神经干细胞的微环境

目的:探讨干细胞生长的微环境。资料来源:应用计算机检索Pubmed1975-01/2004-12和Ovid1975-01/2004-12以及Elserve1992-01/2004-12数据库中与干细胞微环境相关的文章,检索词为“neuralstemcells,nicheormicroenvironment,ortransplantation”,并限定文章语言种类为English。同时检索维普中文科技期刊数据库1990-01/2004-12相关干细胞微环境的文章,检索词为“神经干细胞、微环境或移植”,并限定文章语言种类为中文。资料选择:对资料进行初审,开始查找全文,纳入标准:①近5年文献。②有关干细胞、移植与其微环境关系的文献。排除标准:重复研究、Meta分析和综述类文献。资料提炼:收集了近50篇文章,纳入22篇符合标准的文章进行综述。资料综合:干细胞的自我更新、增殖和分化主要依赖于周围特殊的微环境,即小生境。干细胞小生境可能提供了一种调节体内干细胞数量的手段。小生境不是几种细胞简单的集合体,而是一个有机的组织结构、生理功能整体。成人神经发生是在血管原性的小生境中进行的。基底膜在干细胞小生境中起固定各种因子、细胞和提供各种空间信号的作用。结论:小生境与神经干细胞的生存、分裂、分化及迁移均有关系,要求在移植时尽量满足干细胞的生长微环境。     

神经干细胞的微环境

目的：探讨干细胞生长的微环境。 资料来源：应用计算机检索Pubmed1975-01／2004-12和Ovid 1975-01／2004-12以及Elserve 1992-01／2004-12数据库中与干细胞微环境相关的文章，检索词为“neural stem cells，niche or microenvironment，or transplantation”，并限定文章语言种类为English。同时检索维普中文科技期刊数据库1990-01／2004-12相关干细胞微环境的文章，检索词为“神经干细胞、微环境或移植”，并限定文章语言种类为中文。 资料选择：对资料进行初审，开始查找全文，纳入标准：①近5年文献。②有关干细胞、移植与其微环境关系的文献。排除标准：重复研究、Meta分析和综述类文献。 资料提炼：收集了近50篇文章，纳入22篇符合标准的文章进行综述。资料综合：干细胞的自我更新、增殖和分化主要依赖于周围特殊的微环境，即小生境。干细胞小生境可能提供了一种调节体内干细胞数量的手段。小生境不是几种细胞简单的集合体，而是一个有机的组织结构、生理功能整体。成人神经发生是在血管原性的小生境中进行的。基底膜在干细胞小生境中起固定各种因子、细胞和提供各种空间信号的作用。 结论：小生境与神经干细胞的生存、分裂、分化及迁移均有关系，要求在移植时尽量满足干细胞的生长微环境。     

可溶性调控因子在造血干细胞功能调控中的研究进展

造血微环境可通过释放可溶性调控因子,如细胞因子、趋化因子及黏附因子等促使造血干细胞(HSC)定位于造血微环境内,平衡HSC自我更新与分化状态,并使HSC维持相对稳态.可溶性调控因子可促使HSC黏附于造血微环境,这在HSC增殖与分化中发挥非常重要作用.笔者拟就目前参与HSC功能调控的可溶性调控因子及其所发挥的作用进行综述.     

豆类凝集素FRIL通过调控细胞周期分子的表达维持造血干/祖细胞的静息

目的从细胞周期角度探讨豆类凝集素 FRIL(Flt3 receptor-interacting lectin)体外维持造血干/祖细胞静息的分子机制。方法以添加 FRIL、Flt3配体(FL)和不添加因子的培养基分别培养脐血 CD34~ 细胞,采用 RT-PCR 和 Western blot 法分别从 mRNA 和蛋白水平检测细胞周期相关分子的表达。结果新分离的 CD34~ 细胞中未检测到 G_0/G_1期相关 Cyclin 和 CDK 蛋白的表达,培养3d 时FRIL 组 CyclinD3、CDK6蛋白相对表达量(分别为483±63、553±39)低于两个对照组(FL 组:2437±52、3209±98;空白对照组:914±105、1497±55);培养3 d 时 FRIL 组 P27蛋白相对表达量(0.312±0.030)低于对照组(FL 组:0.787±0.024;空白对照组:0.616±0.029),但表达较高的 P53蛋白(FRIL组、FL 组、空白对照组分别为4.476±0.159、0.581±0.099、2.167±0.114)。FRIL 组细胞周期正向调节因子的 mRNA 相对表达量低于或相当于 FL 组和空白对照组。结论 FRIL 通过抑制参与造血细胞周期调控的 CyclinD3和 CDK6的表达,延迟了造血干/祖细胞的细胞周期,P27在 FRIL 抑制造血干/祖细胞分化中发挥了重要作用,P53也参与了 FRIL 对造血干/祖细胞的维持作用。     

人胚胎干细胞HuES17向造血干细胞的分化

背景:人类胚胎干细胞是来源于着床前囊胚的内细胞团,能在长期培养中无限增殖并保持未分化状态,且具有分化成人体组织各种细胞类型能力的细胞。目的:进一步验证人胚胎干细胞HuES17细胞株向造血干细胞分化的能力。方法:人胚胎干细胞HuES17采用与人包皮成纤维细胞二维共培养的方式培养,采用人胚胎干细胞与小鼠骨髓基质细胞(OP9)二维共培养的方法诱导胚胎干细胞向造血干细胞分化。结果与结论:人胚胎干细胞与小鼠骨髓基质细胞(OP9)二维共培养诱导造血分化的第四五天即开始出现OP9细胞逐渐老化,很快死亡;可以观察到人胚胎干细胞分化,然而,随着OP9细胞死亡,分化的人胚胎干细胞亦死亡,不能诱导人胚胎干细胞向造血干细胞分化。提示人胚胎干细胞HuES17细胞株可能不能向造血干细胞分化,或向造血干细胞分化的能力较低。     

Age-associated characteristics of murine hematopoietic stem cells

Little is known of age-associated functional changes in hematopoietic stem cells (HSCs). We studied aging HSCs at the clonal level by isolating CD34(-/low)c-Kit(+)Sca-1(+) lineage marker-negative (CD34(-)KSL) cells from the bone marrow of C57BL/6 mice. A population of CD34(-)KSL cells gradually expanded as age increased. Regardless of age, these cells formed in vitro colonies with stem cell factor and interleukin (IL)-3 but not with IL-3 alone. They did not form day 12 colony-forming unit (CFU)-S, indicating that they are primitive cells with myeloid differentiation potential. An in vivo limiting dilution assay revealed that numbers of multilineage repopulating cells increased twofold from 2 to 18 mo of age within a population of CD34(-)KSL cells as well as among unseparated bone marrow cells. In addition, we detected another compartment of repopulating cells, which differed from HSCs, among CD34(-)KSL cells of 18-mo-old mice. These repopulating cells showed less differentiation potential toward lymphoid cells but retained self-renewal potential, as suggested by secondary transplantation. We propose that HSCs gradually accumulate with age, accompanied by cells with less lymphoid differentiation potential, as a result of repeated self-renewal of HSCs.     

间充质干细胞在造血干细胞移植中的应用

应用计算机检索PubMed数据库2000—01／2008-01期间有关间充质干细胞与造血干细胞移植相关的文章，检索词为“MSC，HSCT”，限定文章语言种类为English。同时计算机检索维普数据库2000-01／2008-01期间相关文章，检索词为“间充质干细胞，造血干细胞移植”，限定文章语言种类为中文。并查阅与干细胞实验研究有关的书籍。对资料进行初审，选取符合要求的有关文章查找全文。纳入标准：①有关间充质干细胞对造血干细胞移植影响的研究。②造血干细胞移植机制的相关性研究。排除标准：重复性文章。共收集到66篇相关文献，28篇文献符合纳入标准。临床资料显示，两者共移植安全可行，可提高移植效果，降低近期死亡率。但其确切效果还需前瞻性随机对照临床实验进一步证实。     

Thrombopoietin expands hematopoietic stem cells after transplantation

Multiple lines of evidence indicate that thrombopoietin (TPO) contributes to the development of hematopoietic stem cells (HSC), supporting their survival and proliferation in vitro. To determine whether TPO supports the impressive expansion of HSC observed following transplantation, we transplanted normal marrow cells into lethally irradiated Tpo(-/-) and Tpo(+/+) mice and quantified HSC self-renewal and expansion and hematopoietic progenitor cell homing. Although essentially identical numbers of marrow-associated colony forming unit-culture (a surrogate measure of stem cell homing) were observed in each type of recipient 24 hours following transplantation, we found that a minimum of fourfold greater numbers of marrow cells were required to radioprotect Tpo-null mice than to radioprotect controls. To assess whether long-term repopulating (LTR) HSCs self-renew and expand in Tpo(-/-) recipients or controls, we performed limiting-dilution secondary transplants using donor cells from the Tpo(-/-) or Tpo(+/+) recipients 5-7.5 weeks following primary transplantation. We found that LTR HSCs expand to levels 10-20 times greater within this time period in normal recipients than in Tpo-null mice and that physiologically relevant amounts of TPO administered to the Tpo(-/-) recipients could substantially correct this defect. Our results establish that TPO greatly promotes the self-renewal and expansion of HSCs in vivo following marrow transplantation.     

T否决细胞促进造血干细胞植入的研究

否决效应是一种能特异性抑制识别否决细胞自身表面抗原的细胞毒性T细胞前体细胞(CTL-p)的攻击,而CTL-p对识别第三方抗原无抑制作用。具有否决效应的细胞称为否决细胞。细胞毒性T淋巴细胞(cytotoxic Tlymphocyte,CD8+CTL)是现知否决活性最强的细胞。在异基因造血干细胞移植中,输注供者源的CD8+CTL否决细胞清除宿主同种异体反应细胞可以促进供者干细胞的植入。本文就近年来关于CD8+CTL否决效应的机制、GVH效应、抗肿瘤效应、活体内的应用及与药物和细胞之间的协同作用的研究进展做一综述。     

Cryopreservation of hematopoietic and non-hematopoietic stem cells.

Recent studies illustrate the potential for improving the cryopreservation of stem cells. Reduced DMSO concentrations in the cryopreservation medium, post thaw washing of cells and increased cell concentration have been actively studied. Standardization of cell processing has led to the study of liquid storage prior to cryopreservation, validation of mechanical (uncontrolled rate freezing) freezing, and cryopreservation bag failure. Finally, the need for the systematic study and optimization of preservation processes has not been fulfilled. As the sources and applications of stem cells (hematopoietic and non-hematopoietic) continue to be developed, the need for effective preservation methods will only grow.     

In vitro self-renewal division of hematopoietic stem cells

Little is known about how hematopoietic stem cells (HSCs) self-renew. We studied the regeneration of HSCs in culture. Effects of various cytokines on cell division of CD34(-/low) c-Kit(+)Sca-1(+) lineage marker-negative (CD34(-)KSL) bone marrow cells of the mouse were first evaluated in serum-free single cell culture. We then performed a competitive repopulation assay on divided cells to ask if such cell division involved self-renewal of HSCs.In the presence of stem cell factor (SCF), thrombopoietin (TPO) induced a first cell division of CD34(-)KSL cells more efficiently than did interleukin (IL)-3 or IL-6. Multilineage repopulating cells were detected in a significant proportion of cells derived from single cells in culture with TPO and SCF, although this culture condition led to a substantial decrease in HSC number. These regenerated repopulating cells could be further transplanted into secondary recipients. When paired daughter cells were separately studied, one of a pair gave rise to repopulating cells with self-renewal potential, suggesting asymmetric self-renewal division. This study provides evidence that one HSC regenerates at least one HSC in culture.     

人主动脉-性腺-中肾区基质细胞诱导胚胎干细胞分化为造血干细胞及体内造血重建

背景:研究证实多种造血生长因子、基质细胞饲养层及其条件培养液可促进胚胎干细胞向造血干细胞分化.目的:以人主动脉-性腺-中肾(aorta-gonad-mesonephros,AGM)区基质细胞为饲养层体外诱导小鼠胚胎干细胞分化为造血干细胞,并比较不同移植途径对造血干细胞体内造血重建能力的影响.方法:将小鼠E14 胚胎干细胞诱导为拟胚体,采用Transwell非接触共培养体系在人AGM区基质细胞饲养层上诱导6 d,接种NOD-SCID小鼠检测体内致瘤性.再将诱导后的拟胚体细胞移植经致死量60Co γ射线辐照的BALB/C雌鼠,受鼠随机分为静脉移植组、骨髓腔移植组、照射对照组及正常对照组.结果与结论:拟胚体细胞经人AGM区基质细胞诱导后Sca-1+c-Kit+细胞占(13.12±1.30)%.NOD-SCID小鼠皮下接种经人AGM区基质细胞诱导的拟胚体细胞可出现畸胎瘤,经骨髓腔接种未见肿瘤形成.静脉移植组动物全部死亡,骨髓腔移植组生存率为55.6%,移植后21 d外周血象基本恢复,存活受鼠检测到供体来源Sry基因.提示小鼠胚胎干细胞经人AGM区基质细胞诱导分化的造血干细胞通过骨髓腔移植安全并具有一定的造血重建能力.