In vitro differentiation of endothelial cells from AC133-positive progenitor cells

Recent findings support the hypothesis that the CD34(+)-cell population in bone marrow and peripheral blood contains hematopoietic and endothelial progenitor and stem cells. In this study, we report that human AC133(+) cells from granulocyte colony-stimulating factor-mobilized peripheral blood have the capacity to differentiate into endothelial cells (ECs). When cultured in the presence of vascular endothelial growth factor (VEGF) and the novel cytokine stem cell growth factor (SCGF), AC133(+) progenitors generate both adherent and proliferating nonadherent cells. Phenotypic analysis of the cells within the adherent population reveals that the majority display endothelial features, including the expression of KDR, Tie-2, Ulex europaeus agglutinin-1, and von Willebrand factor. Electron microscopic studies of these cells show structures compatible with Weibel-Palade bodies that are found exclusively in vascular endothelium. AC133-derived nonadherent cells give rise to both hematopoietic and endothelial colonies in semisolid medium. On transfer to fresh liquid culture with VEGF and SCGF, nonadherent cells again produce an adherent and a nonadherent population. In mice with severe combined immunodeficiency, AC133-derived cells form new blood vessels in vivo when injected subcutaneously together with A549 lung cancer cells. These data indicate that the AC133(+)-cell population consists of progenitor and stem cells not only with hematopoietic potential but also with the capacity to differentiate into ECs. Whether these hematopoietic and endothelial progenitors develop from a common precursor, the hemangioblast will be studied at the single-cell level.     

Exposure to platelets promotes functional properties of endothelial progenitor cells

Recent evidence indicates that endothelial progenitor cells (EPCs) have an important role in the process of repair following vascular injury, and that platelets mediate their recruitment to sites of injury. Platelets and EPCs can interact and bind directly. However, there is limited information on the effect of platelets on EPC function following this interaction. We, therefore, aimed to assess the in vitro effect of platelets on functional properties of EPCs. Human EPCs were isolated from donated Buffy coats and purified on a magnetic separation column specific for CD133. They were incubated either on fibronectin matrix, or co-incubated with washed platelets (isolated from healthy volunteers), for 7 days. Number of EPC colony forming units (CFU) was quantified, and endothelial cell lineage confirmed by immunostaining. Functional properties of the cultured cells were evaluated by MTT—proliferation assay and migration assay using the Boyden chamber. Co-incubation of EPCs with platelets compared to incubation of EPCs alone (on fibronectin matrix) resulted in higher number of CFUs after 7 days (6.5 ± 1.3 vs. 3.5 ± 0.5 CFUs/well, respectively, P = 0.005). In addition, co-incubation of EPCs with platelets versus EPCs alone was associated with higher proportion of living cells, by the MTT assay (0.2 ± 0.01 vs. 0.12 ± 0.04 MTT 570 nm respectively, P = 0.003), and higher number of migrated EPCs, assessed by the migration assay (1400 ± 212 vs. 580 ± 180 migrated cells/2000 cells, respectively, P < 0.0001). In vitro exposure to platelets promotes the capacity of EPCs to form colonies, proliferate and migrate. Therefore, the interaction with platelets appears to augment EPC functional properties.     

Platelet-induced differentiation of endothelial progenitor cells

Endothelial progenitor cells (EPCs) have the potential to home at sites of vascular lesions and to contribute to revascularization. This homing is a highly concerted mechanism, which involves chemotaxis, adhesion, migration, and finally integration of the cells into the target tissue. Only recently has the platelet been identified as a central mediator of EPC homing. Adherent platelets were able to mediate chemotaxis and adhesion of EPCs, a process that involved P-selectin glycoprotein ligand 1 and very late antigen-4 (VLA-4). Recent studies suggest that platelet-derived stromal cell-derived factor-1 is also involved centrally in the recruitment of EPCs. Furthermore, platelets induce progenitor cell migration by platelet-derived growth factor AB. Recent in vivo data confirm the recruitment of EPCs to sites of vascular lesions after vessel denudation by activated platelets and fibrin. Moreover, when coincubated with platelets, EPCs differentiate to mature endothelial cells and have the potential to migrate and colonize a platelet thrombus. The described interaction of EPCs with platelets represents a novel mechanism of vascular remodeling and healing of endothelial lesions.     

不同诱导因子下内皮祖细胞具有双向分化的潜能

目的探讨内皮祖细胞(EPCs)在不同诱导因子作用下的体外分化潜能。方法人脐血单个核细胞分别予50ng/ml血管内皮生长因子(VEGF组)或50ng/ml血小板源生长因子(PDGF组)诱导分化。光镜形态观察,免疫荧光鉴定。流式细胞分析CD133+EPCs分化特征。结果新鲜脐血分离单个核细胞培养1周后贴壁细胞的EPCs特异的DiI标记乙酰化低密度脂蛋白鉴定为80%阳性。在VEGF或PDGF诱导下1周,单个核细胞大量贴壁生长多呈圆形,少量梭形生长。2周时,被诱导细胞有近50%贴壁呈梭形生长,VEGF组和PDGF组无明显差异。至4周时两组出现明显的分化差异,其中VEGF组呈"铺路石"样细胞融合,血管性假血友病因子免疫荧光呈阳性;而PDGF组呈梭形或长多角形融合,予α-平滑肌肌动蛋白标记部分呈阳性。单个核细胞磁珠分选后得到CD133+较CD133-更多分化为内皮样细胞(P<0.05);而在PDGF的诱导下CD133-较CD133+更多分化为平滑肌样细胞(P<0.05)。结论单个核细胞在体外不同的诱导因子诱导下可以双向分化,CD133+EPCs具有更强的内皮细胞分化潜能。     

雷帕霉素对内皮祖细胞增殖、黏附及迁移能力影响的实验研究

目的药物洗脱支架可抑制支架处血管内膜再内皮化,但对骨髓源性内皮修复作用的影响尚不清楚,为此观察了雷帕霉素对内皮祖细胞(endothelial progenitor cells,EPC)增殖、黏附及迁移的影响。方法采用密度梯度离心法从大鼠骨髓获取单个核细胞,将其接种在纤维连接素包被培养板,加入不同浓度雷帕霉素(0.01～100ng/ml),培养12天后,激光共聚焦显微镜鉴定FITC-UEA-Ⅰ和DiI-acLDL双染阳性细胞为正在分化的EPC,并在倒置荧光显微镜下计数。收集培养8天贴壁细胞,分别加入不同浓度雷帕霉素(0.1～200ng/ml)培养12～96h。然后分别采用MTT比色法、改良的Boyden小室和黏附能力测定实验观察EPC的增殖、迁移和黏附能力。结果雷帕霉素显著抑制骨髓单个核细胞分化为EPC,0.1ng/ml浓度雷帕霉素作用12天,EPC减少了(59.3±5.8)%(P<0.01)。雷帕霉素也显著抑制EPC增殖,其抑制作用随雷帕霉素浓度增加及作用时间延长而增加,1ng/ml浓度雷帕霉素作用24h使EPC数量减少(41.5±2.2)%(P<0.01)。雷帕霉素也显著抑制EPC的黏附和迁移能力。结论雷帕霉素可抑制骨髓单个核细胞分化为EPC,并抑制EPC的增殖及迁移能力。     

Apoptotic bodies from endothelial cells enhance the number and initiate the differentiation of human endothelial progenitor cells in vitro

Endothelial progenitor cells (EPCs) play a role in the repair of ischemic or injured tissue. Because endothelial injury can be associated with apoptosis, we have investigated whether apoptotic bodies from mature endothelial cells (ECs) may affect growth and differentiation of EPCs in vitro. A 24-hour incubation of isolated human EPCs with apoptotic bodies-rich medium (ABRM) from ECs led to a significant increase in the number of spindle-shaped attached cells. EPCs were characterized by DiI-Ac-LDL/lectin staining and measurement of CD34 and kinase insert domain receptor (KDR) expression. The treatment with ABRM resulted in a 2-fold increase of DiI-Ac-LDL/lectin-positive cells and up-regulation of CD34 (22% +/- 2% versus 13% +/- 3%, P < .05 and KDR (49% +/- 12% versus 19% +/- 7%, P < .05). Fluorescence and confocal laser microscopy demonstrated the uptake of apoptotic bodies by the EPCs. Apoptotic bodies-depleted medium had no effect, whereas the incubation with suspension of apoptotic bodies induced effects similar to those of ABRM. Our results suggest that apoptotic bodies from ECs are taken up by EPCs, increasing their number and differentiation state. Such a mechanism may facilitate the repair of injured endothelium and may represent a new signaling pathway between progenitor and damaged somatic cells.     

Impaired interaction between platelets and endothelial progenitor cells in diabetic patients

This editorial focuses on new data on the role of platelets of the recruitment of endothelial progenitor cells to sites of vascular lesion and their differentiation into endothelium. Questions of further research are raised.     

Roles of vascular endothelial growth factor receptor 3 signaling in differentiation of mouse embryonic stem cell-derived vascular progenitor cells into endothelial cells

Vascular endothelial growth factor receptor 2 (VEGFR2/Flk-1)-positive cells derived from embryonic stem (ES) cells serve as vascular progenitors, which differentiate into endothelial cells (ECs) in the presence of VEGF-A. VEGFR3/Flt-4 (fms-like tyrosine kinase 4) signaling is known to be important for the development of lymphatic endothelial cells (LECs). To elucidate the roles of VEGFR3 signaling in the differentiation of vascular progenitor cells into ECs, we introduced various types of VEGFR3 cDNAs into mouse ES cells. VEGF-C, a ligand for VEGFR2 and VEGFR3, stimulated the endothelial differentiation of the VEGFR2+ cells transfected with the VEGFR3 cDNA but not those transfected with kinase-negative mutants of VEGFR3. The VEGFR3-transfected ECs exhibited high expression levels of lymphatic vessel endothelial hyaluronan receptor-1 (LYVE-1), one of the markers of LECs, and showed efficient binding of hyaluronan. VEGF-C(C152S), which is able to activate VEGFR3 but not VEGFR2, failed to induce the endothelial differentiation of mock- and VEGFR3-transfected VEGFR2(+) cells, suggesting the essential role of VEGFR2 signaling for endothelial differentiation. Furthermore, kinase-negative mutants of VEGFR3 prevented the VEGF-C-mediated endothelial differentiation of the vascular progenitor cells. Thus, VEGFR2 signaling is required for the endothelial differentiation of mouse ES cells induced by VEGF-C, and VEGFR3 signaling may confer lymphatic endothelial-like phenotypes to ECs.     

胚胎干细胞体外定向分化为Ngn3+胰岛祖细胞的基因表达谱分析

目的 探讨胚胎干细胞体外定向分化为胰岛祖细胞的基因表达谱.方法 采用逐步诱导分化方案体外传代培养胚胎干细胞,应用RT-PCR和免疫细胞化学方法鉴定各分化阶段相关特异基因的表达,应用Illumina Mouse Ref-8 vl.1小鼠基因表达谱芯片测定胚胎干细胞来源的不同阶段的分化细胞(第4、8、15、20、22和25天)与未分化胚胎干细胞的基因组表达谱.结果 本研究得到了86个阶段特异性表达基因,6组具有相同表达趋势的基因簇,6组阶段差异表达基因组.从数量上看,差异表达基因最多的阶段是后前肠阶段(201个基因),接下来是定形内胚层细胞阶段(17个基因).结论 应用基因芯片对胰腺发育过程中具有相同表达趋势的基因和阶段差异表达基因的分析为早期胚胎发育和胰腺发育研究提供了试验依据.     

辛伐他汀对大鼠平滑肌祖细胞和内皮祖细胞分化的不同影响

目的:观察辛伐他汀对平滑肌祖细胞(SPC)和内皮祖细胞(EPC)分化的影响。方法:采用密度梯度离心法获取大鼠骨髓单个核细胞,将其接种在纤维连接素包被培养板,加入不同浓度辛伐他汀(0.01～10μmol/L)培养8d。采用平滑肌肌动蛋白免疫荧光染色鉴定骨髓源性SPC,激光共聚焦显微镜鉴定FITC-UEA-Ⅰ和DiI-acLDL双染阳性细胞为正在分化的EPC,并在倒置荧光显微镜下计数。结果:辛伐他汀显著抑制骨髓单个核细胞分化为SPC。0.01μmol/L辛伐他汀组与对照组SPC数量分别为79±5对85±4(P0.05)。辛伐他汀显著促进骨髓单个核细胞向EPC分化,其促进作用随辛伐他汀浓度升高而增加,在1.0μmol/L达最大效应。1μmol/L辛伐他汀组与对照组EPC数量分别为87±5对39±4(P0.01)。结论:辛伐他汀选择性抑制骨髓单个核细胞向SPC分化,促进其向EPC分化,局部应用有促进损伤血管再内皮化和抑制新生内膜过度增生的可能。     

辛伐他汀对大鼠平滑肌祖细胞和内皮祖细胞分化的不同影响

目的：观察辛伐他汀对平滑肌祖细胞（SPC）和内皮祖细胞（EPC）分化的影响。方法：采用密度梯度离心法获取大鼠骨髓单个核细胞,将其接种在纤维连接素包被培养板,加入不同浓度辛伐他汀（0．01～10μmol／L）培养8d。采用平滑肌肌动蛋白免疫荧光染色鉴定骨髓源性SPC,激光共聚焦显微镜鉴定FITC—UEA—I和Di I-acLDL双染阳性细胞为正在分化的EPC,并在倒置荧光显微镜下计数。结果：辛伐他汀显著抑制骨髓单个核细胞分化为SPC。0．01μmol／L辛伐他汀组与对照组SPC数量分别为79±5对85±4（P〈0．05）。辛伐他汀显著促进骨髓单个核细胞向EPC分化,其促进作用随辛伐他汀浓度升高而增加,在1．0μmol／L达最大效应。1μmol／L辛伐他汀组与对照组EPC数量分别为87±5对39±4（P〈0．01）。结论：辛伐他汀选择性抑制骨髓单个核细胞向SPC分化,促进其向EPC分化,局部应用有促进损伤血管再内皮化和抑制新生内膜过度增生的可能。     

骨髓间充质干细胞体外定向诱导内皮祖细胞的实验研究

目的:研究兔骨髓间充质干细胞(mensenchymal stem cell,MSC)在体外定向诱导分化为内皮祖细胞(endothelial progenitor cell,EPC)的状况。方法:取兔髂骨骨髓,经密度梯度离心法分离并培养骨髓间充质干细胞,实验组细胞在内皮细胞生长添加剂、血管内皮生长因子、成纤维细胞生长因子等诱导条件下定向分化为内皮祖细胞。对照组不干预,继续培养。结果:实验组细胞集落接近融合时形态呈现“鹅卵石”样或“铺路石”样外观,流式细胞仪检测发现实验组细胞较对照组高度表达CD133、CD34(P<0．05)。结论:体外诱导可使骨髓间充质干细胞分化为内皮祖细胞,并有效扩增。     

T cells induce terminal differentiation of transformed B cells to mature plasma cell tumors.

Major interest in the analysis of mature plasma cell neoplasias of mice and humans has focused on identification of precursor cells that give rise to mature malignant plasma cells. Although several laboratories have recently suggested that such cells are present in the granulomas of pristane-treated mice and the bone marrow of some multiple myeloma patients, the in vivo cellular interactions required for their differentiation into mature plasma cell tumors remains unclear. Given the extensive interactions of peripheral T cells and normal B cells, we assessed the potential role of T cells in plasma-cell tumor development, by using a myc, raf-containing retrovirus, J3V1, to induce plasmacytomas in normal BALB/c mice, T-cell-deficient nude mice, and T-cell-reconstituted nude mice. The B-lineage tumors arising in normal BALB/c mice were uniformly mature plasmacytomas, most of which secreted immunoglobulin. In contrast, nude mice yielded predominantly non-immunoglobulin-secreting B-cell lymphomas with a phenotype characteristic of peripheral B cells. T-cell reconstitution of nude mice prior to tumor induction resulted in a shift from B-cell lymphomas to plasmacytomas. These results imply that transformation can occur prior to terminal differentiation of B cells and that such transformed cells can be driven to terminal differentiation by peripheral T cells. These findings further suggest that, in human multiple myeloma, the ability of T cells to influence the differentiation state of transformed B cells may provide a mechanism by which malignant plasma cells found in the bone marrow could arise from clonotypically related less-mature B cells found in both the bone marrow and periphery.     

Specification of multipotential cardiovascular progenitor cells during embryonic stem cell differentiation and embryonic development

The fully formed heart is composed of diverse cell lineages including myocytes, endothelial cells, vascular smooth muscle cells, and fibroblasts that derive from distinct subsets of mesoderm during embryonic development. Findings from lineage tracing studies indicate that cardiomyocytes develop from cells that express fetal liver kinase-1, suggesting that the cardiac lineages may arise from a progenitor cell with vascular cardiomyocyte potential. Recent studies using the embryonic stem cell model have led to the identification of a fetal liver kinase-1(+) progenitor cell that displays both vascular and cardiomyocyte potential. A comparable progenitor was also isolated from the early mouse embryo. Identification and isolation of these cardiovascular progenitor cells establishes a new model of heart development that will provide insights into the mechanisms regulating cardiovascular lineage diversification. These progenitor cells may also represent a novel cell population for models of congenital heart disease and cell replacement therapy.     

自外周血中获取内皮前细胞的方法

目的探讨自大鼠外周血中获取内皮前细胞（EPC）的方法。方法SD大鼠皮下注射粒细胞集落刺激因子（G-CSF）后抽取外周动脉血,密度梯度离心法获取单个核细胞,用完全培养液在体外培养后进行CD31、CD34、FLK-1和vWF免疫荧光染色,并检测其结合UEA-1、摄取acLDL的能力。结果将此方法收获的细胞进行CD31、CD34、FLK-1和vWF免疫荧光染色并检测其结合UEA-1、摄取ac-LDL的能力,证实为EPC。结论G-CSF刺激、密度梯度离心、完全培养液法可白大鼠外周血中获取较多EPC。     

Erythroid progenitor cells and stimulating factors during murine embryonic and fetal development

Murine embryonic and fetal yolk-sacs, peripheral blood, and livers were assayed for hemopoietic multipotential and progenitor cell content between days 6 and 13 of gestation. Multipotential cells (Mix-CFC), erythroid-committed progenitor cells (BFU-E), and nonerythroid progenitor cells (predominantly GM-CFC) were assayed by their ability to form hemopoietic colonies in vitro when stimulated by pokeweed-mitogen-stimulated spleen-cell-conditioned media (as a source of Multi-CSF) and either human or murine erythropoietin. Late erythroid progenitor cells (CFU-E) were stimulated to form colonies by erythropoietin. Mix-CFC, BFU-E, and nonerythroid cells were first detected on day 8 in yolk-sacs, day 9 in peripheral blood, and day 11 in liver. Maximum absolute numbers of yolk-sac Mix-CFC (182), BFU-E (331), and non-erythroid CFC (1358) occurred at 11 days of gestation. The maximum frequency of peripheral blood mix-CFC (24/10(5) cells) and BFU-E (55/10(5) cells) occurred at ten days of gestation. The absolute numbers of hepatic Mix-CFC, BFU-E, nonerythroid CFC, and CFU-E increased exponentially from 11 to 13 days' gestation. CFU-E were first detected at nine days in peripheral blood, at ten days in yolk-sac, and 11 days in liver and at all ages were equally responsive to erythropoietin. The maximum frequency (151/10(5) cells) of CFU-E in the peripheral blood and the maximum number per yolk-sac (1699) both occurred on day 11 of gestation. In confirmation of previous studies, yolk-sac fluid was found to contain a macrophage colony-stimulating activity. In addition, an activity capable of stimulating fetal liver CFU-E was also detected in yolk-sac fluid. However, no activity (Multi-CSF) capable of stimulating Mix-CFC or BFU-E was detected in either yolk-sac fluid or fetal plasma.     

Benidipine, a dihydropyridine-Ca2+ channel blocker, increases the endothelial differentiation of endothelial progenitor cells in vitro.

Benidipine is a dihydropyridine-Ca2+ channel blocker used in the treatment of hypertension and angina pectoris. In the present study, we examined the effects of benidipine on the endothelial differentiation of circulating endothelial progenitor cells (EPCs) using an in vitro culture method. Peripheral blood derived mononuclear cells (PBMCs) containing EPCs were isolated from C57BL/6 mice, and then the cells were cultured on vitronectin/gelatin-coated slide glasses. After 7 days of culture, endothelial cells differentiated from EPCs were identified as adherent cells with 1,1'-dioctadecyl-3,3,3',3'-tetramethyl-indocarbocyanine-labeled acetylated low density lipoprotein (Dil-Ac-LDL) uptake and lectin binding under a fluorescent microscope. Incubation of PBMCs for 7 days with benidipine (0.01-1 micromol/l) significantly increased the number of Dil-Ac-LDL+/fluorescein isothiocyanate-lectin (FITC-Lectin)+ cells. Wortmannin, a phosphoinositide-3 kinase (PI3K) inhibitor, selectively attenuated the effect of benidipine on the endothelial differentiation. In addition, benidipine treatment augmented the phosphorylation of Akt, indicating that the PI3K/Akt pathway contributed, at least in part, to the endothelial differentiation induced by benidipine. These results suggest that the treatment with benidipine may increase the endothelial differentiation of circulating EPCs and contribute to endothelial protection, prevention of cardiovascular disease, and/or an improvement of the prognosis after ischemic damage.     

外周血单个核细胞向血管内皮祖细胞分化的体外研究

目的该实验从简化方法、提高得率的角度出发,试图建立直接培养单个核细胞(MNC)而得到血管内皮祖细胞(endothelialprogenitorcells,EPCs)的方法。方法抽取人外周抗凝血,用Ficoll密度梯度离心法分离得到MNC,体外对MNC进行诱导分化培养,然后选择免疫荧光、免疫组化、流式细胞记数和RT-PCR方法鉴定培养所得的细胞是否具有EPCs的特征。结果MNC在培养的第2天开始出现成簇现象;第4天细胞由圆形转变为梭形贴壁细胞,呈条索状或管状分布;第7天85%的贴壁细胞摄取Ac-LDL;第14天免疫荧光和免疫组化检测CD31、CD34、vWF、Flk-1均阳性;同时流式细胞记数检测结果显示CD31和CD34均为阳性;另外RT-PCR结果显示培养的细胞表达内皮细胞特异性基因Flt-1,Flk-1、ecNOS、tie-2等。结论用此方法培养的MNC细胞具备了内皮细胞以及干细胞双重特征,故初步认定,人外周血MNC在体外经适当条件的培养,完全可以分化成EPCs。