干细胞的研究进展

在美国《Ｓｃｉｅｎｃｅ》杂志评选出的１９９９年度１０大科学进展中，干细胞（ｓｔｅｍ ｃｅｌｌ， ＳＣ）的研究工作格外令人瞩目。这不仅因为在过去短短的一年里，科学家们在干细胞的功能研究方面发表了１０余篇具有里程碑意义的论文，更重要的是，这些突破性进展使得生物学家和医学家们更进一步地认识到：ＳＣ作为一类既有自我更新能力、又有多分化潜能的细胞，具有非常重要的理论研究意义和临床应用价值［１］。这些成果一方面揭示了许多有关细胞生长和发育的基础理论难题；另一方面，可望将其用于创伤修复、神经再生和抗衰老等临床医…     

干细胞标志物在免疫细胞化学中应用的研究现状

干细胞以其自我更新和分化为成熟组织细胞的能力成为当前科研与临床应用的热点,但干细胞的鉴定目前尚无公认一致的方法,随着干细胞相关的分子标记物的发现以及功能的明晰,免疫细胞化学染色法在各种干细胞的鉴定中以其简便、快速、准确的优势发挥越来越重要的作用。本文就应用免疫细胞化学鉴定干细胞的主要分子标记进行综述。     

干细胞及其诱导技术在培育成体细胞、筛选药物和移植实验中的作用

利用干细胞及其诱导技术在实验室内培育出的成体细胞,可以为干细胞的基础研究及未来开展的针对人类疾病的临床移植试验创造条件。此外,干细胞及其诱导技术在药物筛选中也能发挥积极的作用。     

干细胞基础研究的新进展

近5年来,在世界范围出现干细胞的研究热潮,有关干细胞的论文大量发表,风起云涌。然而,有部分的实验结论缺乏充足的证据,而引起质疑。例如干细胞“横向分化”的假设错误地认为干细胞可以跨胚层、跨系别地任意地变身,脂肪变肝脏,肌肉变神经等等。成体干细胞的存在是21世纪一个伟大的科学发现。越来越多的实验证明成体组织中还存在胚胎发育过程遗留下的各个胚层的干细胞和各类组织干细胞。全身各类组织中的成体干细胞含有除了生殖干细胞外的各种干细胞。至今,只有在生殖组织中才能发现生殖干细胞,因而生殖组织以外的成体干细胞又称为亚全能干细胞。成体干细胞包括造血和非造血的干细胞,非造血的干细胞又包括了各种非造血组织的干细胞,例如神经干细胞和间充质干细胞等。间充质干细胞是全身结缔组织(骨、软骨、肌肉、脂肪、纤维、血管等)的干细胞,它是创伤、烧伤、缺血坏死、骨髓损伤等修复过程中所必不可少的,有巨大的临床应用前景。随着生命科学的全面发展,干细胞领域中的认识误区将逐步得到澄清,干细胞科学也必将健康地发展起来。     

多潜能干细胞的研究进展

多潜能干细胞是一类具有向外胚层、中胚层以及内胚层细胞分化的干细胞,从胚胎发育早期分离获得的胚胎干细胞、胚胎生殖细胞到成体组织骨髓、睾丸中获得的干细胞,都具有三胚层分化能力.近年来,研究证实,可以将成体分化细胞经基因操作逆转为多能干细胞.就各种来源多潜能干细胞的特点予以综述,并对细胞间可能存在的关系加以探讨.     

成体干细胞龛的研究进展

成体正常干细胞具有自我更新与繁衍级别分化后代的双重功能。两种能力的动态平衡维系着组织正常命运。否则,分化过度、削弱自我更新,可致干细胞枯竭;而自我更新过度,则阻碍级别分化,干细胞由之扩增,甚至向肿瘤转化。防止更新与分化的过度,依赖于干细胞遗传程序与龛     

干细胞技术及其在口腔医学中的研究及应用前景

阐述了干细胞技术相关背景及其在口腔医学领域的研究进展，着重介绍了牙髓干细胞，骨髓基质干细胞和胚胎干细胞在口腔医学中诸如修复颅面缺损，重建牙齿缺损以及重建腮腺等其它组织的最新研究，干细胞技术为口腔医学提供了新的选择和广泛的应用前景，值得进一步深入探讨。     

胃癌干细胞表面标记物的研究与最新进展

背景:最近人们研究发现,肿瘤的复发与肿瘤干细胞密切相关。肿瘤干细胞理论为研究胃癌的发病机制以及诊治开辟了新的途径,确定的表型有利于锁定胃癌干细胞,这有助于探讨胃癌干细胞在自我更新和分化过程中的作用,并为治疗胃癌提供新思路,但其表型仍存在争议。目的:综述胃癌干细胞表面标志物的研究进展。方法:由第一作者分别以"Gastric Cancer Stem Cells"为英文关键词检索PubM ed英文数据库(http://www.ncbi.nlm.nih.gov/pubmed)中1965年1月至2015年10月的文献,共保留68篇文献进行综述。结果与结论:通过分析整理,传统上的肿瘤干细胞表型不适合于标记胃癌干细胞。研究发现CD90在胃癌原发性肿瘤中有表达,分离后经无血清肿瘤球培养法培养可获得肿瘤球。CD24的表达有助于提高胃癌细胞的黏附、侵袭、迁移能力。此外研究证实CD44及CD54共表达的细胞会大量出现在胃癌复发早期患者的体内而不是晚期,表达CD44及CD54的肿瘤细胞很可能是导致胃癌发生以及复发的重要原因。综上所述,CD44^+CD24^+CD90^+CD54^+很可能是胃癌干细胞的表型。     

干细胞研究进展

干细胞研究已成为生命科学中的热点，本综述了近年来的有关研究，从以下五个方面介绍了干细胞研究取得的重要进展：(1)干细胞的基本概念，包括定义和分类；(2)小鼠胚胎干细胞、人胚胎干细胞的分离、培养及其特征；(3)骨髓干细胞的表面标志特征等；(4)干细胞向特异组织细胞(如心肌细胞、肝细胞、神经细胞等)分化诱导研究；(5)干细胞在治疗心脏疾病、肝脏疾病、神经系统疾病、糖尿病、角膜疾病等方面取得的研究成果。     

干细胞研究进展

干细胞包括胚胎干细胞与成体干细胞。介绍了近年来诱导胚胎干细胞向多种或某一种组织细胞分化的实验报道 ,并对成体干细胞“可塑性”分化的几个问题进行了讨论     

Effect of CD133 overexpression on the epithelial-to-mesenchymal transition in oral cancer cell lines

Oral squamous cell carcinoma (OSCC) is one of the most common cancers in the world. In OSCC, CD133 promotes tumor invasion and metastasis by inducing the epithelial-to-mesenchymal transition (EMT). A small subset of cancer cells known as cancer stem cells (CSCs) are thought to give rise to differentiated tumor cells and to predict tumor recurrence and metastases, i.e., CSCs may be metastatic precursors. In this study, we show that ectopic overexpression of CD133 in OSCC cell lines KB, YD9, and YD10B cells significantly promotes the EMT and acquisition of stemness properties. CSC properties were analyzed by colony-formation assay and measurement of OCT4, SOX2, and NANOG expression, and the EMT was monitored by cell migration, a cell invasion assay, and analysis of E-cadherin, N-cadherin, and vimentin expression. CD133 overexpression led to formation of irregular spheroid colonies consistent with a stem cell phenotype and increased the expression of OCT4, SOX2, NANOG, N-cadherin, and vimentin. Taken together, these findings show that elevated levels of CD133 lead to OSCC invasiveness and metastasis, associated with the upregulation of EMT and stemness markers.     

抑制LSD1对hiPSCs向定型内胚层分化的调控作用

目的:探讨抑制组蛋白赖氨酸特异性去甲基化酶1(LSD1)对人诱导性多能干细胞(hiPSCs)向定型内胚层(DE)分化的调控作用。方法:利用LSD1抑制剂或shRNA抑制LSD1表达,观察hiPSCs形态变化并检测LSD1活性水平,CCK-8方法检测细胞增殖活性,qPCR检测hiPSCs多能性基因及各胚层标志基因的表达,IP-WB方法检测LSD1调控靶基因的复合体模式,Ch IP-qPCR方法检测DE标志基因启动子区域组蛋白H3第4位赖氨酸二甲基化和三甲基化(H3K4me2/me3)及第9位赖氨酸乙酰化(H3K9ac)水平。结果:(1)抑制LSD1可显著下调hiPSCs多能性基因OCT4、Y染色体性别决定区域盒2(SOX2)及Nanog同源盒(NANOG)的表达水平(P 0. 05);显著上调外胚层标志基因β3-微管蛋白(TUBB3),DE标志基因Y染色体性别决定区域盒17(SOX17)和叉头盒A2(FOXA2),以及中胚层标志基因骨形态发生蛋白2(BMP2)的表达水平(P 0. 05);(2)当LSD1活性为正常水平的53. 4%时利于DE分化;(3) LSD1在hiPSCs核内与组蛋白去乙酰化酶1(HDAC1)及阻遏物元件1沉默转录因子辅阻遏物(CoREST)以复合体的形式调控靶基因;(4)抑制LSD1后,SOX17和FOXA2基因启动子区域LSD1与HDAC1结合水平均显著下降,同时H3K4me2/me3和H3K9ac富集水平显著提高(P 0. 01)。结论:LSD1通过调控DE分化关键基因启动子区域H3K4me和H3K9ac水平来影响hiPSCs向DE的分化能力。     

Expression of pluripotent stem cell markers in the human fetal testis

Human primordial germ cells (PGCs) have proven to be a source of pluripotent stem cells called embryonic germ cells (EGCs). However, the developmental potency of these cells in the fetal gonad still remains elusive. Thus, this study provides a comprehensive analysis of pluripotent and germ cell marker expression in human fetal testis 7-15 weeks postfertilization (pF) and compares this expression to their ability to derive EGCs. Although the majority of germ cells expressed stem cell markers stage-specific embryonic antigen (SSEA) 1, SSEA4, EMA-1, and alkaline phosphatase, only a small percentage of those (<1%) expressed OCT4, CKIT, and NANOG. Specifically, the number of OCT4(+)/CKIT(+)/NANOG(+) cells significantly increased in the developing cords during weeks 7-9, followed by a gradual decline into week 15 pF. By week 15 pF, the remaining OCT4(+)/CKIT(+)/NANOG(+) cells were found in the cords surrounding the periphery of the testis, and the predominant germ cells, CKIT(+) cells, no longer expressed OCT4 or NANOG. Based on morphology and early germ cell marker expression, including VASA, PUM2, and DAZL, we suggest these cells are mitotically active gonocytes or prespermatogonia. Importantly, the number of OCT4(+) cells correlated with an increase in the number of EGC colonies derived in culture. Interestingly, two pluripotent markers, Tra-1-60 and Tra-1-81, although highly expressed in EGCs, were not expressed by PGCs in the gonad. Together, these results suggest that PGCs maintain expression of pluripotent stem cell markers during and after sexual differentiation of the gonad, albeit in very low numbers.     

诱导多能干细胞建系过程中关键转录因子的作用

通过添加OCT4、SOX2等转录因子,体外诱导细胞重编程获得诱导多能干细胞是近年干细胞领域的一大突破.OCT4、SOX2和NANOG等转录因子在启动细胞重编程、维持诱导多能干细胞多能性和决定其是否走向分化方面起了关键作用.对这些转录因子作用机制的了解,有助于细胞莺编程分子机制的进一步阐明.     

Isolation and in Vitro Characterization of Bovine Amniotic Fluid Derived Stem Cells at Different Trimesters of Pregnancy

Amniotic fluid (AF) is a source of multipotent mesenchymal stem cells (MSCs), very promising cells for tissue engineering in clinical application. The aim of this work was to isolate and characterize cells isolated from bovine AF as alternative sources of primitive multipotent stem cells in a species that could be a large-animal model for biomedical and biotechnology researches. Samples were recovered, at slaughterhouse, from 39 pregnant cows at different trimesters of pregnancy and cells were cultured in vitro. At passages (P) 3 and 7 differentiation towards chondrogenic, osteogenic and adipogenic lineages was induced. Flow cytometry analysis for CD90, CD105, CD73, CD44, CD34, CD45 and CD14 was performed, immunocytochemistry (ICC) for Oct4, SSEA4, α-SMA, Vimentin, N- and E- Cadherin and CK and qPCR analysis for OCT4, NANOG and SOX2 were carried out. The cell yield was significantly higher in the first trimester compared to the second and the third one (P?NANOG and SSEA4 but not OCT4. Bovine AF shows a heterogeneous cell population containing also MSCs, multipotent cells that represent an intermediate stage between embryonic stem cells and adult ones.