Expression of the 49 human ATP binding cassette (ABC) genes in pluripotent embryonic stem cells and in early- and late-stage multipotent mesenchymal stem cells

The 49-member human ATP binding cassette (ABC) gene family encodes 44 membrane transporters for lipids, ions, peptides or xenobiotics, four translation factors without transport activity, as they lack transmembrane domains, and one pseudogene. To understand the roles of ABC genes in pluripotency and multipotency, we performed a sensitive qRT-PCR analysis of their expression in embryonic stem cells (hESCs), bone marrow-derived mesenchymal stem cells (hMSCs) and hESC-derived hMSCs (hES-MSCs). We confirm that hES-MSCs represent an intermediate developmental stage between hESCs and hMSCs. We observed that 44 ABCs were significantly expressed in hESCs, 37 in hES-MSCs and 35 in hMSCs. These variations are mainly due to plasma membrane transporters with low but significant gene expression: 18 are expressed in hESCs compared with 16 in hES-MSCs and 8 in hMSCs, suggesting important roles in pluripotency. Several of these ABCs shared similar substrates but differ regarding gene regulation. ABCA13 and ABCB4, similarly to ABCB1, could be new markers to select primitive hMSCs with specific plasma membrane transporter^low phenotypes. ABC proteins performing basal intracellular functions, including translation factors and mitochondrial heme transporters, showed the highest constant gene expression among the three populations. Peptide transporters in the endoplasmic reticulum, Golgi and lysosome were well expressed in hESCs and slightly upregulated in hMSCs, which play important roles during the development of stem cell niches in bone marrow or meningeal tissue. These results will be useful to study specific cell cycle regulation of pluripotent stem cells or ABC dysregulation in complex pathologies, such as cancers or neurological disorders.     

Role of circadian gene Clock during differentiation of mouse pluripotent stem cells

Biological rhythms controlled by the circadian clock are absent in embryonic stem cells (ESCs). However, they start to develop during the differentiation of pluripotent ESCs to downstream cells. Conversely, biological rhythms in adult somatic cells disappear when they are reprogrammed into induced pluripotent stem cells (iPSCs). These studies indicated that the development of biological rhythms in ESCs might be closely associated with the maintenance and differentiation of ESCs. The core circadian gene Clock is essential for regulation of biological rhythms. Its role in the development of biological rhythms of ESCs is totally unknown. Here, we used CRISPR/CAS9-mediated genetic editing techniques, to completely knock out the Clock expression in mouse ESCs. By AP, teratoma formation, quantitative real-time PCR and Immunofluorescent staining, we did not find any difference between Clock knockout mESCs and wild type mESCs in morphology and pluripotent capability under the pluripotent state. In brief, these data indicated Clock did not influence the maintaining of pluripotent state. However, they exhibited decreased proliferation and increased apoptosis. Furthermore, the biological rhythms failed to develop in Clock knockout mESCs after spontaneous differentiation, which indicated that there was no compensational factor in most peripheral tissues as described in mice models before (DeBruyne et al., 2007b). After spontaneous differentiation, loss of CLOCK protein due to Clock gene silencing induced spontaneous differentiation of mESCs, indicating an exit from the pluripotent state, or its differentiating ability. Our findings indicate that the core circadian gene Clock may be essential during normal mESCs differentiation by regulating mESCs proliferation, apoptosis and activity.     

Hypoxia enhances buffalo adipose-derived mesenchymal stem cells proliferation,stemness, and reprogramming into induced pluripotent stem cells

Adipose tissue-derived mesenchymal stem cells (ASCs) from livestock are valuable resources for animal reproduction and veterinary therapeutics. Previous studies have shown that hypoxic conditions were beneficial in maintaining the physiological activities of ASCs. However, the effects of hypoxia on buffalo ASCs (bASCs) remain unclear. In this study, the effects of hypoxia on proliferation, stemness, and reprogramming into induced pluripotent stem cells (iPSCs) of bASCs were examined. The results showed that the hypoxic culture conditions (5% oxygen) enhanced the proliferation and colony formation of bASCs. The expression levels of proliferation-related genes, and secretion of basic fibroblast growth factor (bFGF) and vascular endothelial growth factor (VEGF) were significantly enhanced in hypoxia. Hypoxic culture conditions activated hypoxia-inducible factor-1α (HIF-1α), thereby contributing to the secretion of bFGF and VEGF, which in turn enhanced the expression of HIF-1α and promoted the proliferation of bASCs. Furthermore, in hypoxic culture conditions, bASCs exhibited the main characteristics of mesenchymal stem cells, and the expression levels of the pluripotent markers OCT4, NANOG, C-MYC, and the differentiation capacity of bASCs were significantly enhanced. Finally, bASCs were more efficiently and easily reprogrammed into iPSCs in hypoxic culture conditions and these iPSCs exhibited some characteristics of naïve pluripotent stem cells. These findings provide the theoretical guidance for elucidating the detailed mechanism of hypoxia on physiological activities of bASCs including proliferation, stemness maintenance, and reprogramming.     

Multipotent properties of myofibroblast cells derived from human placenta

Human uterine fibroblasts (HuF) isolated from the maternal part (decidua parietalis) of a term placenta provide a useful model of in vitro cell differentiation into decidual cells (decidualization, a critical process for successful pregnancy). After isolation, the cells adhere to plastic and have either a small round or spindle-shaped morphology that later changes into a flattened pattern in culture. HuF robustly proliferate in culture until passage 20 and form colonies when plated at low densities. The cells express the mesenchymal cell markers fibronectin, integrin-β1, ICAM-1 (CD54), and collagen I. Flow cytometry of HuF has detected the presence of CD34, a marker of the hematopoietic stem cell lineage, and an absence of CD10, CD11b/Mac, CD14, CD45, and HLA type II. Furthermore, they also express the pluripotency markers SSEA-1, SSEA-4, Oct-4, Stro-1, and TRA-1–81 as detected by confocal microscopy. Treatment for 14–21 days with differentiation-inducing media leads to the differentiation of HuF into osteoblasts, adipocytes, and chondrocytes. The presence of α-smooth muscle actin, calponin, and myosin light-chain kinase in cultured HuF implies their similarity to myofibroblasts. Treatment of the HuF with dimethyl sufoxide causes reversion to the spindle-shaped morphology and a loss of myofibroblast characteristics, suggesting a switch into a less differentiated phenotype. The unique abilities of HuF to exhibit multipotency, even with myofibroblast characteristics, and their ready availability and low maintenance requirements make them an interesting cell model for further exploration as a possible tool for regenerative medicine. Electronic Supplementary Material The online version of this article (doi:) contains supplementary material, which is available to authorized user. This work was supported by National Institutes of Health Grant HD-44713 (to Z.S.).     

Identification and characterization of in vitro expanded hematopoietic stem cells

Hematopoietic stem cells (HSCs) cultured outside the body are the fundamental component of a wide range of cellular and gene therapies. Recent efforts have achieved > 200‐fold expansion of functional HSCs, but their molecular characterization has not been possible since the majority of cells are non‐HSCs and single cell‐initiated cultures have substantial clone‐to‐clone variability. Using the Fgd5 reporter mouse in combination with the EPCR surface marker, we report exclusive identification of HSCs from non‐HSCs in expansion cultures. By directly linking single‐clone functional transplantation data with single‐clone gene expression profiling, we show that the molecular profile of expanded HSCs is similar to proliferating fetal HSCs and reveals a gene expression signature, including Esam, Prdm16, Fstl1, and Palld, that can identify functional HSCs from multiple cellular states. This “repopulation signature” (RepopSig) also enriches for HSCs in human datasets. Together, these findings demonstrate the power of integrating functional and molecular datasets to better derive meaningful gene signatures and opens the opportunity for a wide range of functional screening and molecular experiments previously not possible due to limited HSC numbers.     

Morphological and functional characterization of adherent splenic cells of mice

The separation, characterization and functional assay of the inflammatory infiltrate present in the site of the lesion has been useful in the study of many diseases. Histochemical techniques for esterase and acid phosphatase, as well as the Phagocytose test and the Giemsa staining were applied to the study of the spleen-cell population of ten mice. A good characterization of the components of the Phagocytic Mononuclear System and the identification and quantification of the total cell population were obtained.     

Pluripotency of male germline stem cells

The ethical issues and public concerns regarding the use of embryonic stem (ES) cells in human therapy have motivated considerable research into the generation of pluripotent stem cell lines from non-embryonic sources. Numerous reports have shown that pluripotent cells can be generated and derived from germline stem cells (GSCs) in mouse and human testes during in vitro cultivation. The gene expression patterns of these cells are similar to those of ES cells and show the typical self-renewal and differentiation patterns of pluripotent cells in vivo and in vitro. However, the mechanisms underlying the spontaneous dedifferentiation of GSCs remain to be elucidated. Studies to identify master regulators in this reprogramming process are of critical importance for understanding the gene regulatory networks that sustain the cellular status of these cells. The results of such studies would provide a theoretical background for the practical use of these cells in regenerative medicine. Such studies would also help elucidate the molecular mechanisms underlying certain diseases, such as testicular germ cell tumors.     

Isolation, characterization, and differentiation of stem cells derived from the rat amniotic membrane

Abstract Stem-cell-based therapies may offer treatments for a variety of intractable diseases. A fundamental goal in stem-cell biology concerns the characterization of diverse populations that exhibit different potentials, growth capabilities, and therapeutic utilities. We report the characterization of a stem-cell population isolated from tissue explants of rat amniotic membrane. Similar to mesenchymal stem cells, these amnion-derived stem cells (ADSCs) express the surface markers CD29 and CD90, but were negative for the lymphohematopoietic markers CD45 and CD11b. ADSCs exist in culture in a multidifferentiated state, expressing neuroectodermal (neurofilament-M), mesodermal (fibronectin), and endodermal (α-1-antitrypsin) genes. To assess plasticity, ADSCs were subjected to a number of culture conditions intended to encourage differentiation into neuroectodermal, mesodermal, and endodermal cell types. ADSCs cultured in a defined neural induction media assumed neuronal morphologies and up-regulated neural-specific genes. Under different conditions, ADSCs were capable of differentiating into presumptive bone and fat cells, indicated by the deposition of mineralized matrix and accumulated lipid droplets, respectively. Moreover, ADSCs cultured in media that promotes liver cell differentiation up-regulated liver-specific genes (albumin) and internalized low-density lipoprotein (LDL), consistent with a hepatocyte phenotype. To determine whether this observed plasticity reflects the presence of true stem cells within the population, we have derived individual clones from single cells. Clonal lines recapitulate the expression pattern of parental ADSC cultures and are multipotent. ADSCs have been cultured for 20 passages without losing their plasticity, suggesting long-term self-renewal. In sum, our data suggest that ADSCs and derived clonal lines are capable of long-term self-renewal and multidifferentiation, fulfilling all the criteria of a stem-cell population.     

The transfection of embryonic stem cells with Tet-on system and its responsiveness to doxycycline

We transiently transfected pTet-on and pTRE2hyg-luciferase into the mouse embryonic stem cells (ESCs) using lipofectamine, and analyzed its inductive effect by adding serial concentrations of doxycycline (DOX). The results showed that in the transfected group, the luciferase activity of the cells was gradually increased along with the increasing concentration of DOX. While in the non-transfected group, the luciferase activity was not detectable even with DOX treatment. This indicated that the ESCs transfected with Tet-on system could response to DOX very well, and the regulation of target gene expression is dose dependent.     

Identification and characterization of label-retaining cells in mouse pancreas

Pancreatic stem cells (PSCs) may play an important role in maintaining and repairing pancreatic tissues. However, both the existence and localization of PSCs in adult mammalian pancreas still remain elusive. In order to locate the potential pancreatic progenitor/stem cells, we used the tracing label-retaining cells (LRCs) method and identified slow-cycling cells in mouse pancreas. Characterization of the LRCs revealed that the differentiation marker-negative LRCs were located not only within and around the islets but also around the acini and ducts. About 30% of the LRCs around the acini and ducts expressed c-Met, which is a putative pancreatic progenitor/stem cell marker. Moreover, the LRCs around the acini could be activated to form duct-like structures in response to pancreatic damage, and the involvement of these LRCs in the neogenesis of islets and focal areas could also be observed in acini. Our data suggest that the LRCs located around the acini and ducts may represent potential pancreatic progenitor/stem cells, and characterization of these cells may aid in further identification of the specific markers of pancreatic progenitor/stem cells.     

Adult mesenchymal stem cells: characterization, differentiation, and application in cell and gene therapy

A considerable amount of retrospective data is available that describes putative mesenchymal stem cells (MSCs). However, there is still very little knowledge available that documents the properties of a MSC in its native environment. Although the precise identity of MSCs remains a challenge, further understanding of their biological properties will be greatly advanced by analyzing the mechanisms that govern their self-renewal and differentiation potential. This review begins with the current state of knowledge on the biology of MSCs, specifically with respect to their existence in the adult organism and postulation of their biological niche. While MSCs are considered suitable candidates for cell-based strategies owing to their intrinsic capacity to self-renew and differentiate, there is currently little information available regarding the molecular mechanisms that govern their stem cell potential. We propose here a model for the regulation of MSC differentiation, and recent findings regarding the regulation of MSC differentiation are discussed. Current research efforts focused on elucidating the mechanisms regulating MSC differentiation should facilitate the design of optimal in vitro culture conditions to enhance their clinical utility cell and gene therapy.     

干细胞概述

干细胞是存在于胚胎和成体中的一类特殊细胞,它能长期地自我更新,在特定的条件下具有分化形成多种终末细胞的能力,不同来源的干细胞分化潜能各异。从早期胚胎内细胞团分离的胚胎干细胞能分化形成个体所有的细胞类型,并具有在体外无限增殖的能力,是最具有临床应用前景和研究价值的干细胞之一。在成体各种组织和器官中也存在成体干细胞,用于维持机体结构和功能的稳态。近期有关成体干细胞可塑性的研究和成体组织中多能干细胞存在的证据扩大了人们对成体干细胞分化潜能的认识。干细胞具有的多向分化潜能和自我更新能力使其成为未来再生医学的重要种子细胞,并成为研究人类早期胚层特化和器官形成、药物筛选以及基因治疗的最佳工具。     

A novel method of encapsulating and cultivating adherent mammalian cells within collagen microcarriers

A novel method of preparing collagen microcarriers was developed and used to entrap adherent cells for cell culturing. This new technique involved seeding of cells in micro gel beads comprised of collagen fibrils dispersed in alginate. The gel beads were washed with phosphate buffered saline (PBS) to remove alginate and the resulting microspheres, about 300-500 microm in diameter, contained evenly distributed collagen fibrils which provided a 3D biomimetic environment for cell growth. The applicability of this microencapsulating system was demonstrated by its ability to support the growth of C2C12 myoblast cells. When seeded and cultured within the 3D collagen microcarriers, the population of C2C12 cells entrapped within the microcarriers increased by 1.5 folds in 7 days after inoculation. This encapsulation technique is potentially useful for culturing cells and especially useful for adherent cells that require a 3D fibrillar collagen environment.     

A proposed design for the cryopreservation of intact and adherent human embryonic stem cell colonies

Summary Recently, it was demonstrated that the application of slow-cooling cryopreservation protocols to adherent human embryonic stem (hES) cell colonies, cultured on matrigel or murine embryonic fibroblast feeder layers, resulted in marked improvement in postthaw viability and reduction in cell differentiation. However, the use of commercially available culture plates for this purpose presents several limitations. Most obviously, these plates are not designed for cryopreservation or to withstand the low temperatures encountered during liquid nitrogen cryopreservation, or both. The physical storage of cryopreserved plates is another consideration, in addition to difficulty in maintaining sterile conditions in liquid nitrogen storage and during the thaw phase in a water bath. Hence, a redesign of the cell culture plate for the cryopreservation of adherent hES cell colonies is proposed. In this model, a culture plate made of synthetic materials resistant to storage at −196° C of liquid nitrogen is designed, with readily attachable screw-cap culture wells that function as a replacement for cryovial storage. The detachable wells facilitate storage and after thawing can easily be reattached to a specially designed holding plate. Currently, there are no commercially available cell culture plates using this design concept. The proposed design is envisioned to facilitate the cryopreservation of intact adherent hES cell colonies that could assist the development of automated systems for handling bulk quantities of cells.     

Specific lectin biomarkers for isolation of human pluripotent stem cells identified through array-based glycomic analysis

Rapid and dependable methods for isolating human pluripotent stem cell (hPSC) populations are urgently needed for quality control in basic research and in cell-based therapy applications. Using lectin arrays, we analyzed glycoproteins extracted from 26 hPSC samples and 22 differentiated cell samples, and identified a small group of lectins with distinctive binding signatures that were sufficient to distinguish hPSCs from a variety of non-pluripotent cell types. These specific biomarkers were shared by all the 12 human embryonic stem cell and the 14 human induced pluripotent stem cell samples examined, regardless of the laboratory of origin, the culture conditions, the somatic cell type reprogrammed, or the reprogramming method used. We demonstrated a practical application of specific lectin binding by detecting hPSCs within a differentiated cell population with lectin-mediated staining followed by fluorescence microscopy and flow cytometry, and by enriching and purging viable hPSCs from mixed cell populations using lectin-mediated cell separation. Global gene expression analysis showed pluripotency-associated differential expression of specific fucosyltransferases and sialyltransferases, which may underlie these differences in protein glycosylation and lectin binding. Taken together, our results show that protein glycosylation differs considerably between pluripotent and non-pluripotent cells, and demonstrate that lectins may be used as biomarkers to monitor pluripotency in stem cell populations and for removal of viable hPSCs from mixed cell populations.     

The transfection of embryonic stem cells with Tet-on system and its responsiveness to doxycycline

Embryonic stem cells (ESCs) represent a valuable source for clinic application and basic research due to their unlimited self-renew capacity and multilineage differentiation potential. The maintenance of these characteristics is closely related with the gene expres-sion of Oct-4, mTOR, etc.[1,2]. Meanwhile, cell differ-entiation in vitro and in vivo is also related with gene expression changes, such as CyclinD, TGF-β, VEGF[3―5]. In order to study the function of interested genes, a reg…     

Purification of pluripotent embryonic stem cells using dielectrophoresis and a flow control system

Pluripotent stem cells (PSCs) such as embryonic stem cells and induced PSCs can differentiate into all somatic cell types such as cardiomyocytes, nerve cells, and chondrocytes. However, PSCs can easily lose their pluripotency if the culture process is disturbed. Therefore, cell sorting methods for purifying PSCs with pluripotency are important for the establishment and expansion of PSCs. In this study, we focused on dielectrophoresis (DEP) to separate cells without fluorescent dyes or magnetic antibodies. The goal of this study was to establish a cell sorting method for the purification of PSCs based on their pluripotency using DEP and a flow control system. The dielectrophoretic properties of mouse embryonic stem cells (mESCs) with and without pluripotency were evaluated in detail, and mESCs exhibited varying frequency dependencies in the DEP response. Based on the variance in DEP properties, mixed cell suspensions of mESCs can be separated according to their pluripotency with an efficacy of approximately 90%.