Comparative genomic hybridization and karyotyping of human embryonic stem cells reveals the occurrence of an isodicentric X chromosome after long-term cultivation

Human embryonic stem (hES) cells are important research toolsin studies of the physiology of early tissue differentiation.In addition, prospects are high regarding the use of these cellsfor successful cell transplantation. However, one concern hasbeen that cultivation of these cells over many passages mightinduce chromosomal changes. It is thus important to investigatethese cell lines, and check that a normal chromosomal contentis retained even during long-term in vitro culture. Comparativegenomic hybridization (CGH) was used to analyse three hES celllines derived in our laboratory and cultured continuously for30–42 weeks, comprising 35–39 cell passages. CGHcould be successfully performed in 48 out of a total of 50 isolatedsingle cells (96%). All three lines (HS181, HS235 and HS237)were shown to have a normal chromosomal content when analysedby both single cell CGH and by karyotyping up to passages 39,39 and 35 respectively. No aneuploidies or larger deletionsor amplifications were detected, and they were female (46,XX).However, HS237 was reanalysed at passage 61, and at that pointan aberrant X chromosome was detected by karyotyping. The aberrationwas confirmed and characterized by single cell CGH and fluorescencein situ hybridization analysis, 46,X,idic(X)(q21). Thus, chromosomalaberrations may occur over time in stem cell lines, and continuousanalysis of these cells during cultivation is crucial. Singlecell CGH is a method that can be used for continuous analysisof the hES cell lines during cultivation, in order to detectchromosome imbalance.     

Comparative genomic hybridization as a tool in tumour cytogenetics

The quality of cytogenetic analysis of solid tumours has greatly improved in the past decade, but a number of technical difficulties remain which limit the characterization of solid tumour chromosomes by conventional cytogenetics alone. The identification of regions of chromosomal abnormality has been aided by the introduction of molecular cytogenetic techniques such as fluorescence in situ hybridization (FISH). Of these, a recently developed approach, comparative genomic hybridization (CGH), has had a particular impact on the cytogenetic analysis of solid tumours. It incorporates the sensitivity of in situ techniques and overcomes many of the drawbacks of conventional cytogenetic analysis. This review first outlines the CGH method, giving details for the preparation of DNA probes and target human metaphase chromosomes together with information on the in situ technique and data handling criteria used in our laboratory. It then presents an overview of some of the current applications of CGH, together with a discussion of future directions in the field. Copyright © 1999 John Wiley & Sons, Ltd.     

人胚胎干细胞H1培养条件的优化

目的:采用不同培养基和饲养层培养人胚胎干细胞H1,建立适合H1细胞增殖的最佳条件并分析其基本生物学特性。方法:鼠源性饲养层采用ICR品系小鼠胚胎成纤维细胞(MEF),人源性饲养层采用人胚胎成纤维细胞系(HFF-1)。H1基本培养基配制分别采用传统DMEM/F12和改良培养基Knock-outTM DMEM。实验共分为MEF DMEM/F12、MEF K-DMEM、HFF DMEM/F12、HFF K-DMEM组。H1基本生物学特性检测采用免疫荧光、RT-PCR、碱性磷酸酶和核型分析。结果:MEF DMEM/F12组中H1克隆形态规则,不发生分化,增殖速度快;而MEF K-DMEM组细胞克隆传代后第4日发生分化;HFF DMEM/F12组和HFF K-DMEM组细胞传代后第3日就显示出分化趋势,克隆变扁。MEF DMEM/F12组中H1细胞保持正常核型和基本生物学特性。结论:不同的人胚胎干细胞系最佳培养条件是不同的,建立的MEF DMEM/F12组培养条件最适合H1细胞增殖。     

人胚胎干细胞建系、培养及体外诱导分化研究现状

胚胎干细胞具有体外无限增殖和分化成三胚层细胞的潜能,它已被视为治疗多种疾病的一种新兴策略。目前胚胎干细胞常规的建系和培养技术已很成熟,并有一套国际公认的鉴定标准。但常规方法存在异源病原体污染的可能,急需研究适于标准化、无动物源性污染及可大量培养胚胎干细胞的培养体系。在现阶段,通过不同的体外诱导途径可将胚胎干细胞诱导成为胚外和三胚层来源的各种细胞,但定向分化的问题仍亟需解决。     

Comparative evaluation of human embryonic stem cell lines derived from zygotes with normal and abnormal pronuclei

Human embryonic stem (hES) cell lines have been derived from normally or abnormally fertilized zygotes. However, the similar and different properties of these two types of hES cell lines are not well‐known. To address this question, we generated nine hES cell lines from zygotes containing normal (2PN) and abnormal (0PN, 1PN, 3PN) pronuclei. A side‐by‐side comparison showed that all cell lines exhibited distinct identity and karyotypical stability. They expressed similar “stemness” markers and alkaline phosphatase activity and differentiated into three embryonic germ lineages in embryoid bodies and teratomas. Under neural differentiation‐promoting conditions, they were directed into neural progenitors and neurons. However, a variation in cell cycle and the relative abundance of gene expression of undifferentiated and differentiated markers were observed. These variations were also seen among individually derived normal hES cell lines. Thus, normal hES cell lines can be developed from fertilized zygotes with abnormal pronuclei usually excluded from clinical use. Developmental Dynamics 239:425–438, 2010. © 2009 Wiley‐Liss, Inc.     

人胚胎生殖干细胞的分离和体外培养

目的：体外培养人胚胎生殖干细胞(EG),在不添加细胞因子的培养条件下,观察细胞生长情况。方法：取5～10周人胚胎的生殖腺嵴和肠背系膜,进行组织块培养,采用组织化学及免疫细胞化学技术对培养的细胞进行鉴定。结果：培养4d后,在成纤维细胞的上面出现EG细胞集落;培养2周后,显示细胞呈圆形,胞质染成深蓝色;细胞染色体均为正常的二倍体核型;碱性磷酸酶活性强阳性;并检测到SSEA-1。结论：体外培养人胚胎生殖腺嵴,利用源于自身胚胎组织的成纤维细胞作为饲养层,可观察到EG细胞集落的形成;培养的细胞初步鉴定为人胚胎干细胞。     

Laser-assisted derivation of human embryonic stem cell lines from IVF embryos after preimplantation genetic diagnosis

BACKGROUND: Human embryonic stem cells (hESCs) suitable for future transplantation therapy should preferably be developed in an animal-free system. Our objective was to develop a laser-based system for the isolation of the inner cell mass (ICM) that can develop into hESC lines, thereby circumventing immunosurgery that utilizes animal products. METHODS: Hatching was assisted by micromanipulation techniques through a laser-drilled orifice in the zona pellucida of 13 abnormal preimplantation genetic diagnosed blastocysts. ICMs were dissected from the trophectoderm by a laser beam and plated on feeders to derive hESC lines. RESULTS: eight ICMs were isolated from nine hatched blastocysts and gave rise to three hESC lines affected by myotonic dystrophy type 1, hemophilia A and a carrier of cystic fibrosis 405 + 1G > A mutation. Five blastocysts that collapsed during assisted hatching or ICM dissection were plated whole, giving rise to an additional line affected by fragile X. All cell lines expressed markers of pluripotent stem cells and differentiated in vitro and in vivo into the three germ layers. CONCLUSIONS: These hESC lines can serve as an important model of the genetic disorders that they carry. Laser-assisted isolation of the ICMs may be applied for the derivation of new hESC lines in a xeno-free system for future clinical applications.     

Ladder-like amplification of the type I interferon gene cluster in the human osteosarcoma cell line MG63

The organization of the type I interferon (IFN) gene cluster (9p21.3) was studied in a human osteosarcoma cell line (MG63). Array comparative genomic hybridization (aCGH) showed an amplification of ∼6-fold which ended at both ends of the gene cluster with a deletion that extended throughout the 9p21.3 band. Spectral karyotyping (SKY) combined with fluorescence in-situ hybridization (FISH) identified an arrangement of the gene cluster in a ladder-like array of 5–7 ‘bands’ spanning a single chromosome termed the ‘IFN chromosome’. Chromosome painting revealed that the IFN chromosome is derived from components of chromosomes 4, 8 and 9. Labelling with centromeric probes demonstrated a ladder-like amplification of centromeric 4 and 9 sequences that co-localized with each other and a similar banding pattern of chromosome 4, as well as alternating with the IFN gene clusters. In contrast, centromere 8 was not detected on the IFN chromosome. One of the amplified centromeric 9 bands was identified as the functional centromere based on its location at the chromosome constriction and immunolocalization of the CENP-C protein. A model is presented for the generation of the IFN chromosome that involves breakage–fusion–bridge events. Electronic supplementary material   The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Establishment of human embryonic stem cell lines from frozen-thawed blastocysts using STO cell feeder layers

BACKGROUND: Recently, human embryonic stem (hES) cells have become very important resources for basic research on cell replacement therapy and other medical applications. The purpose of this study was to test whether pluripotent hES cell lines could be successfully derived from frozen-thawed embryos that were destined to be discarded after 5 years in a routine human IVF-embryo transfer programme and whether an STO cell feeder layer can be used for the culture of hES cells. METHODS: Donated frozen embryos (blastocysts or pronuclear) were thawed, and recovered or in vitro developed blastocysts were immunosurgically treated. All inner cell masses were cultured continuously on an STO cell feeder layer and then presumed hES cell colonies were characterized. RESULTS: Seven and two cell lines were established from frozen-thawed blastocysts (7/20, 35.0%) and pronuclear stage embryos (2/20, 10.0%), respectively. The doubling time of hES cells on the immortal STO cell feeder layer was approximately 36 h, similar to that of cells grown using fresh mouse embryonic fibroblast (MEF) feeder conditions. Subcultured hES cell colonies showed strong positive immunostaining for alkaline phosphatase, stage-specific embryonic antigen-4 (SSEA-4) and tumour rejection antigen 1-60 (TRA1-60) cell surface markers. Also, the hES colonies retained normal karyotypes and Oct-4 expression in prolonged subculture. When in vitro differentiation of hES cells was induced by retinoic acid, three embryonic germ layer cells were identified by RT-PCR or indirect immunocytochemistry. CONCLUSIONS: This study indicates that establishment of hES cells from frozen-thawed blastocysts minimizes the ethical problem associated with the use of human embryos in research and that the STO cell feeder layer can be used for the culture of hES cells.     

Hematopoiesis in human embryonic liver organ culture

It was shown by the method of multiple organ cultures on Millipore filters that hematopoiesis of predominantly erythroid type is maintained for a long time (over 1.5 months) in cultures of human embryonic liver. The general morphology of 7–50-day-old cultures was studied and described. The myeloid population of cells (the number of colony-forming units) was virtually exhausted by the 14th–16th day of culture.Laboratory of Bone Marrow Culture and Transplantation, Central Institute of Hematology and Blool Transfusion, Ministry of Health of the USSR. Laboratory of Pediatric Hematology, N. I. Pirogov Second Moscow Medical Institute. First Gynecological Department, No. 49 City Hospital, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR, N. A. Fedorov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 83, No. 4, pp. 460–462, April, 1977.     

荧光原位杂交技术研究人类体外未受精卵的17号染色体非整倍体

目的 对比两种不同间期核制备方法的效果，并比较25－30岁和31－35岁这两个女性年龄组、不同的体外受精－胚胎移植（in vitro fertilization-embryo transfer,IVF-ET）指征、不同超排方案等与17号染色体非整倍体率之间的关系。方法 采用0.1% Tween 20/0.01 mol/L HCl和3：1的甲醇：冰醋酸两种方法制备人类未受精卵间期核，选用人类17号染色体端粒探针（17qter），按说明书步骤进行荧光原位杂交并在方法上稍作改进。结果 36个未受精卵中，正常17号单体24枚，二体7枚，三体5枚，非整倍体出现率为33.3%（12／36）；25－30岁和31－35岁这两个女性年龄组、不同IVF指征、不同超排方案的患者的17号染色体非整倍体发生率差异无显著性。结论 两种方法信号检出率均为100％，但前者间期核制备效果较好，易于操作，避免甲醇冰醋酸刺激性气味对环境的污染，卵母细胞17号染色体的非整倍性是造成体外受精失败的重要原因之一。     

Visualization of interphase chromosomes in postmitotic cells of the human brain by multicolour banding (MCB)

Molecular cytogenetics offers the unique possibility of investigating numerical and structural chromosomal aberrations in interphase nuclei of somatic cells. Previous fluorescence in-situ hybridization (FISH) investigations gave hints of numerical chromosomal imbalances in the human brain, present as low-level mosaicism. However, as precise identification of aneuploidy rates in somatic tissues faces major difficulties due to the limitations of FISH using whole chromosome painting or centromeric probes, in this study low-level mosaicism in the human brain was addressed for the first time using microdissection-based multicolour banding (MCB) probe sets. We demonstrated that MCB is suitable for this application and leads to more reliable results than the use of centromeric probes in parallel on the same samples. Autosomes and the active X chromosome appear as discrete metaphase chromosome-like structures, while the inactive X chromosome is condensed in more than 95% of interphase nuclei. The frequency of stochastic aneuploidy was found to be 0.2–0.5% (mean 0.35%) per autosome pair, 2% for the X chromosome in the female brain, and 0.4% in the male brain, giving a cumulative frequency of aneuploidy of approximately 10% in the adult brain. Moreover, MCB as well as multi-probe FISH using centromeric probes revealed associated signals in a large proportion of brain cells (10–40%). While co-localized signals could not be discriminated from numerical chromosome imbalances after FISH using centromeric probes, interphase MCB allows such differentiation. In summary, MCB is the only approach available at present that provides the possibility of characterizing the chromosomal integrity of arbitrary interphase cell populations. Thus, cytogenetics is no longer limited in its application to dividing cells, which is a great step forward for brain research.     

A de novo supernumerary genomic discontinuous ring chromosome 21 in a child with mild intellectual disability

Small supernumerary marker chromosomes (sSMCs) are structurally abnormal extra chromosomes that cannot be unambiguously identified or characterized by conventional banding techniques alone, and they are generally equal in size or smaller than chromosome 20 of the same metaphase spread. Small supernumerary ring chromosomes (sSRCs), a smaller class of marker chromosomes, comprise about 10% of the cases. For various reasons these marker chromosomes have been the most difficult to characterize; although specific syndromes have not yet been defined, 60% of cases are associated with an abnormal phenotype. The chromosomal material involved, the degree and tissutal distribution of mosaicism, and the possible presence of uniparental disomy, are the important factors determining whether or not the ring chromosome will give rise to symptoms. Using conventional and molecular cytogenetics approaches we identified a de novo chromosome 21 sSRC in a child with speech delay and mild intellectual disability. By using aCGH analysis and SNP arrays, we report the presence of two discontinuous regions of chromosome 21 and the paternal origin of the sSRC. A thorough neuropsychiatric evaluation is also provided. Only few other cases of complex discontinuous ring chromosomes have been described in detail.     

Mechanical isolation of the inner cell mass is effective in derivation of new human embryonic stem cell lines

BACKGROUND: For clinical grade human embryonic stem cell (hESC) lines, a robust derivation system without any substances having animal origin would be required. We have gradually improved our hESC derivations. Human skin fibroblasts were used as feeder cells in derivation of all our 25 permanent fully characterized hESC lines. In the first four derivations, fetal calf serum was used as a supplement in the medium, thereafter, serum replacement medium was used. Immunosurgery generally used for isolation of the inner cell mass (ICM) still involves animal serum and complement. METHODS: We developed a practical mechanical isolation method for the ICM. Two flexible metal needles with sharpened tips, 0.125 mm in diameter, were used to open the zona pellucida and extract the ICM under a stereomicroscope. Immunohistochemical and karyotype characterization of the new hESC lines was carried out, and pluripotency was tested in vitro (immunocytochemistry and RT-PCR) and in vivo (teratoma growth). RESULTS :Five hESC lines were obtained from 19 supernumerary blastocysts collected in 2005-2006 (26%), whereas in similar conditions, we obtained 16 lines from 100 blastocysts (16%) using immunosurgery in 2003-2005. The new lines had a normal karyotype and tissues originating from the three embryonic germ cell layers were present. CONCLUSIONS: Mechanical isolation of the ICM proved to be an effective way to derive new hESC lines. The technique is fast, does not require any extra investment and the xeno-components of immunosurgery could be avoided.     

Chromosomal location of endogenous geminivirus-related DNA sequences inNicotiana tabacum L.

TheN. tabacum (tobacco) nuclear genome carries approximately 25 multiple direct repeats of a geminivirus-related DNA (GRD) sequence that probably arose by illegitimate recombination, following geminivrus infection, duringNicotiana evolution. Each GRD repeat carries sequences similar to the geminiviralAL1 gene of the tomato golden mosaic virus (TGMV), encoding a protein required for viral DNA replication, plus thecis-essential replication origin. Using a cloned 14-kb GRD repeat sequence as a probe for fluorescencein situ hybridization (FISH), we identified a unique tobacco chromosome carrying GRD. Translocations between chromosomes of the tobacco S and T genomes were used as physical markers by sequentially hybridizing chromosomes with labelled GRD and total genomic DNA fromN. sylvestris (equivalent to the S genome). The 25S, 18S and 5.8S ribosomal gene clusters were detected in double-labelling experiments for use as additional markers to identify the chromosomal location of GRD. GRD occupies one site on a homologous pair of small submetacentrics from the T genome characterized by a lack of either translocated segments from the S genome or ribosomal genes. GRD provides an additional marker for the small chromosomes of the T genome and a useful phylogenetic tool.     

Comparative genomic in situ hybridization (cGISH) analysis on plant chromosomes revealed by labelled Arabidopsis DNA

A new approach for comparative cytogenetic banding analysis of plant chromosomes has been established. The comparative GISH (cGISH) technique is universally applicable to various complex genomes of Monocotyledonae (Triticumaestivum, Agropyronelongatum, Secalecereale, Hordeumvulgare, Alliumcepa, Muscariarmenaticum and Liliumlongiflorum) and Dicotyledonae (Viciafaba, Betavulgaris, Arabidopsisthaliana). Labelled total genomic DNA of A. thaliana generates signals at conserved chromosome regions. The nucleolus organizing regions (NORs) containing the majority of tandemly repeated rDNA sequences, N-band regions containing satellite DNA, conserved homologous sequences at telomeres and additional chromosome-characteristic markers were detected in heterologous FISH experiments. Multicolour FISH analysis with repetitive DNA probes simultaneously revealed the chromosome assignment of 56 cGISH signals in rye and 61 cGISH signals in barley. Further advantages of this technique are: (1) the fast and straightforward preparation of the probe; (2) the generation of signals with high intensity and reproducibility even without signal amplification; and (3) no requirement of species-specific sequences suitable for molecular karyotype analysis. Hybridization can be performed without competitive DNA. Signal detection without significant background is possible under low stringency conditions. The universal application of this fast and simple one-step fluorescence banding technique for plant cytogenetic and plant genome evolution is discussed.     

Detection of aneuploidy in human spermatozoa using fluorescencein situ hybridization (FISH)

Summary Fluorescencein situ hybridization (FISH) with chromosome specific alpha-satellite DNA probes was used to estimate the rates of aneuploidy of chromosomes 1, 17, 18, X and Y in human ejaculated sperm. Sperm samples were collected from six donors, and biotinylated DNA probes, D1Z5, D17Z1, D18Z1, DXZ1 and DYZ3 were hybridized to interphase sperm which had been pretreated with dithiothreitol to expand their nuclei. A minimum of 3,000 sperm per donor were analyzed. The hybridization efficiency was 99.68% for all the five probes. The frequencies of aneuploidy for chromosomes 1, 17 and 18 were 0.65%, 0.66% and 0.61% respectively. For XX-and YY-sperm the frequencies were 0.28% and 0.27% respectively. To estimate the diploidy and disomy rates, a mixture of D17Z1 and D18Z1 were used as probes, and the frequency of diploid sperm was calculated to be 0.27%. After subtraction of the diploidy rate, the disomy rates for chromosomes 1, 17, and 18 were estimated to be 0.38%, 0.39% and 0.33%, respectively. The proportion of X- and Y-bearing sperm were 49.9% and 49.66%, consistent with an expected 1: 1 ratio.     

Issues in human embryonic stem cell biology

Human embryonic stem cells (hESCs) derived from frozen unused blastocytes from in vitro fertilization clinics exhibit unlimited proliferative capacity, and are pluripotent. The ability to maintain hESCs cultures in an undifferentiated state in vitro and differentiate them along a given lineage in a controlled manner make these cells potentially invaluable in regenerative medicine. Recent developments in the generation of patient-specific hESCs as well as animal product-free culture systems are some of the latest developments in the field; however great challenges lie ahead before the therapeutic application of hESCs becomes a reality. This article addresses some of the successes and roadblocks concerning the hESCs field; including various political, ethical and scientific obstacles.     

Karyotyping mouse chromosomes by multiplex-FISH (M-FISH)

Karyotyping of mouse chromosomes is a skillful art, which is laborious work even for experienced cytogeneticists. With the growing number of mouse models for human diseases, there is an increasing demand for automated mouse karyotyping systems. Here, such a karyotyping system for mouse chromosomes based on the multiplex-fluorescence in-situ hybridization (M-FISH) technology is shown. The system was tested on a number of individual mice with numerical and structural aberrations and its reproducibility and robustness verified. Mouse M-FISH should be a valuable tool for the analysis of chromosomal rearrangements in mice.     

体外构建胚胎干细胞生长分化的三维研究模型

目的以液态胶原为支架,小鼠胚胎干细胞(ESCs)为细胞模型,构建ESCs胶-原复合体,旨在尝试建立一种能够实现干细胞生长、分化的三维培养体系。方法提取鼠尾胶原,观察ESCs在自制胶原条带内增殖的形态特征,并测定葡萄糖/乳酸活性。以ESCs源心肌细胞为目的细胞,利用免疫组化、RT-PCR及电镜技术评价胶原条带内ESCs进行自发性分化的能力。结果ESCs在胶原条带所提供的三维培养体系内生长、增殖状态良好,且彼此间能够建立细胞连接。胶原条带内部分ESCs能够自发性分化为心肌细胞。该心肌细胞均可表达心肌蛋白cTn-T,心肌转录因子NKX2.5及肌球蛋白轻链MLC-2 vmRNA,且肌小节结构发育成熟。结论以液态Ⅰ型胶原为主体的支架材料可以为ESCs提供良好的生长基质,促进其组织化发育。该实验初步明确了体外构建干细胞生长分化三维模型的可行性。