趋化因子基质细胞衍生因子1(SDF-1)及其受体CXCR4

趋化因子及其受体在免疫和炎症反应、造血以及HIV感染等方面发挥重要作用,其中基质细胞衍生因子-1SDF-1及其受体CXCR4由于在造血干细胞迁移、归巢以及HIV感染中的作用而受到关注,并对其作用机制进行了探讨,现就SDF-1及其受体CXCR4的有关内容作一综述。     

Chemokine receptor CXCR4-dependent internalization and resecretion of functional chemokine SDF-1 by bone marrow endothelial and stromal cells

Regulation of the availability of chemokine SDF-1 (CXCL12) in bone marrow is still not fully understood. Here we describe a unique function for the chemokine receptor CXCR4 expressed on bone marrow endothelial cells, which efficiently internalize circulating SDF-1, resulting in its translocation into the bone marrow. Translocated SDF-1 increased the homing of transplanted human CD34(+) hematopoietic progenitors to the bone marrow. The chemokine transporter function of CXCR4 was a characteristic of endothelial and stromal cells but not of hematopoietic cells. Thus, chemokine translocation across the blood-bone marrow barrier allows effective transfer of functional SDF-1 from the periphery to the stem cell niche in the bone marrow during both homeostasis and 'alarm' situations.     

长期培养对基质细胞衍生因子1/CXCR4介导间充质干细胞迁移的影响**◆

背景：人外源性的间充质干细胞能特异性地向损伤部位迁移,参与多种组织的损伤修复,然而其定向迁移的机制尚不清楚。 目的：观察基质细胞衍生因子1对骨髓间充质干细胞定向迁移的影响。 方法：体外培养不同个体的骨髓间充质干细胞,培养至第10代,检测细胞衰老状态。RT-PCR和细胞免疫荧光检测骨髓间充质干细胞CXCR4受体表达情况;体外迁移体系(Transwell)检测基质细胞衍生因子1对骨髓间充质干细胞迁移的影响。 结果与结论：骨髓间充质干细胞在体外长期增殖后生长逐渐缓慢,在第6,7代衰老细胞增多,其CXCR4受体表达减少。基质细胞衍生因子1对骨髓间充质干细胞的趋化作用呈剂量依赖性。 关键词：趋化作用;骨髓间充质干细胞;细胞衰老;基质细胞衍生因子1;CXCR4受体 doi:10.3969/j.issn.1673-8225.2012.01.013      

基质细胞衍化因子-1对人内皮祖细胞迁移的影响

目的 探讨基质细胞衍化因子-1对内皮祖细胞迁移的影响.方法 用流式细胞仪、RT-PCR、内皮功能实验鉴定内皮祖细胞,检测其CXCR4受体表达和迁移功能.结果 培养单个核细胞7 d,CD34阳性率为36.3%±23.8%,CD133为19.7%±10.3%,双阳性率为18.6%±10.7%,表达KDR基因,>90%的细胞吸收DiI-ac LDL和FITC-UEA-1.CXCR4表达率为74.8%,对照组、基质细胞衍化因子-1浓度为10、20和50μg/L时,细胞迁移数分别为3.5、7.4、24.9和28.0个.各组浓度的细胞迁移数均显著高于对照组(P<0.01),20μg/L组显著高于10μg/L组、50μg/L组显著高于10μg/L组(P<0.01),50μg/L组显著高于20μg/L组(P<0.05).结论 (1)从外周血途径分离、培养和扩增获得内皮祖细胞,表达CXCR4受体;(2)内皮祖细胞可在基质细胞衍化因子-1的趋化作用下迁移,且与其浓度呈正相关.     

Long-term hematopoietic stem cells require stromal cell-derived factor-1 for colonizing bone marrow during ontogeny

The physiological role of SDF-1 on hematopoietic stem cells (HSCs) remains elusive. We show that colonization of bone marrow by HSCs in addition to myeloid cells is severely impaired in SDF-1(-/-) embryos by a long-term repopulation assay. Colonization of spleen by HSCs was also affected, but to a lesser extent. Enforced expression of SDF-1 under the control of vascular-specific Tie-2 regulatory sequences could completely rescue the reduction of HSCs but not myeloid cells in SDF-1(-/-) bone marrow. SDF-1 was detected in the vicinity of the vascular endothelial cells in fetal bone marrow. SDF-1 plays a critical role in colonization of bone marrow by HSCs and myeloid cells during ontogeny, and the mechanisms by which SDF-1 functions are distinct between HSCs and myeloid cells.     

基质细胞衍生因子1对骨髓间充质干细胞迁移及皮肤创伤修复的影响

背景：基质细胞衍生因子1对骨髓间充质干细胞具有强烈的趋化作用,且基质细胞衍生因子1与骨髓间充质干细胞均能促进组织创伤愈合,然而有关两者与皮肤创伤愈合的研究文献报道较少。 目的：观察基质细胞衍生因子1在皮肤创伤修复过程中对骨髓间充质干细胞定向迁移及皮肤创面愈合的影响。 方法：选取30只SD大鼠随机分为5组,各组大鼠尾静脉注射PKH26标记的骨髓间充质干细胞,注射1周后于背部制作皮肤创伤模型,造模后于皮肤创伤处多点注射不同质量浓度的基质细胞衍生因子1(1,2,10,50 μg/L)。注射14 d后观察并记录大鼠皮肤愈合情况,免疫荧光染色观察创面组织骨髓间充质干细胞数量、分布情况,苏木精-伊红染色观察创面组织病理变化,Western blot检测创面组织Ⅰ型胶原及Ⅲ型胶原蛋白表达情况。 结果与结论：当基质细胞衍生因子1质量浓度为10 μg/L时,骨髓间充质干细胞在皮肤创面的数量最多,创伤修复效果最好。同样基质细胞衍生因子1能够调节Ⅰ型胶原及Ⅲ型胶原在创面的表达,基质细胞衍生因子1质量浓度为10 μg/L时,Ⅰ型胶原及Ⅲ型胶原表达最高。结果表明适宜质量浓度的基质细胞衍生因子1 (10 μg/L)能够更好地促进骨髓间充质干细胞迁移,从而促进皮肤创伤愈合。中国组织工程研究杂志出版内容重点：干细胞;骨髓干细胞;造血干细胞;脂肪干细胞;肿瘤干细胞;胚胎干细胞;脐带脐血干细胞;干细胞诱导;干细胞分化;组织工程全文链接：     

Hypoxia- and vascular endothelial growth factor-induced stromal cell-derived factor-1alpha/CXCR4 expression in glioblastomas: one plausible explanation of Scherer's structures

The morphological patterns of glioma cell invasion are known as the secondary structures of Scherer. In this report, we propose a biologically based mechanism for the nonrandom formation of Scherer's secondary structures based on the differential expression of stromal cell-derived factor (SDF)-1alpha and CXCR4 at the invading edge of glioblastomas. The chemokine SDF-1alpha was highly expressed in neurons, blood vessels, subpial regions, and white matter tracts that form the basis of Scherer's secondary structures. In contrast, the SDF-1alpha receptor, CXCR4, was highly expressed in invading glioma cells organized around neurons and blood vessels, in subpial regions, and along white matter tracts. Neuronal and endothelial cells exposed to vascular endothelial growth factor up-regulated the expression of SDF-1alpha. CXCR4-positive tumor cells migrated toward a SDF-1alpha gradient in vitro, whereas inhibition of CXCR4 expression decreased their migration. Similarly, inhibition of CXCR4 decreased levels of SDF-1alpha-induced phosphorylation of FAK, AKT, and ERK1/2, suggesting CXCR4 involvement in glioma invasion signaling. These studies offer one plausible molecular basis and explanation of the formation of Scherer's structures in glioma patients.     

Stromal cell-derived factor-1 (SDF-1) signalling regulates human placental trophoblast cell survival

Stromal cell-derived factor-1 (SDF-1 or CXCL12) is the physiologic ligand for the chemokine receptor CXCR4. CXCR4-mediated signalling regulates cell migration and apoptosis in certain haematopoietic and neuronal cells. Using gene profiling, we determined that CXCR4 is the only chemokine receptor for which mRNA expression is regulated during trophoblast differentiation in vitro. Based on the known effects of CXCR4 ligation, we hypothesized that CXCR4 activation may regulate placental trophoblast cell survival (i.e. protection from apoptosis), an important mechanism for the establishment and maintenance of the uteroplacental barrier. Human cytotrophoblasts (CTBs) were cultured in defined media and treated with graded doses of SDF-1 (10-100 ng/ml) or with an anti-CXCR4 neutralizing antibody. Exposure to anti-CXCR4 antibody reduced CTB cell numbers by 25-40%. Treatment with SDF-1 decreased the proportions of apoptotic terminal deoxynucleotidyl transferase-mediated dUTP-FITC nick-end labelling(+) cells (apoptotic index [AI] of 2.79+/-0.61% [control] versus 1.88+/-0.56% [SDF-1]; P<0.05) and caspase-activated cells (AI of 7.95+/-2.49% [control] versus 3.81+/-1.49% [SDF-1]; P<0.05). We determined that SDF-1 also activated the triple MAP Kinase isoforms ERK1/2 and p38 in trophoblasts. Immunocytochemistry confirmed SDF-1-induced nuclear translocation of phosphorylated ERK1/2. Blocking of ERK1/2 signalling with the specific inhibitor PD98059 reversed SDF-1-mediated inhibition of apoptosis (AI of 1.65+/-0.34 [SDF-1] versus 3.50+/-0.5 [SDF-1 + PD98059]; P<0.05), suggesting that SDF-1 acts through this pathway as a trophoblast survival factor. These results indicate that SDF-1/CXCR4 signalling stimulates anti-apoptotic pathways in cultured trophoblasts. This chemotactic ligand/receptor system may promote trophoblast survival during pregnancy. Alterations in SDF-1 and/or CXCR4 expression or function may be associated with specific pregnancy disorders.     

SDF-1/CXCR4生物轴活化诱导对鼠骨髓源性内皮祖细胞生物学性能的影响

目的 观察基质细胞衍生因子-1( SDF-1)及其特异性受体CXCR4生物轴对体外培养的鼠骨髓源性内皮祖细胞(EPCs)生物学性能的影响.方法 以密度梯度离心法获取大鼠骨髓单个核细胞,由Dil-ac-LDL和FITC-UEA-1荧光双染鉴定后确认为EPCs.传代培养后,加入不同浓度SDF-1溶液,培养48 h,然后分别...     

Expression of stromal cell-derived factor-1 and of its receptor CXCR4 in liver regeneration from oval cells in rat

Stromal cell-derived factor-1 is a chemokine that plays a major role during embryogenesis. Since stromal cell-derived factor-1 and its unique receptor CXCR4 are involved in the differentiation of progenitor cells, we studied the expression of this chemokine and of its receptor in hepatic regeneration from precursor oval cells. Hepatic regeneration was induced by treating rats with 2-acetylaminofluorene, and followed by partial hepatectomy. Oval cell accumulation, which predominated in periportal regions, reached a maximum at days 9 to 14 after hepatectomy and declined thereafter. Oval cells strongly expressed stromal cell-derived factor-1 protein and mRNA. CXCR4 mRNA hepatic level paralleled the number of oval cells and in situ hybridization showed CXCR4 mRNA expression by these cells. Treatment of rats with fucoidan, a sulfated polysaccharide which binds to stromal cell-derived factor-1 and blocks its biological effects, markedly decreased oval cell accumulation in five of the seven treated rats. In conclusion, our data demonstrate an expression of stromal cell-derived factor-1 and of its receptor CXCR4 in oval cells during hepatic regeneration and strongly suggest that stromal cell-derived factor-1 stimulates the proliferation of these precursor cells through an autocrine/paracrine pathway.     

Circulating bone marrow-derived osteoblast progenitor cells are recruited to the bone-forming site by the CXCR4/stromal cell-derived factor-1 pathway

Previous studies demonstrated the existence of osteoblastic cells in circulating blood. Recently, we reported that osteoblast progenitor cells (OPCs) in circulation originated from bone marrow and contributed to the formation of ectopic bone induced by implantation of a bone morphogenetic protein (BMP)-2-containing collagen pellet in mouse muscular tissue. However, the character of circulating bone marrow-derived osteoblast progenitor cells (MOPCs) and the precise mechanisms involving the circulating MOPCs in the osteogenic processes, such as signals that recruit the circulating MOPCs to the osseous tissues, have been obscure. In this report, we demonstrated for the first time that the MOPCs were mobilized from intact bones to transiently occupy approximately 80% of the mononuclear cell population in the circulating blood by BMP-2-pellet implantation. The mobilized MOPCs in the circulation did not express the hematopoietic marker CD45 on their surface, but they expressed CD44 and CXCR4, receptors of osteopontin and stromal cell-derived factor-1 (SDF-1), respectively. The MOPCs isolated from the mouse peripheral blood showed the ability to be osteoblasts in vitro and in vivo. Furthermore, the MOPCs in the circulation efficiently migrated to the region of bone formation by chemoattraction of SDF-1 expressed in vascular endothelial cells and the de novo osteoblasts of the region. These data may provide a novel insight into the mechanism of bone formation involving MOPCs in circulating blood, as well as perspective on the use of circulating MOPCs to accelerate bone regeneration in the future.     

基质细胞衍生因子1及其受体CXCR4在内源性神经干细胞迁移中的作用

背景：神经干细胞具有体外、体外迁移的特性,但关于其迁移的具体机制还不十分清楚。 目的：探讨基质细胞衍生因子1及其受体CXCR4在神经干细胞体内迁移中的作用。 方法：制备脑皮质微量注射脂多糖脑损伤大鼠模型,于建模后3,5,7 d灌注取脑,采用冰冻切片免疫组织化学方法,动态监测基质细胞衍生因子1和nestin表达的时相变化。 结果与结论：免疫组织化学染色观察显示：基质细胞衍生因子1随时间推移表达的量逐渐增多。Nestin阳性细胞有明显向外延伸和迁移的迹象,尖端指向脂多糖注射区。结果可见基质细胞衍生因子1趋化体内表达其特异性受体的内源性神经干细胞向脂多糖注射区迁移。     

骨髓间充质干细胞分泌基质细胞衍生因子1保护心肌细胞

背景：有研究显示表达CXCR4的干细胞能够沿着基质细胞衍生因子1的浓度梯度迁移到心肌梗死部位再生心肌和血管而改善心脏的功能。 目的：探索间充质干细胞通过其分泌的基质细胞衍生因子1对心肌细胞的保护作用。 方法：收集培养2 d的间充质干细胞条件培养基。在缺氧条件,利用基质细胞衍生因子1受体CXCR4阻断剂AMD3100或PI3-K/Akt途径阻断剂LY294002预处理H9C2细胞后,利用AnnexinV/PI双标法流式细胞术分析间充质干细胞条件培养基作用下H9C2细胞凋亡的变化;Western blotting分析H9C2细胞磷酸化Akt蛋白的表达;RT-PCR分析间充质干细胞基质细胞衍生因子1的表达。 结果与结论：RT-PCR结果显示间充质干细胞表达基质细胞衍生因子1,Western blotting结果显示间充质干细胞条件培养基增加了H9C2细胞磷酸化Akt蛋白的水平。AnnexinV/PI分析发现间充质干细胞条件培养基明显降低了H9C2细胞缺氧复氧后的凋亡,且这种抗凋亡作用能被CXCR4阻断剂AMD3100或PI3-K/Akt途径阻断剂LY294002所阻断。说明间充质干细胞通过其分泌的基质细胞衍生因子1通过激活PI3-K/Akt途径保护H9C2细胞,增加H9C2细胞的幸存能力。     

SDF-1/CXCR4增强骨髓间质干细胞的造血支持作用

目的探讨基质细胞衍生因子-1(SDF-1)/CXCR4在骨髓间质干细胞(MSCs)支持CD34 造血干/祖细胞(HSPCs)扩增中的作用。方法在长期培养基(LTC)中,以大鼠骨髓MSCs作为饲养层体外扩增骨髓CD34 细胞,每周分别加入SDF-1、SDF-1抗体或CXCR4抗体至5周。计算CD34 细胞数和集落形成细胞(CFC)数,以评价造血支持功能。为评估SDF-1/CXCR4对CD34 细胞增殖周期的影响,进行了杀伤试验以计算增殖指数。流式细胞术检测MSCs和CD34 细胞中SDF-1与CXCR4的表达;ELISA检测MSCs和CD34 细胞培养基中SDF-1的含量。结果CD34 细胞数、CFC数和增殖指数在加入SDF-1后明显增加(P<0.01),加入SDF-1抗体或CXCR4抗体后明显减少(分别为P<0.05,P<0.01)。CD34 细胞表面表达CXCR4,MSCs则不表达;MSCs细胞内表达SDF-1,而CD34 细胞不表达。在MSCs培养基中检测到SDF-1,在CD34 细胞培养基中未发现。结论SDF-1/CXCR4在骨髓MSCs支持HSPCs扩增中起重要作用。     

Endothelial NOS is required for SDF-1alpha/CXCR4-mediated peripheral endothelial adhesion of c-kit+ bone marrow stem cells

In the era of intravascular approaches for regenerative cell therapy, the underlying mechanisms of stem cell migration to non-marrow tissue have not been clarified. We hypothesized that next to a local inflammatory response implying adhesion molecule expression, endothelial nitric oxide synthase (eNOS)-dependent signaling is required for stromal- cell-derived factor-1 alpha (SDF-1alpha)-induced adhesion of c-kit+ cells to the vascular endothelium. SDF-1alpha/tumor necrosis factor-alpha (TNF-alpha)-induced c-kit+-cell shape change and migration capacity was studied in vitro using immunohistochemistry and Boyden chamber assays. In vivo interaction of c-kit+ cells from bone marrow with the endothelium in response to SDF-1alpha/TNF-alpha stimulation was visualized in the cremaster muscle microcirculation of wild-type (WT) and eNOS (-/-) mice using intravital fluorescence microscopy. In addition, NOS activity was inhibited with N-nitro-L-arginine-methylester-hydrochloride in WT mice. To reveal c-kit+-specific adhesion behavior, endogenous leukocytes (EL) and c-kit+ cells from peripheral blood served as control. Moreover, intercellular adhesion molecule-1 (ICAM-1) and CXCR4 were blocked systemically to determine their role in inflammation-related c-kit+-cell adhesion. In vitro, SDF-1alpha enhanced c-kit+-cell migration. In vivo, SDF-1alpha alone triggered endothelial rolling-not firm adherence-of c-kit+ cells in WT mice. While TNF-alpha alone had little effect on adhesion of c-kit+ cells, it induced maximum endothelial EL adherence. However, after combined treatment with SDF-1alpha+TNF-alpha, endothelial adhesion of c-kit+ cells increased independent of their origin, while EL adhesion was not further incremented. Systemic treatment with anti-ICAM-1 and anti-CXCR4-monoclonal antibody completely abolished endothelial c-kit+-cell adhesion. In N-nitro-L-arginine-methylester-hydrochloride-treated WT mice as well as in eNOS (-/-) mice, firm endothelial adhesion of c-kit+ cells was entirely abrogated, while EL adhesion was significantly increased. The chemokine SDF-1alpha mediates firm adhesion c-kit+ cells only in the presence of TNF-alpha stimulation via an ICAM-1- and CXCR4-dependent mechanism. The presence of eNOS appears to be a crucial and specific factor for firm c-kit+-cell adhesion to the vascular endothelium.     

Expression of CXCR4, the receptor for stromal cell-derived factor-1 on fetal and adult human lympho-hematopoietic progenitors.

Stromal cell-derived factor-1 (SDF-1) is a CXC chemokine produced by stromal cells that acts as a chemoattractant for human CD34+ progenitor cells. We investigated the expression of CXCR4, the receptor for SDF-1, on CD34+ cells from different hematopoietic sites and developmental stages. CXCR4 was detected by flow cytometry on 37 % of fetal bone marrow (BM) [gestation weeks (gw) 14-23] and 40% of adult BM CD34+ cells. Interestingly, in fetal liver CD34+ cells, CXCR4 was expressed at lower levels at later stages (9%, gw 20-23) compared to early stages of development (39%, gw 7.5-18), suggesting a development-related change in the migratory capacity of progenitors. CXCR4 was detected at similar levels on both phenotypically primitive and committed progenitors from fetal and adult sites. However, B cell lineage progenitor and precursor cells expressed CXCR4 at the highest density (80% of BM CD34+/CD10+ pro-B cells are CXCR4+). CXCR4 was also expressed in the fetal thymus in early T cell precursors and found to be down-regulated during T cell maturation. Finally, we found that stem cell factor, alone or in combination with other cytokines, can up-modulate CXCR4 expression on CD34+ cells by three- to fourfold. In conclusion, our results suggest that CXCR4 may play an important role in the local and systemic trafficking of human CD34+ cells as well as in human B lymphopoiesis and that its expression can be modulated by cytokines.     

Cyclic variability of stromal cell-derived factor-1 and endothelial progenitor cells during the menstrual cycle

The endometrium goes through a unique cycle of physiological angiogenesis during the normal menstrual cycle (MC). We studied whether there is a correlation between endothelial progenitor cells (EPCs) and plasma and endometrial levels of angiogenic growth factors during the MC. Ten healthy, regularly menstruating women provided blood samples and another 16 supplied endometrial biopsies. Blood samples were obtained over a single MC: twice in the proliferative and once in the secretory phase and at ovulation. Endometrial biopsies were provided in the proliferative or in the secretory phase. We assessed plasma levels of vascular endothelial and fibroblast growth factors, granulocyte and granulocyte-macrophage colony-stimulating factors and stromal cell-derived factor-1 (SDF-1) by ELISA; EPCs by a colony-forming unit (CFU) assay; immunostaining for endometrial SDF-1 by computer-assisted software; and endothelial cell (EC) markers by flow cytometry. In the proliferative phase, SDF-1 levels were significantly higher than during the secretory phase. EPC-CFUs correlated negatively to SDF-1 levels. Endometrial SDF-1 expression tended to be higher in the secretory than in the proliferative phase. Furthermore, vascular endothelial growth factor receptors and Tie-2 EPCs showed a cyclic pattern over the MC. Our results point to SDF-1 as a novel mediator of EPC trafficking during the MC.     

G-CSF induces stem cell mobilization by decreasing bone marrow SDF-1 and up-regulating CXCR4

Granulocyte colony-stimulating factor (G-CSF) induced hematopoietic stem cell mobilization is widely used for clinical transplantation; however, the mechanism is poorly understood. We report here that G-CSF induced a reduction of the chemokine stromal cell derived factor 1 (SDF-1) and an increase in its receptor CXCR4 in the bone marrow (BM), whereas their protein expression in the blood was less affected. The gradual decrease of BM SDF-1, due mostly to its degradation by neutrophil elastase, correlated with stem cell mobilization. Elastase inhibition reduced both activities. Human and murine stem cell mobilization was inhibited by neutralizing CXCR4 or SDF-1 antibodies, demonstrating SDF-1 CXCR4 signaling in cell egress. We suggest that manipulation of SDF-1 CXCR4 interactions may be a means with which to control the navigation of progenitors between the BM and blood to improve the outcome of clinical stem cell transplantation.     

低氧诱导肺动脉内皮细胞间质细胞衍生因子-1的表达及其调控机制

肺血管重塑（PVR）是低氧性肺动脉高压持续且难以逆转的主要原因,其主要病变表现为肺动脉壁细胞增多,但其来源和机制仍不清楚。研究表明骨髓和外周血中存在血管壁细胞的祖细胞,并且参与了PVR的形成。间质细胞衍生因子-1（SDF-1）是特异性介导干细胞归巢至骨髓,介导祖细胞归巢至损伤或缺血组织的关键因子。SDF-1表达在这些部位的血管内皮细胞,而低氧是这些部位的微环境特征,也是诱导SDF-1表达的主要原因。低氧诱导因子-1α（HIF-1α）是特异性介导细胞低氧反应的关键因子,直接调控脐静脉内皮细胞SDF-1基因的表达㈨。我们旨在探讨低氧对肺动脉内皮细胞SDF-1表达的影响及HIF-1α对其表达的调控作用。