基质细胞衍生因子SDF及其受体CXCR4在造血干/祖细胞动员及归巢过程中的作用

基质细胞衍生因子(SDF)属CXC型趋化因子，主要在骨髓基质细胞和骨髓内皮等细胞表达，特异性地引起表达CXCR4的造血干细胞的趋化反应，因此在造血干细胞的迁移和归巢中起着重要作用。本文对SDF及其受体CXCR4在造血干细胞动员以及归巢过程中的机理进行简要综述。     

以SDF-1/CXCR4轴为靶点治疗发性骨髓瘤的研究进展

早期研究发现,由基质细胞衍生因子-1(SDF1,亦被称为CXCL12)与其受体CXCR4结合形成的SDF-1/CXCR4轴在干细胞归巢、迁移中起主要作用.近期研究发现,抑制SDF1/CXCR4轴在多发性骨髓瘤、淋巴瘤和急性白血病等造血系统肿瘤中有潜在治疗价值.笔者将以SDF 1/CXCR4轴为靶点治疗多发性骨髓瘤的研究进展进行综述.     

造血干细胞与骨髓微环境相互作用的研究进展

造血干细胞移植(HSCT)后,供者造血干细胞(HSC)的归巢和植入直接影响移植的效果.HSC位于骨髓微环境即HSC龛中,并与骨髓微环境相互作用调节其自我更新和多向分化,维持骨髓造血功能动态平衡.近期,研究者们采用不同的创新方法观察移植后骨髓中HSC与骨髓微环境的相互作用关系,发现骨髓微环境对HSC稳态起重要作用,同时HSC也对“龛”的完整性形成必不可少.现就HSC与骨髓微环境的相互作用作一简要综述.     

SDF-1-CXCR4生物学轴对造血干/祖细胞的调控作用

基质细胞衍生因子(SDF-1)及其特异性受体(CXCR4)所构成的SDF-1-CXCR4生物学轴在造血干/祖细胞(HSPCs)的归巢、增殖及分化过程中发挥重要作用。本文对其在HSPCs造血调控中的作用及机制进行综述。     

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。     

SDF-1/CXCR-4在造血干细胞归巢中的作用

造血干细胞向骨髓内归巢是影响造血干细胞移植是否成功的一个重要因素,在干细胞归巢环节中,近年来新发现的基质细胞源性细胞因子-1(stromal cell derived factor-1, SDF-1)及其受体CXCR-4(SDF-1/CXCR-4)系统起着重要的作用.本文就该因子系统的结构、表达以及对造血干细胞的趋化作用及其下游信号传导综述.     

白血病微环境的靶向药物趋化因子受体CXCR4拮抗剂作用机制的研究

造血来源的肿瘤细胞表达趋化因子受体CXCR4,是一种7次跨膜G蛋白耦联受体。组成骨髓微环境的基质细胞分泌基质细胞衍生因子SDF-1/CXCL12,是CXCR4的配体。CXCR4的活化可诱导白血病细胞向骨髓微环境的归巢,白血病细胞表达的CXCL12与骨髓基质细胞紧密相连并且提     

造血干细胞归巢及相关分子机制

所有成熟的血细胞均起源于造血干细胞(HSC).HSC的可移动性使造血干细胞移植(HSCT)成为一项临床可行的治疗手段.HSCT首先要求HSC能经由外周血归巢(Homing)于骨髓并稳定"居住"于骨髓微环境中.     

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。     

SDF—1／CXCR—4在造血干细胞归巢中的作用

造血干细胞向骨髓内归巢是影响造血干细胞移植是否成功的一个重要因素。在干细胞归巢环节中，近年来新发现的基质细胞源性细胞因子-1（stromal cell derived factor-1,SDF-1)及其受体CX-CR-4（SDF-1/CXCR-4）系统起着重要的作用。本文就该因子系统的结构。表达以及对造血干细胞的趋化作用及其下游信号传导综述。     

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.     

New agents for mobilizing peripheral blood stem cells

Transplantation with bone marrow (BM) hematopoietic stem cells (HSC) has been used for curative therapy of hematologic diseases and inborn errors of metabolism for decades. More recently, alternative sources of HSC, particularly those induced to exit marrow and traffic to peripheral blood in response to external stimuli, have become the most widely used hematopoietic graft and show significant superiority to marrow HSC. Although a variety of agents can mobilize stem cells with different kinetics and efficiencies and these agents can be additive or synergistic when used in combination, currently G-CSF is the predominant stem cell mobilizer used clinically based upon potency, predictability and safety. Recent studies have demonstrated that the interaction between the chemokine stromal-derived factor 1 (SDF-1/CXCL12) and its receptor CXCR4 serves as a key regulator of HSC trafficking. AMD3100, a novel bicyclam CXCR4 antagonist, induces the rapid mobilization of HSC with both short- and long-term repopulation capacity. Mobilization with G-CSF and AMD3100 in clinical trials resulted in more patients achieving sufficient PBSC for transplantation than with G-CSF alone. Thus, chemokine axis-mobilization could allow rapid PBSC harvests with increased cell yields in difficult-to mobilize patients. Studies of autologous and allogeneic transplantation of AMD3100 mobilized grafts demonstrated prompt and stable engraftment.Enhanced homing properties of chemokine axis-mobilized PBSC suggest that these cells may have greater therapeutic utility in other areas including tissue repair and regeneration.     

HGF,SDF-1, and MMP-9 are involved in stress-induced human CD34+ stem cell recruitment to the liver

Hematopoietic stem cells rarely contribute to hepatic regeneration, however, the mechanisms governing their homing to the liver, which is a crucial first step, are poorly understood. The chemokine stromal cell-derived factor-1 (SDF-1), which attracts human and murine progenitors, is expressed by liver bile duct epithelium. Neutralization of the SDF-1 receptor CXCR4 abolished homing and engraftment of the murine liver by human CD34+ hematopoietic progenitors, while local injection of human SDF-1 increased their homing. Engrafted human cells were localized in clusters surrounding the bile ducts, in close proximity to SDF-1-expressing epithelial cells, and differentiated into albumin-producing cells. Irradiation or inflammation increased SDF-1 levels and hepatic injury induced MMP-9 activity, leading to both increased CXCR4 expression and SDF-1-mediated recruitment of hematopoietic progenitors to the liver. Unexpectedly, HGF, which is increased following liver injury, promoted protrusion formation, CXCR4 upregulation, and SDF-1-mediated directional migration by human CD34+ progenitors, and synergized with stem cell factor. Thus, stress-induced signals, such as increased expression of SDF-1, MMP-9, and HGF, recruit human CD34+ progenitors with hematopoietic and/or hepatic-like potential to the liver of NOD/SCID mice. Our results suggest the potential of hematopoietic CD34+/CXCR4+cells to respond to stress signals from nonhematopoietic injured organs as an important mechanism for tissue targeting and repair.     

Stromal cell-derived factor-1 and CXCR4 receptor interaction in tumor growth and metastasis of breast cancer.

Stromal cell-derived factor-1 (SDF-1)/CXCR4 interaction is critical for the trafficking of lymphocytes, homing and retention of hematopoietic stem cells within the bone marrow and is essential in fetal hematopoiesis. Binding of SDF-1 to CXCR4 activates a variety of intracellular signal transduction pathways and effector molecules that regulate cell survival, proliferation, chemotaxis, migration and adhesion. Recently, intensive research has demonstrated that SDF-1/CXCR4 interaction also regulates several key events in wide variety of cancers. Serum-depleted media in the presence of SDF-1 protected the breast cancer cells from apoptosis. CXCR4-low-expressing MCF-7 formed small tumor at inoculated site in SCID mice 8-9 weeks after inoculation while completely failed to metastasis into various organs. In contrast, CXCR4-high-expressing MDA-231 cells were most efficient in the formation of a large tumor and organ-metastasis within 3 weeks in SCID mice. This review briefly focuses on the role of SDF-1/CXCR4 interaction in tumor growth and metastasis of breast cancer cell both in vitro and in vivo.     

小鼠肿瘤坏死因子α增强造血干/祖细胞归巢效率的机制研究

目的 探讨肿瘤坏死因子(TNF)α在调节造血干/祖细胞(HS/PC)归巢中的增效作用及其机制.方法 将荧光染料CFSE标记的脐血CD34+细胞移植入接受照射(对照组)或联合TNFα预处理(实验组)的BALB/c受鼠.移植后20 h,采用流式细胞术(FACS)检测脐血CD34+细胞在BALB/c受鼠中的分布(外周血、肝脏、肺脏)与归巢(骨髓、脾脏)特征,计算其相应的归巢效率;酶联免疫吸附实验(ELISA)检测BALB/c受鼠血清基质衍生因子(SDF)-1α水平;FACS检测TNFα预处理前、后脐血CD34+细胞表面CXCR4表达水平的变化;免疫组化法检测BALB/c受鼠骨髓及脾脏组织切片中SDF-1α的表达水平.结果 脐血CD34+细胞主要归巢于BALB/c受鼠骨髓和脾脏;经TNFα预处理的实验组BALB/c受鼠骨髓归巢率[(0.65±0.13)%]显著高于对照组[(0.30±0.09)%,P<0.01];但TNFα预处理同时显著抑制脐血CD34+细胞归巢于BALB/c受鼠脾脏(P<0.01);不同剂量的TNFα预处理不影响受鼠血清SDF-1α水平;新鲜分离的脐血CD34+细胞与不同浓度TNFα共孵育18 h后,其表面CXCR4表达水平并无明显变化;但TNFα预处理受鼠骨髓龛组成细胞SDF-1α表达增高,且脾脏红髓区小梁动脉和小梁静脉内皮细胞SDF-1α表达增高.结论 TNFα通过提升骨髓龛SDF-1α浓度梯度促进HS/PC归巢于骨髓,这一发现将有助于为临床提供可行性HS/PC归巢增效剂.     

Loss of CD26 protease activity in recipient mice during hematopoietic stem cell transplantation results in improved transplant efficiency

BACKGROUND: A firm understanding of the biology of hematopoietic stem and progenitor cell (HSC/HPC) trafficking is critical to improve transplant efficiency and immune reconstitution during hematopoietic stem cell transplantation (HSCT). Our earlier findings suggested that suppression of CD26 (dipeptidyl peptidase IV) proteolytic activity in the donor cell population can be utilized as a method for increasing transplant efficiency. However, factors in the recipient should not be overlooked, given the potential for the bone marrow (BM) microenvironment to regulate HSCT. STUDY DESIGN AND METHODS: We first evaluated CD26 expression and then investigated the effects of the CD26 inhibitor diprotin A and the absence of CD26 (CD26?/?) in recipient mice on HSC/HPC homing and engraftment using an in vivo congenic mouse model of HSCT. RESULTS: A significant increase in donor cell engraftment into the peripheral blood (PB), and to a lesser extent homing into the BM, was observed in CD26?/? mice or CD26 inhibitor–treated mice. Increased PB engraftment of CD26?/? mice was significant at 3 and 6 months, but not 1 month, after transplant. It was noted that the increased homing was statistically greater with donor cell manipulation (CD26?/? donor cells) than with recipient manipulation (CD26?/? recipient mice). Conversely, donor and recipient manipulation both worked well to increase PB engraftment at 6 months. CONCLUSION: These results provide preclinical evidence of CD26, in the HSCT recipient, as a major regulator of HSC/HPC engraftment with minor effects on HSC/HPC homing and suggest the potential use of CD26 inhibitors in HSCT patients to improve transplant efficiency.     

Inhibition of CXCR4 with the novel RCP168 peptide overcomes stroma-mediated chemoresistance in chronic and acute leukemias

The chemokine receptor CXCR4 mediates the migration of hematopoietic cells to the stroma-derived factor 1alpha (SDF-1alpha)-producing bone marrow microenvironment. Using peptide-based CXCR4 inhibitors derived from the chemokine viral macrophage inflammatory protein II, we tested the hypothesis that the inhibition of CXCR4 increases sensitivity to chemotherapy by interfering with stromal/leukemia cell interactions. First, leukemic cells expressing varying amounts of surface CXCR4 were examined for their chemotactic response to SDF-1alpha or stromal cells, alone or in the presence of different CXCR4 inhibitors. Results showed that the polypeptide RCP168 had the strongest antagonistic effect on the SDF-1alpha- or stromal cell-induced chemotaxis of leukemic cells. Furthermore, RCP168 blocked the binding of anti-CXCR4 monoclonal antibody 12G5 to surface CXCR4 in a concentration-dependent manner and inhibited SDF-1alpha-induced AKT and extracellular signal-regulated kinase phosphorylation. Finally, RCP168 significantly enhanced chemotherapy-induced apoptosis in stroma-cocultured Jurkat, primary chronic lymphocytic leukemia, and in a subset of acute myelogenous leukemia cells harboring Flt3 mutation. Equivalent results were obtained with the small-molecule CXCR4 inhibitor AMD3465. Our data therefore suggest that the SDF-1alpha/CXCR4 interaction contributes to the resistance of leukemia cells to chemotherapy-induced apoptosis. Disruption of these interactions by the peptide CXCR4 inhibitor RCP168 represents a novel strategy for targeting leukemic cells within the bone marrow microenvironment.