AMD3100动员造血肝脏细胞作用的量效关系

目的 探讨AMD3100动员造血干祖细胞动员作用的量效关系.方法 40只实验小鼠分为A、B、C、D、E五组,A组皮下注射等体积的生理盐水;B、C、D、E组分别皮下注射AMD3100 1.25、2.5、5、10mg/kg.2h后尾静脉取血,分别检测外周血白细胞计数、KSL细胞数及KL细胞.结果 用药后B、C、D、E组白细胞KSL及KL细胞均比用药前升高(P＜0.05),随着用药剂量升高,白细胞、KSL细胞及KL细胞数逐渐升高,当剂量达到5 mg/kg时达到作用高峰.结论 AMD3100对造血干/祖细胞动员作用随着剂量增大而加强,有一定的剂量依从关系.     

Plerixafor, a CXCR4 antagonist for the mobilization of hematopoietic stem cells

Stem cells harvested from peripheral blood are the most commonly used graft source in hematopoietic stem cell transplantation. While G-CSF is the most frequently used agent for stem cell mobilization, the use of G-CSF alone results in suboptimal stem cell yields in a significant proportion of patients undergoing autologous transplantation. Plerixafor (AMD3100, Genzyme Corporation) is a bicyclam molecule that antagonizes the binding of the chemokine stromal cell-derived factor-1 (SDF-1) to its cognate receptor CXCR4. Plerixafor results in the rapid and reversible mobilization of hematopoietic stem cells into the peripheral circulation and is synergistic when combined with G-CSF. In clinical studies of autologous stem cell transplantation, the combination of plerixafor and G-CSF allows the collection of large numbers of stem cells in fewer apheresis sessions and can salvage those who fail G-CSF mobilization alone.     

Plerixafor,a CXCR4 antagonist for the mobilization of hematopoietic stem cells

Stem cells harvested from peripheral blood are the most commonly used graft source in hematopoietic stem cell transplantation. While G-CSF is the most frequently used agent for stem cell mobilization, the use of G-CSF alone results in suboptimal stem cell yields in a significant proportion of patients undergoing autologous transplantation. Plerixafor (AMD3100, Genzyme Corporation) is a bicyclam molecule that antagonizes the binding of the chemokine stromal cell-derived factor-1 (SDF-1) to its cognate receptor CXCR4. Plerixafor results in the rapid and reversible mobilization of hematopoietic stem cells into the peripheral circulation and is synergistic when combined with G-CSF. In clinical studies of autologous stem cell transplantation, the combination of plerixafor and G-CSF allows the collection of large numbers of stem cells in fewer apheresis sessions and can salvage those who fail G-CSF mobilization alone.     

Augmented mobilization and collection of CD34+ hematopoietic cells from normal human volunteers stimulated with granulocyte-colony-stimulating factor by single-dose administration of AMD3100, a CXCR4 antagonist

BACKGROUND: AMD3100, a selective antagonist of CXCR4, rapidly mobilizes CD34+ hematopoietic progenitor cells (HPCs) from marrow to peripheral blood with minimal side effects. STUDY DESIGN AND METHODS: To further investigate potential clinical utility of AMD3100 for CD34+ cell mobilization and collection, a Phase I study in normal volunteers was performed examining single-dose administration of AMD3100 alone and in combination with a standard 5-day granulocyte-colony-stimulating factor (G-CSF) regimen. RESULTS: AMD3100 (160 microg/kg x 1 on Day 5) significantly increased both G-CSF-stimulated (10 microg/kg/day) mobilization of CD34+ cells (3.8-fold) and leukapheresis yield of CD34+ cells. Moreover, collection of CD34+ cells was comparable between individuals mobilized by a single-dose regimen of AMD3100 (240 microg/kg) and individuals mobilized with a 5-day regimen of G-CSF. AMD3100-mobilized leukapheresis products contained significantly greater numbers of T and B cells compared to G-CSF-stimulated leukapheresis products. CONCLUSION: These findings indicate that AMD3100 can be used alone or as an adjunct to G-CSF to mobilize cells for HPC transplantation.     

CXCR4受体阻断剂AMD3100研究进展

AMD3100(Plerixafor)是基质细胞衍生因子(SDF-1)受体CXCR4的阻断剂,能通过竞争与CXCR4的结合位点,有效阻断SDF-1结合CXCR4,从而阻断SDF-1/CXCR4轴的生理功能。SDF-1/CXCR4轴在介入干细胞动员、迁移、归巢、免疫调节、炎症性疾病、自身免疫性疾病、胚胎发育、肿瘤细胞的增殖、迁移和定植等都起到重要作用。AMD3100能够快速有效动员骨髓造血干细胞和间充质干细胞,抑制肿瘤细胞的生长和转移,抑制某些炎症性和自身免疫性疾病进展。因此,对AMD3100的深入研究将有助于进一步从造血微环境等方面阐述肿瘤的发病机制,为临床上安全有效的动员造血干细胞,用于损伤组织的修复,并能够为某些肿瘤治疗提供新的途径。本文对AMD3100生物作用基础及其应用研究等方面的若干重要问题进行了综述。     

A pharmacokinetic-pharmacodynamic model for the mobilization of CD34+ hematopoietic progenitor cells by AMD3100

BACKGROUND: AMD3100 is a small-molecule CXCR4 antagonist that has been shown to induce the mobilization of CD34 + hematopoietic progenitor cells from bone marrow to peripheral blood. AMD3100 has also been shown to augment the mobilization of CD34 + cells in cancer patients when administered in combination with granulocyte colony-stimulating factor (G-CSF) (filgrastim). The purpose of this study was to characterize the exposure-response relationship of AMD3100 in mobilizing CD34 + cells when administered as a single agent in healthy volunteers. METHODS: AMD3100 concentrations and CD34 + cell counts obtained from 29 healthy subjects in a single-dose, intensively sampled pharmacokinetic/pharmacodynamic (PK-PD) study were analyzed by use of nonlinear mixed effects regression with the software NONMEM. FOCE (first order conditional estimation) with interaction was the estimation method, and simultaneous PK-PD fitting was adopted. RESULTS: The pharmacokinetics of AMD3100 was described by a 2-compartment model with first-order absorption. The population estimates (+/-SE) for clearance and central volume of distribution were 5.17 +/- 0.49 L/h and 16.9 +/- 3.79 L, respectively. CD34 + cell mobilization was best described by an indirect effect model that stimulates the entry process of CD34 + from bone marrow to peripheral blood in the form of a sigmoid maximum effect model. The population estimates (+/-SE) of maximum effect, concentration causing 50% of maximum response, and equilibration time were 12.6 +/- 4.89, 53.6 +/- 11.9 mug/L, and 5.37 +/- 1.31 hours, respectively. CONCLUSIONS: This study characterizes the exposure-response relationship of AMD3100 in mobilizing CD34 + cells after subcutaneous administration. This PK-PD model will be useful in assessing relevant covariates and for optimizing the use of AMD3100 in various patient populations.     

The CXCR4 antagonist AMD3100 efficiently inhibits cell-surface-expressed human immunodeficiency virus type 1 envelope-induced apoptosis

Infection by human immunodeficiency virus type 1 (HIV-1) has been associated with increased cell death by apoptosis in infected and uninfected cells. The envelope glycoprotein complex ([gp120/gp41](n)) of X4 HIV-1 isolates is involved in both infected and uninfected cell death via its interaction with cellular receptors CD4 and CXCR4. We studied the effect of the blockade of CXCR4 receptors by the agonist stromal derived factor (SDF-1alpha) and the antagonist bicyclam AMD3100 on apoptotic cell death of CD4(+) cells in different models of HIV infection. In HIV-infected CEM or SUP-T1 cultures, AMD3100 showed antiapoptotic activity even when added 24 h after infection. In contrast, other antiviral agents, such as zidovudine, failed to block apoptosis under these conditions. The antiapoptotic activity of AMD3100 was also studied in coculture of peripheral blood mononuclear cells or CD4(+) cell lines with chronically infected H9/IIIB cells. AMD3100 was found to inhibit both syncytium formation and apoptosis induction with 50% inhibitory concentrations ranging from 0.009 to 0.24 microg/ml, depending on the cell type. When compared to SDF-1alpha, AMD3100 showed higher inhibitory potency in all cell lines tested. Our data indicate that the bicyclam AMD3100 not only inhibits HIV replication but also efficiently blocks cell-surface-expressed HIV-1 envelope-induced apoptosis in uninfected cells.     

Suppression of dualtropic human immunodeficiency virus type 1 by the CXCR4 antagonist AMD3100 is associated with efficiency of CXCR4 use and baseline virus composition

In a phase I/II evaluation of the CXCR4 antagonist AMD3100, human immunodeficiency virus RNA levels were significantly reduced in a single study subject who harbored CXCR4 (X4)-tropic virus, but not in subjects who harbored either dual/mixed (DM)-tropic or CCR5 (R5)-tropic virus (C. W. Hendrix et al., J. Acquir. Immune Defic. Syndr. 37:1253-1262, 2004). In this study, we analyzed the envelope clones of DM-tropic virus in baseline and treated virus populations from 14 subjects. Ten subjects exhibited significant reductions in CXCR4-mediated infectivity after 10 days of AMD3100 therapy relative to baseline (X4 suppressor group), while four subjects had no reduction of CXCR4-mediated infectivity (X4 nonsuppressor group). The baseline viruses of the X4 suppressor group infected CXCR4-expressing cells less efficiently than those of the X4 nonsuppressor group. Clonal analysis indicated that the baseline viruses from the X4 suppressor group contained a higher proportion of R5-tropic variants mixed with CXCR4-using variants, while the X4 nonsuppressor group was enriched for CXCR4-using variants. AMD3100 suppressed X4-tropic variants in all subjects studied, but not all dualtropic variants. Furthermore, dualtropic variants that used CXCR4 efficiently were suppressed by AMD3100, while dualtropic variants that used CXCR4 poorly were not. This study demonstrated that AMD3100 has the ability to suppress both X4-tropic and certain dualtropic variants in vivo. The suppression of CXCR4-using variants by AMD3100 is dependent on both the tropism composition of the virus population and the efficiency of CXCR4 usage of individual variants.     

Disruption of HIV-1 co-receptors CCR5 and CXCR4 in primary human T cells and hematopoietic stem and progenitor cells using base editing

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含人AGM区基质细胞对小鼠胚胎干细胞诱导体外分化为造血干/祖细胞的作用

为探讨人主动脉-性腺-中肾(AGM)区基质细胞对小鼠胚胎千细胞(embryonic stem cells,ESC)体外诱导分化为造血干细胞(HSC)的影响及其作用机制,将小鼠E14 ESC诱导为拟胚体(EB),收获的EB细胞以Tran-swell非接触共培养体系分别在人AGM区、胎肝(FL)或骨髓(BM)基质细胞饲养层上进一步诱导分化,分为EB对照、AGM诱导、FL诱导、BM诱导、AGM + FL诱导和AGM + BM诱导共6组.分别收获各组EB来源细胞,以流式细胞仪检测Sca-1+ c-Kit+细胞含量,并进行各系造血细胞集落形成单位(CFU)分析.结果显示:经不同基质细胞饲养层诱导后EB来源细胞中Sca-1+ c-Kit+细胞比例均较诱导前明显升高(p<0.01),AGM+FL诱导组为(21.96±2.54)%,显著优于其它诱导组(p<0.01),AGM+BM诱导组阳性细胞比例亦较单纯BM诱导组明显增加(p<0.O1);EB对照组造血集落产率明显低于其它诱导组,AGM+FL、AGM+BM诱导组集落产率较高,尤以AGM+FL诱导组最佳(p<0.01).结论:人AGM区基质细胞有助于维持一定的原始HSC数目及高增殖潜能,在AGM区基质细胞诱导基础上可明显提高FL或BM基质细胞对ESC源性原始HSC的进一步扩增作用.     

Membrane-anchored uPAR regulates the proliferation, marrow pool size, engraftment, and mobilization of mouse hematopoietic stem/progenitor cells

The mechanisms of BM hematopoietic stem/progenitor cell (HSPC) adhesion, engraftment, and mobilization remain incompletely identified. Here, using WT and transgenic mice, we have shown that membrane-anchored plasminogen activator, urokinase receptor (^MuPAR) marks a subset of HSPCs and promotes the preservation of the size of this pool of cells in the BM. Loss or inhibition of ^MuPAR increased HSPC proliferation and impaired their homing, engraftment, and adhesion to the BM microenvironment. During mobilization, ^MuPAR was inactivated by plasmin via proteolytic cleavage. Cell-autonomous loss of the gene encoding ^MuPAR also impaired long-term engraftment and multilineage repopulation in primary and secondary recipient mice. These findings identify ^MuPAR and plasmin as regulators of the proliferation, marrow pool size, homing, engraftment, and mobilization of HSPCs and possibly also of HSCs.     

骨髓间充质干细胞诱导成骨细胞模拟造血龛支持造血干/祖细胞增殖

目的探讨骨髓间充质干细胞(MSC)诱导的成骨细胞复合人源生物衍生骨,构建三维培养体系,观察模拟的造血龛(hematopietic niche)对脐血CD34 造血干／祖细胞(HSPC)增殖的支持作用。方法分选人骨髓MSC及胎儿颅骨成骨细胞,将培养3代的MSC定向诱导为成骨细胞,分别将①MSC、②颅骨成骨细胞、③MSC与成骨细胞混合物(比例为1:2)及④MSC诱导的成骨细胞作为饲养细胞复合在人源生物衍生骨上,构建三维培养体系,同时用相应的饲养细胞层构建对应的二维培养体系。免疫磁珠分选脐血CD34 细胞,接种于各培养体系,无外源性细胞因子条件下进行培养。显微镜下观察各饲养细胞与人源生物衍生骨复合情况,通过流式细胞术、半固体细胞集落培养观察比较各培养体系支持HSPC的增殖能力。结果倒置相差显微镜、扫描电子显微镜以及免疫荧光标记观察结果显示,已成功地将MSC、颅骨成骨细胞、MSC和成骨细胞混合物及MSC诱导的成骨细胞复合在人源生物衍生骨上,构建了造血干细胞三维培养体系。在无外源细胞因子作用下,脐血HSPC培养2周造血祖细胞集落(CFU-C)与长期培养起始细胞(LTC-IC)分析,三维培养体系各组(①～④)CFU-C明显多于相应二维培养体系各组(①681．00±44．43比438．20±64．24;②729．80±37．72比536．60±35．31;③697．80±54．09比464．80±41．53;④740．20±47．66比513．40±65．56),P<0．05,但三维培养体系各组间差异无统计学意义(P>0．05)。三维培养体系各组LTC-IC也明显高于相应二维培养体系(分别为①68．00±5．11比26．00±3．73;②93．00±6．12比38．60±4．93;③83．40±5．85比36．20±4．52;④126．00±11．89比59．40±4．25),P<0．05,且三维培养体系中MSC诱导的成骨细胞组(④)LTC-IC明显多于其他各组。脐血HSPC培养5周,二维培养体系中饲养细胞层已逐渐崩解、脱落、死亡;而三维培养体系中饲养细胞层生长情况较好。三维体系各组CFU-C集落分析显示,MSC诱导的成骨细胞组(④)与其他三组间差异有统计学意义(①112．00±14．21;②186．17±24．80;③126．67±11．52;④257．00±28．78),P<0．05。结论骨髓MSC诱导分化的成骨细胞复合人源生物衍生骨构建的三维培养体系,对于脐血HSPC体外培养具有类似体内造血龛的支持作用,成骨细胞对造血干／祖细胞生存、增殖具有重要的调控作用。     

人胎儿血造血干/祖细胞的生物学特性及其移植实验

背景:造血干细胞来源目前包括骨髓干细胞、外周血干细胞和脐带血干细胞,寻找新的干细胞来源以满足临床移植需要一直是人们的希望。从妊娠第5周起,肝脏中发育成完善的血窦系统,此后造血干细胞就可以随血液流动迁移。目的:观察人胎儿血造血干/祖细胞的生物学特性并对其进行非肥胖糖尿病/重症联合免疫缺陷小鼠移植。设计:对照实验。单位:广西医科大学第一附属医院血液科。对象:①细胞来源:21例胎儿血标本取自胎龄为18～29周[(24.2±3.2)周]死亡胎儿及21例足月脐带血标本取自广西医科大学第一附属医院产科2002-10/2003-02。所取的血标本均取得其家属的知情同意。②实验动物:非肥胖糖尿病/重症联合免疫缺陷小鼠12只,6～7周龄,雌性,无菌饲养于超净工作台中。方法:采用流式细胞术,检测胎儿血的造血干/祖细胞表面标志,包括CD34,CD38,HLA-DR及CD90,同时与21例足月儿脐血作比较。并将人胎血单个核细胞移植给6只经亚致死量照射的非肥胖糖尿病/重症联合免疫缺陷小鼠,5周后观察其植入情况,采用流式细胞术检测小鼠骨髓中人白细胞的含量,以及采用聚合酶链反应检测小鼠骨髓中的人Cart-1基因。主要观察指标:①胎血和脐血造血干/祖细胞表面标志的表达情况。②将胎血细胞移植给非肥胖糖尿病/重症联合免疫缺陷小鼠的植入情况。结果:①人胎血中CD34 细胞的百分率显著高于足月脐血[(2.2588±0.7209)%,(1.5729±0.4783)%,P=0.0004],CD34 CD38-细胞和CD34 CD90 细胞的百分率也均显著高于足月脐血[(1.2986±0.4706)%,(0.8710±0.4095)%,P=0.0016;(0.9300±0.4692)%,(0.5600±0.3658)%,P=0.0324]。②6例胎血中的4例可顺利重建经亚致死量照射的非肥胖糖尿病/重症联合免疫缺陷小鼠的造血,移植后5周在小鼠骨髓中仍可检测到人的白细胞和人Cart-1基因。结论:人胎儿血中有比足月脐血更高含量的造血干/祖细胞,其单个核细胞能植入非肥胖糖尿病/重症联合免疫缺陷小鼠骨髓,并重建髓、淋巴系全面造血。胎儿血有望成为多能造血干细胞来源。     

人胎盘组织来源造血干/祖细胞及其特性

背景:近年来的研究表明,除已知的人骨髓、外周血和脐带血中存在造血干/祖细胞外,人胎盘组织中也有造血干/祖细胞存在.目前为止,还缺乏对人胎盘组织造血干/祖细胞的增殖分化特性及人胎盘组织淋巴细胞亚群组成和免疫原性等的深入研究.目的:探究人胎盘组织是否含有比脐带血更丰富的造血干/祖细胞,并对其造血祖细胞系增殖分化能力进行检测,同时对人胎盘组织淋巴细胞亚群组成及表型特征进行分析.设计、时间及地点:开放性实验,于2004-01/2006-12在贵州省细胞工程重点实验室完成.材料:经产妇知情同意,无菌采集遵义医学院附属医院产科健康足月分娩新生儿胎盘和脐带血共12份.淋巴细胞亚群检测试剂盒,CD34绝对计数试剂盒(Becton Dickinson公司):CD34磁珠分选试剂盒,FITC标记的CD38单克隆抗体,抗FITC磁珠和MS/LS免疫磁式细胞分选柱(Miltenyi Biotec).方法:脐带血与RPMI-1640培养基(含体积分数为0.1的胎牛血清)按1:1的比例混合,采用Ficoll-Histopaque分离液离心30min,吸取界面层细胞,PBS洗涤一次,获得脐带血单个核细胞.采用机械法加0.25g/L胶原酶消化制备胎盘组织单个细胞悬液,之后同脐带血单个核细胞分离步骤分离胎盘单个核细胞.流式细胞仪检测胎盘单个核细胞中CD34 CD38-, CD34 CD38 造血干/祖细胞(HSPCs)和淋巴细胞亚群的组成比例.免疫磁珠分选法分选人胎盘CD34 CD38-,CD34 D38 造血干/祖细胞,并分别进行粒细胞-单核细胞集落生成单位、红细胞爆裂型集落生成单位、混合集落生成单位系集落形成培养,以评价其造血祖细胞系增殖分化能力.实验全程用脐带血作平行比较分析.主要观察指标:胎盘和脐带血CD34 造血干/祖细胞组成百分率、祖细胞系集落形成能力、淋巴细胞亚群表型及组成特点.结果:[1]胎盘CD34 造血干/祖细胞百分率是脐带血的8.8倍,差异有显著性意义(P<0.01).[2]胎盘中的淋巴细胞总数、T细胞(CD3 CD2 )、B细胞(CD19 )、Th(CD3 CD4 )细胞及Th/Ts比值均明显低于脐带血,而CD8 CD28-T抑制细胞则明显高于脐带血,差异有显著性意义(P<0.01).[3]胎盘CD34 CD38 造血干/祖细胞亚群培养形成的粒细胞-单核细胞集落生成单位、红细胞爆裂型集落生成单位、混合集落生成单位集落数明显高于CD34 CD38-造血干/祖细胞亚群(P<0.01);胎盘与脐带血造血干/祖细胞中相同表型细胞亚群形成的各系集落数比较,差异无显著性意义(P0.05).结论:人胎盘组织富含CD34 造血干/祖细胞,其CD34 CD38 、CD34 CD38-两个造血干/祖细胞亚群均具有增殖分化为粒细胞-单核细胞集落生成单位、红细胞爆裂型集落生成单位、混合集落生成单位的能力,并且人胎盘组织具有淋巴细胞亚群低比例和抑制性T细胞高比例的特点,使其有望成为造血干/祖细胞移植的新来源.     

人胎儿血造血干／祖细胞的生物学特性及其移植实验

背景：造血干细胞来源目前包括骨髓干细胞、外周血干细胞和脐带血干细胞，寻找新的干细胞来源以满足临床移植需要一直是人们的希望。从妊娠第5周起，肝脏中发育成完善的血窦系统，此后造血干细胞就可以随血液流动迁移。 目的：观察人胎儿血造血干／祖细胞的生物学特性并对其进行非肥胖糖尿病／重症联合免疫缺陷小鼠移植。 设计：对照实验。 单位：广西医科大学第一附属医院血液科。对象：①细胞来源：21例胎儿血标本取自胎龄为18-29周[（24．2&;#177;3．2）周1死亡胎儿及2l例足月脐带血标本取自广西医科大学第一附属医院产科2002-10／2003-02。所取的血标本均取得其家属的知情同意。②实验动物：非肥胖糖尿病／重症联合免疫缺陷小鼠12只，6-7周龄，雌性，无菌饲养于超净工作台中。 方法：采用流式细胞术，检测胎儿血的造血干／祖细胞表面标志，包括CD34,CD38，HLA-DR及CD90，同时与2l例足月儿脐血作比较。并将人胎血单个核细胞移植给6只经亚致死量照射的非肥胖糖尿病／重症联合免疫缺陷小鼠，5周后观察其植人情况，采用流式细胞术检测小鼠骨髓中人白细胞的含量，以及采用聚合酶链反应检测小鼠骨髓中的人Cart-1基因。 主要观察指标：①胎血和脐血造血干／祖细胞表面标志的表达情况。②将胎血细胞移植给非肥胖糖尿病／重症联合免疫缺陷小鼠的植入情况。结果：①人胎血中CD34^＋细胞的百分率显著高于足月脐血[（2．2588&;#177;O．7209）％，（1．5729&;#177;0．4783）％，P=0.00041，CD34^＋CD38^-细胞和CD34^＋CD90^＋细胞的百分率也均显著高于足月脐血[（1．2986&;#177;0.4706）％。（0.87l0&;#177;0.4095）％。P=0．0016；（0.9300&;#177;0.4692）％，（0.560&;#177;0.3658）％，P=0.03241。②6例胎血中的4例可顺利重建经亚致死量照射的非肥胖糖尿病／重症联合免疫缺陷小鼠的造血，移植后5周在小鼠骨髓中仍可检测到人的白细胞和人Cart-l基因。 结论：人胎儿血中有比足月脐血更高含量的造血干／祖细胞，其单个核细胞能植入非肥胖糖尿病／重症联合免疫缺陷小鼠骨髓，并重建髓、淋巴系全面造血。胎儿血有望成为多能造血干细胞来源。     

间充质干细胞和内皮祖细胞对脐血造血干/祖细胞体外扩增效力的影响

目的比较脐带来源的间充质干细胞(Mesenchymal stem cells,MSCs)和内皮祖细胞(Endothelial progeni-tor cells,EPCs)对脐血造血干/祖细胞(Hematopoietic stem/progenitor cells,HSCs/HPCs)的体外扩增效力。方法正常人脐血中分离单个核细胞(Mononuclear cells,MNCs),流式细胞术检测其中HSCs/HPCs所占比例,将MNCs分别接种于处理后的MSCs或EPCs或仅接种于培养液中,比较不同培养条件对HSCs/HPCs扩增能力、表面抗原CD34的表达以及集落形成能力的影响。结果共培养过程中,MSC组和EPC组的MNCs扩增倍数均明显高于对照组,且EPC组更为显著。扩增7天后,对照组、MSC组和EPC组的HSCs/HPCs CD34的表达均较扩增前下降,其中EPC组下降的最为显著,MSC组最不显著。共培养4天后,MSC组的HSCs/HPCs集落形成总数为EPC组的2.47倍(**,P<0.01),共培养7天后,MSC组的HSCs/HPCs集落形成总数为EPC组的3.45倍(**,P<0.01);EPC组与对照组的HSCs/HPCs集落形成总数无显著性差异。结论 MSC和EPC均可为HSCs/HPCs的体外扩增提供适宜的微环境,MSC可抑制HSCs/HPCs的分化,有助于维持其表面抗原CD34的表达,并保持其造血重建潜能和归巢能力;而EPC则可有效促进HSCs/HPCs的分化。     

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.     

New approaches to expand hematopoietic stem and progenitor cells

INTRODUCTION: Hematopoietic stem cells (HSCs) are defined by their capacity to self-renew and to differentiate into all blood cell lineages, and are currently the foundation of HSC transplantation therapy. A variety of methods have recently been explored to find a way to expand hematopoietic stem and progenitor cells (HSCs/PCs) ex vivo in order to improve the efficiency and outcome of HSC transplantation. AREAS COVERED: Recent studies of HSCs/PCs have led to the development of new ways to detect and purify HSCs/PCs and have also revealed several intrinsic and extrinsic factors that control the molecular signals fundamental to self-renewal and differentiation of HSCs. These findings have provided new approaches for expanding HSCs/PCs ex vivo utilizing protein factors and small-molecule compounds (SMCs) and have also demonstrated promising outcomes in clinical trials. EXPERT OPINION: Although further technical innovation is still needed, elucidation of the whole picture of signaling pathways critical to HSCs/PCs and manipulation of such pathways by SMCs could establish efficient, cost-effective, riskless and robust methods for ex vivo expansion of HSCs/PCs. With these efforts, more sophisticated HSC transplantation would be possible in the near future.