超声微泡联合双特异性抗体对骨髓间充质干细胞干预心肌纤维化的实验研究

Objective To explore the effects of transplantated bone marrow mesenchymal stem cells (MSCs) on myocardial fibrosis with the aid of ultrasound-mediated microbubbles (MB) and bispecific antibody(BiAb) combination.Methods With the aid of MB,isolated MSCs from male mice and the BiAb were transfused into female mice with isoproterenol-induced myocardial fibrosis via tail vein (MSCs + BiAb + MB group).BiAb was producted with anti-CD29 which can recognize MSCs and anti-myosin light chain antibody (AMLCA) which can specifically bind to injured myocardium.There were six groups investigated:MSC + BiAb + MB,MSC,BiAb,MB,MSC + BiAb,untreated,and control groups.Five weeks after treatment administration,the expressions of sex-determining region of Y-chromosome (SRY) in myocardium were detected by fluorescent quantitative PCR.The distribution of collagen was observed by sirius red staining.Heat shock protein-70 (HSP-70) in myocardium was detected by immunohistochemistry.Results The highest homing number of MSCs was in the MSCs + BiAb + MB group,MSCs + BiAb group ranked the second,and lowest in MSCs group.Compared to the untreated group,the MSCs + BiAb + MB,MSCs + BiAb and MSCs groups had less collagen deposition (P ＜0.05),and decreased level of HSP-70.Compared to those of the MSCs group,the collagen deposition were decreased in MSCs + BiAb + MB group (P ＜0.05).Conclusions MB and BiAb can promote the homing number of MSCs in mice.MB can further the homing rate and the repairing efficacy of MSCs.The homing MSCs can prevent the process of myocardial fibrosis.And HSP-70 was involved in the internal mechanism.     

诊断超声联合微泡对骨髓间充质干细胞移植改善兔心肌缺血灌注的研究

Objective To explore the value of diagnostic ultrasound mediated microbubble destruction in improving the myocardial perfusion and left ventricular systolic function when cooperated with the mecsenchymal stem cells(MSCs) transplantation in rabbit myocardial ischemia. Methods One week after myocardial ischemia (MI) modeling,36 rabbits were divided into 3 groups,the control group(group Ⅰ) ,intravenous injection of MSCs group(group Ⅱ) and ultrasound + microbubble + MSCs group (group Ⅲ). Myocardial contrast enhancement (MCE) was performed and quantification analysis of anterior wall was assessed with Photoshop. Left ventrieular systolic function was assessed with M-mode echocardiography and bi-plane Simpson's method. CD34 expression in heart was detected with immunohistochemisty(IHC). Western blotting was applied to detect the level of VEGF in three groups. Results The differences of gray scale analyzed with histogram of Photoshop in anterior wall of ischemia myocardium between the group Ⅰ and group Ⅱ or group Ⅲ were significant,and P value was 0. 032 and 0. 000 , respectively. There were significant differences of FS between group Ⅲ (30. 43±4.09)% and group Ⅱ (26.29±2.93)%, P<0.01, and similar to group Ⅰ (19.28 ± 2.84)%. The difference of EF(%) between group Ⅲ and group Ⅱ was significant [(61.5±5.8 vs 53.6±4. 71), P<0. 05] ,or markedly significant between group Ⅲ and group Ⅰ [(61.5±5.8 vs 42.6± 5.0), P <0.01]. EF(%) assessed with bi-plane Simpson's method was significantly increased from (34.64 ± 4.59) in group Ⅰ to (41.78 ± 4.21) in group Ⅱ and (48.6±3.96) in group Ⅲ. The expression of CD34 assessed with immunohistochemistry was the highest in group Ⅲ. The level of VEGF with western blotting in group Ⅲ was significantly higher than other two groups. Conclusions It is an efficacious transplantation means of MSCs infusion under the ultrasound mediated microbubles destruction in improving the myocardial perfusion and cardiac systolic function.     

超声声致孔隙效应致兔前列腺损伤的初步研究

目的 探讨超声联合造影剂微泡的声致空隙效应开放血-前列腺屏障时对前列腺的损伤作用.方法 15只健康8月龄性成熟新西兰兔,随机分为单纯微泡(MB)组、单纯超声(US)组、超声联合微泡(US+MB)组,超声波直接辐射前列腺,光镜、电镜、细胞凋亡指数(AI)观察前列腺组织损伤的情况.结果 MB组与US组前列腺组织在光镜下均未见明显异常,胞浆、细胞核染色均匀,腺体上皮组织排列整齐、完整,腺管腔内未见明显改变;US+MB组腺体上皮组织细胞排列紊乱,腺管腔内可见大量嗜伊红染的液体.透射电镜下MB组与US组前列腺组织微血管内皮细胞排列整齐,细胞间紧密连接形态正常;US+MB组可见线粒体肿胀,微血管内皮细胞间隙增宽,细胞间桥连接断裂,红细胞漏出等改变.US+MB组AI明显高于MB组与US组(P<0.01),而US组则明显高于MB组(P<0.01).结论 利用超声联合造影剂微泡的声致孔隙效应开放血-前列腺屏障的同时可造成前列腺组织损伤.

Abstract：

Objective To explore the damage effect of sonoporation on the prostate of rabbit,while opening up the blood-prostate barrier by microbubble mediated sonoporation.Methods Fifteen male New Zealand white rabbits were randomly divided into 3 groups:ultrasound (US) group,microbubble (MB) group,ultrasound and microbubble (US+MB) group.Ultrasound was insonated directly on the prostate.Optical microscope,electron microscope and apoptosis index (AI) with TUNEL method were applied to trace the changes of the prostate of rabbit under different conditions.Results There was no significant change in prostatic tissues of group US and MB under the optical microscope.Cytoplasm and nucleoli were stained equally,cells of glandular epithelium were intact and formed orderly.Glandular cavities in these two groups were change very slightly.Glandular epithelium cells of Group US+MB were organized optical under the optical microscope,and there was a mass of eosinophilic liquid in the glandular cavities.Vascular endothelial cell were intact and formed orderly and swollen mitochondria were observed under the electron microscope in MB group and US group.Swollen mitochondria,tight junctions among gland cells were opened,and infiltrated erythrocyte could be found under the eletron microscope in US+MB.AI of group US+MB was markedly higher than that of group US and group MB (P<0.01),and AI of group US was higher than that of group MB (P<0.01).Conclusions Microbubble mediated sonoporation causes damage in the prostate tissue of rabbit,while opening up the blood-prostate barrier with an increased permeability of the prostate.     

Study on adenovirus mediated antisense p38α fragment gene in suppressing apoptosis of the myocardium of neonatal rat by burn serum and hypoxia

Objective To investigate the relationship between the activation of p38 mitogen-activated protein kinase (p38MAPK) in the myocardium and the apoptosis in the presence of burn serum and hypoxia. Methods Ventricular myocardium isolated from neonatal rats were employed in this study, and they were divided into three groups as the normal control group, with the myocardium grew naturally; burn serum+ hypoxia group, in which the myocardium was stimulated by the serum collected from the rat 6 hours after burn injury involving 40% of total body surface area (TBSA), and at the same time exposed to 1%O2, 5% CO2, and 94 %N2; antisense blocking group, in which rats were pretreated by AD-antisense (AS) p38α, then exposed to the same conditions as burn serum+hypoxia group.The phosphorylation of p38 in the myocardium was determined by Western blotting.The level of myocardium apoptosis was determined by DNA ladder and flow cytometry.Results Compared with normal control group, the level of phosphorylation of p38 (gray value) was markedly increased (8.68±0.14 vs.3.21±0.05, P＜0.01＝ after being exposed to burn serum and hypoxia, and at the same time myocardium apoptosis was strikingly increased[(50.367±0.451)% vs.(2.063±0.111)%, P＜0.01＝.When the myocardium was transfected by AD-ASp38α, the phosphorylation of p38 (gray level) was decreased remarkably (5.46±0.16 vs.8.68±0.14, P＜0.01＝, the rate of the apoptosis was lowered remarkably[(13.200 ± 0.121 ) % vs.(50.367 ± 0.451)%, P ＜ 0.01]. Conclusion Burn serum combined with hypoxia can induce apoptosis of the myocardium by activating p38MAPK;blockage of p38MAPK signal transduction pathway may lessen the damage of the myocardium in early period of severe burn.     

颅脑疾病患者血清及脑脊液中心肌酶谱检测的意义

Objective To investigate the Clinical Significance of myocardium enzymatic activity levels in serum and Cerebrospinal Fluid(CSF)from patients with brain disease.Methods Serum and CSF were collected from patients with Tuberculous Men-ingitis(TM)、 virus meningitis( VM)、Cerebrovascular Disease(CD)、 Acute Brain's Hurt ( ABH)and cerebroma(CER),then myocardium enzymatic were measured by chemistry colorimetry.Results 1) Serum and CSF of enzymatic activity were higher in every group patients with brain diseases comparing with normal group,significantly higher in ABH group;2)GGT、LDH、HBDH、CK of CSF in TM group was significantly higher than that of VM group.Conclusion Both myocardium enzymatic activity levels of serum and CSF can be used to distinguish TM and VM;myocardium enzymatic activity level in CSF are helpful to the prognostic diagnosis of ABH.     

骨髓间充质干细胞经核转录因子κB途径干预心肌纤维化

背景：骨髓间充质干细胞移植能否直接干预心肌纤维化及其可能的机制尚不完全清楚。目的：观察骨髓间充质干细胞移植干预心肌纤维化的效果并分析其机制。方法：分离培养雄性小鼠骨髓间充质干细胞,经尾静脉输入异丙肾性心肌纤维化雌性小鼠为治疗组,另设未治疗组和正常对照组。5周后处死小鼠,实时荧光定量PCR检测心肌y染色体鉴别基因（SRY）、基质金属蛋白酶9、基质金属蛋白酶组织抑制剂1的表达;天狼猩红染色对比心脏胶原纤维含量;免疫组织化学染色法观察心脏核转录因子κB表达。结果与结论：骨髓间充质干细胞能归巢于纤维化心肌。与未治疗组相比,治疗组的心肌基质金属蛋白酶9、基质金属蛋白酶组织抑制剂1和核转录因子κB表达下调（P〈0.05）,胶原纤维含量下降（P〈0.05）。结果表明,骨髓间充质干细胞移植干预心肌纤维化,其机制可能与抑制核转录因子κB过度活化有关。     

脐带间充质干细胞对CD34+细胞在小鼠体内归巢的影响及其机制研究

目的 探讨脐带来源间充质干细胞(MSC)对脐血来源CD34+细胞在NOD/SCID小鼠体内归巢的影响及其可能的机制.方法 将CD34+细胞与MSC细胞共移植入经放射线照射后的NOD/SCID小鼠,采用流式细胞术和RT-PCR检测移植后20 h NOD/SCID小鼠骨髓及脾脏中人CD34+细胞,计算其相应的骨髓和脾脏的归巢效率.将脐血CD34+细胞与脐带MSC体外共培养,检测MSC细胞对CD34+细胞趋化功能的影响;并于培养4、7 d检测培养后CD34+细胞表面CD49e、CD31、CD62L、CD11a等归巢相关黏附分子表达情况.结果 ①移植后20 h采用流式细胞术成功在小鼠骨髓和脾脏中检测到人CD45+细胞.共移植组CD34+细胞骨髓归巢率[(7.2±1.1)%]高于单移植组[(5.4±0.9)%](P<0.05).②RT-PCR结果 显示共移植组小鼠骨髓细胞和脾脏细胞,单移植组小鼠脾脏细胞扩增得到人GAPDH基因片段,而单移植组小鼠骨髓细胞未见明显扩增条带.③MSC存在时,CD34+细胞的体外迁移能力为(35.7±5.8)%,显著高于CD34+细胞自发迁移率[(3.5±0.6)%,P<0.05].④CD34+细胞与MSC体外共培养后细胞表面CD49e、CD31和CD62L黏附分子的表达水平高于CD34+细胞单独培养组.结论 MSC细胞与CD34+细胞共移植有利于CD34+细胞向骨髓、脾脏等造血器官归巢,这可能与MSC促进CD34+细胞迁移以及维持CD34+细胞表面归巢相关黏附分子的表达相关.     

骨髓间充质干细胞诱导调节性T细胞缓解心肌缺血-再灌注损伤

目的:探讨骨髓间充质干细胞（BM-MSC）对小鼠心肌缺血-再灌注损伤（MIRI）的保护作用及机制。方法:24只C57小鼠随机（随机数字法）分为假手术组（sham operation SO组）、MIRI模型组（RI组）、MIRI模型MSC治疗组（MSC+RI组）、MIRI模型MSC治疗合并调节性T细胞（regulatory T cell,Treg）清除组（MSC+RI+PC61组）。流式细胞仪检测各组小鼠心脏中Treg的比例,ELISA法测血清中肌酸激酶（CK）、肌钙蛋白（TNI）、B型钠尿肽（BNP）、白介素10（interleukin 10,IL-10）和转化生长因子β（transforming Growth Factor,TGF-β）的含量,HE染色观察小鼠心肌组织学改变,TUNEL染色测定心肌细胞凋亡指数,TTC染色测定心肌梗死面积比。采用单因素方差分析统计数据。结果:MSC+RI组较其余实验组相比小鼠心脏中Treg的比例、血清IL-10和TGF-β的数量最高,CK、TNI、BNP值最低（ P<0.01）,并且该组的心肌炎症细胞浸润,心肌凋亡指数和心肌梗死面积比,组织纤维化均最少（ P<0.01）。 结论:MSC通过诱导Treg的产生,增加抑炎型细胞因子IL-10、TGF-β的释放,减轻心肌缺血-再灌注后的炎症损伤。     

Epicardial Placement of Mesenchymal Stromal Cell-sheets for the Treatment of Ischemic Cardiomyopathy; In Vivo Proof-of-concept Study

Transplantation of bone marrow mesenchymal stromal cells (MSCs) is an emerging treatment for heart failure. We have reported that epicardial placement of MSC-sheets generated using temperature-responsive dishes markedly increases donor MSC survival and augments therapeutic effects in an acute myocardial infarction (MI) model, compared to intramyocardial (IM) injection. This study aims to expand this knowledge for the treatment of ischemic cardiomyopathy, which is likely to be more difficult to treat due to mature fibrosis and chronically stressed myocardium. Four weeks after MI, rats underwent either epicardial MSC-sheet placement, IM MSC injection, or sham treatment. At day 28 after treatment, the cell-sheet group showed augmented cardiac function improvement, which was associated with over 11-fold increased donor cell survival at both days 3 and 28 compared to IM injection. Moreover, the cell-sheet group showed improved myocardial repair, in conjunction with amplified upregulation of a group of reparative factors. Furthermore, by comparing with our own previous data, this study highlighted similar dynamics and behavior of epicardially placed MSCs in acute and chronic stages after MI, while the acute-phase myocardium may be more responsive to the stimuli from donor MSCs. These proof-of-concept data encourage further development of the MSC-sheet therapy for ischemic cardiomyopathy toward clinical application.     

旁分泌效应联合超声生物学效应在MSCs归巢与修复缺血心肌的作用

目的 探讨超声联合微泡经静脉移植兔骨髓间充质干细胞(BM-MSCs)中旁分泌效应及超声生物学效应在MSCs归巢和修复缺血心肌中的价值与作用.方法 密度梯度离心法及贴壁细胞培养法培养兔BM-MSCs.培养细胞进行成脂及成骨诱导分化.细胞移植后行免疫组织化学检测心肌缺血区SDF-1表达,Western blotting检测VEGF蛋白的表达并行定量分析.透射电镜观察各组心肌缺血区血管内皮细胞及通透性.结果 培养的细胞可分化成脂肪与骨骼样细胞.免疫组织化学示SDF-1在3组中均有表达,以2个细胞移植组的阳性表达更强.Western blotting VEGF/GAPDH定量分析超声辐照+微泡+细胞组(236.59±47.13)与静脉移植细胞组(151.48±25.07)和对照组(89.43±20.43)比较,P<0.05.透射电镜示超声+微泡+细胞组缺血区血管内皮细胞间隔增大,红细胞漏出,血管通透性增加.结论 移植MSCs通过旁分泌机制促进SDF-1、VEGF等因子分泌,超声生物学效应通过增加心肌血管通透性、上调VEGF的表达,二者协同促进MSCs归巢和修复缺血心肌.     

磁共振活体示踪经冠状动脉骨髓间充质干细胞移植:验证其与病理组织学结果的一致性

背景:目前动物实验及临床研究证明经冠状动脉移植骨髓间充质干细胞可改善心肌梗死后的心脏功能,但骨髓间充质干细胞经冠状动脉移植后能否到达心肌梗死部位仍存在争议.目的:磁共振活体示踪经冠状动脉注射的骨髓间充质干细胞能否到达心肌梗死部位.方法:全骨髓法分离培养猪骨髓间充质干细胞,超顺磁性氧化铁标记后胰酶消化,调整细胞浓度为10~(10)L~(-1).10只猪均建立心肌梗死模型,造模后1周通过OTW球囊导管经冠状动脉将标记好的骨髓间充质干细胞悬液定向移植至梗死区.普鲁士蓝染色评价细胞标记效率,采用快速梯度回波序列完成长轴位四腔心和二腔心扫描,在以长轴位四腔心和二腔心为定位相,垂直于室间隔获得左心室短轴位图像.结果与结论:超顺磁性氧化铁可安全有效标记骨髓间充质干细胞,经冠状动脉注射的骨髓间充质干细胞能到达心肌梗死区及交界区,磁共振能示踪到超顺磁性氧化铁标记的骨髓间充质干细胞,示踪结果与病理组织学检查一致,且磁共振示踪时间可长达5周.     

骨髓间质干细胞移植后心肌梗死区的超微结构变化

目的观察骨髓间质干细胞(MSCs)移植后心肌梗死区的超微结构变化,探讨MSCs移植治疗急性心肌梗死(AMI)的可能机制。方法于冠状动脉左前降支结扎后1～2h,将5-溴脱氧尿核苷(BrdU)标记的MSCs注射至心肌梗死区,6周后采用免疫组化法鉴定宿主心肌内存活的MSCs,于透射电镜下观察心肌梗死区的超微结构。结果MSCs组梗死心肌内可见BrdU阳性细胞。电镜下,MSCs组可见幼稚的细胞:胞核大,染色质颗粒细而均匀,以常染色质为主,可见由肌微丝刚形成的小肌原节和发育程度不同的肌原纤维,部分与正常心肌形成缝隙连接。和MSCs组比较,AMI组可见肌纤维断裂、坏死严重,线粒体肿胀,内有黑色绒球状颗粒。结论MSCs移植能减轻心肌细胞坏死,并有可能通过分化为心肌细胞来修复梗死心肌。     

移植途径对骨髓间质干细胞梗死心肌移植疗效的影响

目的 探讨自体骨髓间质干细胞(MSCs)不同移植途径对梗死心肌心肌收缩力、血管新生及胶原更新的影响.方法 贵州香猪32只,随机分为对照组(C组)、冠状动脉移植组(A组)、局部注射组(T组)、局部注射+动脉移植组(A+T组).抽取骨髓3 ml,按照Wakitani方法 培养出MSCs,经5-氮胞苷诱导后,5-溴脱氧尿苷(BrdU)标记备用.开胸结扎左冠状动脉前降支后,自体MSCs分别经结扎前降支远端灌注、局部注射、局部注射+动脉灌注移植入自体急性心肌梗死区域,对照组以同样方法 注射不合细胞的等量培养液(DMEM).术后3、6周取标本,免疫组化检测组织血管新生、体外药物刺激离体肌条检测心肌收缩情况和血浆Ⅲ型胶原N端肽(PⅢNP)活性.结果 MSCs移植后3周A、T、A+T组心肌收缩恢复[(48.6±5.9)%,(42.1±6.2)%,(56.9±5.1)%]、血管新生(19.6±4.3,17.1±4.0,23.2±5.5)、血浆PⅢ NP活性[(4.6±0.5)μg/L,(5.9±0.7)μg/L,(3.9±0.3)μg/L]较C组[(37.9±5.4)%,13.2±3.8,(8.7±0.8)μg/L]明显改善(P均<0.01),且随时间推移恢复程度增加,以A+T组为最显著(P均<0.05).结论 局部注射+冠状动脉灌注是较为理想的MSCs移植方式.     

不同种类自体骨髓干细胞移植对梗死心肌左室重构的效果比较

背景:骨髓干细胞移植可改善心功能、预防心室重构,目前用于移植的成体骨髓干细胞有骨髓单个核细胞、骨髓间充质干细胞和内皮祖细胞等,不同种类的骨髓干细胞移植后的效果及具体机制尚不清楚。目的:比较自体骨髓单个核细胞、骨髓间充质干细胞冠状动脉移植对急性心肌梗死后心室重构的影响。设计、时间及地点:随机对照动物实验,于2005-03/2006-12在河北省人民医院临床研究中心、河北医科大学电镜室及大连宝生物进行。(basic fibroblast growth factor,bFGF)材料:36只冀中白猪随机分为4组:假手术组6只、模型组10只、骨髓单个核细胞组10只、骨髓间充质干细胞组10只。方法:采用梯度密度离心法分离培养猪自体骨髓单个核细胞,以贴壁法分离培养猪自体骨髓间充质干细胞,移植前均行胶体金标记。除假手术组外,其余3组均以球囊导管压迫冠状动脉前降支的方法建立猪急性心肌梗死模型。造模后90min,经导管由冠状动脉腔内骨髓单个核细胞组移植自体骨髓单个核细胞(6.0±1.3)×107个,骨髓间充质干细胞组移植自体骨髓间充质干细胞(4.5±2.1)×107个,培养28d。主要观察指标:光镜及电镜观察心肌组织病理学改变;超声检查心功能变化;免疫组织化学检测心肌血管数、心肌细胞凋亡、心肌组织核因子κB及肌钙蛋白I阳性表达情况,及其与心功能的关系;RT-PCR法检测心肌血管内皮生长因子(vascular endothelial growth factor,VEGF)、碱性成纤维细胞生长因子(basic fibroblast growth factor,bFGF)mRNA的表达,及其与心功能的关系。结果:①骨髓间充质干细胞组在梗死区、梗死边缘区均可见大量血管增生,冠脉血管周围可见异常细胞团生长,骨髓单个核细胞组有较多的毛细血管"芽生"现象。②细胞移植前各组心功能指标基本相似(F=1.550,P>0.05)。移植后28d与模型组比较,其余3组左心室射血分数均明显降低(F=5.30,P<0.05)。③与模型组比较,骨髓单个核细胞组梗死区及梗死边缘区的血管数明显增加(F=29.56～34.87,P<0.01),骨髓间充质干细胞组无变化;移植细胞两组的梗死区、梗死边缘区心肌细胞凋亡率均显著降低(F=14.31～35.34,P<0.01),肌钙蛋白I阳性率均明显升高(F=19.05,P<0.01);梗死边缘区核因子кB阳性率均明显降低(F=19.05,P<0.01)。④骨髓单个核细胞组梗死边缘区VEGF基因的表达显著高于模型组、骨髓间充质干细胞组(F=49.41,P<0.01)。骨髓间充质干细胞组梗死边缘区bFGF基因的表达显著高于模型组、骨髓单个核细胞组(F=4.71,P<0.01)。⑤左室射血分数与心肌细胞凋亡率、心肌核因子κB呈负相关(r=-0.4411,P<0.05;r=-0.5796,P<0.01);与血管数、VEGF及bFGF表达呈正相关(r=0.775,P<0.01;r=0.5651,P<0.05;r=0.5735,P<0.05)。结论:经冠脉自体骨髓单个核细胞或骨髓间充质干细胞移植均可减轻心肌梗死后左心室重构,心功能的改善与干细胞移植后增加心肌血管数量及心肌VEGF,bFGF表达、减少心肌细胞凋亡及核因子κB水平有关。骨髓单个核细胞移植促心肌血管增生及VEGF的表达均优于骨髓间充质干细胞,而后者促bFGF基因表达的作用优于前者。     

In vivo magnetic resonance imaging of injected mesenchymal stem cells in rat myocardial infarction; simultaneous cell tracking and left ventricular function measurement

To determine whether magnetic resonance imaging (MRI) can enable magnetically labeled mesenchymal stem cell (MSC) tracking and simultaneous in vivo functional data acquisition in rat models of myocardial infarction. Superparamagnetic iron oxide-laden human MSCs were injected into rat myocardium infarcted by cryoinjury 3 weeks after myocardial infarction. The control group received cell-free media injection. Before injection and for 3 months after, in vivo serial MRI was performed. Electrocardiography-gated gradient echo sequence MRI and cine MRI were performed for in vivo cell tracking and assessing cardiac function using left ventricular ejection fraction (LVEF), respectively. MRI revealed a persistent signal-void representing iron-laden MSCs until ten post-injection weeks. Serial follow-up MRI revealed that LVEF was significantly higher in the MSC injection group than in the control group. We conclude that MRI enables in vivo tracking of injected cells and evaluation of the long-term therapeutic potential of MSCs for myocardial infarction.