蛋白质组学在干细胞研究中的应用

蛋白质组学技术通过整合多项技术来分析生物体的全部蛋白质成分,通过考察不同状态下细胞或组织蛋白质组的变化情况来了解细胞活动的分子机理。干细胞分化过程中受外界条件的影响其蛋白表达模式也表现出一定的差异,对干细胞分化过程中进行蛋白质组学研究将有利于从蛋白质分子水平上阐明干细胞的分化机理。本文对蛋白质组学及其在干细胞研究中的应用加以评述。     

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.     

Carbon Quantum Dots as Multi-Purpose Nanomaterial in Stem Cell Therapy

During stem cell therapy, some issues, such as obscure fate of stem cells or their low survival rate in the body, should be addressed to boost their therapeutic efficiency. Nanotechnology offers a suitable solution to combat such limitations. Carbon quantum dots (CQDs) are carbon-based nanomaterials and may be used as multi-purpose compounds in stem cell therapy. CQDs are excellent choices for stem cell labeling thanks to their special features such as optical properties and good biocompatibility. Besides, they can modulate the biological function of stem cells, such as their proliferation, homing ability, and differentiation properties. Considering the charismatic feature of CQDs and their broad unique effect on stem cells, the current review aims to summarize the most advancements in this field. Hence, we first focused on CQDs synthesis and their applications. In the next section, the stem cell categories will be discussed, and the final part is dedicated to the recent research evaluating the impact of CQDs on stem cell therapy.     

诱导性多能干细胞向神经细胞分化的研究进展

诱导性多能干细胞(induced pluripotent stem cell,iPS cell)是通过转染外源特定的基因组合来诱导成体细胞重编程为类似于胚胎干细胞的一种多潜能干细胞,iPS细胞与胚胎干细胞不仅在形态上相似,而且在功能方面几乎相同.另外,iPS细胞的诞生克服了胚胎干细胞在临床应用时涉及的移植免疫排斥与伦理道德问题,因此具有重要的临床应用价值.目前iPS在治疗中枢神经系统性疾病方面的研究已取得很大进展,包括iPS细胞向神经细胞诱导分化方法的改进、分化机理的探索以及iPS细胞分化来源神经细胞在神经系统疾病模型中治疗作用的研究等.从iPS细胞的创建及特点、iPS细胞向神经细胞分化的诱导方法及研究新进展方面予以综述.     

Nanoparticles as tools to study and control stem cells

The use of nanoparticles in stem cell research is relatively recent, although very significant in the last 5 years with the publication of about 400 papers. The recent advances in the preparation of some nanomaterials, growing awareness of material science and tissue engineering researchers regarding the potential of stem cells for regenerative medicine, and advances in stem cell biology have contributed towards the boost of this research field in the last few years. Most of the research has been focused in the development of new nanoparticles for stem cell imaging; however, these nanoparticles have several potential applications such as intracellular drug carriers to control stem cell differentiation and biosensors to monitor in real time the intracellular levels of relevant biomolecules/enzymes. This review examines recent advances in the use of nanoparticles for stem cell tracking, differentiation and biosensing. We further discuss their utility and the potential concerns regarding their cytotoxicity. J. Cell. Biochem. 108: 746–752, 2009. © 2009 Wiley‐Liss, Inc.     

From teratocarcinomas to embryonic stem cells

The recent derivation of human embryonic stem (ES) cell lines, together with results suggesting an unexpected degree of plasticity in later, seemingly more restricted, stem cells (so-called adult stem cells), have combined to focus attention on new opportunities for regenerative medicine, as well as for understanding basic aspects of embryonic development and diseases such as cancer. Many of the ideas that are now discussed have a long history and much has been underpinned by the earlier studies of teratocarcinomas, and their embryonal carcinoma (EC) stem cells, which present a malignant surrogate for the normal stem cells of the early embryo. Nevertheless, although the potential of EC and ES cells to differentiate into a wide range of tissues is now well attested, little is understood of the key regulatory mechanisms that control their differentiation. Apart from the intrinsic biological interest in elucidating these mechanisms, a clear understanding of the molecular process involved will be essential if the clinical potential of these cells is to be realized. The recent observations of stem-cell plasticity suggest that perhaps our current concepts about the operation of cell regulatory pathways are inadequate, and that new approaches for analysing complex regulatory networks will be essential.     

Embryonic stem (ES) cell-derived cardiomyocytes: A good candidate for cell therapy applications

During the last decade, embryonic stem cells (ESC) have unleashed new avenues in the field of developmental biology and emerged as a potential tool to understand the molecular mechanisms taking place during the process of differentiation from the embryonic stage to adult phenotype. Their uniqueness lies in retaining the capacity of unlimited proliferation and to differentiate into all somatic cells. Together with promising results from rodent models, ESC has raised great hope among for human ESC-based cell replacement therapy. ESC could potentially revolutionize medicine by providing a powerful and renewable cell source capable of replacing or repairing tissues that have been damaged in almost all degenerative diseases such as Parkinson's disease, myocardial infarction (MI) and diabetes. Somatic stem cells are an attractive option to explore for transplantation because they are autologous, but their differentiation potential is very limited. Currently, the major sources of somatic cells used for basic research and clinical trials come from bone marrow. But their widespread acceptability has not been gained because many of the results are confusing and inconsistent. The focus here is on human embryonic stem cells (hESCs), using methods to induce their differentiation to cardiomyocytes in vitro. Their properties in relation to primary human cardiomyocytes and their ability to integrate into host myocardium have been investigated into how they can enhance cardiac function. However, important aspects of stem cell biology and the transplantation process remain unresolved. In summary, this review updates the recent progress of ES cell research in cell therapy, discusses the problems in the practical utility of ESC, and evaluates how far this adjunctive experimental approach can be successful.     

Hypoxia,a dynamic tool to amplify the gingival mesenchymal stem cells potential for neurotrophic factor secretion

Gingival mesenchymal stem cells (GMSCs) have significant regenerative potential. Their potential applications range from the treatment of inflammatory diseases, wound healing, and oral disorders. Preconditioning these stem cells can optimize their biological properties. Hypoxia preconditioning of MSCs improves stem cell properties like proliferation, survival, and differentiation potential. This research explored the possible impact of hypoxia on the pluripotent stem cell properties that GMSCs possess. We evaluated the morphology, stemness, neurotrophic factors, and stemness-related genes. We compared the protein levels of secreted neurotrophic factors between normoxic and hypoxic GMSC-conditioned media (GMSC-CM). Results revealed that hypoxic cultured GMSC’s had augmented expression of neurotrophic factors BDNF, GDNF, VEGF, and IGF1 and stemness-related gene NANOG. Hypoxic GMSCs showed decreased expression of the OCT4 gene. In hypoxic GMSC-CM, the neurotrophic factors secretions were significantly higher than normoxic GMSC-CM. Our data demonstrate that culturing of GMSCs in hypoxia enhances the secretion of neurotrophic factors that can lead to neuronal lineage differentiation.     

Placental-derived stem cells: Culture,differentiation and challenges

Stem cell therapy is a promising approach to clinical healing in several diseases. A great variety of tissues (bone marrow, adipose tissue, and placenta) are potentially sources of stem cells. Placenta-derived stem cells (p-SCs) are in between embryonic and mesenchymal stem cells, sharing characteristics with both, such as non-carcinogenic status and property to differentiate in all embryonic germ layers. Moreover, their use is not ethically restricted as fetal membranes are considered medical waste after birth. In this context, the present review will be focused on the biological properties, culture and potential cell therapy uses of placental-derived stem cells. Immunophenotype characterization, mainly for surface marker expression, and basic principles of p-SC isolation and culture (mechanical separation or enzymatic digestion of the tissues, the most used culture media, cell plating conditions) will be presented. In addition, some preclinical studies that were performed in different medical areas will be cited, focusing on neurological, liver, pancreatic, heart, muscle, pulmonary, and bone diseases and also in tissue engineering field. Finally, some challenges for stem cell therapy applications will be highlighted. The understanding of the mechanisms involved in the p-SCs differentiation and the achievement of pure cell populations (after differentiation) are key points that must be clarified before bringing the preclinical studies, performed at the bench, to the medical practice.     

中医药参与干细胞研究特色及进展

干细胞因其具有自我更新、在特定的诱导条件下可以分化为多种工作细胞及向损伤组织迁移的能力,受到越来越多研究者的关注。近年来,有关传统中医药参与干细胞的研究已见诸多报道,本文回顾了近年来中医药参与干细胞研究的诸多报道,总结了得出了在中医经典理论指导下中医药参与干细胞研究多以补肾、益气类中药为主,以中药复方、单味中药以及中药有效组分的形式进行研究,结果表明中药可以影响干细胞的生物学特性及功能,能参与完成干细胞动员、迁移、归巢、增殖、分化等各个环节,传统的中医理论可以拓宽干细胞研究的思路,有望解决干细胞研究中的诸多难题,提示中医药在干细胞研究领域中具有较大的潜能,中医药联合干细胞治疗在临床应用中具有较大的应用前景。     

Physiologically based microenvironment for in vitro neural differentiation of adipose-derived stem cells

The limited capacity of nervous system to promote a spontaneous regeneration and the high rate of neurodegenerative diseases appearance are keys factors that stimulate researches both for defining the molecular mechanisms of pathophysiology and for evaluating putative strategies to induce neural tissue regeneration. In this latter aspect, the application of stem cells seems to be a promising approach, even if the control of their differentiation and the maintaining of a safe state of proliferation should be troubled. Here, we focus on adipose tissue-derived stem cells and we seek out the recent advances on the promotion of their neural differentiation, performing a critical integration of the basic biology and physiology of adipose tissuederived stem cells with the functional modifications that the biophysical, biomechanical and biochemical microenvironment induces to cell phenotype. The pre-clinical studies showed that the neural differentiation by cell stimulation with growth factors benefits from the integration with biomaterials and biophysical interaction like microgravity. All these elements have been reported as furnisher of microenvironments with desirable biological, physical and mechanical properties. A critical review of current knowledge is here proposed, underscoring that a real advance toward a stable, safe and controllable adipose stem cells clinical application will derive from a synergic multidisciplinary approach that involves material engineer, basic cell biology, cell and tissue physiology.     

Gold Nanoparticles Attenuates Antimycin A-Induced Mitochondrial Dysfunction in MC3T3-E1 Osteoblastic Cells

Gold nanoparticles have shown promising biological applications due to their unique properties. Understanding the interaction mechanisms between nanomaterials and biological cells is important for the control and manipulation of these interactions for biomedical applications. In the present study, we investigated the effects of gold nanoparticles on the differentiation of osteoblastic MC3T3-E1 cells and antimycin A-induced mitochondrial dysfunction. The results showed that gold nanoparticles (5, 10, and 20 nm) caused a significant elevation of cell growth, alkaline phosphatase activity, collagen synthesis, and osteocalcin content in the cells (P?<?0.05). Moreover, pretreatment with gold nanoparticles prior to antimycin A exposure significantly reduced antimycin A-induced cell damage by preventing mitochondrial membrane potential dissipation, complex IV inactivation, ATP loss, cytochrome c release, cardiolipin peroxidation, and reactive oxygen species generation. Taken together, our study indicated that gold nanoparticles may improve the differentiation and have protective effects on mitochondrial dysfunction of osteoblastic cells.     

Guiding embryonic stem cells towards differentiation: lessons from molecular embryology

Embryonic stem cells are uniquely endowed with the capacity of self-renewal and the potential to give rise to all possible cell types, including germ cells. These qualities have made mouse embryonic stem cells a valuable resource for genetic manipulation of the mouse genome. In addition, they present a powerful system for the in vitro dissection of mammalian embryonic development. The recent isolation of human embryonic stem cells has raised a lot of interest for the potential of transposing our knowledge of lineage-specific differentiation of embryonic stem cells to cell-based therapy of human disease. Recent reports have provided insights into the specific differentiation of embryonic stem cells to different cell types of the embryo. However, progress in this direction seems to depend on the knowledge of the mechanisms controlling lineage decisions during embryogenesis.     

Stem cells and the Planarian Schmidtea mediterranea

In recent years, stem cells have been heralded as potential therapeutic agents to address a large number of degenerative diseases. Yet, in order to rationally utilize these cells as effective therapeutic agents, and/or improve treatment of stem-cell-associated malignancies such as leukemias and carcinomas, a better understanding of the basic biological properties of stem cells needs to be acquired. A major limitation in the study of stem cells lies in the difficulty of accessing and studying these cells in vivo. This barrier is further compounded by the limitations of in vitro culture systems, which are unable to emulate the microenvironments in which stem cells reside and which are known to provide critical regulatory signals for their proliferation and differentiation. Given the complexity of vertebrate embryonic and adult stem cell populations and their relative inaccessibility to in vivo molecular analyses, the study of stem cells should benefit from analyzing their counterparts in simpler model organisms. In the past, the use of Drosophila or C. elegans has provided invaluable contributions to our understanding of genes and pathways involved in a variety of human diseases. However, stem cells in these organisms are mostly restricted to the gonads, and more importantly neither Drosophila, nor C. elegans are capable of regenerating body parts lost to injury. Therefore, a simple animal with experimentally accessible stem cells playing a role in tissue maintenance and/or regeneration should be very useful in identifying and functionally testing the mechanisms regulating stem cell activities. The planarian Schmidtea mediterranea is poised to fill this experimental gap. S. mediterranea displays robust regenerative properties driven by a stem cell population capable of producing the approximately 40 different cell types found in this organism, including the germ cells. Given that all known metazoans depend on stem cells for their survival, it is extremely likely that the molecular events regulating stem cell biology would have been conserved throughout evolution, and that the knowledge derived from studying planarian stem cells could be vertically integrated to the study of vertebrate stem cells. Current efforts, therefore, are aimed at further characterizing the population of planarian stem cells in order to define its suitability as a model system in which to mechanistically dissect the basic biological attributes of metazoans stem cells.     

Separation technologies for stem cell bioprocessing

Stem cells have been the focus of an intense research due to their potential in Regenerative Medicine, drug discovery, toxicology studies, as well as for fundamental studies on developmental biology and human disease mechanisms. To fully accomplish this potential, the successful application of separation processes for the isolation and purification of stem cells and stem cell‐derived cells is a crucial issue. Although separation methods have been used over the past decades for the isolation and enrichment of hematopoietic stem/progenitor cells for transplantation in hemato‐oncological settings, recent achievements in the stem cell field have created new challenges including the need for novel scalable separation processes with a higher resolution and more cost‐effective. Important examples are the need for high‐resolution methods for the separation of heterogeneous populations of multipotent adult stem cells to study their differential biological features and clinical utility, as well as for the depletion of tumorigenic cells after pluripotent stem cell differentiation. Focusing on these challenges, this review presents a critical assessment of separation processes that have been used in the stem cell field, as well as their current and potential applications. The techniques are grouped according to the fundamental principles that govern cell separation, which are defined by the main physical, biophysical, and affinity properties of cells. A special emphasis is given to novel and promising approaches such as affinity‐based methods that take advantage of the use of new ligands (e.g., aptamers, lectins), as well as to novel biophysical‐based methods requiring no cell labeling and integrated with microscale technologies. Biotechnol. Bioeng. 2012; 109: 2699–2709. © 2012 Wiley Periodicals, Inc.     

The stem cell system in demosponges: suggested involvement of two types of cells: archeocytes (active stem cells) and choanocytes (food-entrapping flagellated cells)

Major questions about stem cell systems include what type(s) of stem cells are involved (unipotent/totipotent/pluripotent/multipotent stem cells) and how the self-renewal and differentiation of stem cells are regulated. Sponges, the sister group of all other animals and probably the earliest branching multicellular lineage of extant animals, are thought to possess totipotent stem cells. This review introduces what is known about the stem cells in sponges based on histological studies and also on recent molecular biological studies that have started to reveal the molecular and cellular mechanisms of the stem cell system in sponges (mainly in demosponges). The currently proposed model of the stem cell system in demosponges is described, and the possible applicability of this model to other classes of sponges is discussed. Finally, a possible scenario of the evolution of stem cells, including how migrating stem cells arose in the urmetazoan (the last common ancestor of metazoans) and the evolutionary origin of germ line cells in the urbilaterian (the last common ancestor of bilaterians), are discussed.     

The search for neural progenitor cells: prospects for the therapy of neurodegenerative disease.

The etiology of many neurodegenerative diseases has been identified in recent years. Treatment of central nervous system (CNS) disease could focus on one or more steps that lead to cell loss. In the past decade, cell therapy and/or ex vivo gene therapy have emerged as possible strategies for the treatment of neurodegenerative diseases. The ability to grow CNS-derived neural progenitor cells using growth factors has been extremely useful to study diverse phenomena including lineage choice, commitment and differentiation. By virtue of their biological properties and their presence in the adult CNS, neural progenitors represent good candidates for multiple cell-based therapies for neural diseases. Further identification of the molecules that direct the differentiation of adult neural progenitors may allow their activation in vivo to induce self-repair. This review addresses the nature, distribution and regulation of neural stem cells and the potential for applying these cells to both structural CNS repair and gene therapy.     

The topographical regulation of embryonic stem cell differentiation

The potential use of pluripotent stem cells for tissue repair or replacement is now well recognized. While the ability of embryonic stem (ES) cells to differentiate into all cells of the body is undisputed, their use is currently restricted by our limited knowledge of the mechanisms controlling their differentiation. This review discusses recent work by ourselves and others investigating the intercellular signalling events that occur within aggregates of mouse ES cells. The work illustrates that the processes of ES cell differentiation, epithelialization and programmed cell death are dependent upon their location within the aggregates and coordinated by the extracellular matrix. Establishment of the mechanisms involved in these events is not only of use for the manipulation of ES cells themselves, but it also throws light on the ways in which differentiation is coordinated during embryogenesis.