Nonylphenol and octylphenol-induced apoptosis in human embryonic stem cells is related to Fas-Fas ligand pathway.

Human embryonic stem (hES) cells have been proposed as a source of various cell types for cell replacement therapy. Besides their potential in therapeutic uses, ES cells also have other potential applications, such as in drug discovery and in vitro screening assays of various toxicants. Nonylphenol (NP) and octylphenol (OP) are common environmental contaminants, known to disrupt the reproductive and endocrine system. However, little is known about their toxicological effects on early embryonic development in humans. In this study, we used undifferentiated hES cells and the neural progenitor cells derived from them to investigate the potential toxicity of NP and OP. Our results show that the cytotoxic effects of NP and OP involve DNA fragmentation, the major characteristic of apoptosis. The NP- and OP-induced apoptosis was concomitant with the increased activity of Caspase-8 and -3. Moreover, both Fas and Fas ligand (FasL) protein expressions were markedly increased in the NP- or OP-exposed hES cells. These results suggest that NP and OP are able to trigger apoptosis in hES cells via a pathway dependent on caspase activation and Fas-FasL interaction. In particular, hES cell-derived neural progenitor cells had a higher sensitivity to the toxicants than undifferentiated hES cells, thereby suggesting that the toxic stress response may differ depending on the developmental stage. These findings offer new perspectives for understanding the fundamental mechanisms in chemical-induced apoptosis in hES cells.     

The future of induced pluripotent stem cells for cardiac therapy and drug development

The field of stem cell research was revolutionized with the advent of induced pluripotent stem cells. By reprogramming somatic cells to pluripotent stem cells, most ethical concerns associated with the use of embryonic stem cells are overcome, such that many hopes from the stem cell field now seem a step closer to reality. Several methods and cell sources have been described to create induced pluripotent stem cells and we discuss their characteristics in terms of feasibility and efficiency. From these cells, cardiac progenitors and cardiomyocytes can be derived by several protocols and most recent advances as well as remaining limitations are being discussed. However, in the short time period this technology has been around, evidence emerges that induced pluripotent stem cells may be more prone to genetic defects and maintain an epigenetic memory and thus may not be entirely the same as embryonic stem cells. Despite the lack of a complete fundamental understanding of stem cell biology, and even more of ways how to coax them into defined cell types, the technology is quickly adopted by industry. This paper gives an overview of the current applications of induced pluripotent stem cells in cardiovascular drug development and highlights active areas of research towards functional repair of the damaged heart. Adult stem cells have already been taken to clinical trials and we discuss these results in light of potential and hurdles to be taken to move induced pluripotent stem cells to the clinic.     

Embryonic stem cells as an in vitro model for mutagenicity, cytotoxicity and embryotoxicity studies: present state and future prospects

Primary cultures or established cell lines of vertebrates are commonly used to analyse the mutagenic, embryotoxic or teratogenic potential of environmental factors, drugs and xenobiotics in vitro. However, these cellular systems do not include developmental processes from early embryonic stages up to terminally differentiated cell types. An alternative approach has been offered by permanent lines of pluripotent stem cells of embryonic origin, such as embryonic carcinoma (EC), embryonic stem (ES) and embryonic germ (EG) cells. The undifferentiated stem cell lines are characterized by nearly unlimited self-renewal capacity and have been shown to differentiate in vitro into cells of all three primary germ layers. Pluripotent embryonic stem cell lines recapitulate cellular developmental processes and gene expression patterns of early embryogenesis during in vitro differentiation, data which are summarized in this review. In addition, recent studies are presented which investigated mutagenic, cytotoxic and embryotoxic effects of chemical substances using in vitro systems of pluripotent embryonic stem cells. Furthermore, an outlook is given on future molecular technologies using embryonic stem cells in developmental toxicology and embryotoxicology.     

Amniotic fluid stem cells: a promising therapeutic resource for cell-based regenerative therapy

Stem cells have been proposed as a powerful tool in the treatment of several human diseases, both for their ability to represent a source of new cells to replace those lost due to tissue injuries or degenerative diseases, and for the ability of produce trophic molecules able to minimize damage and promote recovery in the injured tissue. Different cell types, such as embryonic, fetal or adult stem cells, human fetal tissues and genetically engineered cell lines, have been tested for their ability to replace damaged cells and to restore the tissue function after transplantation. Amniotic fluid -derived Stem cells (AFS) are considered a novel resource for cell transplantation therapy, due to their high renewal capacity, the "in vitro" expression of embryonic cell lineage markers, and the ability to differentiate in tissues derived from all the three embryonic layers. Moreover, AFS do not produce teratomas when transplanted into animals and are characterized by a low antigenicity, which could represent an advantage for cell transplantation or cell replacement therapy. The present review focuses on the biological features of AFS, and on their potential use in the treatment of pathological conditions such as ischemic brain injury and bone damages.     

An update of human mesenchymal stem cell biology and their clinical uses

In the past decade, an increasing urge to develop new and novel methods for the treatment of degenerative diseases where there is currently no effective therapy has lead to the emerging of the cell therapy or cellular therapeutics approach for the management of those conditions where organ functions are restored through transplantation of healthy and functional cells. Stem cells, because of their nature, are currently considered among the most suitable cell types for cell therapy. There are an increasing number of studies that have tested the stromal stem cell functionality both in vitro and in vivo. Consequently, stromal (mesenchymal) stem cells (MSCs) are being introduced into many clinical trials due to their ease of isolation and efficacy in treating a number of disease conditions in animal preclinical disease models. The aim of this review is to revise MSC biology, their potential translation in therapy, and the challenges facing their adaptation in clinical practice.     

Embryonic stem cell therapy

Stem cell therapies, particularly those using embryonic stem cells, offer a novel approach to treating disease. There is an ongoing effort to develop tools and reagents to assist in understanding stem cells at a research level. In addition to these research tools, making stem cell therapy a reality requires the development of tools that enable the translation of research into viable therapies. Three sets of tools are discussed in this article: tools enabling stem cell scale-up and manufacture to GMP standards, tools addressing the behavior of cells in animal models, and tools to assess transplanted cells in early clinical trials. The development of such tools will address many of the safety and efficacy questions that are likely to arise as stem cell therapies move from bench to bedside.     

Regenerative and immunomodulatory potential of mesenchymal stem cells

In the past few years, mesenchymal stem cells (MSCs) have come into the limelight because of their multi-lineage stem cell potential, which retains some aspects of embryonic stem cells, and because of their characteristic immunoregulatory functions exerted on different immune effector cells. The regenerative and immunomodulatory potential of MSCs has been used to support hemopoietic stem cell engraftment; to repair or regenerate damaged or mutated tissues, such as bone, cartilage, myocardial or hepatic tissues; to interfere with neoplastic cell growth by transfecting MSCs with anti-neoplastic molecules; and to modulate autoimmune reactions such as collagenopathies, multiple sclerosis and graft versus host disease. Thus, MSCs appear to be a very promising tool for regenerative and immunoregulatory cell therapy.     

Human embryonic and induced pluripotent stem cells in cardiovascular drug discovery: patents and patented uses

Human embryonic stem cells, hES, and the recently created human induced pluripotent stem cells, hiPS, have a multitude of uses in cardiovascular drug discovery with a significant patent coverage for most applications. The research involving hiPS and hES cells may be subdivided into two main areas: one utilizing undifferentiated cells, and the other using hES and hiPS for in vitro differentiation of mature cell types. Both areas are of use in basic discovery, high throughput screening, and toxicology research. A number of methods have been developed to differentiate stem cells to mature cardiac cell types and to obtain pure populations of cardiomyocytes. This review will discuss three major aspects of stem cell patent landscape: 1) patents pertaining to the basic methodology of obtaining hES and hiPS cells, 2) patents pertaining to the methods of hiPS and hES differentiation to cardiovascular cell types, and 3) patents concerned with the applied uses of differentiated cardiac cells.     

Prospects of embryonic stem cells in treatment of hematopoietic disorders

Cellular therapies derived from embryonic stem (ES) cells have gained a renewed interest with the experimental demonstration that an embryonic stem cell lines can be established from human blastocyst-stage embryos and prompted to differentiate into almost all types of cells present in the body including hematopoietic cells. Hematopoiesis is a series of cellular processes whereby short-lived mature blood cells are continuously replenished from a pool of rare pluripotential hematopoietic stem cells, in a highly orchestrated process. Aberrances in this intricate process may lead to a malignancy of essential blood-forming organs, causing diseases such as leukemia, aplastic anemia, lymphoma, myelodysplasia and myeloproliferative disorders. Embryonic stem cells show great potential and it may be technologically feasible to transplant differentiated ES cells and to cure various kinds of blood disorders. Understanding the biology of ES cell derived hematopoiesis may lead to the development of co-transplantation protocols that will result in a decreased morbidity and mortality by providing safer and simpler transplantation procedures for patients with malignant and non-malignant conditions. The potential utility of ES cells for gene therapy, tissue engineering and the treatment of a wide variety of currently untreatable diseases is simply too essential to ignore, however, our knowledge and ability to deliver these forms of therapy in a safe and efficient manner requires additional advances in the understanding of the basic biology of ES cells. In this article, we will discuss the factors and methodologies responsible for the differentiation of ES cells into hematopoietic progenitors and their potential to treat different blood related diseases.     

The key role of adult stem cells: therapeutic perspectives

ABSTRACT

Background: The origin, function and physiology of totipotent embryonic cells are configured to construct organs and create cross-talk between cells for the biological and neurophysiologic development of organisms. Adult stem cells are involved in regenerating tissues for renewal and damage repair.

Findings: Adult stem cells have been isolated from adult tissue, umbilical cord blood and other non-embryonic sources, and can transform into many tissues and cell types in response to pathophysiological stimuli.

Clinical applications of adult stem cells and progenitor cells have potential in the regeneration of blood cells, skin, bone, cartilage and heart muscle, and may have potential in degenerative diseases. Multi-pluripotent adult stem cells can change their phenotype in response to trans-differentiation or fusion and their therapeutic potential could include therapies regulated by pharmacological modulation, for example mobilising endogenous stem cells and directing them within a tissue to stimulate regeneration. Adult stem cells could also provide a vehicle for gene therapy, and genetically-engineered human adult stem cells have shown success in treatment of genetic disease.

Conclusion: Deriving embryonic stem cells from early human embryos raises ethical, legal, religious and political questions. The potential uses of stem cells for generating human tissues are the subject of ongoing public debate. Stem cells must be used in standardised and controlled conditions in order to guarantee the best safety conditions for the patients. One critical point will be to verify the risk of tumourigenicity; this issue may be more relevant to embryonic than adult stem cells.     

Embryonic stem cell lines for regenerative therapy and pharmaceutical research

The establishment of human embryonic stem (ES) cell lines has brought great potential and expectations for regenerative medicine and pharmaceutical research, because many types of human cells could be produced by their unlimited growth and differentiation in culture. Primate and human ES cell lines have been established from blastocysts of monkey and surplus human blastocysts from fertility clinics. They showed several differences compared to mouse ES cells, including a tendency to produce the trophectoderm lineage and a different expression pattern of surface antigens. This may reflect species-specific differences, or these primate ES cells could represent earlier stages of development than mouse ES cells. Also, they show no response to the LIF and gp130 signals, which are widely used to repress spontaneous differentiation of mouse ES cell colonies. We have established several ES cell lines from blastocysts of the cynomolgus monkey. They can be maintained in culture as stem cell colonies, and they produce several differentiated cell types in culture. When such ES cells were transplanted into SCID mice, they produced teratomas containing many differentiated tissues.     

The architectural organization of human stem cell cycle regulatory machinery

Two striking features of human embryonic stem cells that support biological activity are an abbreviated cell cycle and reduced complexity to nuclear organization. The potential implications for rapid proliferation of human embryonic stem cells within the context of sustaining pluripotency, suppressing phenotypic gene expression and linkage to simplicity in the architectural compartmentalization of regulatory machinery in nuclear microenvironments is explored. Characterization of the molecular and architectural commitment steps that license human embryonic stem cells to initiate histone gene expression is providing understanding of the principal regulatory mechanisms that control the G1/S phase transition in primitive pluripotent cells. From both fundamental regulatory and clinical perspectives, further understanding of the pluripotent cell cycle in relation to compartmentalization of regulatory machinery in nuclear microenvironments is relevant to applications of stem cells for regenerative medicine and new dimensions to therapy where traditional drug discovery strategies have been minimally effective.     

The emerging technologies of neural xenografting and stem cell transplantation for treating neurodegenerative disorders

Neural transplantation has normally been considered in the context of the neurodegenerative disorders, Parkinson's and Huntington's disease, which are characterized pathologically by the predominant loss of specific cells in the basal ganglia. This approach has now emerged from the experimental arena into the level of clinical trial, at least with respect to fetal human allografts. However the ethical and practical problems with using such tissue has led to the search for alternative sources of cells of which two of the most promising are cells from another species, such as the pig (xenografts), and stem cells. Neural transplantation using cells derived from the developing pig brain offers many advantages. Firstly, time-mated litters will overcome the issue of donor tissue supply. Secondly, advances in genetic technology have led to the development of pigs which have a reduced rejection potential. Thirdly, xenografted neural fiber outgrowth may be superior to that from neural grafts derived from the same species (allografts) which may increase the potential for circuit reconstruction. Disadvantages with this tissue source include concerns about transmission of zoonotic infections and the immunological rejection of the xenograft. Stem cells are defined as cells capable of division (self-renewal) and differentiation into a range of different cell types (differentiation). A variety of such cells exist including embryonic stem cells, neural stem cells derived from the developing fetal brain (neural progenitor cells), adult neural stem cells and adult stem cells originating from outside of the central nervous system. Each of these different types of stem cell have their own unique benefits but also disadvantages, and access to each type is constrained by a number of limiting factors. All of this means that the translation of these cell therapies into practice is not straightforward and must be done at a pace dictated by laboratory-based research rather than corporate share price.     

Stem Cell Transplantation: A Promising Therapy for Parkinson’s Disease

Parkinson’s disease is one of the most common neurodegenerative diseases caused by the loss of dopaminergic neurons in the substantia nigra pars compacta. Pharmacological therapies are valuable but suffer from two main drawbacks: side effects and loss of efficacy with disease progression. Surgical treatment is no better than drugs. Transplantation of embryonic mesencephalic tissue has emerged as a therapeutic alternative, but the unstable efficiency and the shortage of embryonic donors limit its clinical application. Recent advances in stem cell research inspire our hope that stem cell transplantation to replace degenerated neurons may be a promising therapy for Parkinson’s disease. There are three sources of stem cells currently in testing: embryonic stem cells, neural stem cells, and mesenchymal stem cells. The stem cell transplantation in the animal model of Parkinson’s disease proves that it is capable of relieving symptoms and restoring damaged brain function. Future stem cell research should focus not only on ameliorating the symptoms of Parkinson’s disease but also on neuroprotection or neurorescue that can favorably modify the natural course and slow the progression of the disease.     

Establishment of an in vitro reporter gene assay for developmental cardiac toxicity.

This study is based on the unique potential of pluripotent embryonic stem (ES) cells to differentiate in vitro into embryoid bodies containing cell lineages representative of most cell types found in the mammalian fetus. However, the use of wild type ES cells as an in vitro assay for embryotoxicological studies is complicated by the simultaneous development of various cellular phenotypes. This prevents a quantitative assessment of drug effects on one specific cell type. Here we report the effects of 15 chemicals on cardiac differentiation as determined by various specific toxicological endpoints such as morphological inspection (contractile activity), quantitative mRNA analysis and cardiac-specific expression of green fluorescent protein (GFP), used as a quantitative reporter. The data from the different endpoints have been subjected to a statistical analysis, and a preliminary prediction model is proposed. The results demonstrate that genetically-engineered ES cells could provide a valuable tool for estimating the developmental cardiotoxic potential of compounds in vitro and form the basis for automated analysis in a high-throughput system.     

Embryonic stem cell-derived embryoid bodies: an in vitro model of eutherian pregastrulation development and early gastrulation

In this review, I describe the dawn of embryoid body research and the influence of stem cell properties on embryoid body development. I will focus on the in vitro differentiation of embryonic stem cells in embryoid bodies. I summarize and combine published data for embryo-like development of embryoid bodies, and based on these findings, I will discuss open questions, concerns, and possible future directions of this still emerging field of research. I hope to provide new perspectives and experimental approaches that go beyond the current state of the art to foster an understanding of eutherian embryogenesis and provide clues for the efficient production of somatic cells for cell therapy.     

Adult mesenchymal stem cells in dental research: a new approach for tissue engineering

Many adult tissues contain a population of stem cells that have the ability to regenerate after trauma, disease or aging. Recently, there has been great interest in mesenchymal stem cells and their roles in maintaining the physiological structure of tissues. The studies on stem cells are thought to be very important and, in fact, it has been shown that this cell population can be expanded ex vivo to regenerate tissues not only of the mesenchymal lineage, such as intervertebral disc cartilage, bone and tooth-associated tissues, but also other types of tissues. Several studies have focused on the identification of odontogenic progenitors from oral tissues, and it has been shown that the mesenchymal stem cells obtained from periodontal ligament and dental pulp could have similar morphological and phenotypical features of the bone marrow mesenchymal cells. In fact a population of homogeneous human mesenchymal stem cells derived from periodontal ligament and dental pulp, and proliferating in culture with a well-spread morphology, can be recovered and characterized. Since these cells are considered as candidates for regenerative medicine, the knowledge of the cell differentiation mechanisms is imperative for the development of predictable techniques in implant dentistry, oral surgery and maxillo-facial reconstruction. Thus, future research efforts might be focused on the potential use of this cell population in tissue engineering. Further studies will be carried out to elucidate the molecular mechanisms involved in their maintenance and differentiation in vitro and in vivo.     

Diabetes treatment: A rapid review of the current and future scope of stem cell research

Diabetes mellitus is a major health concern of the developing and developed nations across the globe. This devastating disease accounts for the 5% deaths around the world annually. The current treatment methods do not address the underlying causes of the disease and have severe limitations. Stem cells are unique cells with the potential to differentiate into any type of specialized cells. This feature of both adult and embryonic stem cells was explored in great detail by the scientists around the world and are successful in producing insulin secreting cells. The different type of stem cells (induced pluripotent stem cells (iPSCs), embryonic stem cells (ESCs) and adult stem cells) proves to be potent in treating diabetes with certain limitations. This article precisely reviews the resources and progress made in the field of stem cell research for diabetic treatment.     

Amniotic fluid-derived stem cells in regenerative medicine research

The stem cells isolated from amniotic fluid present an exciting possible contribution to the field of regenerative medicine and amniotic fluid-derived stem (AFS) cells have significant potential for research and therapeutic applications. AFS cells are multipotent, showing the ability to differentiate into cell types from all three embryonic germ layers. They express both embryonic and adult stem cell markers, expand extensively without feeder cells, double in 36 h, and are not tumorigenic. The AFS cells can be maintained for over 250 population doublings and preserve their telomere length and a normal karyotype. They differentiate easily into specific cell lineages and do not require human embryo tissue for their isolation, thus avoiding the current controversies associated with the use of human embryonic stem (ES) cells. The discovery of the AFS cells has been recent, and a great deal of work remains to be performed on the characterization and use of these cells. This review describes the various differentiated lineages that AFS cells can form and the future of these promising new stem cells in regenerative medicine research.