Spontaneous immortalization of human dermal microvascular endothelial cells

AIM

To establish and characterize a spontaneously immortalized human dermal microvascular endothelial cell line, iHDME1.

METHODS

We developed a spontaneous immortalization method. This approach is based on the application of optimized culture media and culture conditions without addition of any exogenous oncogenes or carcinogens. Using this approach, we have successfully established a microvascular endothelial cell line, iHDME1, from primary human dermal microvascular endothelial cells. iHDME1 cells have been maintained in culture dishes for more than 50 passages over a period of 6 mo. Using a GFP expressing retrovirus, we generated a GFP-stable cell line (iHDME1-GFP).

RESULTS

iHDME1 retain endothelial morphology and uniformly express endothelial markers such as VEGF receptor 2 and VE-cadherin but not α-smooth muscle actin (α-SM-actin) and cytokeratin 18, markers for smooth muscle cells and epithelial cells respectively. These cells retain endothelial properties, migrate in response to VEGF stimulation and form 3-D vascular structures in Matrigel, similar to the parental cells. There is no significant difference in cell cycle profile between the parental cells and iHDME1 cells. Further analysis indicates enhanced stemness in iHDME1 cells compared to parental cells. iHDME1 cells display elevated expression of CD133 and hTERT.

CONCLUSION

iHDME1 cells will be a valuable source for studying angiogenesis.

Adipose tissue-derived progenitor cells and cancer

Recruitment of stem cells and partially differentiated progenitor cells is a process which accompanies and facilitates the progression of cancer. One of the factors complicating the clinical course of cancer is obesity, a progressively widespread medical condition resulting from overgrowth of white adipose tissue (WAT), commonly known as white fat. The mechanisms by which obesity influences cancer risk and progression are not completely understood. Cells of WAT secret soluble molecules (adipokines) that could stimulate tumor growth, although there is no consensus on which cell populations and which adipokines are important. Recent reports suggest that WAT-derived mesenchymal stem (stromal) cells, termed adipose stem cells (ASC), may represent a cell population linking obesity and cancer. Studies in animal models demonstrate that adipokines secreted by ASC can promote tumor growth by assisting in formation of new blood vessels, a process necessary for expansion of tumor mass. Importantly, migration of ASC from WAT to tumors has been demonstrated, indicating that the tumor microenvironment in cancer may be modulated by ASC-derived trophic factors in a paracrine rather than in an endocrine manner. Here, we review possible positive and adverse implications of progenitor cell recruitment into the diseased sites with a particular emphasis on the role in cancer progression of progenitors that are expanded in obesity.

Mesenchymal stromal cells from human perinatal tissues: From biology to cell therapy

Cell-based regenerative medicine is of growing interest in biomedical research. The role of stem cells in this context is under intense scrutiny and may help to define principles of organ regeneration and develop innovative therapeutics for organ failure. Utilizing stem and progenitor cells for organ replacement has been conducted for many years when performing hematopoietic stem cell transplantation. Since the first successful transplantation of umbilical cord blood to treat hematological malignancies, non-hematopoietic stem and progenitor cell populations have recently been identified within umbilical cord blood and other perinatal and fetal tissues. A cell population entitled mesenchymal stromal cells (MSCs) emerged as one of the most intensely studied as it subsumes a variety of capacities: MSCs can differentiate into various subtypes of the mesodermal lineage, they secrete a large array of trophic factors suitable of recruiting endogenous repair processes and they are immunomodulatory.Focusing on perinatal tissues to isolate MSCs, we will discuss some of the challenges associated with these cell types concentrating on concepts of isolation and expansion, the comparison with cells derived from other tissue sources, regarding phenotype and differentiation capacity and finally their therapeutic potential.

Epigenetic states and expression of imprinted genes in human embryonic stem cells

AIM

To investigate the epigenetic states and expression of imprinted genes in five human embryonic stem cell (hESC) lines derived in Taiwan.

METHODS

The heterozygous alleles of single nucleotide polymorphisms (SNPs) at imprinted genes were analyzed by sequencing genomic DNAs of hESC lines and the monoallelic expression of the imprinted genes were confirmed by sequencing the cDNAs. The expression profiles of 32 known imprinted genes of five hESC lines were determined using Affymetrix human genome U133 plus 2.0 DNA microarray.

RESULTS

The heterozygous alleles of SNPs at seven imprinted genes, IPW, PEG10, NESP55, KCNQ1, ATP10A, TCEB3C and IGF2, were identified and the monoallelic expression of these imprinted genes except IGF2 were confirmed. The IGF2 gene was found to be imprinted in hESC line T2 but partially imprinted in line T3 and not imprinted in line T4 embryoid bodies. Ten imprinted genes, namely GRB10, PEG10, SGCE, MEST, SDHD, SNRPN, SNURF, NDN, IPW and NESP55, were found to be highly expressed in the undifferentiated hESC lines and down-regulated in differentiated derivatives. The UBE3A gene abundantly expressed in undifferentiated hESC lines and further up-regulated in differentiated tissues. The expression levels of other 21 imprinted genes were relatively low in undifferentiated hESC lines and five of these genes (TP73, COPG2, OSBPL5, IGF2 and ATP10A) were found to be up-regulated in differentiated tissues.

CONCLUSION

The epigenetic states and expression of imprinted genes in hESC lines should be thoroughly studied after extended culture and upon differentiation in order to understand epigenetic stability in hESC lines before their clinical applications.

A novel strategy for engineering vascularized grafts in vitro

Tissue engineering is an interdisciplinary field promising new therapeutic means for replacing lost or severely damaged tissues or organs. However, the fabrication of complex engineered tissues has been hampered due to the lack of vascularization to provide sufficient blood supply after implantation. In this article, we propose using rapid prototyping technology to prefabricate a scaffold with an inside hollowed vascular system including an arterial end, a venous end and capillary networks between them. The scaffold will be ''printed'' layer by layer. When printing every layer, a ''low-melting point'' material will be used to form a blood vessel network and a tissue-specific material will be used outside it. Hereafter the 'low-melting point' material will be evacuated by vaporization to ensure a hollowed vessel network. Then the inside hollowed capillary network can be endothelialized by using autologous endothelial cells in a cycling bioreactor while the outside material can be embedded with tissue-special cells. In the end, the new vascularized autologous grafts could be transferred to the defect site by using microsurgical techniques to connect the grafts with the host artery and vein. The strategy would facilitate construction of complex tissue engineering if the hypothesis proved to be practical.

Mesenchymal stem cells: Molecular characteristics and clinical applications

Mesenchymal stem cells (MSCs) are non-hematopoietic stem cells with the capacity to differentiate into tissues of both mesenchymal and non-mesenchymal origin. MSCs can differentiate into osteoblastic, chondrogenic, and adipogenic lineages, although recent studies have demonstrated that MSCs are also able to differentiate into other lineages, including neuronal and cardiomyogenic lineages. Since their original isolation from the bone marrow, MSCs have been successfully harvested from many other tissues. Their ease of isolation and ex vivo expansion combined with their immunoprivileged nature has made these cells popular candidates for stem cell therapies. These cells have the potential to alter disease pathophysiology through many modalities including cytokine secretion, capacity to differentiate along various lineages, immune modulation and direct cell-cell interaction with diseased tissue. Here we first review basic features of MSC biology including MSC characteristics in culture, homing mechanisms, differentiation capabilities and immune modulation. We then highlight some in vivo and clinical evidence supporting the therapeutic roles of MSCs and their uses in orthopedic, autoimmune, and ischemic disorders.

Host tissue response in stem cell therapy

Preclinical and clinical trials of stem cell therapy have been carried out for treating a broad spectrum of diseases using several types of adult stem cells. While encouraging therapeutic results have been obtained, much remains to be investigated regarding the best cell type to use, cell dosage, delivery route, long-term safety, clinical feasibility, and ultimately treatment cost. Logistic aspects of stem cell therapeutics remain an area that requires urgent attention from the medical community. Recent cardiovascular trial studies have demonstrated that growth factors and cytokines derived from the injected stem cells and host tissue appear to contribute largely to the observed therapeutic benefits, indicating that trophic actions rather than the multilineage potential (or stemness) of the administered stem cells may provide the underlying tissue healing power. However, the capacity for trophic factor production can be aberrantly downregulated as seen in human heart disease. Skeletal muscle is a dynamic tissue with an impressive ability to continuously respond to environmental stimuli. Indeed, a relation exists between active skeletal muscle and low cardiovascular risk, highlighting the critical link between the skeletal muscle and cardiovascular systems. Adding to this notion are recent studies showing that stem cells injected into skeletal muscle can rescue the failing rodent heart through activation of the muscle trophic factor network and mobilization of bone marrow multilineage progenitor cells. However, aging and disease can adversely affect the host tissue into which stem cells are injected. A better understanding of the host tissue response in stem cell therapy is necessary to advance the field and bridge the gap between preclinical and clinical findings.

Vessel-associated stem cells from skeletal muscle: From biology to future uses in cell therapy

Over the last years, the existence of different stem cells with myogenic potential has been widely investigated. Besides the classical skeletal muscle progenitors represented by satellite cells, numerous multipotent and embryologically unrelated progenitors with a potential role in muscle differentiation and repair have been identified. In order to conceive a therapeutic approach for degenerative muscle disorders, it is of primary importance to identify an ideal stem cell endowed with all the features for a possible use in vivo. Among all emerging populations, vessel-associated stem cells are a novel and promising class of multipotent progenitors of mesodermal origin and with high myogenic potential which seem to best fit all the requirements for a possible cell therapy. In vitro and in vivostudies have already tested the effectiveness and safety of vessel-associated stem cells in animal models. This leads to the concrete possibility in the future to start pilot human clinical trials, hopefully opening the way to a turning point in the treatment of genetic and acquired muscle disorders.

Immunological properties of embryonic and adult stem cells

The possibility of treating degenerative diseases by stem cell-based approaches is a promising therapeutical option. Among major concerns for the clinical application of stem cells, some derive from the possibility that stem cells may be rejected by the immune system as a consequence of histoincompatibility and that stem cells themselves may interfere with the normal functions of host immune response. Therefore, the immunogenicity and the immunomodulatory properties of stem cells must be carefully addressed. Although these properties are common features of different stem cell types, some peculiarities can be recognized and characterized for their proper clinical use.

Mesenchymal stem cells: From bench to bedside

Human mesenchymal stem cells (hMSCs) have tremendous promise for use in a variety of clinical applications. The ability of these cells to self-renew and differentiate into multiple tissues makes them an attractive cell source for a new generation of cell-based regenerative therapies. Encouraging results from clinical trials have also generated growing enthusiasm regarding MSC therapy and related treatment, but gaps remain in understanding MSC tissue repair mechanisms and in clinical strategies for efficient cell delivery and consistent therapeutic outcomes. For these reasons, discoveries from basic research and their implementation in clinical trials are essential to advance MSC therapy from the laboratory bench to the patient's bedside.

Hematopoietic stem cells in research and clinical applications: The "CD34 issue"

In this paper, experimental findings concerning the kinetics of hematopoietic reconstitution are compared to corresponding clinical data. Although not clearly apparent, the transplantation practice seems to confirm the basic proposals of experimental hematology concerning hematopoietic reconstitution resulting from successive waves of repopulation stemming from different subpopulations of progenitor and stem cells. One of the "first rate" parameters in clinical transplantations in hematology; i.e. the CD34+ positive cell dose, has been discussed with respect to the functional heterogeneity and variability of cell populations endowed by expression of CD34. This parameter is useful only if the relative proportion of stem and progenitor cells in the CD34+ cell population is more or less maintained in a series of patients or donors. This proportion could vary with respect to the source, pathology, treatment, processing procedure, the graft ex vivo treatment and so on. Therefore, a universal dose of CD34+ cells cannot be defined. In addition, to avoid further confusion, the CD34+ cells should not be named "stem cells" or "progenitor cells" since these denominations only concern functionally characterized cell entities.

Human pluripotent stem cells: from biology to cell therapy

Human pluripotent stem cells (PSCs), encompassing embryonic stem cells and induced pluripotent stem cells, proliferate extensively and differentiate into virtually any desired cell type. PSCs endow regenerative medicine with an unlimited source of replacement cells suitable for human therapy. Several hurdles must be carefully addressed in PSC research before these theoretical possibilities are translated into clinical applications. These obstacles are: (1) cell proliferation; (2) cell differentiation; (3) genetic integrity; (4) allogenicity; and (5) ethical issues. We discuss these issues and underline the fact that the answers to these questions lie in a better understanding of the biology of PSCs. To contribute to this aim, we have developed a free online expression atlas, Amazonia!, that displays for each human gene a virtual northern blot for PSC samples and adult tissues (http://www.amazonia.transcriptome.eu).

Application of human umbilical cord blood-derived mesenchymal stem cells in disease models

Human umbilical cord blood-derived mesenchymal stem cells (hUCB-MSCs) are regarded as an alternative source of bone marrow-derived mesenchymal stem cells because collection of cord blood is less invasive than that of bone marrow. hUCB-MSCs have recently been studied for evaluation of their potential as a source of cell therapy. In this review, the general characteristics of hUCB-MSCs and their therapeutic effects on various diseases in vitro and in vivo will be discussed.

Advances in stem cell therapy for the lower urinary tract

Lower urinary tract diseases are emotionally and financially burdensome to the individual and society. Current treatments are ineffective or symptomatic. Conversely, stem cells (SCs) are regenerative and may offer long-term solutions. Among the different types of SCs, bone marrow SCs (BMSCs) and skeletal muscle-derived SCs (SkMSCs) have received the most attention in pre-clinical and clinical trial studies concerning the lower urinary tract. In particular, clinical trials with SkMSCs for stress urinary incontinence have demonstrated impressive efficacy. However, both SkMSCs and BMSCs are difficult to obtain in quantity and therefore neither is optimal for the eventual implementation of SC therapy. On the other hand, adipose tissue-derived SCs (ADSCs) can be easily and abundantly obtained from "discarded" adipose tissue. Moreover, in several head-on comparison studies, ADSCs have demonstrated equal or superior therapeutic potential compared to BMSCs. Therefore, across several different medical disciplines, including urology, ADSC research is gaining wide attention. For the regeneration of bladder tissues, possible differentiation of ADSCs into bladder smooth muscle and epithelial cells has been demonstrated. For the treatment of bladder diseases, specifically hyperlipidemia and associated overactive bladder, ADSCs have also demonstrated efficacy. For the treatment of urethral sphincter dysfunction associated with birth trauma and hormonal deficiency, ADSC therapy was also beneficial. Finally, ADSCs were able to restore erectile function in various types of erectile dysfunction (ED), including those associated with diabetes, hyperlipidemia, and nerve injuries. Thus, ADSCs have demonstrated remarkable therapeutic potentials for the lower urinary tract.

The bad and the good of mesenchymal stem cells in cancer: Boosters of tumor growth and vehicles for targeted delivery of anticancer agents

In cancer biology, mesenchymal stem cells (MSCs) display aspects that can appear contradictory. On one hand, these cells possess several features which give them the ability to specifically target and then sustain cancer cells in their ability to survive the multifaceted host response against cancer. On the other hand, due to this excellent aptitude to home-in on tumor tissues, regardless their location in the host's body, MSCs are considered to be extremely selective vehicles to reach cancer cells specifically. Recently, MSC sustainment of cancer cell growth is a hot research topic. Indeed, these cells are known to sustain tumor angiogenesis and metastasis formation, to create a microenvironment favorable for cancer cell growth and to down-modulate the immune system capabilities in the host organism. On the other hand, since scientists became able to take advantage of their extremely selective capability to target cancer cells, MSCs are now also thought of in a different light. Indeed, MSCs are now considered a promising vehicle for local expression or delivery of even particularly toxic anticancer agents, ranging from Herpes Simplex Virus to locally-acting antineoplastic drugs. On this basis, investigation is now focused on how to impair the pro-neoplastic features of MSCs on one hand whilst taking advantage of their specific tropism toward cancer cells, on the other. As with the two faces of Janus, this review will concisely explore the research activity in these two apparently conflicting fields.

The famous versus the inconvenient - or the dawn and the rise of 3D-culture systems

One of the greatest impacts on in vitro cell biology was the introduction of three-dimensional (3D) culture systems more than six decades ago and this era may be called the dawn of 3D-tissue culture. Although the advantages were obvious, this field of research was a "sleeping beauty" until the 1970s when multicellular spheroids were discovered as ideal tumor models. With this rebirth, organotypical culture systems became valuable tools and this trend continues to increase. While in the beginning, simple approaches, such as aggregation culture techniques, were favored due to their simplicity and convenience, now more sophisticated systems are used and are still being developed. One of the boosts in the development of new culture techniques arises from elaborate manufacturing and surface modification techniques, especially micro and nano system technologies that have either improved dramatically or have evolved very recently. With the help of these tools, it will soon be possible to generate even more sophisticated and more organotypic-like culture systems. Since 3D perfused or superfused systems are much more complex to set up and maintain compared to use of petri dishes and culture flasks, the added value of 3D approaches still needs to be demonstrated.

Microenvironment at tissue injury, a key focus for efficient stem cell therapy: A discussion of mesenchymal stem cells

Stem cell therapy is not a new field, as indicated by the success of hematopoietic stem cell reconstitution for various hematological malignancies and immune-mediated disorders. In the case of tissue repair, the major issue is whether stem cells should be implanted, regardless of the type and degree of injury. Mesenchymal stem cells have thus far shown evidence of safety, based on numerous clinical trials, particularly for immune-mediated disorders. The premise behind these trials is to regulate the stimulatory immune responses negatively. To apply stem cells for other disorders, such as acute injuries caused by insults from surgical trauma and myocardial infarction, would require other scientific considerations. This does not imply that such injuries are not accompanied by immune responses. Indeed, acute injuries could accompany infiltration of immune cells to the sites of injuries. The implantation of stem cells within a milieu of inflammation will establish an immediate crosstalk among the stem cells, microenvironmental molecules, and resident and infiltrating immune cells. The responses at the microenvironment of tissue injury could affect distant and nearby organs. This editorial argues that the microenvironment of any tissue injury is a key consideration for effective stem cell therapy.

Tumor initiating cells in pancreatic cancer: A critical view

Emerging evidence points to the existence of pancreatic cancer stem cells (CSC) as the culprit in the initiation, maintenance, metastasis, and treatment resistance of pancreatic cancer. The existence of such a cell population would have an important impact on the design of novel therapies against this devastating disease. However, no in vivo validation or rebuttal of the pancreatic CSC hypothesis exists. Major backlashes in the discussion on CSC are firstly, the confusion between the terms CSC and cell of origin of pancreatic ductal adenocarcinoma (PDAC), secondly the ambiguity of the cell of origin itself and thirdly, the fact that the CSC hypothesis is based on cell sorting and xenografting experiments; the latter of which often precludes solid conclusions because of the lack of a natural microenvironment and differences in drug delivery. Nonetheless, recent studies in other cancers partially support the CSC hypothesis by demonstrating a link between epithelial-to-mesenchymal transdifferentiation/transition (EMT) and CSC properties. Such a link is again open to dispute as EMT is a reversible process which is highly dependent on major oncogenic pathways in PDAC [e.g. K-Ras, transforming growth factor-β (TGF-β)] rather than on presumed cancer stem cell pathways. Hence, the available evidence does not robustly support the CSC concept in PDAC and a thorough validation of this hypothesis in well-defined genetically engineered mouse models of pancreatic cancer is required.

Twisting immune responses for allogeneic stem cell therapy

Stem cell-derived tissues and organs have the potential to change modern clinical science. However, rejection of allogeneic grafts by the host's immune system is an issue which needs to be addressed before embryonic stem cell-derived cells or tissues can be used as medicines. Mismatches in human leukocyte class I antigens and minor histocompatibility antigens are the central factors that are responsible for various graft-versus-host diseases. Traditional strategies usually involve suppressing the whole immune systems with drugs. There are many side effects associated with these methods. Here, we discuss an emerging strategy for manipulating the central immune tolerance by naturally "introducing" donor antigens to a host so a recipient can acquire tolerance specifically to the donor cells or tissues. This strategy has two distinct stages. The first stage restores the thymic function of adult patients with sex steroid inhibitory drugs (LHRH-A), keratinocyte growth factor (KGF), interleukin 7 (IL-7) and FMS-like tyrosine kinase 3 (FLT3). The second stage introduces hematopoietic stem cells and their downstream progenitors to the restored thymus by direct injection. Hematopoietic stem cells are used to introduce donor antigens because they have priority access to the thymus. We also review several clinical cases to explain this new strategy.

Targeting leukemia stem cells: The new goal of therapy in adult acute myeloid leukemia

The most popular view of hematopoietic cell lineage organization is that of complex reactive or adaptative systems. Leukemia contains a subpopulation of cells that display characteristics of stem cells. These cells maintain tumor growth. The properties of leukemia stem cells indicate that current conventional chemotherapy, directed against the bulk of the tumor, will not be effective. Leukemia stem cells are quiescent and do not respond to cell cycle-specific cytotoxic agents used to treat leukemia and thus contribute to treatment failure. New strategies are required that specifically target this malignant stem cell population.

Effects of nanotopography on stem cell phenotypes

Stem cells are unspecialized cells that can self renew indefinitely and differentiate into several somatic cells given the correct environmental cues. In the stem cell niche, stem cell-extracellular matrix (ECM) interactions are crucial for different cellular functions, such as adhesion, proliferation, and differentiation. Recently, in addition to chemical surface modifications, the importance of nanometric scale surface topography and roughness of biomaterials has increasingly becoming recognized as a crucial factor for cell survival and host tissue acceptance in synthetic ECMs. This review describes the influence of nanotopography on stem cell phenotypes.

Germline competence of mouse ES and iPS cell lines: Chimera technologies and genetic background

In mice, gene targeting by homologous recombination continues to play an essential role in the understanding of functional genomics. This strategy allows precise location of the site of transgene integration and is most commonly used to ablate gene expression ("knock-out"), or to introduce mutant or modified alleles at the locus of interest ("knock-in"). The efficacy of producing live, transgenic mice challenges our understanding of this complex process, and of the factors which influence germline competence of embryonic stem cell lines. Increasingly, evidence indicates that culture conditions and in vitro manipulation can affect the germline-competence of Embryonic Stem cell (ES cell) lines by accumulation of chromosome abnormalities and/or epigenetic alterations of the ES cell genome. The effectiveness of ES cell derivation is greatly strain-dependent and it may also influence the germline transmission capability. Recent technical improvements in the production of germline chimeras have been focused on means of generating ES cells lines with a higher germline potential. There are a number of options for generating chimeras from ES cells (ES chimera mice); however, each method has its advantages and disadvantages. Recent developments in induced pluripotent stem (iPS) cell technology have opened new avenues for generation of animals from genetically modified somatic cells by means of chimera technologies. The aim of this review is to give a brief account of how the factors mentioned above are influencing the germline transmission capacity and the developmental potential of mouse pluripotent stem cell lines. The most recent methods for generating specifically ES and iPS chimera mice, including the advantages and disadvantages of each method are also discussed.

Recent advances in stem cell research for the treatment of diabetes

The success achieved over the last decade with islet transplantation has intensified interest in treating diabetes, not only by cell transplantation, but also by stem cells. The formation of insulin-producing cells from pancreatic duct, acinar, and liver cells is an active area of investigation. Protocols for the in vitro differentiation of embryonic stem (ES) cells based on normal developmental processes, have generated insulin-producing cells, though at low efficiency and without full responsiveness to extracellular levels of glucose. Induced pluripotent stem cells, which have been generated from somatic cells by introducing Oct3/4, Sox2, Klf4, and c-Myc, and which are similar to ES cells in morphology, gene expression, epigenetic status and differentiation, can also differentiate into insulin-producing cells. Overexpression of embryonic transcription factors in stem cells could efficiently induce their differentiation into insulin-expressing cells. The purpose of this review is to demonstrate recent progress in the research for new sources of β-cells, and to discuss strategies for the treatment of diabetes.

What is the purpose of launching World Journal of Stem Cells?

The first issue of World Journal of Stem Cells (WJSC), whose preparatory work was initiated on September 27, 2008, will be published on December 31, 2009. The WJSC Editorial Board has now been established and consists of 281 distinguished experts from 28 countries. Our purpose of launching WJSC is to publish peer-reviewed, high-quality articles via an open-access online publishing model, thereby acting as a platform for communication between peers and the wider public, and maximizing the benefits to editorial board members, authors and readers.

Embryoid body formation from embryonic and induced pluripotent stem cells: Benefits of bioreactors

Embryonic stem (ES) cells have the ability to differentiate into all germ layers, holding great promise not only for a model of early embryonic development but also for a robust cell source for cell-replacement therapies and for drug screening. Embryoid body (EB) formation from ES cells is a common method for producing different cell lineages for further applications. However, conventional techniques such as hanging drop or static suspension culture are either inherently incapable of large scale production or exhibit limited control over cell aggregation during EB formation and subsequent EB aggregation. For standardized mass EB production, a well defined scale-up platform is necessary. Recently, novel scenario methods of EB formation in hydrodynamic conditions created by bioreactor culture systems using stirred suspension systems (spinner flasks), rotating cell culture system and rotary orbital culture have allowed large-scale EB formation. Their use allows for continuous monitoring and control of the physical and chemical environment which is difficult to achieve by traditional methods. This review summarizes the current state of production of EBs derived from pluripotent cells in various culture systems. Furthermore, an overview of high quality EB formation strategies coupled with systems for in vitro differentiation into various cell types to be applied in cell replacement therapy is provided in this review. Recently, new insights in induced pluripotent stem (iPS) cell technology showed that differentiation and lineage commitment are not irreversible processes and this has opened new avenues in stem cell research. These cells are equivalent to ES cells in terms of both self-renewal and differentiation capacity. Hence, culture systems for expansion and differentiation of iPS cells can also apply methodologies developed with ES cells, although direct evidence of their use for iPS cells is still limited.