搜索结果: 'methocult media formulations for human hematopoietic cells serum containing'

Translation of stem cell research to industrial and clinical settings mostly requires large quantities of cells,especially those involving large organs such as the liver. A scalable reactor system is desirable to ensure a reliable supply of sufficient quantities of differentiated cells. To increase the culture efficiency in bioreactor system,high surface to volume ratio needs to be achieved. We employed a microcarrier culture system for the expansion of undifferentiated human embryonic stem cells (hESCs) as well as for directed differentiation of these cells to hepatocyte-like cells. Cells in single cell suspension were attached to the bead surface in even distribution and were expanded to 1??106cells/ml within 2 days of hESC culture with maintenance of the level of pluripotency markers. Directed differentiation into hepatocyte-like cells on microcarriers,both in static culture and stirred bioreactors,induced similar levels of hepatocyte-like cell differentiation as observed with cells cultured in conventional tissue culture plates. The cells expressed both immature and mature hepatocyte-lineage genes and proteins such as asialoglycoprotein receptor-1 (ASGPR-1) and albumin. Differentiated cells exhibited functional characteristics such as secretion of albumin and urea,and CYP3A4 activity could be detected. Microcarriers thus offer the potential for large-scale expansion and differentiation of hESCs induced hepatocyte-like cells in a more controllable bioreactor environment. ?? 2014. View Publication

Progenitor cells have been extensively studied and therapeutically applied in tissue reconstructive therapy. Stromal vascular fraction (SVF) cells,which are derived from adipose tissue,may represent a potential source of the cells which undergo phenotypical differentiation into many lineages both in vitro as well as in vivo. The goal of this study was to check whether human SVF cells may differentiate into cardiomyocyte-like entities. Human SVF cells were induced to differentiate by their incubation in Methocult medium in the presence of SCF,IL-3 and IL-6. Morphological transformation of the cells was monitored using optical light microscope,whereas changes in expression of the genes typical for cardiac phenotype were measured by qRT-PCR. Incubation of the human SVF cells in the medium that promotes cardiomyocyte differentiation in vitro resulted in formation of myotubule-like structures accompanied by up-regulation of the myocardium-characteristic genes,such as GATA,MEF2C,MYOD1,but not ANP. Human SVF cells differentiate into cardiomyocyte-like cells in the presence of the certain set of myogenesis promoting cytokines. View Publication

A major road-block in stem cell therapy is the poor homing and integration of transplanted stem cells with the targeted host tissue. Human induced pluripotent stem (hiPS) cells are considered an excellent alternative to embryonic stem (ES) cells and we tested the feasibility of using small,physiological electric fields (EFs) to guide hiPS cells to their target. Applied EFs stimulated and guided migration of cultured hiPS cells toward the anode,with a stimulation threshold of textless30 mV/mm; in three-dimensional (3D) culture hiPS cells remained stationary,whereas in an applied EF they migrated directionally. This is of significance as the therapeutic use of hiPS cells occurs in a 3D environment. EF exposure did not alter expression of the pluripotency markers SSEA-4 and Oct-4 in hiPS cells. We compared EF-directed migration (galvanotaxis) of hiPS cells and hES cells and found that hiPS cells showed greater sensitivity and directedness than those of hES cells in an EF,while hES cells migrated toward cathode. Rho-kinase (ROCK) inhibition,a method to aid expansion and survival of stem cells,significantly increased the motility,but reduced directionality of iPS cells in an EF by 70-80%. Thus,our study has revealed that physiological EF is an effective guidance cue for the migration of hiPS cells in either 2D or 3D environments and that will occur in a ROCK-dependent manner. Our current finding may lead to techniques for applying EFs in vivo to guide migration of transplanted stem cells. View Publication

Avian species are important model animals for developmental biology and disease research. However,unlike in mice,where clonal lines of pluripotent stem cells have enabled researchers to study mammalian gene function,clonal and highly proliferative pluripotent avian cell lines have been an elusive goal. Here we demonstrate the generation of avian induced pluripotent stem cells (iPSCs),the first nonmammalian iPSCs,which were clonally isolated and propagated,important attributes not attained in embryo-sourced avian cells. This was accomplished using human pluripotency genes rather than avian genes,indicating that the process in which mammalian and nonmammalian cells are reprogrammed is a conserved process. Quail iPSCs (qiPSCs) were capable of forming all 3 germ layers in vitro and were directly differentiated in culture into astrocytes,oligodendrocytes,and neurons. Ultimately,qiPSCs were capable of generating live chimeric birds and incorporated into tissues from all 3 germ layers,extraembryonic tissues,and potentially the germline. These chimera competent qiPSCs and in vitro differentiated cells offer insight into the conserved nature of reprogramming and genetic tools that were only previously available in mammals. View Publication

Embryonic stem cells (ESCs) are unique cells,which have the ability to differentiate into all cell types that comprise the adult organism. Furthermore,ESCs can infinitely self-renew under optimized conditions. These features place human ESCs (hESCs) in a position where these cells can be exploited for tissue engineering and regenerative medicine approaches in treating human degenerative disorders. However,cell therapy approaches will require large amounts of clinically useable cells,not typically achievable using standard static cell culture methods. Here,we describe a method wherein clinically relevant numbers of hESCs can be generated in a cost and time effective manner. View Publication

We have previously reported that high concentrations of basic fibroblast growth factor (bFGF) support feeder-independent growth of human embryonic stem (ES) cells,but those conditions included poorly defined serum and matrix components. Here we report feeder-independent human ES cell culture that includes protein components solely derived from recombinant sources or purified from human material. We describe the derivation of two new human ES cell lines in these defined culture conditions. View Publication

Human embryonic stem cells (hESCs) share an identical genome with lineage-committed cells,yet possess the remarkable properties of self-renewal and pluripotency. The diverse cellular properties in different cells have been attributed to their distinct epigenomes,but how much epigenomes differ remains unclear. Here,we report that epigenomic landscapes in hESCs and lineage-committed cells are drastically different. By comparing the chromatin-modification profiles and DNA methylomes in hESCs and primary fibroblasts,we find that nearly one-third of the genome differs in chromatin structure. Most changes arise from dramatic redistributions of repressive H3K9me3 and H3K27me3 marks,which form blocks that significantly expand in fibroblasts. A large number of potential regulatory sequences also exhibit a high degree of dynamics in chromatin modifications and DNA methylation. Additionally,we observe novel,context-dependent relationships between DNA methylation and chromatin modifications. Our results provide new insights into epigenetic mechanisms underlying properties of pluripotency and cell fate commitment. textcopyright 2010 Elsevier Inc. View Publication

BACKGROUND: Constitutive promoters that ensure sustained and high level gene expression are basic research tools that have a wide range of applications,including studies of human embryology and drug discovery in human embryonic stem cells (hESCs). Numerous cellular/viral promoters that ensure sustained gene expression in various cell types have been identified but systematic comparison of their activities in hESCs is still lacking. METHODOLOGY/PRINCIPAL FINDINGS: We have quantitatively compared promoter activities of five commonly used constitutive promoters,including the human β-actin promoter (ACTB),cytomegalovirus (CMV),elongation factor-1α,(EF1α),phosphoglycerate kinase (PGK) and ubiquitinC (UbC) in hESCs. Lentiviral gene transfer was used to ensure stable integration of promoter-eGFP constructs into the hESCs genome. Promoter activities were quantitatively compared in long term culture of undifferentiated hESCs and in their differentiated progenies. CONCLUSION/SIGNIFICANCE: The ACTB,EF1α and PGK promoters showed stable activities during long term culture of undifferentiated hESCs. The ACTB promoter was superior by maintaining expression in 75-80% of the cells after 50 days in culture. During embryoid body (EB) differentiation,promoter activities of all five promoters decreased. Although the EF1α promoter was downregulated in approximately 50% of the cells,it was the most stable promoter during differentiation. Gene expression analysis of differentiated eGFP+ and eGFP- cells indicate that promoter activities might be restricted to specific cell lineages,suggesting the need to carefully select optimal promoters for constitutive gene expression in differentiated hESCs. View Publication

A new method of spatially controlled gene regulation in 3D-cultured human embryonic stem cells is developed using hollow gold nanoshells (HGNs) and near-infrared (NIR) light. Targeted cell(s) are discriminated from neighboring cell(s) by focusing NIR light emitted from a two-photon microscope. Irradiation of cells that have internalized HGNs releases surface attached siRNAs and leads to concomitant gene downregulation. View Publication

The spinal cord consists of multiple neuronal cell types that are critical to motor control and arise from distinct progenitor domains in the developing neural tube. Excitatory V2a interneurons in particular are an integral component of central pattern generators that control respiration and locomotion; however,the lack of a robust source of human V2a interneurons limits the ability to molecularly profile these cells and examine their therapeutic potential to treat spinal cord injury (SCI). Here,we report the directed differentiation of CHX10(+) V2a interneurons from human pluripotent stem cells (hPSCs). Signaling pathways (retinoic acid,sonic hedgehog,and Notch) that pattern the neural tube were sequentially perturbed to identify an optimized combination of small molecules that yielded ∼25% CHX10(+) cells in four hPSC lines. Differentiated cultures expressed much higher levels of V2a phenotypic markers (CHX10 and SOX14) than other neural lineage markers. Over time,CHX10(+) cells expressed neuronal markers [neurofilament,NeuN,and vesicular glutamate transporter 2 (VGlut2)],and cultures exhibited increased action potential frequency. Single-cell RNAseq analysis confirmed CHX10(+) cells within the differentiated population,which consisted primarily of neurons with some glial and neural progenitor cells. At 2 wk after transplantation into the spinal cord of mice,hPSC-derived V2a cultures survived at the site of injection,coexpressed NeuN and VGlut2,extended neurites textgreater5 mm,and formed putative synapses with host neurons. These results provide a description of V2a interneurons differentiated from hPSCs that may be used to model central nervous system development and serve as a potential cell therapy for SCI. View Publication

Cryopreservation is an essential technique to preserve stem cells,semipermanently sustaining their potentials. There are two main approaches of cryopreservation for human pluripotent stem cells (hPSCs). The first is the vitrification,which involves instantaneous freeze and thaw of hPSCs. The second is the conventional slow-cooling method and a rapid thaw. Both cryopreservation protocols have been standardized and optimized to yield high survivability of hPSCs. View Publication