EGFP在EGFP/GDNF融合基因修饰骨髓基质干细胞中的示踪作用

目的探索增强型绿色荧光蛋白(EGFP)能否作为标记基因追踪胶质源性神经生长因子(GDNF)基因修饰的骨髓基质干细胞(MSC)在体内外的存活、生长、分化和表达外源目的基因的情况.方法应用逆转录聚合酶链反应(RT-PCR)方法从新生小鼠大脑皮质细胞克隆出GDNF cDNA片断,连入pEGFP-C1载体,构建表达EGFP和GDNF融合蛋白的质粒并转染MSC,将稳定表达EGFP-GDNF基因的细胞株植入小鼠纹状体.用荧光显微镜和免疫组织化学的方法在体内外观察MSC.结果成功制备EGFP-GDNF融合基因修饰的MSC工程细胞,免疫组织化学方法检测显示GDNF呈强阳性,在体内外MSC工程细胞均发出明亮的绿色荧光,并且绿色荧光可反映细胞形态学变化.结论在EGFP-GDNF融合基因修饰的MSC工程细胞中EGFP可作为标记基因同时标记GDNF和MSC.     

GFP转基因小鼠神经干细胞移植治疗大鼠帕金森病的实验研究

目的观察GFP(绿色荧光蛋白)转基因小鼠胚胎神经干细胞植入帕金森病大鼠纹状体后的存活、分化情况及治疗作用。方法建立PD模型大鼠及体外培养神经干细胞,然后将GFP转基因小鼠神经干细胞定向植入帕金森病大鼠毁损侧纹状体内,于移植后不同时间诱发旋转行为,并与对照组相比,观察症状的改善,并用酪氨酸羟化酶(TH)免疫组织化学染色方法检测移植GFP转基因小鼠神经干细胞的存活及分化状况。结果 GFP转基因小鼠神经干细胞脑内移植后,帕金森病大鼠的旋转行为明显改善。移植后2至4周时可检测到成片或散在的TH免疫阳性细胞。结论 GFP转基因小鼠神经干细胞移植至帕金森病大鼠纹状体后,可分化为多巴胺能神经元并能改善旋转症状。     

兔椎间盘移植人骨髓间充质干细胞的实验观察

背景：国内外动物实验多是研究同种异体骨髓间充质干细胞的移植,但对人骨髓间充质干细胞在活体椎间盘内的存活情况还知之甚少。 目的：观察人骨髓间充质干细胞在兔椎间盘内的存活情况。 方法：选取新西兰大白兔15只,每只兔子的椎间盘被分为3组,即空白组(L1~2)、生理盐水组(L2~3)、绿色荧光蛋白标记的人骨髓间充质干细胞移植组(L3~4,L4~5,L5~6)。空白组不注射,生理盐水组髓核内注射生理盐水25 μL,绿色荧光蛋白标记的人骨髓间充质干细胞移植组注射1×109 L-1绿色荧光蛋白标记的人骨髓间充质干细胞生理盐水混悬液25 μL。移植后1,2,4,6,8周取材,荧光显微镜观察荧光细胞的分布情况及其数量。 结果与结论：绿色荧光蛋白标记的人骨髓间充质干细胞移植组移植后1,2,4,6,8周标本切片,髓核内均可见绿色荧光细胞。移植后6,8周的荧光细胞数量明显少于移植后1,2,4周(P < 0.001)。提示移植后8周以内,人骨髓间充质干细胞可在兔椎间盘内存活。     

骨髓源干细胞在脑组织的迁移和分化

骨髓源干细胞（bone marrow-derived stem cells，BMDSCs）能否迁移至脑组织并分化为神经胶质细胞和神经细胞是近年来成体干细胞研究的热点领域。有一些学者采用Y染色体和GFP基因作为骨髓源细胞标记物，通过血行输入受体动物后，在脑组织内发现了标记阳性细胞，并证实这些细胞有向神经胶质细胞和神经细胞分化的趋势；另有一些学者也采用GFP基因作为细胞标记物，但在受体动物脑组织并未发现标记阳性细胞。这些实验结果差异可能与观察时间长短、细胞标记方法和神经组织中标记基因沉默事件有关。就迁移到脑组织的BMDSCs是否与宿主神经细胞整合的问题，有研究认为存在转分化（transdifferentiation）机制，也有实验发现BMDSCs与小脑Purkinje神经元之间有细胞融合现象。细胞转分化和细胞融合有可能是中胚层来源的BMDSCs向神经外胚层细胞变化的两种必要机制。讨论这些问题对阐明神经细胞的新老更替、损伤和修复机制是很有意义的。     

菲立磁标记兔骨髓基质源神经干细胞自体移植入纹状体后的形态学观察

目的将体外标记的骨髓基质源神经干细胞经单细胞悬液微移植后观察其在兔纹状体的存活、迁移、分化和整合情况，为细胞移植治疗疾病奠定基础。方法分离兔骨髓基质细胞，利用神经干细胞培养基、白血病抑止因子和碱性成纤维母细胞生长因子进行细胞扩增并诱导成骨髓基质源神经干细胞，再经菲立磁和活细胞荧光染料PKH67标记后．采用微移植的方法，通过脑立体定位仪，用微玻璃针将干细胞分别植入兔脑纹状体内。存活1、4、8周后处死动物，组织切片，利用光镜和电镜观察标记细胞在脑内的形态学情况。结果菲立磁标记的兔骨髓基质源神经干细胞经微移植后可在兔脑内纹状体区域存活，移植的干细胞可向周围的脑实质内迁移和整合，迁移细胞沿特定的纹状体结构分布。少量菲立磁标记的干细胞可以分化成神经元。结论骨髓基质源神经干细胞移植后．可在脑实质内存活、迁移、分化和整合，这种细胞可能成为中枢神经系统自体移植的细胞来源。     

骨髓基质干细胞和神经干细胞移植治疗帕金森病大鼠的效果比较**☆

目的：目前对应用神经干细胞和骨髓基质干细胞移植治疗帕金森病效果进行对比的研究很少，实验观察比较同种异体来源的中脑神经干细胞和骨髓基质干细胞对帕金森大鼠行为学及损伤脑组织形态学的影响。 方法：实验于2006-03/2007-09在河北医科大学第一医院脑老化与认知神经科学实验室完成。SD大鼠麻醉后建立右侧帕金森病模型，随机分为神经干细胞组14只、骨髓基质干细胞组10只、空白对照组10只。选取右侧纹状体2个坐标点（in mm: A +0.6；R +4.0；V -5.0）、（in mm: A -0.7；R +3.0；V -5.0），前两组每个坐标点分别注入经Brd-U标记的神经干细胞悬液、骨髓基质干细胞悬液5 μL，约1×106个细胞，空白对照组注射等量磷酸盐缓冲液。细胞移植后各组大鼠腹腔注射阿朴吗啡诱导旋转。 结果：①行为学改变：与空白对照组比较，移植2~8周神经干细胞组和骨髓基质干细胞组大鼠的旋转次数均明显减少（P < 0.01）。②纹状体切片免疫组织化学荧光染色鉴定：移植8周后，神经干细胞组和骨髓基质干细胞组均可见一定数量双标的神经元、星形胶质细胞和酪氨酸羟化酶阳性细胞，且后者的双标细胞相对多于前者。空白对照组未发现Brd-U阳性细胞、微管相关蛋白2阳性细胞及酪氨酸羟化酶阳性细胞的表达。各组损毁侧黑质酪氨酸羟化酶阳性细胞残存率基本相似（P > 0.05）。 结论：神经干细胞和骨髓基质干细胞移植均可改善帕金森病大鼠的旋转行为，且至少在脑内存活8周，并可分化成神经元、星形胶质细胞和多巴胺能神经元。     

局部注射骨髓间充质干细胞治疗大鼠脊髓损伤：运动功能有改善吗？

背景：目前研究多为骨髓间充质干细胞的体外培养及细胞移植对颅内疾病的治疗,对植入细胞在损伤脊髓中的成活、分化、迁移、结构重建等了解有限。 目的：探讨局部骨髓间充质干细胞移植在脊髓损伤修复中的作用和骨髓间充质干细胞替代治疗的可行性。 方法：成年健康雌性SD大鼠随机分为细胞移植组和对照组,建立SD大鼠脊髓横断损伤模型,伤后即刻分别向损伤区局部移植大鼠骨髓间充质干细胞悬液或无钙镁磷酸缓冲液。在术前和术后1 d,1周,2周,3周,4周和8周进行BBB评分,观测大鼠的运动功能,并于移植后1周免疫组织化学染色法观察BrdU标记的骨髓间充质干细胞在脊髓损伤处的存活情况,移植后4周进行损伤脊髓的大体观察和组织学检测。 结果与结论：移植后第1~8周细胞移植组BBB评分均髙于对照组;术后1周免疫组织化学染色结果显示在细胞移植组大鼠脊髓远端检测到BrdU阳性细胞,术后4周脊髓损伤处发现有神经纤维。证实通过损伤后立即局部注射的方式将骨髓间充质干细胞移植进大鼠脊髓损伤区,细胞可在损伤区存活;存活的骨髓间充质干细胞可分化为神经元,在损伤局部形成神经元通路,从而促进脊髓神经纤维传导功能的恢复,并促进高位脊髓损伤后大鼠后肢运动功能恢复。     

脑梗死恢复期大鼠经腹腔及尾静脉注射骨髓间充质干细胞在体内的分布与分化：哪种移植途径更好？

背景：研究发现,骨髓间充质干细胞(BMSCs)可在体内神经组织中分化为神经元样细胞,并且对神经元的损伤发挥保护作用。 目的：本试验旨在探讨骨髓间充质干细胞经过腹腔或尾静脉注射对梗死21天的大鼠神经功能的保护作用。 设计、时间及地点： 随机对照动物实验及细胞学观察,于2007-11至2008-09在南京医科大学附属脑科医院细胞实验室和病理实验室完成。 材料：Sprague-Dawle大鼠45只随机分成对照组、骨髓间充质干细胞静脉注射组和骨髓间充质干细胞腹腔注射组,每组15只。 方法：采用密度梯度离心法分离培养大鼠骨髓间充质干细胞,以Brdu标记细胞核。建立大脑中动脉闭塞(MCAO)动物模型。造模手术后第21天对照组不予治疗,另外两组分别经尾静脉或者腹腔注射BMSCs细胞悬液。各组大鼠又分别在注射后第7、14或21天处死取脑组织行免疫组织化学观察。 主要观察指标：采用神经功能损伤严重程度评分(NSS)和黏附物移除实验评估神经功能。显微镜观察脑组织形态学变化和移植细胞的存活情况。对微管相关蛋白(MAP-2)和胶质纤维酸性蛋白(GFAP)行免疫组织化学染色 ,以评估细胞移植对神经再生的作用。 结果：各组实验动物随时间推移NSS评分逐渐降低,BMSCs治疗后NSS评分加速下降,静脉注射组尤其明显。黏附物移除实验表现出和NSS相同的趋势。光学显微镜下可见各组各时间点均有Angiogenin染色阳性的新生血管弥漫分布于双侧纹状体、海马和大脑皮层。各时间点未治疗组几乎没有BrdU阳性的细胞,腹腔组可见散在阳性细胞,尾静脉组阳性细胞显著多于腹腔组(P<0.01)。荧光显微镜下可见绿色荧光标记的BrdU和红色荧光标记的MAP2或GFAP共区域表达。 结论：脑梗死恢复期行BMSCs移植治疗能够显著改善梗死大鼠神经功能。BMSCs经腹腔或者尾静脉注射后均能进入脑组织,通过促进神经再生和血管再生等机制改善神经功能缺损,静脉注射的疗效优于腹腔注射。     

以CM-DiI作为骨髓干细胞移植示踪剂的可行性

背景：供体细胞的示踪始终是干细胞移植研究中面临的一个重要问题，以往用于干细胞移植的示踪技术主要有核素、5-溴脱氧尿嘧啶核苷、绿色荧光蛋白、Hoechst和荧光原位杂交等。 目的：探讨CM-DiI作为骨髓干细胞移植示踪剂的可行性和示踪效果。 设计、时间及地点：细胞学体内观察，于2004-10/2007-12在中山大学附属第一医院神经科实验室完成。 材料：四五周龄雄性DL小鼠80只为供体，2月龄遗传性肝功能障碍模型TX小鼠40只为受体，均由澳大利亚Dean教授馈赠。CM-DiI为Molecular Probes公司产品。 方法：全骨髓法体外分离培养供体鼠骨髓干细胞，加入CM-DiI行荧光标记，无菌条件下经尾静脉注入已放疗的受体鼠体内，注射悬液量为0.2 mL/只，细胞数1.2×107个/只，于移植后不同时间取肝脏标本制备切片。 主要观察指标：荧光倒置显微镜下观察CM-DiI标记细胞情况，流式细胞仪测定荧光标记率。供体细胞移植后在受体鼠肝脏的示踪。PCR半定量分析供体细胞在受体鼠肝脏中的比例。 结果：荧光显微镜下CM-DiI标记的骨髓干细胞呈红色荧光，CM-DiI标记率为99.9%。在受体鼠肝脏组织内，CM-DiI的荧光在移植后第1天即可看到，渐增多，第4周达高峰，后渐下降。移植后第7天可检测到Sry基因，随后其变化趋势同CM-DiI荧光。 结论：CM-DiI是良好的骨髓干细胞移植示踪剂，第4周时示踪效果最为显著。     

全骨髓贴壁法获纯化骨髓间充质干细胞向神经干细胞的诱导分化*★

目的：来源于骨髓间充质干细胞的神经干细胞是最近研究的一个热点。实验拟进一步验证通过全骨髓贴壁法分离纯化骨髓间充质干细胞并诱导分化为神经干细胞的效率，并对其的体内外标记进行了观察。 方法：实验于2006-11/2007-05在青岛大学医学院附属医院脑血管病研究所完成。①实验材料：选取出生4周左右Wistar大鼠，雌雄不拘，SPF级，体质量200 g左右，由青岛市实验动物和动物实验中心提供，实验过程中对动物处置符合动物伦理学标准。②实验方法：选用出生4周左右Wistar大鼠，由其股骨和胫骨分离纯化骨髓间充质干细胞，加碱性成纤维细胞生长因子和表皮生长因子诱导其分化为神经干细胞，并进行免疫组织化学鉴定。以5-溴脱氧尿嘧啶核苷（BrdU）标记神经干细胞，在24孔板中进行细胞免疫组织化学和免疫荧光鉴定。将标记的神经干细胞定位注入大鼠基底节区, 1周后取脑作石蜡切片, 进行免疫组织化学和免疫荧光染色。 结果：获得了较纯化的骨髓间充质干细胞，经诱导72 h后，部分细胞增殖分裂成小圆形,呈团簇状半悬浮状态。继续培养 72 h可见细胞呈现典型神经元样改变，细胞伸出两个或多个突起, 胞体呈多角形或不规则形, 折光性较强, 细胞突起之间相互连接成网状,可见细胞核及核仁，经诱导后有巢蛋白、神经元特异性烯醇化酶、胶质纤维酸性蛋白阳性细胞表达。采用BrdU掺入DNA合成期的神经干细胞，1周后体内外标记阳性率> 85%。 结论：采用全骨髓贴壁法可获得较纯化的骨髓间充质干细胞，其在适宜的诱导分化条件下可诱导分化神经干细胞。BrdU可作为神经干细胞体内示踪的理想标记物。     

骨髓源干细胞参与的血管内皮更新*☆

背景：研究表明骨髓源干细胞可塑性强,但其参与组织更新及修复的机制在转分化及细胞融合间尚存在争议。 目的：通过性别交叉骨髓移植建立雌雄嵌合体小鼠模型,观察骨髓源性干细胞是否参与内皮细胞的更新并探讨其可能的机制。 方法：采用雌性C57BL/6-GFP小鼠为供体,雄性C57BL/6小鼠为受体进行骨髓移植建立嵌合体小鼠,并应用流式细胞术分析骨髓嵌合情况。骨髓移植后20周采用Y染色体荧光原位杂交法对脑、肾、肝、脾及心脏组织Y染色体进行标记,荧光显微镜观察各组织器官中血管内皮细胞Y染色体及绿荧光蛋白表达情况。 结果与结论：①嵌合体小鼠骨髓细胞流式细胞学检测显示移植骨髓后1周骨髓GFP+细胞为(7.48±1.38)%、4周时达(73.92±5.57)%,结果表明成功建立性别交叉骨髓移植模型。②骨髓移植后20周嵌合体小鼠脑、肾、肝和脾组织血管壁可见绿荧光蛋白表达,且部分细胞同时表达Y染色体,表明发生骨髓源细胞和血管内皮细胞融合。脑实质及心肌组织未见绿荧光蛋白表达。结果提示骨髓源干细胞可能通过细胞融合机制参与不同组织器官中血管内皮细胞的更新。     

Do bone marrow stromal cells proliferate after transplantation into mice cerebral infarct?--a double labeling study

The present study was aimed to clarify the proliferation capacity of the bone marrow stromal cells (BMSC) transplanted into the brain. The BMSC were harvested from green fluorescence protein (GFP)-transgenic mice, grown to the confluency and passed three times. They were labeled by co-culture with Ferucarbotran, a superparamagnetic iron oxide (SPIO) agent. The proportions of the SPIO-positive cells were evaluated from P3 to P7, using Turnbull blue staining. The GFP-BMSC labeled by Ferucarbotran were transplanted into the ipsilateral striatum of the mice brain subjected to permanent focal ischemia at 7 days after the insult. The distribution and differentiation of GFP- and SPIO-positive cells in the brain were studied 3 months after transplantation, using immunohistochemistry and Turnbull blue staining. As the results, the proportions of the SPIO-positive cells gradually decreased from 93.6% at P3 to 6.5% at P7. Fluorescence immunohistochemistry revealed that the GFP-positive cells were widely distributed around infarct and partially expressed MAP2 and NeuN 3 months after transplantation. However, only a smaller number of SPIO-positive cells could be detected on Turnbull blue staining. The ratio of the SPIO- to GFP-positive cells was approximately 2.7%. The results strongly suggest that the BMSC repeat proliferation many times, migrate into the lesion, and partially express the neuronal phenotype in the host brain during 3 months after transplantation. The double labeling technique would be valuable to prove the proliferation of the transplanted cells in the host tissue because GFP gene and SPIO nanoparticles have different inheritance characteristics.     

小鼠真皮多能干细胞在缺血性损伤脑组织移植后的分布与分化

目的探讨小鼠真皮多能干细胞(SKP)经股静脉移植后在缺血性损伤脑组织中的分布及分化情况。方法分离培养绿色荧光蛋白转基因小鼠(C57BL/6-gfp)SKP,随机选取5只同基因型小鼠采用线栓法制作局灶性大脑中动脉栓塞(MCAO)模型,缺血2h后行再灌注,再灌注24h后将C57BL/6-gfp来源的SKP经小鼠股静脉输入动物模型体内,植入后第7天处死小鼠,作冷冻切片,采用免疫组织荧光染色法,检测SKP在脑缺血小鼠体内的分布及分化情况。结果移植SKP7d后,MCAO小鼠脑组织冷冻切片在荧光显微镜下可见移植的SKP主要分布在缺血灶周围,且这些细胞表达胶质纤维酸性蛋白(GFAP)和神经元特异性烯醇化酶(NSE)。结论经股静脉移植的SKP主要分布在MCAO模型鼠脑缺血损伤区周围,并可向神经细胞分化。     

Participation of bone marrow-derived cells in long-term repair processes after experimental stroke.

Bone marrow-derived cells participate in remodeling processes of many ischemia-associated diseases, which has raised hopes for the use of bone marrow as a source for cell-based therapeutic approaches. To study the participation of bone marrow-derived cells in a stroke model, bone marrow from C57BL/6-TgN(ACTbEGFP)1Osb mice that express green fluorescent protein (GFP) in all cells was transplanted into C57BL/6J mice. The recipient mice underwent permanent occlusion of the middle cerebral artery, and bone marrow-derived cells were tracked by fluorescence. The authors investigated the involvement of bone marrow-derived cells in repair processes 6 weeks and 6 months after infarction. Six weeks after occlusion of the artery, more than 90% of the GFP-positive cells in the infarct border zone were microglial cells. Very few GFP-positive cells expressed endothelial markers in the infarct/infarct border zone, and no bone marrow-derived cells transdifferentiated into astrocytes, neurons, or oligodendroglial cells at all time points investigated. The results indicate the need for additional experimental studies to determine whether therapeutic application of nonselected bone marrow will replenish brain cells beyond an increase in microglial engraftment.     

GFP转基因骨髓基质干细胞移植对癫痫鼠脑电的影响

目的　观察绿色荧光蛋白（GFP）转基因骨髓基质干细胞（BMSCs）移植至致痫鼠后的存活、迁移及其对癫痫鼠脑电的影响。方法　分离、培养GFP转基因小鼠BMSCs，移植至青霉素致痫鼠的右侧海马内，比较移植后1w、2w、4wBMSCs在脑内的存活和迁移情况及大鼠脑电改变。结果　BMSCs可以在致痫鼠脑内存活和迁移，随移植时间延长，细胞存活数逐渐减少（P〈0．01）；BMSCs移植可减少癫痫大鼠脑电的痫性放电，降低癫痫波波幅。结论　BMSCs移植于青霉素诱发的癫痫鼠脑内后能够存活、迁移，并能够改善癫痫鼠的脑电生理功能，提示干细胞移植可能成为一种有效的癫痫     

Freshly dissociated fetal neural stem/progenitor cells do not turn into blood

Earlier studies suggested that stem cells from one somatic tissue may generate differentiated elements of another, embryologically unrelated, tissue after an exchange in their positions through transplantation. Two reports indicated that murine and human neural stem cells of clonogenic origin after in vitro expansion in growth factor-supplemented media, may sustain hematopoiesis when injected into sublethally irradiated mice. Here we investigated if freshly dissociated fetal neural cells (fNC) share the reported hemopoietic potential of in vitro expanded neural cells. In order to minimize the risk of hemopoietic contamination, donor cells were taken from mouse E10.5 developing brains, before completion of blood vessel ingrowth into the brain; 10(6) fNC derived directly from fetal brains of transgenic mouse expressing an enhanced version of the green fluorescent protein were injected into the tail vein or directly into the bone marrow of sublethally irradiated (6 Gy) C57B16 mice. After transplantation, the presence of donor-derived cells was assessed at different survival times by FACS analysis, PCR, and clonogenic stem cell assays on peripheral blood and bone marrow. While bone marrow-derived cells were detected from 2 weeks onward after grafting, none of the mice grafted with neural embryonic cells demonstrated any sign of transdifferentiation into hemopoietic cells up to 16 months after transplantation. Our data indicate that ability to transdifferentiate from neural into the hematopoietic phenotype, if present, is acquired only after in vitro expansion of neural stem/progenitor cells and it is not present in vivo.     

Differential expression of angiopoietin-1 and angiopoietin-2 may enhance recruitment of bone-marrow-derived endothelial precursor cells into brain tumors

OBJECTIVES: Angiogenesis is necessary for sustained neoplastic development. The angiopoietins Ang-1 and Ang-2 have been implicated in the regulation of this process; recent reports have suggested that a net gain in Ang-2 activity may be an initiating factor for tumor angiogenesis. We examined the recruitment of bone marrow-derived endothelial precursor cells into developing tumor neovasculature, and the spatial relationship between these cells and angiopoietin (Ang-1 and Ang-2) expression. METHODS: For this study T-cell depleted knockout mice (RAG-2/KO-5.2) were lethally irradiated and their bone marrow was reconstituted by bone marrow cells (BMCs) from transgenic mice (C57BL/Ka-Thy1.1) expressing green fluorescent protein (GFP). Rat glioma cells (RT-2/RAG) were then injected into the transplanted animals to form solid brain tumors. The animals were killed and their brains were analysed using immunohistochemistry and fluorescence-activated cell sorting. RESULTS: We found that BMCs migrated preferentially into the tumor when compared to adjacent healthy brain parenchyma. Furthermore, GFP+/CD34+ cells represented up to 8% of endothelial-like cells within the walls of tumor blood vessels. In the tumor, significant colocalization of Ang-2 with GFP+/CD34+ cells was noted (>80%), but colocalization with Ang-1 never exceeded 20%. In normal tissue directly surrounding the tumor, GFP+/CD34+ cells colocalized strongly with both angiopoietins (>75% and >70% for Ang-1 and Ang-2, respectively). DISCUSSION: The relative increase in angiopoietin-2 activity in brain tumors may result in the creation of a pro-angiogenic environment that enhances the recruitment of putative bone marrow-derived endothelial precursor cells into the tumor's developing vascular tree.     

SDF-1 (CXCL12) is upregulated in the ischemic penumbra following stroke: association with bone marrow cell homing to injury

The chemokine stromal-derived factor-1 (SDF-1, also known as CXCL12) and its receptor CXCR4 have been implicated in homing of stem cells to the bone marrow and the homing of bone marrow-derived cells to sites of injury. Bone marrow cells infiltrate brain and give rise to long-term resident cells following injury. Therefore, SDF-1 and CXCR4 expression patterns in 40 mice were examined relative to the homing of bone marrow-derived cells to sites of ischemic injury using a stroke model. Mice received bone marrow transplants from green fluorescent protein (GFP) transgenic donors and later underwent a temporary middle cerebral artery suture occlusion (MCAo). SDF-1 was associated with blood vessels and cellular profiles by 24 hours through at least 30 days post-MCAo. SDF-1 expression was principally localized to the ischemic penumbra. The majority of SDF-1 expression was associated with reactive astrocytes; much of this was perivascular. GFP+ cells were associated with SDF-1-positive vessels and were also found in the neuropil of regions with increased SDF-1 immunoreactivity. Most vessel-associated GFP+ cells resemble pericytes or perivascular microglia and the majority of the GFP+ cells in the parenchyma displayed characteristics of activated microglial cells. These findings suggest SDF-1 is important in the homing of bone marrow-derived cells, especially monocytes, to areas of ischemic injury.