Effects of nerve growth factor and Noggin-modified bone marrow stromal cells on stroke in rats

Treatment with bone marrow stromal cells (BMSCs) ameliorates neurological functional deficits after stroke. Nerve growth factor (NGF) is a neurotrophic factor that supports the survival and growth of neural cells. Noggin, an antagonist of bone morphogenetic protein (BMP), promotes the differentiation of stem cells into neurons. In this study, we hypothesize that transfection of NGF and Noggin in BMSC treatment of stroke promotes BMSC neuronal differentiation and improves functional outcome after stroke. Adenovirus was used to trasfect NGF and Noggin and the transfection efficiency was measured by Western blot and immunostaining in vitro. The transfected BMSCs with NGF and/or Noggin were administered intravenously at 5 days after middle cerebral artery occlusion (MCAo) in rats. The neurological functional outcome and BMSC migration and differentiation in the ischemic brain were measured. The transplantation of BMSCs with NGF or Noggin elicited neurological functional improvement, promoted BMSCs present in the ischemic brain, and also up-regulated neuro-like cell differentiation as well as increased synaptophysin expression in the ischemic brain compared with nontreatment control animals (P< 0.05). Treatment of stroke with a combination of transfection of NGF and Noggin in BMSCs induced a synergistic effect on improved neurological functional outcome, BMSCs present in the ischemic brain, and synaptophysin expression in the ischemic brain compared with BMSCs transfected with an NGF- or Noggin-alone group (P < 0.05). These data demonstrate that increasing NGF or Noggin expression in BMSCs contributes to brain plasticity after stroke and that a synergistic effect is induced on the coexistence of NGF and Noggin in BMSCs treatment of stroke.     

Bone marrow stromal cells as a therapeutic treatment for ischemic stroke

Cerebral ischemia remains the most frequent cause of death and quality-of-life impairments due to neurological deficits, and accounts for the majority of total healthcare costs. However, treatments for cerebral ischemia are limited. Over the last decade, bone marrow stromal cell (BMSC) therapy has emerged as a particularly appealing option, as it is possible to help patients even when initiated days or even weeks after the ischemic insult. BMSCs are a class of multipotent, self-renewing cells that give rise to differentiated progeny when implanted into appropriate tissues. Therapeutic effects of BMSC treatment for ischemic stroke, including sensory and motor recovery, have been reported in pre-clinical studies and clinical trials. In this article, we review the recent progress in BMSC-based therapy for ischemic stroke, focusing on the route of delivery and pre-processing of BMSCs. Selecting an optimal delivery route is of particular importance. The ideal approach, as well as the least risky, for translational applications still requires further identification. Appropriate preprocessing of BMSCs or combination therapy has the benefit of achieving the maximum possible restoration. Further pre-clinical studies are required to determine the time-window for transplantation and the appropriate dosage of cells.     

Bone marrow stromal cells induce BMP2/4 production in oxygen-glucose-deprived astrocytes, which promotes an astrocytic phenotype in adult subventricular progenitor cells

Bone morphogenetic proteins (BMPs) affect cell proliferation and differentiation. Astrocytes in ischemic brain are highly responsive to bone marrow stromal cell (BMSC) treatment. We investigated the effects of BMSCs on astrocytes cultured under oxygen- and glucose-deprived conditions, which in part simulate in vivo stroke conditions, to test the hypothesis that BMSCs alter astrocytic expression of BMPs which may contribute to neurological functional recovery of stroke. Quantitative real-time RT-PCR showed that the expression of BMP2/4 mRNAs decreased within ischemic astrocytes, In contrast, BMP2/4 mRNA was significantly increased after cocultured with BMSCs. Western blotting also confirmed this increase at the protein level in the medium of ischemic astrocytes after coculture with BMSCs. As a source of neural stem and progenitor cells, cultured subventricular zone (SVZ) neurospheres exposed to medium obtained from ischemic astrocytes cocultured with BMSCs were significantly enriched in cells expressing the astrocytic marker glial fibrillary acidic protein (GFAP), but not at the expense of beta-III-tubulin-positive SVZ neuroblasts. The expression of BMP2/4 subsequently increased the phosphorylation of downstream effector Smad1 and the expression of notch signal pathway-induced protein Hes1 in cultured SVZ neurospheres. BMP antagonist Noggin blocked the elevation of phosphorylated Smad1 and the expression of Hes1 as well as reducing the percentage of astrocytic SVZ progenitor cells. Our results indicate that BMSCs increase BMP2/4 expression in ischemic astrocytes. These changes enhance subventricular progenitor cell gliogenesis by activating relevant signaling pathways. BMSC-stimulated signaling of endogenous astrocytes may alter the ischemic environment, promoting remodeling of brain and hence, improve functional recovery after stroke.     

Chemokine, vascular and therapeutic effects of combination Simvastatin and BMSC treatment of stroke

We investigated the additive therapeutic effect of the combination treatment of stroke with sub-therapeutic doses of Simvastatin, a HMG-CoA reductase inhibitor, and bone marrow stromal cells (BMSCs). Rats were administered Simvastatin (0.5 mg/kg), BMSCs (1 × 10⁶) or combination of Simvastatin and BMSCs starting at 24 h after stroke. Combination treatment significantly improved neurological outcome, enhanced angiogenesis and arteriogenesis, and increased the number of engrafted-BMSCs in the ischemic brain. The number of engrafted-BMSCs and arteriogenesis was significantly correlated with functional outcome. Simvastatin significantly increased stromal cell-derived factor-1 (SDF1) expression in the ischemic brain and chemokine (CXC motif) receptor-4 (CXCR4) in BMSCs, and increased BMSC migration to RBMECs and astrocytes. Combination treatment of stroke upregulates the SDF1/CXCR4 axis and enhances BMSC migration into the ischemic brain, amplifies arteriogenesis and angiogenesis, and improves functional outcome after stroke.     

The effect of bone marrow stromal cells on neuronal differentiation of mesencephalic neural stem cells in Sprague-Dawley rats

There are numerous parallels between the heamatolymphopoietic and nervous systems in terms of the mechanisms regulating their development. We proposed that neural stem cells (NSCs) may respond to the microenvironmental signals provided by bone marrow stromal cells (BMSCs) which regulate the differentiation and maturation of hematolymphopoietic stem cells. First, we isolated and proliferated BMSCs from the femur and tibia, and NSCs from the midbrain of Sprague-Dawley (SD) rats, and then investigated the effects of BMSCs on the differentiation of NSCs into neurons, astrocytes and oligodendrocytes by directly plating neurospheres on BMSC monolayers in serum-free conditions. The results confirmed that BMSCs induced NSCs to differentiate selectively into neurons. The percentage of neurons significantly increased in 7 days in vitro co-cultures of NSCs and BMSCs as compared to NSCs cultures alone. When the duration of the cultures was extended to 12 days in vitro, BMSCs enhanced the survival of neurons derived from these NSCs; our investigation then focused on the underlying mechanism for this effect of BMSCs. NSCs were cultured with BMSC conditioned-medium and co-cultured with membrane fragments of live BMSCs or paraformaldehyde fixed BMSCs, the inducing activity of BMSCs was solely detectable in BMSC conditioned-medium, indicating that soluble factors secreted by BMSCs were responsible for its effect on the neuronal differentiation of NSCs. Therefore, BMSCs may provide a powerful tool for therapeutic neurological applications.     

Astrocytic endogenous glial cell derived neurotrophic factor production is enhanced by bone marrow stromal cell transplantation in the ischemic boundary zone after stroke in adult rats

Bone marrow stromal cells (BMSCs) facilitate functional recovery in rats after focal ischemic attack. Growing evidence suggests that the secretion of various bioactive factors underlies BMSCs' beneficial effects. This study investigates the expression of glial cell derived neurotrophic factor (GDNF) in the ischemic hemisphere with or without BMSC administration. Adult male Wistar rats were subjected to 2 h of middle cerebral artery occlusion followed by an injection of 3 × 10⁶ BMSCs (n = 11) or phosphate‐buffered saline (n = 10) into the tail vein 24 h later. Animals were sacrificed seven days later. Single and double immunohistochemical staining was performed to measure GDNF, Ki67, doublecortin, and glial fibrillary acidic protein expression as well as the number of apoptotic cells along the ischemic boundary zone (IBZ) and/or in the subventricular zone (SVZ). BMSC treatment significantly increased GDNF expression and decreased the number of apoptotic cells in the IBZ (P < 0.05). GDNF expression was colocalized with GFAP. Meanwhile, BMSCs increased the number of Ki‐67 positive cells and the density of DCX positive migrating neuroblasts (P < 0.05). GDNF expression was significantly increased in single astrocytes collected from animals treated with BMSCs, and in astrocytes cocultured with BMSCs after OGD (P < 0.05). Our data suggest that BMSCs increase GDNF levels in the ischemic hemisphere; the major source of GDNF protein is reactive astrocytes. We propose that the increase of GDNF in response to BMSC administration creates a hospitable environment for local cellular repair as well as for migrating neuroblasts from the SVZ, and thus contributes to the functional improvement. © 2010 Wiley‐Liss, Inc.     

Bone marrow mesenchymal stem cells transplantation promotes the release of endogenous erythropoietin after ischemic stroke

This study investigated whether bone marrow mesenchymal stem cell(BMSC) transplantation protected ischemic cerebral injury by stimulating endogenous erythropoietin. The model of ischemic stroke was established in rats through transient middle cerebral artery occlusion. Twenty-four hours later, 1 × 106 human BMSCs(h BMSCs) were injected into the tail vein. Fourteen days later, we found that h BMSCs promoted the release of endogenous erythropoietin in the ischemic region of rats. Simultaneously, 3 μg/d soluble erythropoietin receptor(s EPOR) was injected into the lateral ventricle, and on the next 13 consecutive days. s EPOR blocked the release of endogenous erythropoietin. The neurogenesis in the subventricular zone was less in the h BMSCs + s EPOR group than in the h BMSCs + heat-denatured s EPOR group. The adhesive-removal test result and the modified Neurological Severity Scores(m NSS) were lower in the h BMSCs + s EPOR group than in the heat-denatured s EPOR group. The adhesive-removal test result and m NSS were similar between the h BMSCs + heat-denatured s EPOR group and the h BMSCs + s EPOR group. These findings confirm that BMSCs contribute to neurogenesis and improve neurological function by promoting the release of endogenous erythropoietin following ischemic stroke.     

Expression of brain natriuretic peptide by human bone marrow stromal cells

Bone marrow stromal cells (BMSC) have been shown to generate neural cells under experimental conditions in vitro and following transplantation into animal models of stroke and traumatic CNS injury. Hastened recovery from the neurological deficit has not correlated with structural repair of the lesion in the stroke model. Secretory functions of BMSC, such as the elaboration of growth factors and cytokines, have been hypothesized to play a role in the enhanced recovery of neurological function. Using gene expression arrays, real time RT-PCR and radioimmunoassay, we have found that brain natriuretic peptide (BNP) is synthesized and released by BMSC at physiologically relevant levels in vitro. BNP, like its close homolog atrial natriuretic peptide (ANP), exerts powerful natriuretic, diuretic and vasodilatory effects. We speculate that transplanted BMSCs facilitate recovery from brain and spinal cord lesions by releasing BNP and other vasoactive factors that reduce edema, decrease intracranial pressure and improve cerebral perfusion.     

骨髓基质干细胞移植对缺血性卒中大鼠PSD-95表达的影响

目的 应用骨髓基质干细胞（BMSCs）治疗缺血性卒中大鼠,观察BMSCs的治疗效果,检测突触后密度蛋白-95（PSD-95）的表达水平,进而研究BMSCs治疗缺血性卒中的机制.方法 将40只成年雌性SD大鼠制备成大脑中动脉缺血2h再灌注24h动物模型,随机分为梗死对照组和BMSCs组,每组20只.每组再按梗死后3,7d分为2个亚组,每组10只.梗死对照组于缺血再灌注24 h后经尾静脉注射PBS液1ml,BMSCs组同时经尾静脉注射BMSCs 3×106.所有大鼠于梗死后1,3,7d分别进行神经功能评分,应用免疫组化法测定PSD-95表达水平,用TUNEL测定凋亡细胞水平.结果 （1）神经功能评分：梗死后3,7 d BMSCs组神经功能评分明显低于梗死对照组,差异有统计学意义（t分别为2.138,3.417;P＜0.05）.（2） PSD-95表达：BMSCs组在梗死后3d时PSD-95表达较梗死对照组的表达有增多,但差异无统计学意义;BMSCs组在梗死后7d时PSD-95表达明显多于梗死对照组,且差异有统计学意义（t=6.013,P＜0.05）.（3）TUNEL细胞凋亡染色：梗死后3d时梗死对照组大鼠缺血侧可见许多凋亡细胞,显多于BMSCs组,且差异有统计学意义（t=4.978,P＜ 0.05）.结论 BMSCs移植能促进缺血性卒中大鼠的神经功能的恢复.BMSCs移植后能明显增加缺血性卒中大鼠PSD-95的表达,减少细胞的凋亡,对缺血性卒中有保护作用.     

干细胞疗法治疗缺血性卒中的研究进展

目前缺血性卒中所致神经损伤修复的传统治疗方法尚无突破,而以干细胞为基础的新型治疗策略正成为研究热点。大量动物实验和部分临床实验已经证实,无论是机体自身干、祖细胞的动员、募集,还是自体或异体干细胞移植,都显著改善了受损的神经功能。目前已证实局部植入、静脉注入、或全身动员的干细胞在基质细胞衍生因子-1/基质细胞衍生因子-1受体4（Stromal cell-derived Factor-1/CXC Chemokine Receptor-4,SDF-1/CXCR4）趋化分子和β2-整联蛋白等因子的作用下归巢至脑缺血区域;提供富含营养因子的微环境,保护坏死灶周围缺血半暗带组织;增强血管发生和血管生成;促进卒中后内源性干、祖细胞的迁移、存活和分化;并逐渐分化为神经细胞替代丢失的神经元。这几重因素可能共同参与了结构重建和功能修复。     

Granulocyte-macrophage colony-stimulating factor-transfected bone marrow stromal cells for the treatment of ischemic stroke

Adult,male,Sprague-Dawley rats were injected with granulocyte-macrophage colony-stimulating factor-transfected bone marrow stromal cells(GM-CSF-BMSCs) into the ischemic boundary zone at 24 hours after onset of middle cerebral artery occlusion.Results showed reduced infarct volume,decreased number of apoptotic cells,improved neurological functions,increased angiogenic factor expression,and increased vascular density in the ischemic boundary zone in rats that underwent GM-CSF-BMSCs transplantation compared with the BMSCs group.Experimental findings suggested that GM-CSF-BMSCs could serve as a potential therapeutic strategy for ischemic stroke and are superior to BMSCs alone.     

干细胞移植治疗缺血性脑卒中的研究与现状

近年来，随着成年个体神经系统内神经干细胞的发现以及对其研究的不断深入，应用干细胞治疗缺血性脑卒中受到各国学者的广泛关注。大量的实验研究表明，干细胞可从不同程度上改善脑卒中后的神经功能，具有良好的临床应用前景。目前此类研究主要集中于2种途径，其一是利用内源性神经干细胞的激活治疗脑卒中，其二是利用外源性干细胞移植治疗脑卒中。文章就近年来应用各种干细胞治疗缺血性脑卒中的动物及临床实验研究现状进行综述，并对其存在的问题进行了分析和展望。     

骨髓基质细胞移植缺血性脑梗死大鼠后神经营养因子的表达

背景：骨髓基质细胞在适宜条件下可分化为神经元和星形胶质细胞,分泌可溶性分子促进神经元存活。 目的：观察骨髓基质细胞移植后缺血性脑梗死大鼠脑组织神经营养因子表达情况及其对神经功能的影响。 方法：改良的Longa栓线法制作大鼠大脑中动脉缺血模型,1 h后再灌注,24 h后治疗组尾静脉注射3×106骨髓基质细胞,盐水对照组尾静脉注射1 mL生理盐水,空白对照组不进行注射。 结果与结论：在梗死后第7,14天治疗组的神经损伤评分明显低于对照组(P < 0.05);治疗组神经生长因子和脑源性神经营养因子表达在各时间点均高于对照组(P < 0.05)。结果显示静脉移植骨髓基质细胞可改善缺血性脑梗死大鼠神经功能,移植骨髓基质细胞后缺血脑组织中神经生长因子及脑源性神经营养因子表达促进了神经功能的恢复。     

Down-regulation of neurocan expression in reactive astrocytes promotes axonal regeneration and facilitates the neurorestorative effects of bone marrow stromal cells in the ischemic rat brain

The glial scar, a primarily astrocytic structure bordering the infarct tissue inhibits axonal regeneration after stroke. Neurocan, an axonal extension inhibitory molecule, is up-regulated in the scar region after stroke. Bone marrow stromal cells (BMSCs) reduce the thickness of glial scar wall and facilitate axonal remodeling in the ischemic boundary zone. To further clarify the role of BMSCs in axonal regeneration and its underlying mechanism, the current study focused on the effect of BMSCs on neurocan expression in the ischemic brain. Thirty-one adult male Wistar rats were subjected to 2 h of middle cerebral artery occlusion followed by an injection of 3 x 10(6) rat BMSCs (n = 16) or phosphate-buffered saline (n = 15) into the tail vein 24 h later. Animals were sacrificed at 8 days after stroke. Immunostaining analysis showed that reactive astrocytes were the primary source of neurocan, and BMSC-treated animals had significantly lower neurocan and higher growth associated protein 43 expression in the penumbral region compared with control rats, which was confirmed by Western blot analysis of the brain tissue. To further investigate the effects of BMSCs on astrocyte neurocan expression, single reactive astrocytes were collected from the ischemic boundary zone using laser capture microdissection. Neurocan gene expression was significantly down-regulated in rats receiving BMSC transplantation (n = 4/group). Primary cultured astrocytes showed similar alterations; BMSC coculture during reoxygenation abolished the up-regulation of neurocan gene in astrocytes undergoing oxygen-glucose deprivation (n = 3/group). Our data suggest that BMSCs promote axonal regeneration by reducing neurocan expression in peri-infarct astrocytes.     

Transfection of Noggin in bone marrow stromal cells (BMSCs) enhances BMSC-induced functional outcome after stroke in rats

Early intervention with intravenous administration of bone marrow stromal cells (BMSCs) reduces infarction size and ameliorates functional deficits in rat ischemia models. Noggin, an inhibitor of bone morphogenetic protein (BMP), has been demonstrated to provide protection from ischemic disease. In the present work, we hypothesize that administering Noggin-transfected BMSCs enhances BMSC-induced brain repair after cerebral ischemia. We compared the effects of BMSCs alone and Noggin-transfected BMSCs (Noggin-BMSCs) systematically delivered into the middle cerebral artery occlusion (MCAo) rat model. Noggin expression in BMSCs was achieved using adenoviral infection together with a green fluorescent protein (GFP) vector to monitor transduction efficiency and facilitate posttransplantation tracking. BMSCs and Noggin-BMSCs were intravenously injected into the rats 6 hr after MCAo. At 7 days after MCAo, the GFP-expressing BMSCs and Noggin-BMSCs were found primarily in the ischemic penumbra, which indicated that the intravenously delivered cells survived and reached in the lesion site. Both BMSC and Noggin-BMSC treatment significantly promoted neurogenesis in the ipsilateral subventrical zone (SVZ), reduced infarct volume, and led to functional improvement compared with the control group. Moreover, these beneficial effects were significantly greater in the Noggin-BMSC-treated group compared with BMSCs alone treatment (P < 0.05). Noggin expression in the ischemic hemisphere was significantly increased in the Noggin-BMSC-treated group as revealed by enzyme-linked immunosorbent assay (ELISA) at 7 days after MCAo compared with BMSC-treated and control groups (P < 0.05). These results indicate that transfection of Noggin in BMSCs enhances BMSC-induced neuroprotective effects when administered intravenously during the acute phase after stroke.     

Stem cell therapy for cerebral ischemia: from basic science to clinical applications

Recent stem cell technology provides a strong therapeutic potential not only for acute ischemic stroke but also for chronic progressive neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis with neuroregenerative neural cell replenishment and replacement. In addition to resident neural stem cell activation in the brain by neurotrophic factors, bone marrow stem cells (BMSCs) can be mobilized by granulocyte-colony stimulating factor for homing into the brain for both neurorepair and neuroregeneration in acute stroke and neurodegenerative diseases in both basic science and clinical settings. Exogenous stem cell transplantation is also emerging into a clinical scene from bench side experiments. Early clinical trials of intravenous transplantation of autologous BMSCs are showing safe and effective results in stroke patients. Further basic sciences of stem cell therapy on a neurovascular unit and neuroregeneration, and further clinical advancements on scaffold technology for supporting stem cells and stem cell tracking technology such as magnetic resonance imaging, single photon emission tomography or optical imaging with near-infrared could allow stem cell therapy to be applied in daily clinical applications in the near future.     

骨髓间充质干细胞在心肌梗死犬心肌内分化及对心肌细胞凋亡的影响

背景：体内移植骨髓间充质干细胞对实验动物的心肌梗死和心力衰竭有较好的改善作用，但具体机制尚不清楚。 目的：观察骨髓间充质干细胞在心肌梗死犬梗死区的分化以及对心肌细胞凋亡的影响。 设计、时间及地点：随机对照动物实验，于2005-03/2007-12在美国Texas Heart Institute干细胞研究室进行骨髓间充质干细胞移植，在第三军医大学完成免疫组织化学染色。 材料：成年杂种犬，平均体质量25~35 kg。 方法：采用密度梯度离心法提取犬骨髓间充质干细胞，移植前以BrdU标记骨髓间充质干细胞。采用外科手术于近端冠状动脉左前降支植入布洛芬缩肌装置并结扎相连分支的方法制作犬心肌梗死模型。造模后分为实验组与对照组，实验组于损伤缺血部位注射同种异体骨髓间充质干细胞。对照组注射等量生理盐水。 主要观察指标：对移植BrdU标记的骨髓间充质干细胞的心肌梗死犬心肌梗死区组织细胞进行免疫组织化学染色，同时采用DeadEndTM Colorimetric TUNEL System对心梗标本进行凋亡细胞的染色观察。 结果： 注射骨髓间充质干细胞的心脏组织切片BrdU免疫组织化学染色可见大量细胞核呈现深褐色或黑色的阳性反应，在心脏组织的不同区域表现出不同的形态特征，其中大多数植入心肌细胞间的骨髓间充质干细胞，形态上与心肌细胞无异，而其他区域的骨髓间充质干细胞则与间质细胞较相似，无特定的形状。骨髓间充质干细胞移植组心肌梗死区凋亡的心肌细胞数少于未移植组。 结论：骨髓间充质干细胞心肌内移植后可在心肌梗死区分化成心肌细胞，并减轻犬心肌梗死后的细胞凋亡。     

骨髓间充质干细胞体外诱导分化为神经元的研究进展

骨髓间充质干细胞除了分化为间质细胞谱系外, 还具有向非间质细胞谱系,如神经细胞分化的多向分化潜能, 可充当多种器官改建或损伤后修复反应的细胞源。骨髓间充质干细胞的多向分化潜能和超强的自我更新能力,在细胞和基因治疗中可能更具有优越性。值得注意的是,无论是自体移植还是异体移植,局部移植还是全身注入,均未引起宿主体内的免疫反应,提示骨髓间充质干细胞可在基因治疗中作为理想的基因转移载体。尽管骨髓间充质干细胞向神经细胞分化的研究已获得了一些令人鼓舞的结果,并且自体骨髓间充质干细胞用于个体化治疗已经取得了较满意的动物试验和初步临床试验结果, 但仍存在许多尚待解决的问题。     

Therapeutic benefit of bone marrow stromal cells administered 1 month after stroke.

Bone marrow stromal cells (BMSCs) facilitate functional recovery in rats after stroke when administered acutely (1 day) or subacutely (7 days). In this study, we postponed the time of cell transplantation to 1 month after stroke. Female retired breeder rats were subjected to 2 h of middle cerebral artery occlusion (MCAo). Male BMSCs (3 x 10(6)) or phosphate-buffered saline were administered intravenously, and the animals were killed 3 months later. An additional population of nontreated rats was killed at 1 month after MCAo. Significant recovery of behavior was found in BMSC-treated rats beginning at 1 month after cell injection in the modified neurologic severity score test and the adhesive-removal test compared with control animals (P<0.05). In situ hybridization showed that BMSCs survived and preferentially localized to the ipsilateral hemisphere. Double staining revealed that approximately 13% and 6% Y-chromosome-positive cells expressed the astrocyte marker, glial fibrillary acidic protein, and the neuronal marker, microtubule-associated protein-2, respectively. In addition, BMSC treatment reduced scar thickness, and increased the number of proliferating cells and oligodendrocyte precursor cells along the subventricular zone in the ipsilateral hemisphere. Expression of the chemokine stromal-cell-derived factor-1 (SDF-1) was significantly increased along the ischemic boundary zone compared with the corresponding areas in the contralateral hemisphere at 1 month and 4 months (P<0.01) after stroke. The SDF-1 receptor, CXC-chemokine receptor-4 (CXCR4), was expressed in BMSCs both in vitro and in vivo. Our data show that the time window of BMSC therapy is at least 1 month after stroke; the interaction of SDF-1/CXCR4 may contribute to the trafficking of transplanted BMSCs.