CD56-positive cells with or without synaptophysin expression are recognized in the pancreatic duct epithelium: a study with adult and fetal tissues and specimens from chronic pancreatitis

We observed the distribution of CD56+ epithelial cells in the pancreatic duct system using 25 fetal, one infantile, 3 normal adult, 4 diabetic, and 8 chronically inflamed pancreatic tissue samples. In the early stage of gestation (12 to 17 weeks), CD56+ cells were commonly seen in the immature tubular structures. They were often continuous to pancreatic islets, and their distribution was similar to that of synaptophysin (Syn)+ cells, suggesting that they are precursors of islet neogenesis. Their number decreased in proportion to gestational age. Instead, from 24 weeks of gestation, luminal cell clusters that were common in interlobular ducts revealed CD56+. These cell clusters were unrelated to islet neogenesis and Syn expression. Similar CD56+ luminal cell clusters were also observed in cases of chronic pancreatitis, whereas they were scarce in normal adult and diabetic tissues. CD56+ cells were also occasionally seen in intralobular ducts, intercalated ducts, and centroacinar cells in cases of chronic pancreatitis. We conclude that there are two types of CD56+ epithelial cells in the pancreatic duct system: CD56+ endocrine cells are numerous during the early stage of gestation, when islet neogenesis appears, while CD56+ luminal cells may represent developmental and regenerative changes of pancreatic ducts.     

Hematopoietic stem cell therapy for type 1 diabetes: induction of tolerance and islet cell neogenesis

Diabetes is a chronic disease with significant morbidity and mortality. Pancreas or islet cell transplantation is limited by a shortage of donors and chronic immune suppression to prevent allograft rejection. Consequently, interest exists in islet cell neogenesis from embryonic or mesenchymal stem cell as a possible cure for diabetes. However, unless tolerance to islet cells is re-established, diabetes treated by islet cell transplantation would remain a chronic disease secondary to immune suppression related morbidity. If islet cell tolerance could be re-induced, a major clinical hurdle to curing diabetes by islet cell neogenesis may be overcome. Recent studies suggest that adult hematopoietic stem cells (HSC) can reintroduce tolerance to auto-antigens. It is possible that HSC may also be able to switch lineage and, therefore, be a convenient source of stem cells for both inducing tolerance and islet cell regeneration.     

Would pancreas duct-epithelium-derived stem/progenitor cells enhance islet allograft survival by means of islets recruitment and tolerance induction in Edmonton protocol era?

Rates of insulin independence at 1 year with current Edmonton protocol are impressive. However, obstacles such as the restricted availability of donor pancreas, coupled with recipient's pharmacologic immunosuppression, have lent strong impetus to the search for new sources of insulin-producing cells. But work with stem cells has not yet produced cells with the phenotype of true beta cells. Recently the data have shown that the presence of duct-epithelium in clinical islet transplantation may improve the long-term metabolic outcome. The underlying mechanisms are not well understood. The pancreatic duct-epithelium has been considering as a pool of pancreatic stem/progenitor cells, cytokeratin-19 positive stem cells, which have been proved to be capable of differentiating into endocrine cells and inducing immune tolerance. Based on these findings, we speculate that pancreatic stem/progenitor cells derived from ductal epithelium may enhance islet allograft survival through two aspects: islet recruitment and tolerance induction. The proposition may have clues on the further improvement in clinical islet transplantation long-term outcome.     

Regional differences in the cellular proliferation activity of the regenerating rat pancreas after partial pancreatectomy

The proliferation activity of component cells and its regional differences in the regenerating rat pancreas after 90% pancreatectomy were examined by bromodeoxyuridine (BrdU) immunohistochemistry. Cells of the ductal system and the centroacinar cells showed a rapid increase in labeling indices at day 2 after pancreatectomy, followed by a second peak of a mild increase at days 5 to 7. No regional difference in the labeling index was recognized in the ductal elements. In contrast, the labeling index of acinar cells started to increase at day 3, reaching a definite peak at day 5. Furthermore, acinar cells in the region close to the duodenum had labeling indices more than 2 times higher than those in the portions further away from the duodenum. Acinar cells increased in number as early as from day 3 after surgery. These result suggested that the parental cells of regeneration were located in the ductal epithelium. It is highly probable that the proliferation of acinar cells is controlled by some unknown trophic factor(s) which is released locally from the duodenum, but does not involve a neural or a circulatory route. The phenomenon may be closely linked to the known fact that the incidence of pancreatic cancer is highest in the head region.     

骨髓间充质干细胞及与胰岛细胞共移植治疗糖尿病

背景：药物是目前糖尿病治疗最主要的方法,但病情的进展以及相关并发症的发生使药物的作用受到挑战。 目的：探讨骨髓间充质干细胞与胰岛细胞共移植治疗糖尿病的应用效果以及可行性。 方法：分离、纯化大鼠骨髓间充质干细胞并进行体外培养,建立糖尿病模型,对糖尿病模型大鼠分别注射骨髓间充质干细胞、骨髓间充质干细胞和胰岛细胞共培养混合物以及生理盐水或磷酸盐缓冲液作为对照。通过观察监测各糖尿病模型大鼠血糖水平的变化、胰岛素分泌情况以及胰腺组织的病理学变化评估移植治疗效果。 结果与结论：骨髓间充质干细胞移植治疗糖尿病模型大鼠,移植后C-肽值明显升高,血糖水平明显下降,但仍未降至正常范围内,且随着时间的延长,血糖水平再次升高。骨髓间充质干细胞与胰岛细胞共移植治疗糖尿病模型大鼠,血糖水平亦明显下降,且下降程度大于单纯骨髓间充质干细胞移植治疗,可下降至正常水平,并在一定时间内能够维持。骨髓间充质干细胞与胰岛细胞共移植治疗糖尿病具有一定的效果,具有应用的可行性。     

干细胞移植治疗糖尿病的国内外研究趋势分析

背景：糖尿病是一种特异性针对胰岛β细胞的自身免疫性疾病,可以通过胰腺移植或胰岛移植达到治疗效果,由于供体困难和排斥反应限制了临床应用。 目的：对干细胞移植治疗糖尿病研究文献的发展趋势进行多层次探讨分析。 方法：对中国CNKI数据库学术期刊和Web of Science数据库2002/2011收录有关干细胞移植治疗糖尿病研究的文献进行分析,运用数据库的分析功能和Excel软件图表的功能分析数据特征。并对CNKI数据库收录不同干细胞移植治疗糖尿病研究的文献进行分析。 结果与结论：CNKI数据库学术期刊2002/2011共收录128篇与干细胞移植治疗糖尿病研究相关的文献,Web of Science数据库共收录725篇相关文献,文献数量均处于逐年上升的趋势。CNKI数据库收录的文献主要以骨髓间充质干细胞、胰腺干细胞和造血干细胞的研究最多。文献的学科类别均以内分泌代谢分类为主。Web of Science数据库收录发文量较多的来源期刊和相关机构的文献数量均多于CNKI数据库,发文量较多的国家是美国。中国的国家自然科学基金在干细胞移植治疗糖尿病研究领域做出重要贡献。     

Cytokeratins and cell differentiation in the pancreas

Keratins, or cytokeratins, represent a family of more than 20 different polypeptides which are important markers of epithelial cell differentiation. This review deals with the use of keratin immunohistochemistry in the study of pancreatic cell differentiation. Exocrine acinar cells and endocrine islet cells are well-differentiated cells which express the keratin combination 8 and 18, whereas the less-differentiated cells of the ductal tree are characterized by the additional expression of keratin 7, keratin 19, and, in the rat, keratin 20. Keratin expression is stable and can be used for cell identification after isolation and culture, and in clinical or experimental injury. The intercalated ductal cells and centroacinar cells are inconspicuous unless specific immunohistochemical markers, such as keratins, are used. In conditions where there is morphogenetic differentiation such as in fetal life, or where transdifferentiation is occurring, keratins have been used to trace the origin and fate of pancreatic cells. © 1998 John Wiley & Sons, Ltd.     

Human marrow-derived mesodermal progenitor cells generate insulin-secreting islet-like clusters in vivo

Transplantation of pancreatic islet cells is the only known potential cure for diabetes mellitus. However, the difficulty in obtaining sufficient numbers of purified islets for transplantation severely limits its use. A renewable and clinically accessible source of stem cells capable of differentiating into insulin-secreting beta-cells might circumvent this limitation. Here, we report that human fetal bone marrow (BM)-derived mesodermal progenitor cells (MPCs) possess the potential to generate insulinsecreting islet-like clusters (ISILCs) when injected into human fetal pancreatic tissues implanted in severe combined immunodeficiency (SCID) mice. Seven essential genes involved in pancreatic endocrine development, including insulin, glucagon, somatostatin, pdx-1, glut-2, nkx 2.2, and nkx 6.1, are expressed in these BM-MPC-derived ISILCs, suggesting that ISILCs are generated through neogenesis of BM-MPCs. Our data further suggest that differentiation of BM-MPCs into ISILCs is not mediated by cell fusion. Insulin secretion from these ISILCs is regulated by glucose concentration in vitro, and transplantation of purified ISILCs normalizes hyperglycemia in streptozocin (STZ)- induced nonobese diabetic (NOD)/SCID mice.     

The expression of pancreatic endocrine markers in centroacinar cells of the normal and regenerating rat pancreas: their possible transformation to endocrine cells

To determine the progenitor nature of centroacinar cells (CACs), we attempted to compare the expression pattern of endocrine cell markers and PDX-1 (pancreatic duodenal homeobox gene 1) in CACs of both the quiescent and the regenerating rat pancreas. In the normal pancreas, most CACs were relatively small cells with sparse cytoplasm and oval or elongated nuclei. In addition, we noticed a distinct population of a small number of large cells with round nuclei in the centroacinar region. By immunohistochemistry, 0.21% and 0.3% of CACs in normal rat pancreas were respectively found positive for glucagon and insulin, being large CACs and designated as GL-CAC and IL-CAC. They also exhibited the mRNA of each hormone by in situ hybridization (ISH). The ISH signal for glucagon but not insulin was also detected in a subset of small CACs (designated GS-CAC). The expression of PDX-1 was also observed in subsets of small and large CACs (PS-CAC and PL-CAC, respectively). After a 90% pancreatectomy, the relative frequency for GS-CACs, but not those for other CACs, was significantly reduced in two days after surgery. On day 7 after surgery, the number of GS-CACs recovered to preoperative levels, whereas GL-CACs, IL-CACs, PS-CAC, and PL-CAC gradually increased to about double in number. From these results, a portion of CACs was suggested to differentiated into endocrine cells. A possible cell lineage is discussed for endocrine neogenesis during pancreatic regeneration.     

Differential distribution of fibroblast growth factor (FGF)-7 and FGF-10 in L-arginine-induced acute pancreatitis

The regenerative process of the pancreas after acute pancreatitis (AP) is characterized by acinar and ductal cell proliferation with synthesis and transient deposition of extracellular matrices. Various growth factors were reported to be highly expressed in AP, but their regulation has not yet been clarified. Fibroblast growth factor (FGF)-7, also known as keratinocyte growth factor (KGF), and FGF-10 are members of the FGF family and show high structural homology and similar biological characteristics. Both are mainly synthesized by mesenchymal cells and stimulate epithelial cells via KGF receptor (KGFR) which is a splice variant of FGFR-2. In the present study, we attempted to immunohistochemically determine the localization of FGF-7 and FGF-10 in pancreatic tissues of an L-arginine-induced rat pancreatitis model. Furthermore, highly specific KGFR antibodies were prepared and used for Western blot analysis and immunohistochemistry. In the normal pancreas, FGF-7 was localized in alpha cells of islets, but FGF-10 was not detected. KGFR was also localized in islet cells, ductal cells, and centroacinar cells in the normal pancreas. In the pancreatic tissues of rats with L-arginine-induced pancreatitis, FGF-7 was localized in alpha cells, whereas FGF-10 was expressed in vascular smooth muscle cells (VSMCs). KGFR was not expressed in centroacinar cells and its level decreased after L-arginine treatment. However, KGFR was detected instead in some acinar cells and VSMCs in addition to islet cells. These findings suggest that FGF-7 and FGF-10 contribute to the regeneration and differentiation of acinar cells and angiogenesis in AP through KGFR.     

Islets of Langerhans from prohormone convertase‐2 knockout mice show α‐cell hyperplasia and tumorigenesis with elevated α‐cell neogenesis

Antagonism of the effects of glucagon as an adjunct therapy with other glucose‐lowering drugs in the chronic treatment of diabetes has been suggested to aggressively control blood glucose levels. Antagonism of glucagon effects, by targeting glucagon secretion or disabling the glucagon receptor, is associated with α‐cell hyperplasia. We evaluated the influence of total glucagon withdrawal on islets of Langerhans using prohormone convertase‐2 knockout mice (PC2‐ko), in which α‐cell hyperplasia is present from a young age and persists throughout life, in order to understand whether or not sustained glucagon deficit would lead to islet tumorigenesis. PC2‐ko and wild‐type (WT) mice were maintained drug‐free, and cohorts of these groups sampled at 3, 12 and 18 months for plasma biochemical and morphological (histological, immunohistochemical, electron microscopical and image analytical) assessments. WT mice showed no islet tumours up to termination of the study, but PC2‐ko animals displayed marked changes in islet morphology from α‐cell hypertrophy/hyperplasia/atypical hyperplasia, to adenomas and carcinomas, these latter being first encountered at 6–8 months. Islet hyperplasias and tumours primarily consisted of α‐cells associated to varying degrees with other islet endocrine cell types. In addition to substantial increases in islet neoplasia, increased α‐cell neogenesis associated primarily with pancreatic duct(ule)s was present. We conclude that absolute blockade of the glucagon signal results in tumorigenesis and that the PC2‐ko mouse represents a valuable model for investigation of islet tumours and pancreatic ductal neogenesis.     

Regulation of pancreatic beta-cell mass

Beta-cell mass regulation represents a critical issue for understanding diabetes, a disease characterized by a near-absolute (type 1) or relative (type 2) deficiency in the number of pancreatic beta cells. The number of islet beta cells present at birth is mainly generated by the proliferation and differentiation of pancreatic progenitor cells, a process called neogenesis. Shortly after birth, beta-cell neogenesis stops and a small proportion of cycling beta cells can still expand the cell number to compensate for increased insulin demands, albeit at a slow rate. The low capacity for self-replication in the adult is too limited to result in a significant regeneration following extensive tissue injury. Likewise, chronically increased metabolic demands can lead to beta-cell failure to compensate. Neogenesis from progenitor cells inside or outside islets represents a more potent mechanism leading to robust expansion of the beta-cell mass, but it may require external stimuli. For therapeutic purposes, advantage could be taken from the surprising differentiation plasticity of adult pancreatic cells and possibly also from stem cells. Recent studies have demonstrated that it is feasible to regenerate and expand the beta-cell mass by the application of hormones and growth factors like glucagon-like peptide-1, gastrin, epidermal growth factor, and others. Treatment with these external stimuli can restore a functional beta-cell mass in diabetic animals, but further studies are required before it can be applied to humans.     

通过基因转染诱导骨髓间充质干细胞为胰岛样细胞的进展

随着器官和组织移植技术的进步,胰腺和胰岛移植已开始用于治疗糖尿病并成为热点,但是关于胰岛细胞的来源问题还是存在着许多不足和改进之处。其中骨髓间充质干细胞(BMSCs)因为具有获取简单、易于培养和免疫抑制等优点成为被诱导为胰岛样细胞的热点。近几年来人工构建类胰岛细胞（即利用基因重组及基因转染再造胰岛样细胞）的技术提高了单...     

The patterns of extrainsular endocrine cells in pancreatic cancer

Abnormal glucose tolerance and frank diabetes mellitus develop in up to 80% of pancreatic cancer patients. Islets within these tumors show a decreased number of beta cells and increased number of alpha cells. The reduced number of beta cells could induce beta cell neogenesis in extrainsular tissue to compensate for the loss of insulin in islets. On the other hand, because the beta cell depletion in pancreatic cancer seems to be the effect of substances released by cancer cells, suppression of extrainsular endocrine cells is expected. We compared the pattern of extrainsular endocrine cells in pancreatic cancer patients with normal pancreas as well as chronic pancreatitis, which is known to be associated with impaired glucose tolerance or frank diabetes. As in the normal tissue, extrainsular endocrine cells were found in chronic pancreatitis and pancreatic cancer. However, in the chronic pancreatitis specimens insulin cells were the predominant cell type, whereas in pancreatic cancer specimens more glucagon than insulin cells were found, although the differences were statistically insignificant. Thus, our results indicate that the alteration of beta cells in pancreatic cancer patients is mainly restricted to the endocrine cells within the islets and that there is no compensatory proliferation of beta cells.     

干细胞治疗1型糖尿病的研究与应用进展

背景：通过胰腺或胰岛移植等重建胰岛素分泌系统是治疗1型糖尿病的有效方法,但材料来源受限,移植后免疫排斥反应易导致治疗失败。 目的：简要总结了胚胎干细胞、成体干细胞及诱导性多能干细胞等治疗1型糖尿病的研究进展。 方法：应用计算机检索CNKI和PubMed数据库中2008-01/2011-12关于干细胞治疗1型糖尿病的文章,在标题和摘要中以“胚胎干细胞;成体干细胞;诱导性多能干细胞;1型糖尿病”或“Embryonic stem cells,somatic stem cells,induced pluripotent stem cells,type 1 diabetes”为检索词进行检索。选择文章内容与干细胞治疗1型糖尿病相关,同一领域文献则选择近期发表或发表在权威杂志文章。初检得到128篇文献,根据纳入标准选择33篇文章进行综述。 结果与结论：目前,不同来源的干细胞在体内外均能被诱导为产生胰岛素的细胞,并且这种诱导细胞用于1型糖尿病动物模型治疗,具有一定治疗效果,甚至能使受体血糖恢复正常水平,但干细胞是否参与胰岛细胞再生或修复尚存在争议。     

Development of the endocrine pancreas and novel strategies for β-cell mass restoration and diabetes therapy

Diabetes mellitus represents a serious public health problem owing to its global prevalence in the last decade. The causes of this metabolic disease include dysfunction and/or insufficient number of β cells. Existing diabetes mellitus treatments do not reverse or control the disease. Therefore, β-cell mass restoration might be a promising treatment. Several restoration approaches have been developed: inducing the proliferation of remaining insulin-producing cells, de novo islet formation from pancreatic progenitor cells (neogenesis), and converting non-β cells within the pancreas to β cells (transdifferentiation) are the most direct, simple, and least invasive ways to increase β-cell mass. However, their clinical significance is yet to be determined. Hypothetically, β cells or islet transplantation methods might be curative strategies for diabetes mellitus; however, the scarcity of donors limits the clinical application of these approaches. Thus, alternative cell sources for β-cell replacement could include embryonic stem cells, induced pluripotent stem cells, and mesenchymal stem cells. However, most differentiated cells obtained using these techniques are functionally immature and show poor glucose-stimulated insulin secretion compared with native β cells. Currently, their clinical use is still hampered by ethical issues and the risk of tumor development post transplantation. In this review, we briefly summarize the current knowledge of mouse pancreas organogenesis, morphogenesis, and maturation, including the molecular mechanisms involved. We then discuss two possible approaches of β-cell mass restoration for diabetes mellitus therapy: β-cell regeneration and β-cell replacement. We critically analyze each strategy with respect to the accessibility of the cells, potential risk to patients, and possible clinical outcomes.     

人胰腺导管上皮表达胰岛淀粉样多肽

目的　观察人胰腺导管上皮胰岛淀粉样多肽的分布。　方法　 4例正常成人胰腺组织石蜡切片 ,用免疫组织化学 PAP方法显示 IAPP- IR细胞 ,Mayer苏木素复染。　结果　发现胰腺小叶间导管、小叶内导管、闰管上皮细胞至泡心细胞均呈胰岛淀粉样多肽免疫反应性 ,阳性物质主要分布于核上方及两侧。　结论　本研究证明人胰腺导管上皮细胞表达胰岛淀粉样多肽 ,推测其可能与胰腺的自我保护和胰液中碳酸氢盐的分泌有关     

小鼠胚胎胰腺移植治疗糖尿病

背景：胚胎胰腺组织具有来源广泛,细胞增殖分化能力强,低免疫排斥性等优点。 目的：探索小鼠胚胎胰腺组织的分离技术,观察其对糖尿病模型小鼠的血糖调节作用。 方法：体视显微镜下分离E11.5~E16.5 C57BL/6小鼠胰腺组织。链唑霉素诱导雄性C57BL/6小鼠建立糖尿病模型,随机分为2组：移植组模型小鼠肾被膜下移植5个E16.5胰腺组织,假手术组模型小鼠肾被膜下注入0.05 mL RPMI1640培养液。移植组小鼠血糖水平≤11.2 mmol/L后,利用IPGTT和IPITT方法检测移植后胚胎胰腺组织的内分泌功能,并摘除移植物观察血糖变化。 结果与结论：体视显微镜下可分离出较完整的E11.5~E16.5小鼠胰腺组织,≤ E12.5 d小鼠胚胎胰腺组织的形态和颜色均难以与周围组织分辨,需根据其与毗邻脏器的关系仔细辨别;> E12.5 d的小鼠胚胎胰腺已初具形态,颜色略发白。组织学和ELISA分别显示胚胎胰腺组织可表达并分泌胰岛素,其表达强度随发育时间逐渐增加。E16.5小鼠胰腺组织移植能有效地控制受体的血糖水平,使受体的体质量和糖耐量恢复正常;胚胎胰腺在受体的肾被膜下可生长发育,摘除的移植物胰岛素和胰高血糖素的表达均较移植前增强。说明胚胎胰腺组织可能成为治疗糖尿病的种子来源。