脐血间质干细胞:神经干细胞的新来源

目的:脐血间质干细胞经诱导分化为神经干细胞的方法,已成为近来细胞移植治疗中枢神经系统疾病研究的热点问题。资料来源:应用计算机检索Medline1994-01/2004-08以及NCBI1994-01/2004-08期间的关于脐血间质干细胞与神经干细胞的文章,检索词“humanumbilicalcordbloodmesenchymalstemcells,neuralstemcells,并限定语言种类为English。同时计算机检索中文数据库CNKI1994-01/2004-08期间的相关文章,检索词“脐血,间质干细胞,神经干细胞”。资料选择:对资料进行初审,选取有关中分离脐血间质干细胞,诱导分化为神经细胞的相关实验研究,及脐血细胞移植治疗中枢神经系统疾病方面的论著。资料提炼:共收集到关于脐血脐血间质干细胞诱导分化为神经细胞及用于细胞移植治疗中枢神经系统疾病的文献37篇,中文4篇,英文33篇。资料综合:神经干细胞移植已被用于促进神经系统疾病的修复,但神经干细胞的来源十分有限。脐血间质干细胞是中胚层发育的早期细胞,有多向分化潜能,可以通过骨髓、脐血和周围血获得。脐血间质干细胞在适宜的体内或体外环境下,可分化为神经元及神经胶质细胞,并在分化过程中表达神经干细胞特异性标志。加之脐血来源丰富,采集方便,免疫排斥反应低,使脐血间质干细胞成为用于细胞移植治疗神经系统疾患的又一     

微载体技术培养人骨髓间充质干细胞的成骨诱导实验

目的:以微载体技术成骨诱导培养人骨髓间充质干细胞,建立一种大量、快速获得骨组织工程种子细胞的方法。方法:实验于2002-12/2003-08在第三军医大学西南医院中心实验室完成。将普通培养瓶培养的第3代人骨髓间充质干细胞采用搅拌式生物反应器和微载体成骨诱导培养,观察细胞增殖情况,作出生长曲线。分别于培养的第2,4,6,8,10,12,14d检测诱导细胞的碱性磷酸酶活性,并与普通成骨诱导方法进行对比。最后进行细胞碱性磷酸酶染色、Ⅰ型胶原、骨钙素的免疫组织化学染色,观察培养细胞的成骨细胞表型的表达。结果:微载体法接种24h后约87%的人骨髓间充质干细胞贴附于微载体并铺展,3d后生长加速,约10～11d后细胞生长达最大值,最终细胞收获密度为接种时的约15～20倍。诱导细胞的碱性磷酸酶活性在培养的第12天达最大值,并表达碱性磷酸酶、Ⅰ型胶原、骨钙素等成骨细胞表型。微载体成骨诱导细胞的碱性磷酸酶活性与普通成骨诱导方法差异无显著性意义(P>0.05)。结论:应用微载体可以成功进行人骨髓间充质干细胞的成骨诱导扩增,可以满足骨组织工程量和质的需要。     

Mesenchymal stem cells in rheumatology: a regenerative approach to joint repair

The advent of biologics in rheumatology has considerably changed the evolution and prognosis of chronic inflammatory arthritis. The success of these new treatments has contributed to steering more attention to research focussed on repair and remodelling of joint tissues. Indeed, when the tissue damage is established, treatment options are very limited and the risk of progression towards joint destruction and failure remains high. Increasing evidence indicates that mesenchymal stem cells persist postnatally within joint tissues. It is postulated that they would function to safeguard joint homoeostasis and guarantee tissue remodelling and repair throughout life. Alterations in mesenchymal stem cell biology in arthritis have indeed been reported but a causal relationship has not been demonstrated, mainly because our current knowledge of mesenchymal stem cell niches and functions within the joint in health and disease is very limited. Nonetheless, mesenchymal stem cell technologies have attracted the attention of the biomedical research community as very promising tools to achieve the repair of joint tissues such as articular cartilage, subchondral bone, menisci and tendons. This review will outline stem-cell-mediated strategies for the repair of joint tissues, spanning from the use of expanded mesenchymal stem cell populations to therapeutic targeting of endogenous stem cells, resident in their native tissues, and related reparative signals in traumatic, degenerative and inflammatory joint disorders.     

一种获得神经干细胞单细胞的新方法

目的 寻找一种有效分离神经干细胞球以获得单个神经干细胞的方法。方法 应用不同浓度的胰蛋白酶、EDTA及组织培养用酵素(Dispase)分别对神经干细胞进行消化．免疫组织化学技术鉴定其分化。结果 应用Dispase消化神经球．可以得到大量单个神经干细胞，且浓度以2000U／ml为佳；而应用0．25％胰蛋白酶、0．25％胰蛋白酶／0．02?TA混合液消化神经干细胞球则得不到大量状态较好的单细胞。结论 应用Dispase消化神经干细胞球是一种理想的获得神经干细胞单细胞的好方法。     

Entry: a new approach

Despite all of the protections promised through grandfathering and pathways to educational mobility, the entry movement tends to be perceived by many to be "demoting" the lives and livelihoods of hundreds of thousands of RNs who do not possess the education to meet the proposed standard. Here is a proposal for a way out of the quagmire.     

Interleukin 7-engineered stromal cells: a new approach for hastening naive T cell recruitment

In this study we determined whether human stromal cells could be engineered with a retroviral vector carrying the interleukin 7 (IL-7) gene and investigated the effects on T cells in vitro and in vivo in a murine model. Transduced mesenchymal cells strongly express CD90 (98.15%), CD105 (87.6%), and STRO-1 (86.7%). IL-7 production was 16.37 (+/-2 SD) pg/ml, which remained stable for 60 days. In vitro-immunoselected naive T cells maintained the CD45RA+ CD45RO- naive phenotype (4.2 times more than controls) after 7 days of culture with IL-7-engineered stromal cells. The apoptosis rate (4.7%) of the naive T cells cultured with transduced stromal cells overlapped with that of freshly isolated cells. Immunohistological analysis detected stromal cells in bone marrow, spleen, and thymus. Cotransplantation of IL-7-engineered stromal cells with CD34+ cells improved engraftment in terms of CD45+ cells and significantly increased the CD3+ cell count in peripheral blood, bone marrow, and spleen. These data demonstrate the following: (1) human stromal cells can be transduced, generating a normal layer; (2) transduced stromal cells in vitro maintain the naive T cell phenotype; and (3) IL-7-transduced stromal cells in vivo home to lymphoid organs and produce sufficient IL-7 in loco, supporting T cell development in a cotransplantation model. Because of their efficient cytokine production and homing, IL-7-engineered stromal cells might be an ideal vehicle to hasten immunological reconstitution in T cell-depleted hosts.     

Cancer stem cells: the development of new cancer therapeutics

Introduction: Cancer stem cells (CSCs) are a subpopulation of tumor cells with indefinite proliferative potential that drive the growth of tumors. CSCs seem to provide a suitable explanation for several intriguing aspects of cancer pathophysiology.

Areas covered: An explosion of therapeutic options for cancer treatment that selectively target CSCs has been recorded in the recent years. These include the targeting of cell-surface proteins, various activated signalling pathways, different molecules of the stem cell niche and various drug resistance mechanisms. Importantly, approaching cancer research by investigating the pathogenesis of these intriguing cancer cells is increasing the knowledge of the pathophysiology of the disease, emphasizing certain molecular mechanisms that have been partially neglected.

Expert opinion: The characterization of the molecular phenotype of these cancer stem-like cells, associated with an accurate definition of their typical derangement in cell differentiation, can represent a fundamental advance in terms of diagnosis and therapy of cancer. Preliminary results seem to be promising but further studies are required to define the therapeutic index of this new anticancer treatment. Moreover, understanding the pathogenetic mechanisms of CSCs can expand the therapeutic applications of normal adult stem cells by reducing the risk of uncontrolled tumorigenic stem cell differentiation.     

Embryonic stem cells: new possible therapy of degenerative diseases

The capacity of embryonic stem (ES) cells for virtually unlimited self-renewal and differentiation has opened up the prospect of widespread applications in biomedical research and regenerative medicine. The use of these cells would allow to overcome the problems of donor tissue shortage and also implant rejection if the cells are made immunocompatible with the recipient. Since the derivation in 1998 of human ES cell lines from pre-implantation embryos, considerable research is centered on their biology, on how differentiation can be encouraged towards particular cell lineages and also on means to enrich and purify derivative cell types. In addition, ES cells may be used as an in vitro system not only to study cell differentiation but also to evaluate the effects of new drugs and the identification of genes as potential therapeutic targets. This review will summarize what is known about animal and human ES cells with particular emphasis on their application in four animal models of human diseases. Present studies of mouse ES cell transplantation reveal encouraging results but also technical barriers that have to be overcome before clinical trials can be considered.     

Brain tumour stem cells: possibilities of new therapeutic strategies

Cancers are composed of heterogeneous cell populations, including highly proliferative immature precursors and differentiated cells, which may belong to different lineages. Recent advances in stem cell research have demonstrated the existence of tumour-initiating, cancer stem cells (CSCs) in non-solid and solid tumours. These cells are defined as CSCs because they show functional properties that resemble those of their normal counterpart to a significant extent. This concept applies to CSCs from brain tumours and, particularly, to glioblastoma stem-like cells, which self-renew under clonal conditions and differentiate into neuron- and glia-like cells, and into aberrant cells, with mixed neuronal/astroglia phenotypes. Notably, across serial transplantation into immunodeficient mice, glioblastoma stem-like cells are able to form secondary tumours which are a phenocopy of the human disease. A significant effort is underway to identify both CSC-specific markers and the molecular mechanism that underpin the tumorigenic potential of these cells, for this will have a critical impact on the understanding of the origin of malignant brain tumour and the discovery of new and more specific therapeutic approaches. Lately, the authors have shown that some of the bone morphogenetic proteins can reduce the tumorigenic ability of CSCs in GBMs. This suggests that mechanisms regulating the physiology of normal brain stem cells may be still in place in their cancerous siblings and that this may lead to the development of cures that selectively target the population CSCs found in the patients' tumour mass.     

Cancer stem cells: the development of new cancer therapeutics

INTRODUCTION: Cancer stem cells (CSCs) are a subpopulation of tumor cells with indefinite proliferative potential that drive the growth of tumors. CSCs seem to provide a suitable explanation for several intriguing aspects of cancer pathophysiology. AREAS COVERED: An explosion of therapeutic options for cancer treatment that selectively target CSCs has been recorded in the recent years. These include the targeting of cell-surface proteins, various activated signalling pathways, different molecules of the stem cell niche and various drug resistance mechanisms. Importantly, approaching cancer research by investigating the pathogenesis of these intriguing cancer cells is increasing the knowledge of the pathophysiology of the disease, emphasizing certain molecular mechanisms that have been partially neglected. EXPERT OPINION: The characterization of the molecular phenotype of these cancer stem-like cells, associated with an accurate definition of their typical derangement in cell differentiation, can represent a fundamental advance in terms of diagnosis and therapy of cancer. Preliminary results seem to be promising but further studies are required to define the therapeutic index of this new anticancer treatment. Moreover, understanding the pathogenetic mechanisms of CSCs can expand the therapeutic applications of normal adult stem cells by reducing the risk of uncontrolled tumorigenic stem cell differentiation.     

Brain tumour stem cells: possibilities of new therapeutic strategies

Cancers are composed of heterogeneous cell populations, including highly proliferative immature precursors and differentiated cells, which may belong to different lineages. Recent advances in stem cell research have demonstrated the existence of tumour-initiating, cancer stem cells (CSCs) in non-solid and solid tumours. These cells are defined as CSCs because they show functional properties that resemble those of their normal counterpart to a significant extent. This concept applies to CSCs from brain tumours and, particularly, to glioblastoma stem-like cells, which self-renew under clonal conditions and differentiate into neuron- and glia-like cells, and into aberrant cells, with mixed neuronal/astroglia phenotypes. Notably, across serial transplantation into immunodeficient mice, glioblastoma stem-like cells are able to form secondary tumours which are a phenocopy of the human disease. A significant effort is underway to identify both CSC-specific markers and the molecular mechanism that underpin the tumorigenic potential of these cells, for this will have a critical impact on the understanding of the origin of malignant brain tumour and the discovery of new and more specific therapeutic approaches. Lately, the authors have shown that some of the bone morphogenetic proteins can reduce the tumorigenic ability of CSCs in GBMs. This suggests that mechanisms regulating the physiology of normal brain stem cells may be still in place in their cancerous siblings and that this may lead to the development of cures that selectively target the population CSCs found in the patients' tumour mass.     

Falls prevention revisited: a call for a new approach

Background. Patient falls constitute a major threat to health services’ ability to provide care. Previous studies confirm that nurses can identify patients at risk and that a preventative programme can reduce the rate of falls but few studies have been evaluated over time. Aims and objectives. A study was undertaken to test a Falls Prevention Programme in an acute medical area that was re‐evaluated 5 years later to determine if the effects were sustainable. Design. The design included two groups of patients admitted before and after the programme. Variables such as staffing, equipment, environment and routines were controlled. However, because of ethical approval constraints, some variables such as age, mental status, mobility and gender were not. Methods. The programme included a risk assessment tool, a choice of interventions, a graphic that alerted others to ‘at risk patients’ and simple patient and staff education. Data were collected using incident forms and a formula was used to calculate a rate of falls. A non‐paired t‐test compared rates and anova examined the relationship of age, gender, mobility and mental status on the incidence of falls. Control graphs determined the stability of the process. Results. The falls rate was significantly reduced. Control graphs demonstrate that the process achieved greater control with less variation. In the next 5 years the falls rate increased to preprogramme levels and control graphs demonstrated that the process was no longer controlled. Compliance with the programme had deteriorated. Conclusions. The practice review considered skill mix, patient activity and acuity but provided no definitive answers to explain non‐compliance. The implications to nursing are discussed. Relevance to clinical practice. Clinicians are called to conduct more rigorous research into falls prevention but it may be more useful to direct research towards examining nursing work and increasing nurse autonomy in falls prevention.     

Blood platelet production: a novel approach for practical optimization

BACKGROUND: The challenge of production and inventory management for blood platelets (PLTs) is the requirement to meet highly uncertain demands. Shortages are to be minimized, if not to be avoided at all. Overproduction, in turn, leads to high levels of outdating as PLTs have a limited "shelf life." Outdating is to be minimized for ethical and cost reasons.
STUDY DESIGN AND METHODS: Operations research (OR) methodology was applied to the PLT inventory management problem. The problem can be formulated in a general mathematical form. To solve this problem, a five-step procedure was used. This procedure is based on a combination of two techniques, a mathematical technique called stochastic dynamic programming (SDP) and computer simulation.
RESULTS: The approach identified an optimal production policy, leading to the computation of a simple and nearly optimal PLT production "order-up-to" rule. This rule prescribes a fixed order-up-to level for each day of the week. The approach was applied to a test study with actual data for a regional Dutch blood bank. The main finding in the test study was that outdating could be reduced from 15-20 percent to less than 0.1 percent with virtually no shortages. Blood group preferences and extending the shelf life of more than 5 days appeared to be of marginal effect.
CONCLUSION: In this article the worlds of blood management and the mathematical discipline of OR are brought together for the optimization of blood PLT production. This leads to simple nearly optimal blood PLT production policies that are suitable for practical implementation.     

Expansion of human mesenchymal stromal cells on microcarriers: growth and metabolism

Adult stem cells, or mesenchymal stromal cells (MSCs), are of great potential for cell therapy and tissue‐engineering applications. However, for therapeutic use, these cells need to be isolated from tissue or a biopsy and efficiently expanded, as they cannot be harvested in sufficient quantities from the body. In our opinion, efficient expansion of MSCs can be achieved in a microcarrier‐based cultivation system. This study selected a suitable microcarrier for human bone marrow‐derived stromal cells (HBMSCs), optimized cell‐seeding strategies by varying serum concentrations, and optimized dynamic expansion of the HBMSCs in a microcarrier‐based spinner flask cultivation system by applying various feeding regimes. Cytodex 1 microcarriers in combination with a low‐serum concentration (0–5%) in the medium resulted in the highest seeding efficiency for the HBMSCs. Subsequently, significant expansion of the HBMSCs on these carriers has been observed. The highest number of HBMSCs population doublings (4.8 doublings) was obtained by a combination of 50% medium refreshment combined with addition of 30% medium containing microcarriers every 3 days. Exponential cell growth was observed for at least 9 days after seeding, provided that sufficient nutrients (such as glucose) were present, metabolite concentrations (such as ammonia) were kept below growth‐inhibitory concentrations and adequate surface area was present for the cells. After dynamic expansion of the HBMSCs, the cells retained their differentiation potential and their cell surface markers, indicating that HBMSCs expansion on Cytodex 1 microcarriers did not alter the phenotypic properties of the cells. Copyright © 2009 John Wiley & Sons, Ltd.