,以细胞免疫化学方法检测PDX1表达,行STZ染色和葡萄糖刺激的胰岛素释放试验鉴定其功能.结果 糖尿病小鼠胰腺干细胞经体外培养和诱导分化后,PDX1阳性,并形成胰岛样细胞团;胰岛样细胞对高糖刺激(15.0 mmol/L)的胰岛素释放较低糖(5.6 mmol/L)时增加了1.4倍(37.2±11.2比25.9±7.6,t =2.830,P＜0.05),DTZ染色阳性.结论 链脲佐菌素所致糖尿病小鼠胰腺干细胞在体外培养条件下可转分化为胰岛素分泌细胞.     

PDX-1促进大鼠胰腺导管上皮细胞向胰岛细胞分化的研究

胰岛移植是治疗I型糖尿病的有效手段,但胰岛来源的不足限制了胰岛移植的临床应用[1].我们采用含PDX-1(蟾蜍同系物XIHbox8)的真核表达载体体外转染大鼠胰腺导管上皮细胞,诱导其分化为胰岛β细胞,探讨外源性PDX-1在胰腺导管上皮细胞向β细胞定向分化中的作用.     

子鼠胰腺干细胞与胰岛联合移植治疗糖尿病

目的 探讨利用子鼠胰腺干细胞与胰岛联合移植保护移植胰岛,提高糖尿病移植疗效的可行性.方法 分离纯化孕16 d SD大鼠子鼠:胰腺干细胞培养传代,行Nestin免疫组织化学及流式细胞术鉴定;分离纯化SD大鼠胰岛,分联合移植组(10只)、单独移植组(10只)及正常对照组(10只),分别将2×105个子鼠:胰腺干细胞与800个胰岛和单纯800个胰岛移植至糖尿病大鼠模型左肾包膜下,定期监测各组大鼠血糖情况及留取血浆ELISA测胰岛素含量,观察胰岛存活时间.结果 子鼠:胰腺干细胞培养传代3代后细胞涂片免疫组织化学示存在Nestin阳性细胞,流式细胞术测定nestin阳性细胞含量占74.1%.联合移植组大鼠均于术后第3天起血糖开始下降,血浆胰岛素水平逐渐升高,术后5 d内血糖可降至正常[(5.4±0.6)mmol/L],血浆胰岛素达到正常水平[(509.8±16.6)ng/L],胰岛存活时间(18.2±2.4)d;单独移植组大鼠血糖可于术后1周内降至正常[(6.1±0.9)mmol/L],胰岛存活时间(14.4±2.1)d;两组胰岛存活时间差别有统计学意义(P《0.05).结论 子鼠胰腺干细胞与胰岛联合移植可保护胰岛功能,延长胰岛体内存活时间,提高移植疗效.     

成人胰腺干细胞转分化为胰岛的研究

目的：通过对成人胰腺干细胞转分化为胰岛过程的研究以便更深入了解及改进胰腺干细胞分离、培养、鉴定方法。方法：成人胰腺组织经胶原酶消化后,用密度梯度离心法将胰腺外分泌细胞、导管上皮细胞和胰岛分离、纯化,导管上皮细胞即具有转分化潜能的干细胞,在体外先后以CMRL1066和无血清DMEM／F12培养液共培养27d,在培养的不同时间点取样本于光镜和电镜下观察细胞形态学变化及干细胞特异性转录基因PDX－1,CK－19蛋白等单抗的免疫组化染色,并测定培养液中的淀粉酶和胰岛素含量。结果：上述方法可获得大量以往在胰岛分离时丢弃的胰腺导管上皮细胞。经体外一定条件的培养后,第1天即可见PDX－1,CK－19阳性细胞,胰腺导管上皮细胞迅速分裂增殖并转变为有分化能力的干细胞继而转分化为三维结构的胰岛细胞。培养27d后,平均每克胰腺组织可生成760个胰岛。结论：成人胰腺的导管上皮具有干细胞潜能并可在体外转分化为大量具有内分泌功能的胰岛,用此方法获得大量的胰岛可能为克服胰岛移植的供体短缺提供一条新的途径。     

大鼠胰腺导管上皮细胞体外分离与定向分化

目的分离和纯化大鼠的胰腺导管上皮细胞，在体外培养并诱导其向胰岛细胞定向分化。方法采用胶原酶逆行灌注法消化、密度梯度离心结合不同细胞贴壁差异性分离和纯化胰腺导管上皮细胞；以角蛋白-19（CK-19）免疫细胞化学染色进行鉴定；用RMPI1640＋含体积分数为10％的胎牛血清（FBS）培养基培养促进胰导管上皮细胞增殖，1周后，更换无血清培养基DMEM／F12并加入角朊细胞生长因子等进一步促进其增殖，细胞达80％汇合时传代，加入高糖及尼克酰胺促进胰导管上皮细胞向胰岛细胞定向分化；对胰岛样结构行双硫腙染色。结果CK-19染色结果证实所获细胞绝大多为导管上皮细胞。体外培养中导管上皮细胞24h开始贴壁，14-21d达80％融合并形成细胞克隆，第28d胰岛细胞样结构形成，且被双硫腙染成猩红色。结论采用密度梯度离心结合差异贴壁法可获得纯化的大鼠胰腺导管上皮细胞，在体外培养与诱导分化条件下可生成胰岛样结构。     

骨髓基质干细胞及其来源的产胰岛素细胞移植对受体胰岛和新生血管的影响

目的 观察骨髓基质干细胞(MSCs)及其来源的产胰岛素细胞(IPCs)移植对受体残余胰岛和其周围新生血管增殖的影响.方法 对大鼠MSCs进行体外诱导成为IPCs.对1型糖尿病大鼠随机分为胰岛素控制血糖组(对照组)、MSCs移植组及IPCs移植组3个治疗组(每组10只).至血糖开始下降至10mmoL/L,同期移除3组大鼠右肾及胰腺,分别进行PCNA、胰岛素和CD31抗体染色,观察3组大鼠肾脏和胰腺的胰岛素及血管内皮细胞表达情况.结果 MSCs诱导生成IPCs.移植物:移植侧的右肾均可见到较多的胰岛素和CD31阳性细胞.胰腺组织:(1)对照组:胰岛萎缩.(2)细胞移植组:残余胰岛增殖率:(20.84±3.48)%和(18.43±2.84)%(P>0.05),胰岛周围均有少量CD31阳性细胞.结论 MSCs及其来源的IPCs明显促进了受体残余胰岛周围新生血管的生成,进而使残余胰岛得到增殖,而MSCs在体内也可分化成IPCs和血管内皮细胞.     

成人胰腺干细胞转分化为胰岛细胞过程中的形态学观察

目的：观察成人胰腺干细胞转化化为胰岛过程中的形态学变化，以便更深入了解有关机制。方法：人胰腺组织经胶原酶消化后，用梯度离心法将胰腺外分泌细胞和胰岛分离，混于外分泌组织中的导管上皮细胞即具有转分化潜能的干细胞。在体外经CMRL1066及不含血清的DMEM／F12加多种营养因子的培养液中培养27d，在培养的不同时间点取细胞作PDX－1、CK－19等单抗的免疫组化染色。光镜和电镜观察不同时间点的形态学变化。结论：上述方法可获得大量以往在胰岛分离时丢弃的胰腺导管上皮细胞。经体外一定条件的培养后，其形态学变化过程为：导管上皮细胞迅速分裂增殖转变为有分化能力的干细胞继而转分化为胰岛细胞。结论：成人胰腺的导管上皮具有干细胞潜能，并可在体外转分化为大量具有内分泌功能的胰岛。用此方法获得大量的胰岛可能为克服胰岛移植的供体短缺提供一条新的途径。     

大鼠胰腺干细胞转分化为胰岛样细胞簇的研究

胰岛细胞来源有限，且受到伦理及免疫排斥等因素的制约，极大地限制了胰岛移植治疗糖尿病在临床上的广泛应用。成体干细胞能避开上述缺陷，且其可塑性为临床应用提供了可能。我们进行了将大鼠胰腺干细胞转分化为胰岛样细胞簇的研究，现报告如下。     

胰腺导管上皮细胞来源的胰岛样细胞移植治疗1型糖尿病

目的 观察小鼠胰腺导管上皮细胞向胰岛样细胞转分化及其在治疗糖尿病小鼠中的作用.方法 分离培养昆明小鼠胰腺导管上皮细胞,经体外扩增及诱导培养后,进行体外和体内功能评价.结果 小鼠胰腺导管上皮细胞经体外扩增和诱导分化后,逆转录-聚合酶链反应(RT-PCR)显示培养1周和2周后胰岛素mRNA的IA值为(1.892±0.119比3.135±0.092,P＜0.05),胰高血糖素为(1.564±0.087比2.271±0.042,P＜0.05),表达明显上调;胰岛样细胞对高糖刺激(15.0 mmol/L)的胰岛素释放较低糖(5.6 mmol/L)时增加了1.7倍[(52.3±10.5)mmol/L比(30.2±9.7)mmol/L,P＜0.05];DTZ染色阳性;将其移植入糖尿病小鼠体内后,移植组小鼠较对照组血糖下降,差异有统计学意义(P＜0.05).结论 昆明小鼠胰腺导管上皮细胞在体外培养条件可转分化胰岛素分泌细胞,该细胞团可在体内环境下发挥生物学功能.

Abstract：

Objective To investigate the differentiation of stem cells deived from mouse pancreatic ductal epithelial cells toward insulin secreting cells and the potential application for diabetes therapy.Methods Pancreatic ductal epithelial cells were separated and differentiated into islet-like cells. Study was performed to determine whether these islet-like clusters could secrete insulin in response to glucose both in vivo and in vitro. Results Pancreatic ductal epithelial cells were separated and cultured in vitro.The expression of insulin mRNA in the stem cells was significantly up-regulated ( 1. 892 ±0. 119 vs 3. 135± 0. 092,P ＜ 0. 05 ), and also in glucagon ( 1. 564 ± 0. 087 vs 2. 271 ± 0. 042, P ＜ 0. 05 ). Immunofluoresence staining indicated that there were a lot of insulin positive cells. Insulin released from cells in response to glucose stimulation in vitro was increased [ ( 52. 3 ± 10. 5 ) mmol/L vs ( 30. 2± 9. 7 ) mmol/L, P ＜0. 05 ]. Hyperglycemia in diabetic animals was alleviated after cell transplantation. Conclusion Islet-like cell clusters generated in vitro from Kunming mice pancreatic ductal epithelial cells could secrete insulin and have some effects on reversing the diabetes in diabetic mice.     

胚胎胰腺原基同种和异种移植

胰腺、胰岛和胚胎干细胞移植等用于治疗糖尿病各有优缺点。胰腺原基移植是目前的一种新尝试。由于胰腺原基拥有分化潜能高的β细胞团前体细胞,具有产生大量胰岛素的潜力,且具有低免疫原性、未血管化等特点,移植后能使免疫功能正常的动物血糖水平得到长时间控制。特别是利用猪胰腺原基植入灵长类动物肠系膜,可在不使用免疫抑制剂的情况下跨越异种移植屏障,甚至产生免疫耐受,为人类糖尿病的治疗提供了一种新思路。     

Donor islet endothelial cells participate in formation of functional vessels within pancreatic islet grafts

Pancreatic islet transplantation has emerged as a therapy for type 1 diabetes and is today performed using both freshly isolated and cultured islets. Islet blood vessels are disrupted during islet isolation; therefore, proper revascularization of the transplanted islets is of great importance for islet graft function and survival. We have studied intraislet endothelial cells after islet isolation, during islet culture, and following islet transplantation. By isolating islets from the transgenic Tie2-GFP (green fluorescent protein) mouse, characterized by an endothelial cell-specific expression of GFP, living endothelial cells could be studied in intact islets utilizing two-photon laser-scanning microscopy (TPLSM). Intraislet endothelial cells were found to survive islet transplantation but to rapidly disappear during islet culture. By transplanting freshly isolated Tie2-GFP islets and applying a novel ex vivo model for simultaneous perfusion and TPLSM imaging of the graft-bearing kidneys, GFP fluorescent endothelial cells were found to extensively contribute to vessels within the islet graft vasculature. Real-time imaging of the flow through the islet graft vasculature confirmed that the donor-derived vessels were functionally integrated. Hence, intraislet endothelial cells have the capability of participating in revascularization of pancreatic islets subsequent to transplantation. Therefore, preservation of intraislet endothelial cell mass may improve long-term graft function.     

Potential role of mesenchymal stromal cells in pancreatic islet transplantation

Pancreatic islet transplantation is an attractive option for treatment of type 1 diabetes mellitus but maintaining long term islet function remains challenging. Mesenchymal stromal cells (MSCs), derived from bone marrow or other sources, are being extensively investigated in the clinical setting for their immunomodulatory and tissue regenerative properties. Indeed, MSCs have been already tested in some feasibility studies in the context of islet transplantation. MSCs could be utilized to improve engraftment of pancreatic islets by suppressing inflammatory damage and immune mediated rejection. In addition to their immunomodulatory effects, MSCs are known to provide a supportive microenvironmental niche by secreting paracrine factors and depositing extracellular matrix. These properties could be used for in vivo co-transplantation to improve islet engraftment, or for in vitro co-culture to prime freshly isolated islets prior to implantation. Further, tissue specific pancreatic islet derived MSCs may open new opportunities for its use in islet transplantation as those cells might be more physiological to pancreatic islets.     

Combination therapy with glucagon-like peptide-1 and gastrin induces beta-cell neogenesis from pancreatic duct cells in human islets transplanted in immunodeficient diabetic mice

Pancreatic islet transplantation as a treatment for type 1 diabetes is limited by human donor tissue availability. We investigated whether the beta-cell mass in human isolated islets could be expanded by treatments with glucagon-like peptide-1 (GLP-1) and gastrin, peptides reported to stimulate beta-cell growth in mice and rats with deficits in beta-cell mass. Human islets with low endocrine cell purity (7% beta-cells, 4% alpha-cells) and abundant exocrine cells (29% duct cells and 25% acinar cells) were implanted under the renal capsule of nonobese diabetic-severe combined immune deficiency (NOD-scid) mice made diabetic with streptozotocin. The mice were treated with GLP-1 and gastrin, separately and together, daily for 5 weeks. Blood glucose was significantly reduced only in mice implanted with human pancreatic cells and treated with GLP-1 plus gastrin. Correction of hyperglycemia was accompanied by increased insulin content in the human pancreatic cell grafts as well as by increased plasma levels of human C-peptide in the mice. Immunocytochemical examination revealed a fourfold increase in insulin-positive cells in the human pancreatic cell grafts in GLP-1 plus gastrin-treated mice, and most of this increase was accounted for by the appearance of cytokeratin 19-positive pancreatic duct cells expressing insulin. We conclude that combination therapy with GLP-1 and gastrin expands the beta-cell mass in human islets implanted in immunodeficient diabetic mice, largely from pancreatic duct cells associated with the islets, and this is sufficient to ameliorate hyperglycemia in the mice.     

Experimental pancreatic islet transplantation.

Transplantation of isolated islets of Langerhans has been suggested as a treatment of certain forms of diabetes mellitus. Injection of 200-400 syngeneic pancreatic islets isolated by collagenase digestion into the pancreas or submandibular gland of diabetic rats rendered most of the hosts nearly normoglycaemic. Blood glucose determinations were monitored for 2 months after islet transplantation. Although intrapancreatic and intrasubmandibular implantation reduced hyperglycaemia and polyuria in these animals, consistent normal values were rarely achieved.     

Transplantation of cultured pancreatic islets to BB rats

Pancreatic islets held in tissue culture before transplantation into artificially induced diabetics are not rejected. In animals and human identical twin transplants, the autoimmunity of naturally occurring diabetes may destroy islets, even if rejection is avoided. Therefore we studied whether autoimmune damage of islets can be avoided by pretransplant culture. Recipients were BB rats, which spontaneously developed diabetes. Donors were either Wistar Furth (WF) (major histocompatibility [MHC] identical to BB rats) or Lewis (MHC nonidentical to BB rats). Islets were inoculated into the portal vein either immediately after isolation or after 14 days in tissue culture (95% air, 5% CO2, 24 degrees C). Recipients of cultured islets received a single injection of 1 ml of antilymphocyte serum at the time of transplant. Recurrence of diabetes after transplantation of freshly isolated MHC incompatible Lewis islets occurred rapidly on the basis of rejection or autoimmune damage (or both). Precultured Lewis islets had prolonged or permanent survival. Freshly isolated MHC compatible WF islets were destroyed, and no improvement was seen with culture. We conclude that autoimmune destruction of transplanted islets can be avoided by tissue culture, as can rejection. This is important because this strategy is effective only if recipient and donor differ at the MHC locus. Islet donors may need to be selected on the basis of disparity of histocompatibility factors.     

Generation of functional islet-like clusters after monolayer culture and intracapsular aggregation of adult human pancreatic islet tissue

BACKGROUND: Cellular replacement therapy represents a promising strategy for treating type I diabetes; however, such an approach is limited due to the inadequate availability of human donor tissue. Here we investigated the extent to which human islet tissue can be expanded in monolayer culture and brought back to islet function. METHODS: Adult human pancreatic cells were proliferated with a serum-free media in monolayer cultures through multiple passages. Expanded cells were dispersed and encapsulated in alginate-poly-l-lysine microcapsules wherein the cells spontaneously coalesced into islet-like clusters. Encapsulated cell clusters were subsequently transplanted into the peritoneal cavity of streptozotocin-induced diabetic severe combined immunodeficiency mice. RESULTS: The cultured monolayer cells secreted insulin in response to glucose stimulation and maintained endocrine gene expression. Encapsulated islet-like clusters displayed cellular architecture similar to freshly isolated and encapsulated adult human islets maintained in culture, exhibiting an immunoreactive core of insulin, glucagon, and somatostatin, as well as peripheral cytokeratin-19 staining. Encapsulated aggregates significantly reduced hyperglycemia in transplanted mice within 1 week and normoglycemia was achieved after 5 weeks. Human C-peptide was detected in transplanted mice concomitant with the reduction in hyperglycemia. Capsules recovered 8 weeks posttransplantation exhibited insulin immunoreactivity. CONCLUSIONS: Collectively, these data indicate that adult human pancreatic islet cells can be expanded by three serial passages while maintaining their endocrine properties and can yield functional islet-like cell clusters through intracapsular aggregation that reverse hyperglycemia in diabetic mice. This culture and aggregation process could serve as a platform for proliferation and differentiation studies of endocrine lineage cells.