造血干细胞骨髓特定微环境的研究进展

造血干细胞（HSC）成功植入到骨髓需要两个条件：①HSC能归巢于骨髓特定的造血微环境;②HSC能在这一特定的微环境内维持长期造血.早在1978年Schofield就提出龛（niche）的概念来定义骨髓中适宜HSC生存的特定微环境结构.该假说认为HSC定位（lodge）于骨髓特定的三维环境内,以维持其自我更新的特性,而一旦离开龛,HSC在基质细胞和各种细胞因子作用下进入分化和增殖状态.     

多发性骨髓瘤龛位

既往研究提示造血干细胞(HSC)的自我更新、分化等生物学特性受骨髓内特定的微环境即龛位调节.HSC龛位由黏附分子、细胞表达的信号分子、骨髓基质细胞、血管内皮细胞和成骨细胞等非细胞与细胞成分构成.近期多项研究提示在骨髓瘤的发生、发展过程中,骨髓中也存在与HSC龛位类似的骨髓瘤细胞龛位.骨髓瘤细胞通过细胞间直接接触,或可溶...     

造血干细胞出髓及回髓机制研究

随着造血干细胞(HSC)移植的广泛开展,对造血干细胞回输后的回髓及造血干细胞的出髓机制的研究也不断深入。HSC的回髓是一个多步骤过程,研究发现,HSC与造血组织血管内皮细胞的结合与多种粘附分子有关;大剂量化/放疗使内皮细胞结构功能发生变化,使HSC更易通过血管屏障;HSC与造血微环境的结合与lectin及粘附分子有关;HSC细胞表面lectin或回髓受体与基质细胞表面配体的特异结合是HSC与造血微环境结合的启动步骤;HSC通过粘附分子与基质及细胞外介质结合。化疗及细胞因子对骨髓微环境及HSC生物学功能的改变是HSC出髓的关键。     

SDF-1/CXCR4信号通路在造血干细胞归巢中作用的研究进展

造血干细胞移植(HSCT)是治疗白血病、淋巴瘤、再生障碍性贫血等恶性血液病的一种有效治疗手段.但是,HSCT后造血功能的恢复与归巢至骨髓造血微环境中的造血干细胞(HSC)数目有关.HSCT输注入受者体内的HSC不会立刻发挥作用,而是先经历一系列复杂的过程归巢至骨髓造血微环境后,才能继续增殖并分化为相应的效应细胞发挥作用.其中,供者HSC与众多细胞及细胞因子间的相互作用是决定HSC归巢、增殖及分化的关键因素.基质细胞衍生因子(SDF)-1及其唯一的受体CXC趋化因子受体(CXCR)4所构成的SDF-1/CXCR4信号通路,可能在HSC归巢中发挥重要作用.为了更深入地研究HSC归巢的具体过程和SDF-1/CXCR4信号通路在该过程中发挥的作用,现对SDF-1、CXCR4的结构、作用机制,以及SDF1/CXCR4信号通路在HSC归巢中作用的研究进展进行综述.     

影响造血干细胞归巢机制的研究

造血干细胞移植(HSCT)已成为血液学基础研究和临床研究中一个活跃领域,是目前治疗一些难治性血液病及急重度放射病的有效措施。造血干细胞(HSC)植入率是影响HSCT成功的关键之一,干细胞归巢的能力反映其植入效率,归巢受HSC性能和受体造血微环境影响,其中主要涉及细胞粘附分子(CAMs)表达、细胞周期状态、基质细胞与细胞因子作用和龛位腾空等。本文就这方面的研究进展进行综述。     

影响造血干细胞归巢机制的研究

造血干细胞移植（HSCT）已成为血液学基础研究和临床研究中一个活跃领域,是目前治疗一些难治性血液病及急重度放射病的有效措施。造血干细胞（HSC）植入率是影响HSCT成功的关键之一,干细胞归巢的能力反映其植入效率,归巢受HSC性能和受体造血微环境影响,其中主要涉及细胞粘附分子（CAMs）表达、细胞周期状态、基质细胞与细胞因子作用和龛位腾空等。本文就这方面的研究进展进行综述。     

造血干细胞归巢研究进展

造血干细胞 (ＨＳＣ)归巢是指ＨＳＣ通过静脉移植经外周血循环进入受体后 ,经复杂的分子间相互作用而介导的其在骨髓内的识别与定位。归巢包括一系列过程 ,以移植的干细胞滚动粘附于骨髓血窦内皮始 ,继之以稳定的粘附并穿行内皮细胞 ,最终达到血管外骨髓微环境并开始重建造血[1 ] 。尽管由于造血干细胞移植已广泛地应用于临床 ,但调节造血干细胞归巢的机制尚未完全清楚[2 ] 。同淋巴细胞归巢一样 ,ＨＳＣ归巢也是由粘附分子和趋化分子介导的。该过程有骨髓内皮细胞、ＨＳＣ、骨髓造血微环境及其分泌或表达的分子共同参与。目前已知免疫球蛋…     

骨髓内皮细胞在造血微环境中作用的研究进展

骨髓造血微环境,即“龛”是由基质细胞、细胞因子及细胞外基质组成.成骨细胞及内皮细胞是造血微环境的重要组成部分,与造血干细胞(HSCs)关系密切.成骨细胞参与构成的成骨龛是造血干/祖细胞定居的主要场所,对HSCs的自我更新和稳态起着重要的作用；而内皮细胞参与构成的血管龛造血调控中的作用近年也成为研究热点.内皮细胞通过与其他基质细胞的协同作用,合成和分泌多种造血调控因子,具有支持营养和调控HSCs的增殖和分化、协助HSCs的跨内皮迁移,在其归巢和动员中也起着重要的作用.笔者就骨髓内皮细胞在造血龛中作用的研究进展进行综述.     

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.     

激光扫描共聚焦显微镜在骨髓造血微环境观测中的应用

近年来,造血干细胞(hematopoietic stem cell,HSC)的研究为血液系统疾病的诊断和治疗起到了重要的推动作用.伴随对骨髓造血微环境的发现及其调节作用的不断认知,HSC增殖和分化途径的研究更加深入.成像技术的应用,尤其是通过激光扫描共聚焦显微镜(confocal laser scanning micr...     

The Stromal Activity of Mesenchymal Stromal Cells

SUMMARY: The mechanism that regulates self-renewal and differentiation of hematopoietic stem cells (HSC) is a central question in stem cell biology that might ultimately lead to reliable protocols for in vitro expansion of HSC. Cellular fate is governed by cell-cell interaction with the microenvironment in the bone marrow, the stem cell niche. Mesenchymal stromal cells (MSC) are precursors of the cellular components, and they secrete extracellular matrix proteins of the bone marrow stroma. Therefore, MSC feeder layer might provide a suitable in vitro model system for the stem cell niche. In vitro assays demonstrate that MSC maintain the stem cell function of HSC and that MSC from bone marrow have a higher hematopoiesis supportive activity than MSC from adipose tissue. Co-cultivation with MSC might pave the way for expansion of long-term repopulating HSC, and various clinical trials indicate that co-transplantation of HSC and MSC might enhance engraftment. Thus, MSC are promising tools to elucidate the underlying mechanism of the cellular microenvironment. The large variety of preparative protocols for isolation and cultivation of MSC affects their stromal activity. Standardized isolation methods and molecular characterization of MSC are of utmost importance for reproducible isolation of hematopoiesis supportive stromal cells and for their potential clinical application.     

Closer to Nature: The Role of MSCs in Recreating the Microenvironment of the Hematopoietic Stem Cell Niche in vitro

BackgroundThe stem cell niche in human bone marrow provides scaffolds, cellular frameworks and essential soluble cues to support the stemness of hematopoietic stem and progenitor cells (HSPCs). To decipher this complex structure and the corresponding cellular interactions, a number of in vitro model systems have been developed. The cellular microenvironment is of key importance, and mesenchymal stromal cells (MSCs) represent one of the major cellular determinants of the niche. Regulation of the self-renewal and differentiation of HSPCs requires not only direct cellular contact and adhesion molecules, but also various cytokines and chemokines. The C-X-C chemokine receptor type 4/stromal cell-derived factor 1 axis plays a pivotal role in stem cell mobilization and homing. As we have learned in recent years, to realistically simulate the physiological in vivo situation, advanced model systems should be based on niche cells arranged in a three-dimensional (3D) structure. By providing a dynamic rather than static setup, microbioreactor systems offer a number of advantages. In addition, the role of low oxygen tension in the niche microenvironment and its impact on hematopoietic stem cells need to be taken into account and are discussed in this review.SummaryThis review focuses on the role of MSCs as a part of the bone marrow niche, the interplay between MSCs and HSPCs and the most important regulatory factors that need to be considered when engineering artificial hematopoietic stem cell niche systems.ConclusionAdvanced 3D model systems using MSCs as niche cells and applying microbioreactor-based technology are capable of simulating the natural properties of the bone marrow niche more closely than ever before.     

The stem cell niches in bone

The stem cell niche is composed of a specialized population of cells that plays an essential role in regulating adult stem cell self-renewal and differentiation. In adults, osteoblasts, responsible for osteogenesis, and hematopoietic cells, responsible for hematopoiesis, are closely associated in the bone marrow, suggesting a reciprocal relationship between the two. It was recently discovered that a subset of osteoblasts functions as a key component of the HSC niche (namely, the osteoblastic niche), controlling HSC numbers. HSCs interact not only with osteoblasts but also with other stromal cells, including endothelial cells. Sinusoidal endothelial cells in bone marrow have been revealed as an alternative HSC niche called the vascular niche. In this Review we compare the architecture of these 2 HSC niches in bone marrow. We also highlight the function of osteoblasts in maintaining a quiescent HSC microenvironment and the likely role of the vascular niche in regulating stem cell proliferation, differentiation, and mobilization. In addition, we focus on studies of animal models and in vitro assays that have provided direct insights into the actions of these osteoblastic and vascular niches, revealing central roles for numerous signaling and adhesion molecules. Many of the discoveries described herein may contribute to future clinical treatments for hematopoietic and bone-related disorders, including cancer.     

按造血发育程序诱导小鼠胚胎干细胞为造血干细胞重建体内造血的实验研究

为研究小鼠胚胎干细胞(ESC)定向诱导分化为造血干细胞(HSC)在体内重建造血的功能,将小鼠E14ESC诱导为拟胚体(EB),EB细胞利用Transwell非接触共培养体系在人主动脉-性腺-中肾(AGM)区、胎肝(FL)及骨髓(BM)基质细胞饲养层上依次诱导,收获各阶段EB细胞,以流式细胞仪检测Sca-1+c-Kit+细胞含量,并接种于NOD-SCID小鼠以检测体内致瘤性。再将不同诱导阶段的EB来源细胞移植到经致死量60Coγ射线照射的BALB/c雌鼠,将受鼠随机分为5组:①AGM组,②AGM+FL组,③AGM+FL+BM组,④照射对照组,⑤正常对照组。观察各组生存率、造血重建和植入状况。结果显示:EB细胞经人AGM区和FL基质细胞共培养后Sca-1+c-Kit+细胞达到峰值(21.96±2.54)%;NOD-SCID小鼠在接种经人AGM区基质细胞诱导的EB细胞后可出现畸胎瘤,而接种经人AGM区+FL基质细胞诱导EB细胞后未见肿瘤形成;AGM组及照射对照组动物全部死亡,而AGM+FL组及AGM+FL+BM组生存率分别为77.8%、66.7%,移植后21天外周血象基本恢复,在存活受鼠检测到供体来源Sry基因。结论:按胚胎造血发育程序,体外经人AGM区、FL及BM基质细胞连续诱导小鼠ESC分化的HSC可安全、有效地重建体内造血。     

可视性观测造血干细胞归巢的研究进展简

造血干细胞移植（hematopoietic stem cell transplantation,HSCT）是治疗血液病、恶性肿瘤、某些遗传性疾病和自身免疫性疾病的重要手段.植入的造血干细胞（hematopoietic stem cell,HSC）能否顺利归巢至骨髓并重建造血是HSCT成功的关键.伴随着对HSC归巢机制的不断认知,人们已不再满足于纯粹的体外功能学研究,如何实现造血干细胞归巢的可视性观测、了解植入细胞在骨髓微环境中的定植程序成为研究者们迫切希望解决的问题.近年来,随着成像技术的发展,激光扫描共聚焦显微镜（confocal laser scanning microscope,CLSM）和双光子显微镜（two-photon microscope）能够对组织或细胞进行三维重建和实时观测,使可视性研究HSC归巢成为现实.本文对可视性研究方法及其在HSC归巢研究中的应用做一综述.     

骨髓微环境变化引发的疾病

背景：骨髓微环境发生改变与血液疾病的发生和发展密切相关。目的：通过综述骨髓微环境中的细胞组分,非细胞组分和信号通路的调控作用,探讨骨髓微环境改变与疾病发生的关系。方法：应用计算机检索2001年1月至2012年4月的Pubmed数据库和万方数据库,英文检索词为＂bone marrow niche,hematopoietic stem cell（HSC）＂,中文检索词为＂骨髓微环境,造血干细胞＂,检索文献总量为424篇,最终纳入61篇进入结果分析。结果与结论：骨髓中的成体造血干细胞是血液系统和淋巴系统的发源细胞。骨髓微环境是支持造血干细胞自我更新和分化的场所,它由多种造血细胞成分、非造血细胞、胞外基质和其他信号蛋白组成。正常的骨髓微环境对造血干细胞发挥正常功能十分重要。一旦发生紊乱,会引发血液疾病和癌症等病症。因此,深入研究骨髓微环境,揭示调控机制以及相关的干细胞命运决定机制,将极大的推动骨髓移植、组织修复和再生医学等领域的发展。     

骨髓间充质干细胞对造血干细胞移植免疫的影响及其机理

骨髓间充质干细胞具有自我更新及多向分化的潜能,在骨髓中合成分泌多种细胞因子,并通过细胞间相互作用为造血干细胞的分裂、增殖与分化提供良好的微环境.有研究显示,骨髓间充质干细胞能够促进异基因造血干细胞植入,并在一定程度上减轻移植物抗宿主病的作用.这种对移植免疫的影响可能与其保护MHC相合造血干细胞逃脱抗原识别,抑制非特异性淋巴细胞活化增殖有关.本文对骨髓间充质干细胞特性、骨髓间充质干细胞影响移植免疫的表现、骨髓间充质干细胞影响移植免疫的机理进行了综述.     

采用多功能流式细胞术分析分选造血干细胞和髓系定向分化祖细胞

目的 探讨富集纯化造血干细胞(HSC)和髓系定向分化祖细胞的新实验方案.方法 根据造血干细胞和定向分化祖细胞在发育过程中表达某些特异性分化抗原的特性,通过免疫磁珠分选技术结合四色和六色流式细胞术分析14只健康小鼠的骨髓造血干细胞、造血祖细胞及定向分化祖细胞系列的表达,并对其进行分选,以进一步通过集落细胞培养和传代试验对分选后细胞的活性进行检测.结果 经上述实验方案分析,14只健康小鼠骨髓造血祖细胞(HPC)的表达率约为HSC的10倍;但其牛成活性远不如造血干细胞,共同髓系祖细胞(CMP)的传代能力仅为HSC的1/2,且次级分化的粒系单核系祖细胞(GMP)和红系巨核系祖细胞(MEP)的生成活性更弱,其传代次数为零.结论 通过多色流式细胞术实验方案可以分析纯化HSC和髓系定向分化祖细胞的表达,并精确计数HSC和祖细胞.     

Hematopoietic stem cells.

The adequate production of blood cells is maintained by a set of immature hematopoietic stem cells (HSC) located in the bone marrow after birth. HSC are able to reconstitute the hematopoietic system in disease-related bone marrow failure and bone marrow aplasia. Nowadays, HSC cells can be mobilized from the bone marrow into the peripheral blood using hematopoietic cytokines, allowing a convenient harvest of these cells for clinical transplantation. This review outlines the development of the hematopoietic system in the embryo and in adults and the characterization, enumeration, purification and ex vivo expansion of HSC for clinical use. Future directions include the genetic manipulation of HSC and the identification/expansion of bone marrow-derived stem cells capable of generating non-hematopoietic tissues.