Magnetic resonance imaging of targeted catheter-based implantation of myogenic precursor cells into infarcted left ventricular myocardium

OBJECTIVES: This study was designed to test the hypothesis that myocardial implantation of myogenic precursor cells (MPC) loaded with iron oxide can be reliably detected in vivo by cardiac magnetic resonance imaging (MRI). BACKGROUND: In vivo imaging of targeted catheter-based implantation of MPC into infarcted left ventricular (LV) myocardium is unavailable. METHODS: The study was conducted in seven farm pigs (four with anterior myocardial infarction), in which autologous MPC were injected through a percutaneous catheter allowing for LV electromechanical mapping and guided micro-injections into normal and infarcted myocardium. Cardiac MRI was used to detect implanted MPC previously loaded with iron oxide nanoparticles. RESULTS: Magnetic resonance imaging data were compared with LV electromechanical mapping and cross-registered pathology. All 9 injections into normal and 12 injections into locally damaged myocardium were detected on T2-weighted spin echo and inversion-recovery true-fisp MRI (low signal areas) with good anatomical concordance with sites of implantation on electromechanical maps. All sites of injection were confirmed on pathology that showed in all infarct animals iron-loaded MPC at the center and periphery of the infarct as expected from MRI. CONCLUSIONS: Targeted catheter-based implantation of iron-loaded MPC into locally infarcted LV myocardium is accurate and can be reliably demonstrated in vivo by cardiac MRI. The ability to identify noninvasively intramyocardial cell implantation may be determinant for future experimental studies designed to analyze subsequent effects of such therapy on detailed segmental LV function.     

Differentiation, engraftment and functional effects of pre-treated mesenchymal stem cells in a rat myocardial infarct model

BACKGROUND: Mesenchymal stem cells (MSCs) offer a novel therapeutic option in the treatment of acute myocardial infarction. MSCs are able to differentiate into myogenic cells after 5-azacytitdine treatment. However, 5-azacytidine might have genotoxic effects. Recently, it was reported that combined treatment with bone morphogenetic protein-2(BMP-2) and fibroblast growth factor-4(FGF-4) caused cardiac differentiation in non-precardiac mesoderm explants. Therefore, we investigated whether MSCs treated with combined BMP-2 and FGF-4 showed evidence of myogenic differentiation in vitro, and whether these cells resulted in sustained engraftment, myogenic differentiation, and improved cardiac function after implantation in infarcted myocardium. METHODS AND RESULTS: In vitro study: MSCs were treated with BMP-2 + FGF-4 (GF-MSCs) and myogenic phenotype was evaluated immunohistochemically. Cell growth curve was used to compare MSC proliferative capacity between the growth factors and 5-azacytidine treatments. In vivo study: two weeks after coronary artery occlusion, GF-MSCs (n=15), MSCs (n=5) labelled with PKH26 were injected into infarcted myocardium. Control animals (n=5) received a culture medium into the infarcted myocardium.Two weeks after implantation, some engrafted GF-MSCs or MSCs expressed sarcomeric-alpha-actinin and cardiac myosin heavy chain, as was observed in culture. Echocardiography showed that the GF-MSC group had a better (p < 0.05) left ventricular performance than the other groups. CONCLUSION: GF-MSCs induced myogenic differentiation in vitro. Moreover, GF-MSCs engrafted into the infarcted myocardium increased myogenic differentiation, prevented dilation of the infarcted region, and eventually improved heart function.     

应用自制心内膜注射导管移植自体骨髓间充质干细胞治疗急性心肌梗死

目的探讨心内膜注射导管应用于干细胞移植治疗心肌梗死的可行性。方法将移植组和对照组分别经自制的心内膜注射导管梗死心肌内移植体外扩增的自体骨髓间充质干细胞(mesenchymal stem cells,MSCs)和无血清培养,移植前后、6周及3个月超声评价左心功能,3个月时取梗死周围心肌组织冷冻切片,免疫荧光法鉴定结蛋白(desmin)和心肌特异性肌钙蛋白I(cTnI)的表达。结果自制的可调节注射导管,制作方法简单,安全有效;MSCs移植数量平均为(3.81±0.09)×107个;左室射血分数正常为(69.3±2.5)%,心肌梗死后降为(34.9±0.9)%,移植后3个月升至(56.7±0.8)%,超声提示室壁运动增强;与对照组相比,移植组左室收缩末压、左室舒张末压及左室压力最大上升/下降速率改善更明显(均为P<0.01),荧光显微镜下可见DAPI标记胞核为蓝色荧光的移植细胞,免疫组化提示结蛋白及cTnI表达阳性。结论实验用注射导管可以完成细胞的心内膜移植,移植的MSCs体内定位明确,移植后心功能改善,并有心肌相关蛋白的表达。     

Mesenchymal stem cells neither fully acquire the electrophysiological properties of mature cardiomyocytes nor promote ventricular arrhythmias in infarcted rats

Electrophysiological properties of implanted mesenchymal stem cells (MSCs) in infarcted hearts remain unclear, and their proarrhythmic effect is still controversial. The intent of this study was to investigate electrophysiological properties and proarrhythmic effects of MSCs in infarcted hearts. Rats were randomly divided into a myocardial infarction (MI) group, a MI-DMEM group (received DMEM medium injection) and MI-MSCs group (received MSCs injection). Survival analysis showed that the majority of engrafted MSCs died at day 9 after transplantation. Engrafted MSCs expressed cardiac markers (MYH, cTnI, Cx43), cardiac ion channel genes (Kv1.4, Kv4.2 and Kir2.1) and potassium currents (I (to), I (K1) and I (KDR)), but did not express Nav1.5, Cav1.2, Na(+) current and Ca(2+) current during their survival. When induced by Ca(2+), implanted MSCs exhibited no contraction ability after being isolated from the heart. Following 8-week electrocardiography monitoring, the cumulative occurrence of ventricular arrhythmias (VAs) was not different among the three groups. However, the prolonged QRS duration in infarcted rats without VAs was significantly decreased in the MI-MSCs group compared with the other two groups. The inducibility of VAs in the MI-MSCs group was much lower than that in the MI and MI-DMEM groups (41.20 vs. 86.67?% and 92.86?%; P?相似文献   

A quantitative, randomized study evaluating three methods of mesenchymal stem cell delivery following myocardial infarction.

AIMS: Mesenchymal stem cells (MSCs), rare bone marrow-derived stem cell precursors of non-haematopoietic tissues, have shown promise in potentially repairing infarcted myocardium. These and similar cell types are being tested clinically, but understanding of delivery and subsequent biodistribution is lacking. This study was designed to quantitatively compare MSC engraftment rates after intravenous (IV), intracoronary (IC), or endocardial (EC) delivery in a porcine myocardial infarction (MI) model. METHODS AND RESULTS: Allogeneic, male MSCs were cultured from porcine bone marrow aspirates. Iridium nanoparticles were added during culturing and internalized by the MSCs. An MI was induced in female swine (27-40 kg in size) by prolonged balloon occlusion of the mid-left anterior descending artery. Animals (n = 6 per group) were randomized to one of three delivery methods. Cellular engraftment was determined 14+/-3 days post-delivery by measuring ex-vivo the iridium nanoparticle concentration in the infarct. Confirmation of cellular engraftment utilized both DiI and fluorescence in situ hybridization (FISH) labelling techniques. During MSC infusion, no adverse events were noted. However, following IC infusion, half of the pigs exhibited decreased blood flow distal to the infusion site. At 14 days, the mean number of engrafted cells within the infarct zone was significantly greater (P< or =0.01) following IC infusion than either EC injection or IV infusion and EC engraftment was greater than IV engraftment (P< or =0.01). There was less systemic delivery to the lungs following [EC vs. IV (P = 0.02), EC vs. IC (P = 0.06)]. Both DiI and FISH labelling demonstrated the presence of engrafted male MSCs within the female infarcted tissue. CONCLUSION: IC and EC injection of MSCs post-MI resulted in increased engraftment within infarcted tissue when compared with IV infusion, and IC was more efficient than EC. However, IC delivery was also associated with a higher incidence of decreased coronary blood flow. EC delivery into acutely infarcted myocardial tissue was safe and well tolerated and was associated with decreased remote organ engraftment with compared with IC and IV deliveries.     

骨骼肌卫星细胞移植后心肌梗死区血管内皮因子表达及血管新生作用

目的:研究骨骼肌卫星细胞移植后心肌梗死(MI)区血管内皮因子(VEGF)表达及血管新生作用。方法:成年Louis近交系大鼠,结扎前降支建立急性MI模型,将骨骼肌卫星细胞移植到梗死区,2W后应用免疫组化方法鉴定梗死区VEGF的表达及新生血管密度。结果:骨骼肌卫星细胞在梗死区增殖、分化良好,梗死区VEGF表达移植组明显高于对照组(P<0.05),新生血管密度移植组也高于对照组(P<0.05)。结论:移植区卫星细胞可以分泌生长因子,促进血管形成,改善梗死区细胞的生存环境。     

IGF-1-overexpressing mesenchymal stem cells accelerate bone marrow stem cell mobilization via paracrine activation of SDF-1alpha/CXCR4 signaling to promote myocardial repair

We hypothesized that mesenchymal stem cells (MSCs) overexpressing insulin-like growth factor (IGF)-1 showed improved survival and engraftment in the infarcted heart and promoted stem cell recruitment through paracrine release of stromal cell-derived factor (SDF)-1alpha. Rat bone marrow-derived MSCs were used as nontransduced ((Norm)MSCs) or transduced with adenoviral-null vector ((Null)MSCs) or vector encoding for IGF-1 ((IGF-1)MSCs). (IGF-1)MSCs secreted higher IGF-1 until 12 days of observation (P<0.001 versus (Null)MSCs). Molecular studies revealed activation of phosphoinositide 3-kinase, Akt, and Bcl.xL and inhibition of glycogen synthase kinase 3beta besides release of SDF-1alpha in parallel with IGF-1 expression in (IGF-1)MSCs. For in vivo studies, 70 muL of DMEM without cells (group 1) or containing 1.5x10(6) (Null)MSCs (group 2) or (IGF-1)MSCs (group 3) were implanted intramyocardially in a female rat model of permanent coronary artery occlusion. One week later, immunoblot on rat heart tissue (n=4 per group) showed elevated myocardial IGF-1 and phospho-Akt in group 3 and higher survival of (IGF-1)MSCs (P<0.06 versus (Null)MSCs) (n=6 per group). SDF-1alpha was increased in group 3 animal hearts (20-fold versus group 2), with massive mobilization and homing of ckit(+), MDR1(+), CD31(+), and CD34(+) cells into the infarcted heart. Infarction size was significantly reduced in cell transplanted groups compared with the control. Confocal imaging after immunostaining for myosin heavy chain, actinin, connexin-43, and von Willebrand factor VIII showed extensive angiomyogenesis in the infarcted heart. Indices of left ventricular function, including ejection fraction and fractional shortening, were improved in group 3 as compared with group 1 (P<0.05). In conclusion, the strategy of IGF-1 transgene expression induced massive stem cell mobilization via SDF-1alpha signaling and culminated in extensive angiomyogenesis in the infarcted heart.     

兔骨髓间充质干细胞自体移植治疗扩张型心肌病的实验研究

目的 研究骨髓间充质干细胞(MSCs)自体移植于扩张型心肌病后的增殖分化情况和对心功能的保护作用。方法 日本大耳白兔随机分为4组:(1)扩张型心肌病(DCM)细胞移植组(n=12);(2)DCM对照组(n=12);(3)DCM假手术组(n=12);(4)正常对照组(n=10)。分离培养DCM细胞移植组MSCs后,前3组动物用盐酸阿霉素建立兔DCM模型,第4组注射等量生理盐水。模型建立成功后第3周,将5溴脱氧尿嘧啶(BrdU)标记的MSCs自体移植到细胞移植组心肌内,对照组注射培养基,假手术组只开胸,不做注射。4周后采用超声心动图和血流动力学参数评价各组动物的心脏结构和功能,并取移植区心肌组织行免疫荧光染色以观察移植细胞的增殖分化情况。另选部分心肌组织做HE染色查看心肌组织形态学改变。结果 与正常对照组相比,DCM各组心功能明显受损。细胞移植4周后,可以在移植组心肌内找到BrdU标记的阳性细胞,且一部分表现为心肌特异性肌钙蛋白T染色阳性,一部分Ⅷ因子相关抗原染色阳性并参与形成新生血管,其他组中没有发现。且细胞移植组心功能较对照组和假手术组有明显改善。组织学检查示前3组均有心肌细胞变性坏死。结论 MSCs自体移植到DCM后有可能增殖分化为心肌样细胞和血管内皮样细胞并改善心功能。     

Potential risks of bone marrow cell transplantation into infarcted hearts

Cellular replacement therapy has emerged as a novel strategy for the treatment of heart failure. The aim of our study was to determine the fate of injected mesenchymal stem cells (MSCs) and whole bone marrow (BM) cells in the infarcted heart. MSCs were purified from BM of transgenic mice and characterized using flow cytometry and in vitro differentiation assays. Myocardial infarctions were generated in mice and different cell populations including transgenic MSCs, unfractionated BM cells, or purified hematopoietic progenitors were injected. Encapsulated structures were found in the infarcted areas of a large fraction of hearts after injecting MSCs (22 of 43, 51.2%) and unfractionated BM cells (6 of 46, 13.0%). These formations contained calcifications and/or ossifications. In contrast, no pathological abnormalities were found after injection of purified hematopoietic progenitors (0 of 5, 0.0%), fibroblasts (0 of 5, 0.0%), vehicle only (0 of 30, 0.0%), or cytokine-induced mobilization of BM cells (0 of 35, 0.0%). We conclude that the developmental fate of BM-derived cells is not restricted by the surrounding tissue after myocardial infarction and that the MSC fraction underlies the extended bone formation in the infarcted myocardium. These findings seriously question the biologic basis and clinical safety of using whole BM and in particular MSCs to treat nonhematopoietic disorders.     

心肌梗死后基质细胞衍生因子-1的表达及其意义

目的 探讨大鼠心肌梗死(MI)后不同时间,梗死组织基质细胞衍生因子-1(SDF-1)的表达以及与骨髓间充质干细胞（MSC）迁移的关系,为细胞移植提供可靠依据。方法 在MI后不同时间,用PCR测定梗死组织中SDF-1表达的水平。提取梗死心肌组织提取液,在Costar Transwell 双层细胞培养皿观察MI后不同时间梗死心肌组织对MSC迁移能力的影响。结果 SDF-1在组织脏器内的表达存在差异,MI梗死心肌组织中SDF-1的表达呈现出时间变化的趋势,梗死后48 h 达到高峰水平。梗死后的心肌组织对MSC迁移的影响与SDF-1的表达呈相同的变化程序,梗死后48 h 对MSC的趋化作用最强。经SDF-1的受体CXCR4特异性阻滞剂处理后,MSC向梗死组织提取液迁移的能力受到明显抑制。结论 MI后的早期,局部组织中SDF-1的表达明显升高,并可在MI后2周内维持在一个相对高的水平,其对于移植细胞向梗死区域迁移具有重要的作用。     

Substrain heterogeneity in prostaglandin E2 synthesis of human dermal fibroblasts. Differences in prostaglandin E2 synthetic capacity of substrains are not stimulus-restricted

We examined prostaglandin E2 (PGE2) biosynthetic heterogeneity in fibroblast substrains and possible mechanisms that might mediate this heterogeneity. PGE2 synthesis of fibroblast substrains, in response to phytohemagglutinin-stimulated mononuclear cell supernates, ranged from 9.0 +/- 1.0 ng/ml to 79.3 +/- 7.4 ng/ml (mean +/- SD). The phenotypic behavior of individual substrains was stable. Substrains were also heterogeneous in PGE2 response to phorbol myristate acetate, and displayed stability in this phenotype as well. Substrains which were high responders to mononuclear cell supernate also ranked high in response to phorbol myristate acetate. Similar heterogeneity was observed in response to purified interleukin-1. Arachidonic acid added exogenously did not raise interleukin-1 responsiveness of low-producer substrains to that of high producers, suggesting that differences in PGE2 synthesis among substrains did not reflect differences in substrate availability or phospholipase activity. Supernates of high- and low-responder phenotype substrains, when added to cells of the reciprocal strain or to unrelated fibroblasts, did not affect the pattern of PGE2 synthesis. The concordance of substrain responsiveness to mononuclear cell supernate and phorbol myristate acetate suggests that heterogeneity among substrains in PGE2 synthesis is related to the ability to produce PGE2, rather than to the ability to respond to a given mediator. In addition, differences in PGE2 synthesis among substrains do not appear to result from release of regulatory autokines.     

Human stem/progenitor cells from bone marrow promote neurogenesis of endogenous neural stem cells in the hippocampus of mice

Stem/progenitor cells from bone marrow and other sources have been shown to repair injured tissues by differentiating into tissue-specific phenotypes, by secreting chemokines, and, in part, by cell fusion. Here we prepared the stem/progenitor cells from human bone marrow (MSCs) and implanted athem into the dentate gyrus of the hippocampus of immunodeficient mice. The implanted human MSCs markedly increased the proliferation of endogenous neural stem cells that expressed the stem cell marker Sox2. Labeling of the mice with BrdUrd demonstrated that, 7 days after implantation of the human MSCs, BrdUrd-labeled endogenous cells migrated throughout the dorsal hippocampus (positive for doublecortin) and expressed markers for astrocytes and for neural or oligodendrocyte progenitors. Subpopulations of BrdUrd-labeled cells exhibited short cytoplasmic processes immunoreactive for nerve growth factor and VEGF. By 30 days after implantation, the newly generated cells expressed markers for more mature neurons and astrocytes. Also, subpopulations of BrdUrd-labeled cells exhibited elaborate processes immunoreactive for ciliary neurotrophic factor, neurotrophin-4/5, nerve growth factor, or VEGF. Therefore, implantation of human MSCs stimulated proliferation, migration, and differentiation of the endogenous neural stem cells that survived as differentiated neural cells. The results provide a paradigm to explain recent observations in which MSCs or related stem/progenitor cells were found to produce improvements in disease models even though a limited number of the cells engrafted.     

内皮细胞特异性分子-1预处理干细胞用于心肌梗死治疗的实验研究

目的:探讨内皮细胞特异性分子-1(endothelial cell-specific molecule 1,ESM-1)预处理的大鼠骨髓间充质干细胞(bone marrow-derived mesenchymal stem cells,BM-MSCs)植入心肌梗死(MI)大鼠后,是否能增加干细胞的存活,改善MI大鼠的心功能。方法:将用5-溴脱氧尿嘧啶核苷(Brd U)标记的BM-MSCs与ESM-1孵育预处理后,以注射器自心外膜注入SD大鼠梗死心肌周围组织。将30只SD大鼠随机分为3组,即空白组、对照组及预处理组,每组10只大鼠(n=10)。于MI后4周、干细胞移植后4周分别检测各组的超声参数:左室射血分数(LVEF)、左室舒张末期内径(LVEDD)、左室收缩末期内径(LVESD)、室间隔厚度(IVST)和左室后壁厚度(LVPWT);用ELISA法定量检测血清脑钠尿肽(BNP)的分泌以及移植细胞的存活情况。结果:干细胞移植后4周,预处理组大鼠心脏超声检测提示LVESD、LVEDD缩小、LVEF提高,BNP含量降低,与对照组比较差异具有统计学意义(P0.01)。干细胞移植后4周,预处理组梗死周围心肌组织Brd U+的细胞数明显增多,与对照组比较差异具有统计学意义(P0.01)。结论:将ESM-1与BM-MSCs共孵育可活化BM-MSCs,促进其增殖、分化,改善心功能。     

Allogeneic mesenchymal stem cells restore cardiac function in chronic ischemic cardiomyopathy via trilineage differentiating capacity

The mechanism(s) underlying cardiac reparative effects of bone marrow-derived mesenchymal stem cells (MSC) remain highly controversial. Here we tested the hypothesis that MSCs regenerate chronically infarcted myocardium through mechanisms comprising long-term engraftment and trilineage differentiation. Twelve weeks after myocardial infarction, female swine received catheter-based transendocardial injections of either placebo (n = 4) or male allogeneic MSCs (200 million; n = 6). Animals underwent serial cardiac magnetic resonance imaging, and in vivo cell fate was determined by co-localization of Y-chromosome (Y^pos) cells with markers of cardiac, vascular muscle, and endothelial lineages. MSCs engrafted in infarct and border zones and differentiated into cardiomyocytes as ascertained by co-localization with GATA-4, Nkx2.5, and α-sarcomeric actin. In addition, Y^pos MSCs exhibited vascular smooth muscle and endothelial cell differentiation, contributing to large and small vessel formation. Infarct size was reduced from 19.3 ± 1.7% to 13.9 ± 2.0% (P < 0.001), and ejection fraction (EF) increased from 35.0 ± 1.7% to 41.3 ± 2.7% (P < 0.05) in MSC but not placebo pigs over 12 weeks. This was accompanied by increases in regional contractility and myocardial blood flow (MBF), particularly in the infarct border zone. Importantly, MSC engraftment correlated with functional recovery in contractility (R = 0.85, P < 0.05) and MBF (R = 0.76, P < 0.01). Together these findings demonstrate long-term MSC survival, engraftment, and trilineage differentiation following transplantation into chronically scarred myocardium. MSCs are an adult stem cell with the capacity for cardiomyogenesis and vasculogenesis which contribute, at least in part, to their ability to repair chronically scarred myocardium.     

Preconditioning enhances cell survival and differentiation of stem cells during transplantation in infarcted myocardium

AIMS: We hypothesized that preconditioning (PC) with stromal-derived factor 1 alpha (SDF-1) significantly enhances cell survival, proliferation, and engraftment of bone marrow-derived mesenchymal stem cells (MSCs) via SDF-1/CXCR4 signaling. METHODS AND RESULTS: MSCs were cultured and then incubated in medium for 60 min without SDF-1 (control group) or with SDF-1 0.05 microg/mL (SDF-1 group) or CXCR4-selective antagonist, AMD 3100 (AMD) (5 microg/mL, AMD group) or SDF-1 and AMD (0.05 microg/mL, 5 microg/mL, respectively, SDF-1+AMD group). MSCs were treated for 60 min, washed in normal medium, and then exposed to H2O2 (100 micromol/L) for 60 min to determine the effects of various treatments on cell injury, viability, and proliferation. For in vivo studies, rats were grouped (n = 6) after left anterior descending coronary artery ligation to receive 20 microL Dulbecco's modified Eagle's medium without cells or with 5 x 10(5) non-preconditioned MSCs (control group), SDF-1 preconditioned MSCs (SDF-1 group), AMD (AMD group), or MSCs treated with SDF-1 plus AMD (SDF-1+AMD group). Heart function, infarct size, fibrosis, and MSC proliferation and differentiation in infarcted myocardium were determined after 4 weeks. In vitro data showed a marked increase in cell viability and proliferation following SDF-1 PC. In vivo data in preconditioned group showed a robust cell proliferation, reduction in infarct size and fibrosis, and significant improvement in cardiac function. Effects of SDF-1 PC were abrogated by CXCR4 antagonist. CONCLUSION: We conclude that PC with the chemokine SDF-1 suppresses MSCs apoptosis, enhances their survival, engraftment, and vascular density, and improves myocardial function via SDF/CXCR4 signaling. Chemokine PC is a novel approach for enhancing stem cell survival and regeneration of infarcted myocardium.     

骨髓间充质干细胞移植在心肌病大鼠体内存活、分化的实验研究

目的:研究骨髓间充质干细胞（MSCs）移植在心肌病大鼠体内存活、分化的情况。方法:将雌性W istar大鼠30只经腹腔注射阿霉素6次（总剂量15mg/kg）,建立心肌病的动物模型,在此模型的左室前壁采用微静脉注射法植入MSCs。8周后处死大鼠,取出心脏标本,做冰冻切片进行HE染色,观察植入的MSCs在病损心肌组织中的变化及免疫荧光检查观察植入MSCs心肌肌球蛋白重链（MHC）及心肌特有的连接蛋白（CX43）表达情况。结果:HE染色检查显示,植入的MSCs存活并有新生血管形成;免疫荧光检查显示植入的MSCs,表达MHC及CX43,但较宿主表达弱。结论:MSCs移植在心肌病大鼠体内心肌微环境中能存活,并向心肌细胞分化。     

血管内皮生长因子基因转染骨髓间充质干细胞移植促进缺血心肌血管生成的研究

目的研究血管内皮生长因子(vascularendothelial growth factor,VEGF)基因转染骨髓间充质干细胞(mesenchymalstem cells,MSCs)移植对缺血心肌的血管生成作用。方法于2004年5月至2005年8月取第四军医大学西京医院分离、培养Wistar大鼠的MSCs,用真核表达载体pcDNA3.1(-)/hVEGF165转染MSCs。45只近交系Wistar大鼠随机均分为转染组(MSCs/VEGF组)、对照组(MSCs组)、无血清培养基组(DMEM组),结扎前降支建立急性心肌梗死模型后在梗死区边缘区行5×106细胞移植,DMEM组行等量培养基注射。细胞移植前行CM-DiI标记。移植1个月后行心脏B超测量射血分数值,组织化学染色评价新生血管密度。结果培养的MSCs呈典型贴壁生长成纤维样外观,pcDNA3.1(-)/hVEGF165能有效转染大鼠MSCs,移植1个月后MSCs/VEGF组较其余各组左室射血分数(LVEF),再生血管密度明显增加,差异均有显著性(P<0.01)。结论VEGF基因转染MSCs移植能显著促进缺血心肌血管再生,进而改善心脏功能。     

同种异体移植骨髓间充质干细胞治疗大鼠心肌梗死

目的　探讨同种异体骨髓间充质干细胞 (MSCs)在梗死大鼠心脏局部存活、迁移、分化及对心功能的影响 ;明确同种异体细胞移植治疗心肌梗死 (MI)的可行性及效果。方法　雌性Wistar大鼠 3 5只 ,随机分为正常对照组、急性心肌梗死 (AMI)组及MI MSCs治疗组。分离纯化雄性Wistar大鼠骨髓MSCs ,于左冠状动脉前降支结扎后 1～ 3h植入到雌性大鼠心脏组织 ,移植后 10周检测心功能并取心脏检测各种相关指标。结果　异体大鼠MSCs经纯化后可在梗死心脏组织定居、生存 ,并与宿主心肌纤维排列方向一致 ,免疫组化检测胞质心肌特异蛋白染色阳性 ,与MI组比较 ,异体细胞移植组左室收缩压升高 (P <0 0 5) ,舒张末压明显降低 (P <0 0 1)、左心室内压最大上升和下降速率显著增快 (P <0 0 5) ,梗死边缘区心肌面毛细血管数目明显增加 (P <0 0 5) ,多功能真彩色病理图像分析系统显示MI面积缩小 (P <0 0 5)。结论　同种异体MSCs移植治疗MI可行、有效     

Tritiated digoxin. XX. Tissue distribution in experimental myocardial infarction

The role and potential hazards of digitalis glycoside administration in acute myocardial infarction remain controversial. We investigated the concentration of tritiated digoxin in normal, ischemic, and infarcted left ventricular myocardium of the dog after ligation of the anterior interventricular coronary artery. The normal homogeneous distribution of tritiated digoxin in the normal canine left ventricle was altered following acute myocardial infarction. The ischemic and infarcted zones exhibited a marked diminution in digoxin concentration. Oxidative phosphorylation determinations confirmed tissue hypoxia in the infarcted zone. The gradient of digoxin concentration between normal, ischemic, and infarcted zones of myocardium may potentiate the development of an arrhythmia in the electrically unstable infarcted myocardium.     

Local activation or implantation of cardiac progenitor cells rescues scarred infarcted myocardium improving cardiac function

Ischemic heart disease is characterized chronically by a healed infarct, foci of myocardial scarring, cavitary dilation, and impaired ventricular performance. These alterations can only be reversed by replacement of scarred tissue with functionally competent myocardium. We tested whether cardiac progenitor cells (CPCs) implanted in proximity of healed infarcts or resident CPCs stimulated locally by hepatocyte growth factor and insulin-like growth factor-1 invade the scarred myocardium and generate myocytes and coronary vessels improving the hemodynamics of the infarcted heart. Hepatocyte growth factor is a powerful chemoattractant of CPCs, and insulin-like growth factor-1 promotes their proliferation and survival. Injection of CPCs or growth factors led to the replacement of approximately 42% of the scar with newly formed myocardium, attenuated ventricular dilation and prevented the chronic decline in function of the infarcted heart. Cardiac repair was mediated by the ability of CPCs to synthesize matrix metalloproteinases that degraded collagen proteins, forming tunnels within the fibrotic tissue during their migration across the scarred myocardium. New myocytes had a 2n karyotype and possessed 2 sex chromosomes, excluding cell fusion. Clinically, CPCs represent an ideal candidate cell for cardiac repair in patients with chronic heart failure. CPCs may be isolated from myocardial biopsies and, following their expansion in vitro, administered back to the same patients avoiding the adverse effects associated with the use of nonautologous cells. Alternatively, growth factors may be delivered locally to stimulate resident CPCs and promote myocardial regeneration. These forms of treatments could be repeated over time to reduce progressively tissue scarring and expand the working myocardium.