Stem cells in mammary development and carcinogenesis

Recently, substantial progress has been made in the identification and characterization of stem and progenitor cells in the mouse and human mammary gland. Furthermore, there is increasing evidence that a variety of neoplasms, including breast cancer, may result from transformation of normal stem and progenitor cells. Consistent with this model of carcinogenesis, a breast cancer stem cell population, with the phenotype CD24-CD44+ lineage, was recently identified utilizing flow-cytometry based cell sorting and nonobese diabetic/severe combined immunodeficient (NOD/SCID) mice xenografts. As few as 200 cells of this cancer stem cell population were capable of generating tumors in animals, whereas the bulk of the tumor population was tumorigenic only when implanted in high numbers. Like their normal counterparts, the cancer stem cells have the ability to self-renew, driving tumorigenicity and possibly recurrence and metastasis, and have the ability to differentiate, generating the heterogeneity of the tumors. This stem cell model of carcinogenesis has important implications for understanding the basic biology of breast cancer, as well as other cancers. Furthermore, the concept of cancer as a disease of stem and progenitor cells has profound implications for the development of new strategies for cancer prevention and therapy.     

Stem cells and cartilage development: complexities of a simple tissue

Cartilage is considered to be a simple tissue that should be easy to engineer because it is avascular and contains just one cell type, the chondrocyte. Despite this apparent simplicity, regenerating cartilage in a form that can function effectively after implantation in the joint has proven difficult. This may be because we have not fully appreciated the importance of different structural regions of articular cartilage or of understanding the origins of chondrocytes and how this cell population is maintained in the normal tissue. This review considers what is known about different regions of cartilage and the types of stem cells in articulating joints and emphasizes the potential importance of regeneration of the lamina splendens at the joint surface and calcified cartilage at the junction with bone for long-term survival of regenerated tissue in vivo.     

Stem cells adaptive network: mechanism and implications for evolution and disease development

During development, different cells and tissues acquire different programmes of gene expression, so that cells are related to each other through a somatic cells tree or cluster and adult pluripotential stem cells (PSC) may be defined as progenitors that we distinguish in four types according to their biological behaviour. This clustering may segregate specific pathways establishing spatial patterns of cell-cell communications. Thus, we suggest that normal somatic cells renewal is tributary of multipotential stem cells (MSC), while renewal of cells undergoing stress or abnormal death is tributary of PSC through specific pathway(s) from cluster, thus, defining the cell repertoire that will be produced. We also assume that PSC play a pivotal role in evolutionary and propose the theory of "internal clusters competition". According to the functional duality of stem cells (SC) we define a stem cells adaptive network (SCAN) which we believe is linked to the central clock and display two pathways. The diurnal pathway includes SC-somatic cells communications, while the nocturnal pathway includes inter-SC network. These alternate pathways could be activated or repressed as a consequence of change in the biological chirality. This new approach of SC may contribute to our understanding on how some diseases may develop including cancer which could be linked to "cluster illness", while demyelinating and systemic diseases could be related to "PSC locus illness" or "focalised SCAN disturbances" and it explains how any environment stress may act on organism evolution.     

干细胞与肺移植

背景：肺移植是治疗多种终末期肺病的惟一有效方法,但围手术期风险大,干细胞在肺移植肺损伤修复的基础研究及临床工作中有较好的应用前景。 目的：总结干细胞的生物学特性及其与免疫系统的相互作用,介绍干细胞在肺移植实验和临床研究中的应用现状。 方法：以“lung,pulmonary,transplantation,stem cell”为检索词,检索Pubmed数据库、Springlink数据库、ScienceDirect数据库,检索年限为1990-01/2011-03,限定语种为英文;以“移植、肺、干细胞”为检索词,检索CNKI数据库、万方数据库、维普数据库,检索年限为1990-01/2011-03,限定语种为中文。共检索156篇文献,根据纳入排除标准,对其中50篇文献进行分析。 结果与结论：干细胞通过替代损伤的肺组织、旁分泌作用减少细胞凋亡参与组织修复,减轻炎症反应及肺组织纤维化。以间充质干细胞为例,由于免疫原性较弱,在诱导器官移植的免疫耐受中有较好的应用,一方面通过调节多种因子减轻免疫排斥反应,另一方面通过抑制T细胞、B细胞、NK细胞、树突状细胞、中性粒细胞的活性来减少免疫应答。基于干细胞独特的生物学特性,其在诱导免疫嵌合减少肺移植慢性排斥反应有一定作用,也为干细胞介导的细胞和基因治疗提供可能。     

Stem cells and diabetes treatment

Diabetes mellitus types 1 and 2 are characterized by absolute versus relative lack of insulin-producing beta cells, respectively. Reconstitution of a functional beta-cell mass by cell therapy--using organ donor islets of Langerhans--has been demonstrated to restore euglycaemia in the absence of insulin treatment. This remarkable achievement has stimulated the search for appropriate stem cell sources from which adequate expansion and maturation of therapeutic beta cells can be achieved. This recent activity is reviewed and presented with particular focus on directed differentiation from pluripotent embryonic stem cells (versus other stem/progenitor cell sources) based on knowledge from pancreatic beta-cell development and the parallel approach to controlling endogenous beta-cell neogenesis.     

Stem cells and solid cancers

Recently, there have been significant advances in our knowledge of stem cells found in tissues that can develop solid tumours. In particular, novel stem cell markers have been identified for the first time identifying multipotential cells: a required characteristic of a stem cell. The scarcity of cancer stem cells has been questioned. Current dogma states that they are rare, but novel research has suggested that this may not be the case. Here, we review the latest literature on stem cells, particularly cancer stem cells within solid tumours. We discuss current thinking on how stem cells develop into cancer stem cells and how they protect themselves from doing so and do they express unique markers that can be used to detect stem cells. We attempt to put into perspective these latest advances in stem cell biology and their potential for cancer therapy. Stuart A. C. McDonald, Trevor A. Graham and Stefanie Schier contributed equally to this work.     

Stem cells and breast cancer

Proliferation in continuously renewing tissues, including the mammary gland, is hierarchically organized with a small number of slowly dividing stem cells and a greater number of more rapidly proliferating 'transit amplifying' cells. Mammary stem cells have been recently identified and purified based on their surface antigen expression. The recognition of mammary epithelial stem cells had led to the hypothesis that these may be at the root of breast cancer. In support of this, a highly tumorigenic subpopulation of cancer cells – cancer stem cells – has recently been identified in primary and metastatic breast cancer samples and in a number of established breast cancer cell lines. The existence of cancer stem cells would explain why only a small minority of cancer cells is capable of extensive proliferation and transferral of the tumour. In this article we aim to review the evidence in support of the existence of both normal mammary stem cells and breast cancer stem cells, and provide further insight into how taking this subpopulation of cells into account may affect the way we treat epithelial cancers in the future.     

IV. Stem cells

These pages contain guidelines and other articles compiled byESHRE Special Interest Groups and others, and agreed by theEHSRE Executive Committee. They are not submitted to journalpeer review. In this fourth statement of the ESHRE Taskforce on Ethics andLaw, the focus is on ethical issues raised by the possible therapeuticuse of stem cells, and in particular from embryo stem cells.General ethical principles are discussed, including autonomy,beneficience, maleficience and freedom of research. Specificpoints are raised concerning the source of embryos for stemcells and of oocytes for somatic cell nuclear transfer.     

Stem cells, dot-com

Direct-to-consumer (DTC) advertising of suspect goods and services has burgeoned because of the Internet. Despite very limited approval for use, DTC stem cell-marketed "treatments" have emerged for an array of conditions, creating global public health and safety risks. However, it remains unclear whether such use of stem cells is subject to drugs or biologics regulations. To address this gap, regulatory agencies should be given clear authority, and the international community should create a framework for appropriate stem cell use. In addition, consumer protection laws should be used to scrutinize providers.     

Stem cells: shibboleths of development, part II: Toward a functional definition

Our previous discourse on stem cell characteristics led to the conclusion that the qualities deemed essential for a cell to be considered a "stem cell" are neither firmly established nor universally accepted, and this we accept as editorial policy. In that study, self-renewal, asymmetric division, phenotypic markers, and other attributes touted as being indicative of cells being stem cells were critically questioned as fundamental to the definition of a stem cell, leading us to seek a functional definition instead. Here, we offer further considerations, and elaborate on the characteristics that diverse investigators feel are essential for a cell to function as a stem cell, either in development or body maintenance. We hope that this discourse will promote further reflection, culminating with a definition that is widely accepted and universally applicable. We confess this goal has not been reached, neither here nor elsewhere. The outstanding goal of understanding what stem cells are, a prerequisite of characterizing what stem cells do and how they do it, is still outstanding.     

干细胞移植与心脏疾病治疗

干细胞是一类具有自我更新能力和分化潜能的细胞,在临床上应用干细胞移植技术可治疗心脏疾病,主要应用于急性心肌梗死、扩张型心肌病和心脏的起搏治疗。干细胞移植的主要途径包括经外周静脉注射、经冠状动脉注射、心内膜注射、经心外膜直视注射及干细胞自体动员。此项技术的开展使临床获益很大,但同时也存在一些问题亟待解决,如移植的安全性、移植细胞数量的选择、移植后的评价问题等。该学科尚在进一步发展中。