养心通脉有效部位方与急性心肌梗死大鼠骨髓间充质干细胞的动员及定向归巢

背景:急性梗死心肌修复过程中,寻找可有效提高外周血骨髓间充质干细胞的数量、并动员其定向归巢于损伤心肌的骨髓间充质干细胞动员剂尤为关键。目的:探讨养心通脉有效部位方对急性心肌梗死大鼠骨髓间充质干细胞动员入血及定向归巢于梗死心肌的影响。方法:养心通脉有效部位方主要成分包括人参皂苷、丹参酮ⅡA、总生物碱、人参多糖等,由中南大学药学院依课题组稳定的制作工艺制作提供。SD大鼠70只,取8只大鼠作为正常对照组,剩余62只大鼠建立急性心肌梗死模型。取造模成功的32只大鼠,随机分为养心通脉有效部位方组、复方丹参注射液组、重组人粒细胞集落刺激因子组、模型对照组,各组均于造模3h后给与对应药物,连续5d。流式细胞仪检测外周血CD34+细胞数,免疫组化染色检测梗死心肌边缘区CD34+细胞数。结果与结论:与模型对照组比较,重组人粒细胞集落刺激因子组、养心通脉有效部位方组外周血CD34+细胞数均明显增加(P0.01);心肌梗死边缘区胞浆CD34+细胞数均显著增加(P0.01)。与重组人粒细胞集落刺激因子组比较,养心通脉有效部位方组心肌梗死边缘区胞浆CD34+细胞数显著增加(P0.01)。养心通脉有效部位方能促进骨髓干细胞动员入血,并定向归巢于梗死心肌,其作用与重组人粒细胞集落刺激因子大体相当,在归巢CD34+细胞方面甚至强于重组人粒细胞集落刺激因子,是一种良好的骨髓间充质干细胞动员剂。     

骨髓干细胞动员对大鼠缺血心肌的治疗作用

目的：了解干细胞动员剂动员的骨髓干细胞的心肌细胞分化潜能及对缺血心肌的影响。方法：用异丙肾上腺，素(ISO)制作大鼠心肌梗死模型，联用粒细胞集落刺激因子(C-CSV)和辛伐他汀动员大鼠自体骨髓干细胞释放和迁移至心肌梗死区，用ISO后24小时、4周杀死大鼠，取出心脏，通过免疫组化、HE染色和VG染色方法观察大鼠心梗灶的CD34^ 细胞的浸润及心肌血管再生、心肌纤维化的情况。结果：用ISO后24小时，动员组大鼠心梗区可见CD34^ 细胞浸润，并有CD34^ 的新生心肌细胞生长，4周时瘢痕组织少，心肌纤维化程度轻，缺血心肌基本结构得到保护。结论：急性心梗发生后，联用粒细胞集落刺激因子(G-CSF)和辛伐他汀能迅速动员自体骨髓干细胞向心梗区内迁移、存活和向心肌细胞、血管内皮细胞等分化；并能抑制缺血心肌纤维化和保护缺血心肌基本结构。     

EP_2A体外可促进人CD34~+细胞归巢而不能促进其增殖

目的:探讨前列腺素E_2受体2激动剂(EP_2A)在体外对人CD34~+细胞的归巢与增殖作用。方法:收集健康供者经粒细胞集落刺激因子动员后的外周血,免疫磁珠法分选出人CD34~+细胞;同时收集健康供者动员前骨髓液,分离单个核细胞,并行骨髓间充质干细胞(BMMSC)培养。人CD34~+细胞和BMMSC经前列腺素E_2(阳性对照)、DMSO(阴性对照)、EP_2A和EP_2A+前列腺素E_2受体2拮抗剂(EP_2AA)处理后,对人CD34~+细胞用CCK-8法检测细胞活力,集落形成实验检测集落形成数目,流式细胞术检测G_2/M期细胞比例,Western blot检测细胞中survivin、β-catenin及CXC趋化因子受体4(CXCR4)的蛋白表达;ELISA法检测BMMSC中基质细胞衍生因子1α(SDF-1α)的含量。结果:EP_2A组与阴性对照组相比,人CD34~+细胞在细胞活力、集落形成数目、G_2/M期比例及survivin和β-catenin蛋白表达方面均无明显差别。但EP_2A组人CD34~+细胞CXCR4及BMMSC SDF-1α的表达均明显高于阴性对照组。结论:EP_2A体外可促进人CD34~+细胞归巢但不能促进其增殖。     

心肌梗死大鼠体外培养心肌组织对间充质干细胞迁移的作用

背景:间充质干细胞具有改善心脏功能的潜力,间充质干细胞移植后向心脏归巢的机制尚不完全清楚。目的:观察心肌梗死大鼠体外培养的心肌组织对间充质干细胞迁移的作用及可能机制。方法:建立大鼠心肌梗死模型,培养大鼠心脏组织块,密度梯度离心及贴壁筛选法分离培养骨髓间充质干细胞,24只SD大鼠随机抽签法分为心肌梗死组、假手术组及正常对照组。假手术组只穿线不结扎,正常对照组不做任何处理。荧光染料DAPI标记间充质干细胞,利用transwell模型进行共培养,共培养48h。荧光镜下计数迁移细胞数,CD34/CD44免疫细胞化学染色进行迁移细胞定性,免疫荧光检测迁移细胞CXCR4的表达情况,心脏组织切片行免疫组织化学染色检测基质细胞衍生因子1的表达情况并进行平均吸光度分析。结果与结论:心肌梗死组单位视野迁移细胞数显著高于假手术组(P0.05),正常对照组未见迁移细胞。免疫细胞化学染色显示迁移细胞CD44阳性而CD34阴性,符合间充质干细胞特点,其膜受体CXCR4阳性表达。心肌梗死组及假手术组心脏切片基质细胞衍生因子1阳性表达,正常对照组心肌组织不表达基质细胞衍生因子1。心肌梗死组心脏组织基质细胞衍生因子1平均吸光度显著高于其他组别(P0.05)。提示心肌梗死后大鼠心脏组织能促进间充质干细胞迁移,这一效应的实现可能与基质细胞衍生因子1-CXCR4轴的作用有关。     

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。     

CD34+细胞的心肌细胞分化潜能研究

目的:了解粒细胞集落刺激因子(G-CSF)动员的CD34+细胞的心肌细胞分化潜能。方法:用异丙肾上腺素(ISO)复制急性心肌梗死大鼠动物模型,于3 h后用G-CSF动员骨髓造血干细胞进行心肌梗死动物模型的“自身干细胞移植”,用免疫组化和HE染色方法检测动物模型心梗区的CD34⁺细胞浸润以及心肌细胞再生情况。结果:用ISO后24 h,G-CSF处理组大鼠心梗区可见大量CD34⁺单个核细胞浸润,并有CD34⁺的新生心肌细胞生长,2周后疤痕组织不明显;而对照组心梗坏死区有大量以中性粒细胞为主的炎症细胞浸润,无CD34+细胞浸润及新生心肌细胞生长,2周后出现较大量的疤痕组织。结论:G-CSF动员CD34⁺细胞具有向心肌细胞分化的潜能,用G-CSF 动员造血干细胞的“干细胞自身移植”,可治疗急性心肌梗死。     

表达SDF-1/HOXB4融合基因的间充质干细胞联合脐血CD34~+干细胞共移植对辐射损伤小鼠的影响

目的观察表达SDF-1/HOXB4融合基因的间充质干细胞(mesenchymal stem cells,MSCs)联合脐血CD34+造血干细胞(hematopoietic stem cells,HSCs)共移植对辐射损伤小鼠的影响。方法表达SDF-1、HOXB4和SDF-1/HOXB4基因的3个腺病毒载体分别转染正常人骨髓MSCs,将其联合脐血CD34+细胞经尾静脉移植到辐射损伤的NOD/SCID小鼠体内(MSCs 8×105细胞/只,CD34+1×105细胞/只),分别为SDF-1/MSCs+CD34+组(SDF-1组)、HOXB4/MSCs+CD34+组(HOXB4组)、SDF1-HOXB4/MSCs+CD34+组(S-H组),另外3组为未转染MSCs+CD34+组(MSC-HSC组)、单纯CD34+组(HSC组)、单纯辐照组(IR组)。检测移植后各组小鼠存活率、外周血象恢复、骨髓病理变化及人源CD45+细胞植入率。结果 S-H组小鼠存活率高,且外周血WBC、HGB、PLT和骨髓造血功能恢复快。在移植后6周骨髓CD45+细胞植入率(47.43%±8.89%)较其余各组高。结论表达SDF-1/HOXB4融合基因的间充质干细胞(MSCs)联合脐血CD34+造血干细胞(HSCs)共移植能促进造血重建及植入,提高移植成功率。     

G-CSF动员自体造血干细胞在大鼠MCAO/R模型分化为神经元样细胞

探讨G-GSF动员自体HSCs在大鼠MCAO／R模型中分化为神经元样细胞的研究。采用大鼠大脑中动脉栓塞／再灌注(MCAO／R)模型,应用粒细胞集落刺激因子(G-GSF),促进骨髓造血干细胞(HSCs)分裂增殖并向靶区“归巢”,达到动员目的。观察大鼠神经病学评分,HE染色和免疫组化法观察病理改变及CD34、巢蛋白(Nestin)阳性细胞的表达。模型大鼠脑缺血／再灌注后24h时,大量淋巴、单核细胞浸润,脑缺血区少量Nestin细胞表达,无CD34细胞表达。模型动员组48h后,脑缺血区尤其是皮层缺血区大量CD34及Nestin阳性细胞表达,72h后CD34^ 细胞消失,但仍存在大量Nestin阳性细胞,且胞突增长;模型未动员组各时段未发现CD34^ 细胞,且Nestin阳性细胞明显少于动员组。结论：应用G-GSF可动员大鼠自体HSCs并向脑缺血区迁移,并可以分化为神经元前体细胞。     

基质细胞衍生因子受体在造血干/祖细胞宫内移植中的作用

目的探讨基质细胞衍生因子受体(CXCR4)在造血干/祖细胞(HSC)宫内移植归巢中的作用。方法分离人脐血CD34+细胞,用流式细胞仪检测SCF、IL-6处理前后细胞表面CXCR4(CD184)的表达及在Transwell板中的迁移率。在BALB/c胎鼠孕13～14d期间,经胎鼠腹腔注射经不同处理的CD34+细胞,胎鼠出生1个月后取骨髓,用流式细胞仪检测人CD45细胞。结果预处理后表达CD184的CD34+细胞的百分数由原来的9.58%±1.56%上升为19.32%±3.64%。CD34+/CXCR4high细胞迁移率显著增高,但迁移作用可以被antiCXCR4mAb和PTX明显抑制。SCF和IL-6预处理组胎鼠人CD45细胞阳性率显著高于其他组。抗CXCR4抗体或PTX预处理组人CD45细胞检出率显著降低。结论增加CD34+细胞CXCR4的表达有助于宫内移植HSC的归巢,HSC宫内移植归巢过程依赖CXCR4受体,SDF-1/CXCR4调节信号通过Gi蛋白进行跨膜传导。     

三七总皂苷通过活化骨髓来源的间充质干细胞改善急性心肌梗死大鼠的心功能

目的观察三七总皂苷(PNS)对急性心肌梗死(AMI)大鼠心功能的影响并探讨其对骨髓来源的间充质干细胞(BM-MSC)的动员作用。方法将48只大鼠随机分成假手术组、AMI组(模型组)、PNS低剂量组(在造模后给予100 mg/kg PNS灌胃)、PNS高剂量组(在造模后给予500 mg/kg PNS灌胃)。使用冠脉结扎法建立AMI动物模型,分别用高低剂量PNS处理7 d和21 d后,每组处死6只大鼠;处死前超声检测大鼠心功能,随后取外周血和心脏组织。流式细胞术检测CD90、CD105、CD54、CD106的频数反映BM-MSC的动员情况,ELISA检测干细胞因子(SCF)含量,2,3,5-三苯基氯化四氮唑(TTC)染色观察心肌梗死面积,原位末端转移酶标记技术(TUNEL)检测心肌细胞凋亡,免疫组织化学染色法检测CD105表达。结果与假手术组相比,模型组细胞凋亡水平显著增加; PNS处理7 d和21 d后,与模型组比较,低剂量和高剂量PNS组心肌梗死面积和细胞凋亡水平均降低。与假手术组比较,术后7 d和21 d,模型组左室射血分数(LVEF)和左室缩短分数(LVFS)降低,而收缩期左室内径(LVID)、舒张期左室内径(LVIDd)、左心室舒张末期容积(LVEDV)和左心室收缩末期容积(LVESV)增加;而PNS处理可有效改善上述指标。与模型组比较,PNS呈浓度依赖性增加外周血中CD90、CD105阳性细胞数和SCF的含量,降低CD54和CD106阳性细胞数。PNS处理组心脏组织内CD105表达明显高于模型组。结论 PNS处理可改善心肌梗死后左心室功能,可能与PNS抑制心肌细胞凋亡,促进BM-MSC动员有关。     

S1P(1) overexpression stimulates S1P-dependent chemotaxis of human CD34+ hematopoietic progenitor cells but strongly inhibits SDF-1/CXCR4-dependent migration and in vivo homing

The CXC chemokine receptor 4 (CXCR4) and its ligand stromal derived factor 1 (SDF-1) regulate egress and homing of hematopoietic stem cells. Activation of sphingosine-1-phosphate (S1P) receptors (S1P(1-5)) modulates chemokine-induced migration of lymphocytes and hematopoietic stem cells. To analyze the influence of S1P(1) on SDF-1-dependent chemotaxis and trafficking, we overexpressed S1P(1) in CD34+ mobilized peripheral blood progenitor cells (PBPCs). Using a gamma-retroviral vector, transgene overexpression was achieved in more than 90% of target cells. S1P(1) transgene positive PBPCs showed enhanced chemotaxis towards S1P. S1P(1) overexpression resulted in reduced CXCR4 surface expression levels and strong inhibition of SDF-1-dependent ERK1/2 phosphorylation and Ca(2+) flux. Furthermore, SDF-1-dependent migration of S1P(1) overexpressing PBPCs or Jurkat cells was reduced up to 10-fold. Sublethally irradiated NOD/SCID mice were transplanted with 6-day cultured PBPCs overexpressing either S1P(1)-IRES-GFP or GFP alone. Screening for GFP positive human cells in the mouse bone marrow 20h after transplantation revealed an eightfold reduction in bone marrow homing of S1P(1) transgene expressing cells. Our data suggest that S1P(1) acts as an inhibitor of CXCR4-dependent migration of hematopoietic cells to sites of SDF-1 production.     

Cytokine expansion culture of cord blood CD34+ cells induces marked and sustained changes in adhesion receptor and CXCR4 expressions

Recent studies have demonstrated defective bone marrow homing of hematopoietic stem cells after cytokine expansion culture. Adhesion receptors (ARs) are essential to the homing process, and it is possible that cytokine culture modulates AR expression. We studied changes in expression of very late antigen-4 (VLA-4), VLA-5, L-selectin, leukocyte function-associated antigen-1 (LFA-1), CD44, and the stromal cell-derived factor-1 (SDF-1) receptor, CXCR4, during cytokine culture of cord blood (CB) CD34(+) cells. Expression of ARs was studied by flow cytometry on CB CD34(+) cells in whole blood, after purification and during culture for up to 10 days. Cells were cultured with stem cell factor (SCF), thrombopoietin (TPO), Flt3-ligand (Flt3), and G-CSF. Results showed that 80% or more of uncultured CD34(+) cells were positive for VLA-4, L-selectin, LFA-1, CD44, and CXCR4 while 50% were positive for VLA-5. Purification of CD34(+) cells did not affect AR expression, but cytokines increased expression three- to nine-fold throughout the 10-day culture period. In contrast, expression of CXCR4 decreased. Expression changes of ARs and CXCR4 on CD34(+)/CD38(-) cells mirrored those of the total CD34(+) population. The results indicate that cytokine culture significantly increases AR expression on CB CD34(+) cells, which may be related to the decrease in homing of cytokine-cultured hematopoietic stem cells.     

Expression of functional CXCR4 by muscle satellite cells and secretion of SDF-1 by muscle-derived fibroblasts is associated with the presence of both muscle progenitors in bone marrow and hematopoietic stem/progenitor cells in muscles

We found that the murine cell lines C2C12 and G7 derived from muscle satellite cells, which are essential for muscle regeneration, express the functional CXCR4 receptor on their surface and that the specific ligand for this receptor, alpha-chemokine stromal-derived factor 1 (SDF-1), is secreted in muscle tissue. These cell lines responded to SDF-1 stimulation by chemotaxis, phosphorylation of mitogen-activated protein kinase (MAPK) p42/44 and AKT serine-threonine kinase, and calcium flux, confirming the functionality of the CXCR4 receptor. Moreover, supernatants derived from muscle fibroblasts chemoattracted both satellite cells and human CD34(+) hematopoietic stem/progenitor cells. In a similar set of experiments, supernatants from bone marrow fibroblasts were found to chemoattract CXCR4(+) satellite cells just as they chemoattract CD34(+) cells. Moreover, preincubation of both muscle satellite cells and hematopoietic stem/progenitor CD34(+) cells before chemotaxis with T140, a specific CXCR4 inhibitor, resulted in a significantly lower chemotaxis to media conditioned by either muscle- or bone marrow-derived fibroblasts. Based on these observations, we postulate that the SDF-1-CXCR4 axis is involved in chemoattracting circulating CXCR4(+) muscle stem/progenitor and circulating CXCR4(+) hematopoietic CD34(+) cells to both muscle and bone marrow tissues. Thus, it appears that tissue-specific stem cells circulating in peripheral blood could compete for SDF-1(+) niches, and this would explain, without invoking the concept of stem cell plasticity, why hematopoietic colonies can be cultured from muscles and early muscle progenitors can be cultured from bone marrow.     

细胞因子短期扩增对造血干/祖细胞黏附和迁移能力的影响

目的：探讨干细胞因子（SCF）+白细胞介素-6（IL-6）短期扩增对CD34+造血干/祖细胞黏附和迁移能力的影响。方法:用密度剃度离心的方法分离脐血CD34+细胞，经SCF和IL-6孵育48 h，用CCK-8方法检测CD34+细胞增殖能力；用流式细胞仪检测处理前后的CD49d（VLA-4）、CD11a（LFA-1）、CD62L（L-selectin）及CD184（CXCR4）的表达。用纤连蛋白（FN）包被96孔板，检测经或未经因子扩增的CD34+细胞的黏附能力。扩增的CD34+细胞悬浮于transwell培养板的上层，下层添加基质细胞衍生因子（SDF-1），流式细胞仪检测迁移细胞数，计算迁移率。结果:经SCF+IL-6处理48h后CD34+细胞扩增近3倍；表达CD49d、CD11a、CD62L及CD184的CD34+细胞的百分数分别由原来的26.34%±5.37%、17.63%±4.57%、46.38%±6.61%和9.58%±1.56%增加到65.67%±8.72%、56.67%±6.34%、84.76%±9.57%和19.32%±3.64%（P<0.01）。扩增后的CD34+细胞对FN的黏附能力及在SDF-1诱导下的迁移作用都显著增强（P<0.01）。结论:SCF+IL-6短期扩增CD34+ 造血干/祖细胞显著增加细胞的黏附能力，增加SDF-1诱导的迁移作用，可能是SCF+IL-6促进归巢的主要机制之一。     

Controlled release of stromal cell-derived factor-1 alpha in situ increases c-kit+ cell homing to the infarcted heart

Stromal-derived factor 1alpha (SDF-1alpha) is a key stem cell homing factor that is crucial for mobilization of stem cells from bone marrow to peripheral blood and subsequent engraftment to the tissue of diseased organs. It has been reported that SDF-1alpha is transiently over-expressed in ischemic myocardium. Therefore, there may be a limited time window after acute myocardial infarction (AMI) during which stem cells are recruited to injured myocardium for repair. This study aimed at investigating whether controlled release of SDF-1alpha via a novel conjugated poly(ethylene glycol) (PEG) (PEGylated) fibrin patch at the infarct site would increase the rate of stem cell recruitment and offer potential therapeutic benefits. Recombinant mouse SDF-1alpha was covalently bound to the PEGylated fibrinogen as evidenced by immunoprecipitation and western blotting. The PEGylated fibrinogen, bound with recombinant mouse SDF-1alpha, was mixed with thrombin to form the PEGylated fibrin patch. The release kinetics of SDF-1alpha were detected in vitro using enzyme-linked immunosorbent assay. Using a mouse AMI model produced by a ligature on the left anterior descending coronary artery, a PEGylated fibrin patch bound with SDF-1alpha (100 ng) was placed on the surface of the infarct area of the left ventricle. Infarct size, left ventricular (LV) function, and the percentage of sca-1(+)/c-kit(+) cells within the infarct area were measured at days 7, 14, and 28 after AMI. In vitro results showed that SDF-1alpha was successfully bound to the PEGylated fibrin patch and can be released from the patch constantly for up to 10 days. Two weeks after infarction, the myocardial recruitment of c-kit(+) cells was significantly higher in the group treated with the SDF-1alpha PEGylated fibrin patch (n = 9) than in the AMI control group (n = 10) (p < 0.05; 11.20 +/- 1.71% vs. 4.22 +/- 0.96%, respectively). At day 28 post-AMI, unlike the control group, the group with the SDF-1alpha-releasing patch maintained stable release of SDF-1alpha concurrent with additional stem cell homing. Moreover, LV function was significantly better than in the control group. These data demonstrate that the PEGylated fibrin patch based SDF-1alpha delivery can improve the rate of c-kit(+) cell homing and improve LV function in hearts with postinfarction LV remodeling.     

Stromal cell-derived factor-1 potentiates bone morphogenetic protein-2 induced bone formation

The mechanisms driving bone marrow stem cell mobilization are poorly understood. A recent murine study found that circulating bone marrow-derived osteoprogenitor cells (MOPCs) were recruited to the site of recombinant human bone morphogenetic protein-2 (BMP-2)-induced bone formation. Stromal cell-derived factor-1α (SDF-1α) and its cellular receptor CXCR4 have been shown to mediate the homing of stem cells to injured tissues. We hypothesized that chemokines, such as SDF-1, are also involved with mobilization of bone marrow cells. The CD45(-) fraction is a major source of MOPCs. In this report we determined that the addition of BMP-2 or SDF-1 to collagen implants increased the number of MOPCs in the peripheral blood. BMP-2-induced mobilization was blocked by CXCR4 antibody, confirming the role of SDF-1 in mobilization. We determined for the first time that addition of SDF-1 to implants containing BMP-2 enhances mobilization, homing of MOPCs to the implant, and ectopic bone formation induced by suboptimal BMP-2 doses. These results suggest that SDF-1 increases the number of osteoprogenitor cells that are mobilized from the bone marrow and then home to the implant. Thus, addition of SDF-1 to BMP-2 may improve the efficiency of BMPs in vivo, making their routine use for orthopaedic applications more affordable and available to more patients.     

Adhesion molecules involved in transendothelial migration of human hematopoietic progenitor cells

In the process of homing, CD34(+) hematopoietic progenitor cells migrate across the bone marrow endothelium in response to stromal cell-derived factor (SDF)-1. To develop more efficient stem cell transplantation procedures, it is important to define the adhesion molecules involved in the homing process. Here, we identified the adhesion molecules that control the migration of primary human CD34(+) cells across human bone marrow endothelial cells. Migration of CD34(+) cells is enhanced across interleukin 1beta prestimulated bone marrow endothelium, suggesting an important role for the endothelium in adhesion and formation of the chemotactic gradient. Under these conditions, 30-100 ng/ml SDF-1 induced a rapid and efficient migration of CD34(+) cells (+/- 46% migration in 4 h). In contrast, 600-1,000 ng/ml SDF-1 were required for optimal migration across fibronectin-coated filters. Subsequent studies revealed that transendothelial migration of CD34(+) cells is mediated by beta1- and beta2-integrins and PECAM-1 (CD31) but not by CD34 or E-selectin. Whereas these antibodies individually blocked migration for 25%-35%, migration was reduced by 68% when the antibodies were combined. Thus, these adhesion molecules play specific and independent roles in the transmigration process. Finally, O-glycosylated proteins appeared to play a role, since SDF-1-induced migration of CD34(+) cells (treated with a glycoprotease from Pasteurella haemolytica) across endothelial cells was clearly inhibited. In conclusion, we show that efficient SDF-1-induced migration of primary human CD34(+) cells across bone marrow endothelium is mediated by beta1-integrins, beta2-integrins, CD31 and O-glycosylated proteins.