Multipotent cells from mammalian iris pigment epithelium

The regeneration of lens tissue from the iris of newts has become a classical model of developmental plasticity, although little is known about the corresponding plasticity of the mammalian iris. We here demonstrate and characterize multipotent cells within the iris pigment epithelium (IPE) of postnatal and adult rodents. Acutely-isolated IPE cells were morphologically homogeneous and highly pigmented, but some produced neurospheres which expressed markers characteristic of neural stem/progenitor cells. Stem/progenitor cell markers were also expressed in the IPE in vivo both neonatally and into adulthood. Inner and outer IPE layers differentially expressed Nestin (Nes) in a manner suggesting that they respectively shared origins with neural retina (NR) and pigmented epithelial (RPE) layers. Transgenic marking enabled the enrichment of Nes-expressing IPE cells ex vivo, revealing a pronounced capacity to form neurospheres and differentiate into photoreceptor cells. IPE cells that did not express Nes were less able to form neurospheres, but a subset initiated the expression of pan-neural markers in primary adherent culture. These data collectively suggest that discrete populations of highly-pigmented cells with heterogeneous developmental potencies exist postnatally within the IPE, and that some of them are able to differentiate into multiple neuronal cell types.     

Immortalization with telomerase of the Nestin-positive cells of the human pancreas

Cells expressing the neuronal stem cell marker Nestin are present in the human pancreas but the biological role of these cells has yet to be resolved. We report here the establishment with the catalytic subunit of human telomerase (hTERT) of a line of normal human cells representing this cell type. Primary human cells derived from the ducts of the pancreas were transduced with an hTERT cDNA. The infected cells became positive for telomerase, failed to senesce, and were still proliferating after more than 150 doublings. The immortalized cells were positive for the expression of Nestin (at both the mRNA and protein levels) and were found to be free of cancer-associated changes: diploid and expressing wild type p16(INK4a), p53, and K-Ras. An established line of normal human cells representing this cell type should be of great value to help define the biological properties of this novel cell type.     

Sexual dimorphism on the neurogenic potential of rhesus monkeys mesenchymal stem cells

Bone marrow mesenchymal stem cells (BMSCs) have been shown to differentiate into cells of a neural lineage. However, no studies have examined whether gender influences the differentiation potential of BMSCs. Here, we explore the possible differences in BMSC’s neurogenic potential in vitro between female rhesus monkey BMSCs (F-rhBMSCs) and male rhBMSCs (M-rhBMSCs). We first isolated and cultured rhBMSCs from female and male donors (n = 6, 2 years old), identified their sex origin by karyotype assay, and assessed their expression of nestin and CD34 at passage 1 and 10. Then, nestin-positive F- and M-rhBMSCs at P10 were differentiated into neural-like cells. After induction, the neurogenic potential of these cells was assessed by morphological observation and protein expression analysis of neural markers, including class III β-tubulin, neurofilament light polypeptide, tau, and gamma-aminobutyric acid (GABA) neurotransmitter. Furthermore, GABA content was assayed using high-pressure liquid chromatography. The results showed that F-rhBMSCs produced significantly more nestin-positive cells compared with M-rhBMSCs at P10 and that nestin-positive F-rhBMSCs acquired higher neurogenic potential accompanied by increased synthesis and excretion of GABA compared with nestin-positive M-rhBMSCs under conditions of differentiation. These results indicated that gender may play an important role in the neurogenic potential of BMSCs, and a further understanding of the cellular biology underlying these differences may contribute to the development of new therapeutic strategies for neurological repair and regeneration.     

Cell autonomous requirement for TGF-beta signaling during odontoblast differentiation and dentin matrix formation

TGF-β subtypes are expressed in tissues derived from cranial neural crest cells during early mouse craniofacial development. TGF-β signaling is critical for mediating epithelial-mesenchymal interactions, including those vital for tooth morphogenesis. However, it remains unclear how TGF-β signaling contributes to the terminal differentiation of odontoblast and dentin formation during tooth morphogenesis. Towards this end, we generated mice with conditional inactivation of the Tgfbr2 gene in cranial neural crest derived cells. Odontoblast differentiation was substantially delayed in the Tgfbr2^fl/fl;Wnt1-Cre mutant mice at E18.5. Following kidney capsule transplantation, Tgfbr2 mutant tooth germs expressed a reduced level of Col1a1 and Dspp and exhibited defects including decreased dentin thickness and absent dentinal tubules. In addition, the expression of the intermediate filament nestin was decreased in the Tgfbr2 mutant samples. Significantly, exogenous TGF-β2 induced nestin and Dspp expression in dental pulp cells in the developing tooth organ. Our data suggest that TGF-β signaling controls odontoblast maturation and dentin formation during tooth morphogenesis.     

Redifferentiation of insulin-secreting cells after in vitro expansion of adult human pancreatic islet tissue

Cellular replacement therapy holds promise for the treatment of diabetes mellitus but donor tissue is severely limited. Therefore, we investigated whether insulin-secreting cells could be differentiated in vitro from a monolayer of cells expanded from human donor pancreatic islets. We describe a three-step culture protocol that allows for the efficient generation of insulin-producing cell clusters from in vitro expanded, hormone-negative cells. These clusters express insulin at levels of up to 34% that of average freshly isolated human islets and secrete C-peptide upon membrane depolarization. They also contain cells expressing the other major islet hormones (glucagon, somatostatin, and pancreatic polypeptide). The source of the newly differentiated endocrine cells could either be indigenous stem/progenitor cells or the proliferation-associated dedifferentiation and subsequent redifferentiation of mature endocrine cells. The in vitro generated cell clusters may be efficacious in providing islet-like tissue for transplantation into diabetic recipients.     

Zonal hierarchy of differentiation markers and nestin expression during oval cell mediated rat liver regeneration

Oval cells constitute a heterogeneous population of proliferating progenitors found in rat livers following carcinogenic treatment (2-acetylaminofluorene and 70% hepatectomy). The aim of this study was to investigate the cellular pattern of various differentiation and cell type markers in this model of liver regeneration. Immunophenotypic characterisation revealed at least two subtypes emerging from the portal field. First, a population of oval cells formed duct-like structures and expressed bile duct (CD49f) as well as hepatocytic markers (α-foetoprotein, CD26). Second, a population of non-ductular oval cells was detected between and distally from the ductules expressing the neural marker nestin and the haematopoietic marker Thy1. Following oval cell isolation, a subset of the nestin-positive cells was shown to co-express hepatocytic and epithelial markers (albumin, CD26, pancytokeratin) and could be clearly distinguished from anti-desmin reactive hepatic stellate cells. The gene expression profiles (RT-PCR) of isolated oval cells and oval cell liver tissue were found to be similar to foetal liver (ED14). The present results suggest that the two oval cell populations are organised in a zonal hierarchy with a marker gradient from the inner (displaying hepatocytic and biliary markers) to the outer zone (showing hepatocytic and extrahepatic progenitor markers) of the proliferating progeny clusters.     

胶质瘤干细胞标记物的研究进展

胶质瘤作为一种恶性脑肿瘤,具有预后差、易复发、对放化疗有抵抗性等特点。为了提高对胶质瘤的分级及预后评价的准确性,获得有效的、有针对性的胶质瘤干细胞(glioma stem cell,GSC)标记物具有十分重要的意义。本文主要对CD133、SSEA-1、Nestin等干细胞标记物在胶质瘤临床诊治中的应用特征与相互联系进行了综述。CD133作为一种最早发现的胶质瘤干细胞标志物应用广泛,但其分布无特异性、表达不稳定限制了其预后评价的精确性,其有效性目前仍存在争议。SSEA-1(CD15)与Nestin等分子弥补了CD133的部分不足。这三种标记物的联合应用为胶质瘤的临床诊断和治疗提供了重要的参考依据。后续研究陆续发现的A2B5、BMI1、LGR5等标记物有助于进一步了解GSC的性质,提高胶质瘤的诊治水平和预后评价的准确度。     

兔抗人NESTIN抗血清的制备与鉴定(简报)

巢蛋白(nestin)属Ⅵ类中等纤维蛋白。最初在神经系统发育早期发现有该蛋白的表达。后在正常神经系统中发现仅在未分化的神经前体细胞中有nestin的短暂表达,分化后在神经元和神经胶质细胞中分别被NF(neurofilament,神经丝)和GFAP(Glial fibrillary acidic protein,神经胶质元纤维酸性蛋白)所代替。所以nestin的表达通常被视为神经前体细胞的标志之一。就我们所知,目前商品化nestin的抗体都是鼠抗鼠(克隆Rat401)的抗体,而人鼠之间该蛋白序列的同源性仅为50%左     

大鼠胚胎神经干细胞单克隆化及单层化培养和鉴定

采用原代培养SD胎鼠神经干细胞,在形成神经球之后,传代至0.1%明胶包被的培养皿,显微镜下挑取一个神经球贴壁后的细胞团,吹打后贴壁培养．同样方法挑细胞团并传代培养5～6次,得到纯化的由一个神经干细胞扩增的克隆,对得到的神经干细胞进行鉴定以及分化能力的评估,证明得到的细胞就是神经干细胞．结果表明,成功分离了SD胎鼠的神经干细胞,进行单克隆化单层培养,神经干细胞和分化后的细胞标志基因都可以检测到．上述工作为疾病模型大鼠治疗及相关基础研究提供细胞来源及形态标准．