肾上腺髓质素基因转染增强骨髓间充质干细胞移植对心肌梗死大鼠心室重构及心功能的影响

目的： 研究肾上腺髓质素（ADM）基因转染增强骨髓间充质干细胞（MSCs）移植对心肌梗死大鼠心室重构及心功能的治疗作用。方法：贴壁法体外分离、扩增培养大鼠骨髓间充质干细胞,用X-gal染色测含ADM基因的重组腺病毒(Ad-ADM)对MSCs感染率,ELISA检测Ad-ADM转染后细胞上清液ADM的含量。通过结扎左冠状动脉前降支制备大鼠心肌梗死模型;以DAPI标记细胞通过心肌局部注射移植MSCs;采用生理记录仪测量大鼠的心功能,荧光显微镜观察移植细胞在心脏存活及分布,免疫组化检测ADM在心肌梗死区的表达及心梗区血管密度;天狼猩红染色检测胶原含量,用偏振光显微镜分析Ⅰ/Ⅲ型胶原比率。结果：重组腺病毒对MSCs的转染率与病毒感染复数（MOI）具有量效关系,MOI为150时细胞的感染率达95.4%;转染Ad-ADM后,MSCs可有效表达ADM,7 d时达到表达高峰,与对照组相比明显增加［(26.53±1.42 vs 1.34±0.08) ng/L,P＜0.05］,15 d后与空白对照组无差别［（2.20±1.44 vs 1.52±0.33) ng/L,P＞0.05］;在受体大鼠的心脏切片上有DAPI标记的移植细胞的存活;与对照组及其它组相比,ADM基因修饰的MSCs组心肌梗死区ADM的表达增加;与对照组比较,单纯细胞移植组心梗区新生血管密度增高（P＜0.01）;而与单纯MSCs移植组及单纯Ad-ADM注射组比较,ADM基因修饰的MSCs移植组梗死区血管密度增高更明显（P＜0.05）;单纯MSCs移植组能降低梗死区Ⅰ/Ⅲ型胶原比率（P＜0.01）,并能改善左室功能;与单纯细胞组比较ADM基因修饰的MSCs移植组梗死区Ⅰ/Ⅲ型胶原比率降低更明显（P＜0.05）,而左室功能改善更多。结论：ADM转染的MSCs移植可能通过局部ADM表达的增加,增强MSCs移植的血管新生作用及降低梗死区Ⅰ/Ⅲ型胶原比率,从而增强单纯MSCs细胞移植改善心功能的作用。     

血管内皮生长因子基因转染骨髓间充质干细胞同种异体移植治疗大鼠急性心肌梗死

目的探讨同种异体血管内皮生长因子(VEGF)基因转染的骨髓间充质干细胞(MSCs)在大鼠梗死心脏局部存活、分化及对心功能的影响;明确同种异体干细胞及VEGF基因转染干细胞移植治疗急性心肌梗死(AMI)的可行性及效果。方法雄性SD大鼠30只,随机分为单纯注射培养基对照组、MSCs治疗组及VEGF基因转染MSCs治疗组。分离纯化雄性Wistar大鼠骨髓间充质干细胞(rMSCs),于左冠状动脉前降支结扎1h后植入到SD大鼠心组织,移植4周后检测心功能并取心脏行组织染色检查。结果异体大鼠MSCs可在梗死心组织定居、生存;免疫组化检测MSCs转化为心肌细胞及血管内皮细胞;与对照组比较VEGF基因转染异体细胞移植组左室射血分数升高(P<0.05),梗死边缘区心肌面毛细血管数目明显增加(P<0.05)。结论同种异体VEGF基因转染MSCs移植治疗AMI可行、有效。     

骨髓间充质干细胞移植对大鼠心梗后细胞因子VEGF、SDF-1、TGF-β1表达及心脏功能的影响

目的 观察急性心肌梗死大鼠移植异体骨髓间充质干细胞后血管内皮生长因子（VEGF）、基质细胞源性因子－1（SDF-1）、转化生长因子β1（TGF-β1）及心脏功能的变化。方法 密度梯度离心法和贴壁筛选法获得SD大鼠骨髓间充质干细胞,实验动物随机分为2组：细胞移植组即实验组（n＝8）、无细胞移植组即对照组（n＝8）。于移植4周后处死动物,免疫组化检测VEGF、SDF-1、TGF-β1及Buxco 系统测大鼠的心功能。结果 实验组在移植4周后免疫组化显示VEGF表达较对照组明显升高（15.02±1.87 VS 5.45±0.90,P<0.05）, SDF－1较对照组明显升高（20.02±3.87 VS 8.24±1.17, P<0.01）、TGF-β1较对照组降低（13.24±2.07 VS 26.33±4.17,P<0.01）;心脏功能亦较对照组显著改善（P<0.05）。结论 骨髓间充质干细胞移植到梗死心肌后可以干预VEGF、SDF－1、TGF-β1的分泌促进梗死后心脏功能的恢复。     

骨髓基质干细胞缺血心肌内移植早期:可减少心肌细胞凋亡但未改善心功能

背景:骨髓基质干细胞移植到梗死心肌组织能够起到抑制和减少心肌细胞凋亡的效应,而这一作用与心功能改善是否有相关性还不清楚。目的:观察缺血心肌内移植骨髓基质干细胞早期对心脏功能的影响。方法:采用结扎左前降支的方法建立大鼠急性心肌梗死模型,假手术组仅穿线不结扎。骨髓基质干细胞移植组于心肌梗死术后30 min分5个位置于梗死边缘向心肌组织内移植大鼠骨髓基质干细胞0.1 m L(2×106),而假手术组、模型组术后分别向心肌内注射相同剂量的生理盐水。细胞移植后3 d监测血流动力学、超声心动图,TUNEL法检测心肌细胞凋亡的变化。结果与结论:移植后第3天,与假手术组相比,模型组梗死区及缺血区心肌细胞凋亡明显;骨髓基质干细胞移植组梗死区和缺血区心肌细胞凋亡数目均较模型组显著减少。与假手术组相比,模型组和骨髓基质干细胞移植组大鼠平均动脉压、左心室收缩压明显下降,左心室舒张末压显著升高,左心室射血分数及缩短分数显著降低(P0.05),骨髓基质干细胞移植组和模型组比较差异无显著性意义(P0.05)。结果表明骨髓基质干细胞移植早期能减少心肌细胞凋亡但不改善急性心肌梗死后大鼠的心功能。     

骨髓间充质干细胞对衰老大鼠肠损伤修复作用的研究

 目的 探讨骨髓间充质干细胞（MSCs）在D-半乳糖制备的衰老大鼠小肠损伤中的作用。方法SD大鼠30只，随机均分为3组：对照组、衰老模型组和MSCs防治组。给衰老模型组大鼠每日皮下注射D-半乳糖400mg/kg，连续4个月。MSCs防治组在衰老模型制备成功后，给予尾静脉输注3×106 个MSCs。分别采用硫代巴比妥酸和黄嘌呤氧化法检测小肠组织中丙二醛(MDA)含量和超氧化物歧化酶(SOD)活性；观察3组大鼠小肠组织结构的差异，并用表达绿色荧光蛋白（GFP）的慢病毒载体标记MSCs，以确定MSCs的植入情况。结果 GFP标记的MSCs移植给大鼠后，能向小肠组织迁移并存活。与衰老模型组相比，MSCs防治组SOD 的活性明显升高，MDA含量明显降低，差异有显著性意义，分别为：（133.7±3.6），（105.1±4.3）U/ml，P <0.01；（5.9±0.1），（6.9±0.1）(nmol/ml)，P <0.01。模型组大鼠肠道粘膜损伤严重，而MSCs防治组大鼠的小肠损伤有明显修复。结论 骨髓间充质干细胞能够一定程度上减轻D-半乳糖致衰老大鼠的小肠损伤。     

胚胎干细胞移植治疗急性心肌梗死后心肌病理形态学及血流动力学变化

目的：探讨胚胎干细胞(ESC)移植治疗急性心肌梗死(AMI)后心肌组织形态学及血液动力学变化。 方法： Wistar大鼠40只随机分为正常对照组、梗死未治疗组(梗死组)、梗死中心移植组(中心组)、梗死周边移植组(周边组)共4组。结扎冠状动脉左前降支制成心肌梗死模型，梗死后1周移植体外分化并经标记的ESCs，移植后4周分别检测组织形态及血流动力学指标的改变。 结果： 移植后4周，周边组移植细胞稳定存活，而中心组移植细胞未能存活。心功能及组织学检测表明中心组与梗死组无显著差异(P＞0.05)；与梗死组比较，周边组梗死面积显著小于梗死组(P＜0.01)，(21.0±1.3)% vs (40.7±2.2)%；左室重量小于梗死组(P＜0.01)，(702.0±24.0)mg vs (882.2±32.6)mg；反映左室收缩功能的指标+dp/dtmax和LVSP均大于梗死组(P＜0.01)，分别为 (7.9±0.7)×103mmHg/s vs (5.9±0.5)×103 mmHg/s和(117.5±10.7) mmHg vs (89.2±8.1) mmHg；而LVEDP均明显小于梗死组(P＜0.01)，(8.5±0.3)mmHg vs (13.6±1.2)mmHg。 结论： 急性心肌梗死后于梗死周边区移植ESCs可以阻止心室重构、减少瘢痕面积、改善心功能。     

经皮球囊封堵冠状动脉法制备小型猪心肌梗死模型及评价

目的: 探讨球囊封堵法建立小型猪心肌梗死模型的可行性,以及骨髓间充质干细胞(MSCs)移植治疗心肌梗死疗效初探。方法: 选用小型藏猪20只,麻醉后经股动脉置入经皮腔内冠状动脉成形术(percutaneous transluminal coronary angioplasty, PTCA)球囊至左前降支中远段,完全堵闭血流90 min,行心电图、心脏超声心动图、心肌核素显像、心脏核磁共振及病理检查。随机分2组:MSCs移植组,OTW球囊将MSCs移植到梗死心肌处;生理盐水组,注入等量生理盐水。观察2组的左室射血分数(LVEF)和短轴缩短率(FS)、左室舒张末期内径(EDV)和左室收缩末期内径(ESV)的变化。结果: 20只猪均完成冠脉造影,造模成功10只,,死亡10只,成功率50%。与造模之前比, LVEF、FS显著下降(P<0.05),EDV、ESV显著延长。8周后,MSCs移植组均较移植前好转(P<0.05, P<0.01),而生理盐水组亦有所改善,但无显著差异;MSCs移植组的LVEF和FS较生理盐水组明显增加(P<0.05,P<0.01),MSCs移植组的EDV和ESV较生理盐水组明显缩少(P<0.05,P<0.01)。结论: 球囊封堵法可成功建立小型猪心肌梗死模型,并且适合行骨髓干细胞移植的研究,但须特别注意预防心室纤颤的发生。MSCs移植可明显改善小型猪梗死心肌的功能。     

粒细胞集落刺激因子治疗兔急性心肌梗死的时间窗研究

 目的 探讨应用粒细胞集落刺激因子（G-CSF）动员骨髓干细胞对兔急性心肌梗死的治疗作用及较佳的治疗时间窗。 方法 33 只健康大耳兔开胸结扎左室后支中下段建立心肌梗死模型后，随机分为对照组（9 只）、早期动员组（12 只）、延迟动员组（12 只）。对照组于心肌梗死后第 3 小时皮下注射生理盐水；早期动员组和延迟动员组分别于心肌梗死后第 3 小时和第 7 天开始皮下注射 G-CSF，每天 1 次，每次 20 μg/kg，连续 5 d。模型制备前和制备成功后 7 、28 d 行超声心动图检查，测量左室舒张末期内径（Dd）、收缩末期内径（Ds）并计算左室短轴缩短率[（Dd－Ds）/Dd]，测量左室后壁厚度和左室射血分数；心肌梗死后 28 d 取心脏做心肌组织病理学检查和内皮细胞 Ⅷ 因子免疫组织化学染色，计算心肌梗死总面积占左室总面积百分比和心肌毛细血管内皮细胞 Ⅷ 因子染色阳性率。 结果 心肌梗死后 28 d，延迟动员组兔心脏结构与功能均有明显改善，左室短轴缩短率（0.30 ± 0.05）、左室后壁厚度（0.19 cm ± 0.02 cm）和左室射血分数(56.7% ± 3.4%)均大于对照组(分别为 0.20 ± 0.02、0.17 cm ± 0.02 cm、47.7% ± 3.5%，均 P < 0.05）；心肌梗死面积占左室总面积的（18 ± 3）%，低于对照组的（22 ± 2）%（P < 0.05）和早期动员组的（21 ± 2）%（P < 0.05）；梗死区心肌毛细血管内皮细胞Ⅷ因子染色阳性率（90.8%）明显高于对照组（25.2%，P < 0.01）和早期动员组（72.0%，P < 0.05）。实验结束时，动物病死率延迟动员组为 16.7%（2/12），早期动员组 25.0%（3/12），对照组 33.3%（3/9），延迟动员组与对照组比较，差异有统计学意义（P < 0.05）。 结论 骨髓干细胞动员治疗心肌梗死可明显改善心脏功能；心肌梗死后 7 d 是进行骨髓干细胞动员的较佳时间窗。     

骨髓间充质干细胞移植对梗死心脏血流动力学及心肌重塑的影响

目的血流动力学异常和心肌重塑是心肌梗死（MI）后室性心律失常形成的基础,本研究拟调查猪骨髓间充质干细胞（MSCs）移植对梗死心脏血流动力学和心肌重塑的影响。方法除正常对照组（Control组）外,MSCs移植组（MSCs组）和MI模型组（MI组）在完成MI动物模型制作时分别经左冠状动脉前降支移植MSCs悬液或等量生理盐水对照,6周后记录左室血流动力学参数值,检测心肌组织血管紧张素Ⅱ（AngⅡ）和胶原含量,并行心肌组织染色分析毛细血管密度和Ⅰ/Ⅲ型胶原比例。结果（1）MSCs组梗死区毛细血管密度显著高于MI组和Control组（P分别〈0.01）;（2）MSCs组血流动力学各参数值虽未恢复正常（同Control组相比,P分别〈0.01）,但较MI组均有显著改善（P分别〈0.05）;（3）MI组和MSCs组非梗死区心肌组织AngⅡ、胶原含量和Ⅰ/Ⅲ型胶原比例同Control组相比均有显著升高（P分别〈0.01）,但MSCs组心肌组织AngⅡ、胶原含量和Ⅰ/Ⅲ型胶原比例同MI组相比均有不同程度下降（P分别〈0.05、0.01和0.01）。结论MSCs移植能显著增加梗死区毛细血管网重建,改善血流动力学状况,减轻心肌重塑程度,有助于减少室性心律失常的基质形成。     

兔骨髓间充质干细胞来源的心肌(样)细胞的诱导分化研究

目的体外诱导骨髓间充质干细胞(Mesenchymal stem cells,MSCs)向肌源性细胞分化,探索诱导后的MSCs移植于心肌梗死区的存活和分化情况。方法提取、分离、培养兔的MSCs。经5-氮胞苷诱导后,进行免疫组化,电镜观察。4',6二乙酞基-2-苯基吲哚(DAPI)标记MSCs,建立兔心肌梗死模型。实验动物随机分两组:实验组(n=10)在心梗区域注入经诱导后的MSCs;对照组(n=10)在心梗区域注入不含MSCs的培养液。移植4周后,进行病理标本观察和免疫组化检测。结果5-氮胞苷诱导MSCs4周,部分细胞表达肌钙蛋白T(troponin T),电镜观察到肌丝形成。MSCs在体外用DAPI标记,用荧光显微镜观察细胞发蓝色荧光。移植4周后,在实验组中用荧光显微镜观察可见梗死区组织标本中可见DAPI标记带蓝色荧光的供体细胞核,移植细胞表达troponin T。结论MSCs经5-氮胞苷诱导后可向心肌细胞转化。移植细胞可在心肌存活,并向心肌细胞(样)转化。     

Donor Mesenchymal Stromal Cells (MSCs) Undergo Variable Cardiac Reprogramming in Vivo and Predominantly Co-Express Cardiac and Stromal Determinants after Experimental Acute Myocardial Infarction

We previously showed the emergence of predominantly non-fused murine cells co-expressing cardiac and stromal determinants in co-cultures of murine mesenchymal stromal cells (MSCs) and rat embryonic cardiomyocytes. To determine whether a similar phenotype is detectable in vivo in ischemic myocardium, we infused green fluorescence protein (GFP)-marked MSCs intravenously into wild-type mice in an acute myocardial infarction (AMI) model generated by ischemia/reperfusion (I/R) or fixed coronary artery ligation. We found that infused GFP+ cells were confined strictly to ischemic areas and represented approximately 10 % of total cellularity. We showed that over 60 % of the cells co-expressed collagen type IV and troponin T or myosin heavy chain, characteristic of MSCs and cardiomyocytes, respectively, and were CD45(-). Nonetheless, up to 25 % of the GFP+ donor cells expressed one of two cardiomyocyte markers, either myosin heavy chain or troponin T, in the absence of MSC determinants. We also observed a marked reduction in OCT4 expression in MSCs pre-infusion compared with those lodged in the myocardium, suggesting reduced stem cell properties. Despite the low frequency of lodged donor MSCs, left-ventricular end-diastolic pressure was significantly better in experimental versus saline animals for both AMI (12.10?±?1.81 vs. 20.50?±?1.53 mmHg, p?<?0.001) and I/R models (8.75?±?2.95 vs. 17.53?±?3.85 mmHg, p?=?0.004) when measured 21 days after MSC infusion and is consistent with a paracrine effect. Our data indicate that donor MSCs undergo variable degrees of cardiomyocyte reprogramming with the majority co-expressing cardiomyocyte and stromal markers. Further studies are needed to elucidate the factors mediating the extent of cardiomyocyte reprogramming and importance of the cellular changes on tissue repair.     

Impact of myocardial infarct proteins and oscillating pressure on the differentiation of mesenchymal stem cells: effect of acute myocardial infarction on stem cell differentiation

Stem cell transplantation in acute myocardial infarction (AMI) has emerged as a promising therapeutic option. We evaluated the impact of AMI on mesenchymal stem cell (MSC) differentiation into cardiomyocyte lineage. Cord blood-derived human MSCs were exposed to in vitro conditions simulating in vivo environments of the beating heart with acute ischemia, as follows: (a) myocardial proteins or serum obtained from sham-operated rats, and (b) myocardial proteins or serum from AMI rats, with or without application of oscillating pressure. Expression of cardiac-specific markers on MSCs was greatly induced by the infarcted myocardial proteins, compared with the normal proteins. It was also induced by application of oscillating pressure to MSCs. Treatment of MSCs with infarcted myocardial proteins and oscillating pressure greatly augmented expression of cardiac-specific genes. Such expression was blocked by inhibitor of transforming growth factor beta(1) (TGF-beta(1)) or bone morphogenetic protein-2 (BMP-2). In vitro cellular and electrophysiologic experiments showed that these differentiated MSCs expressing cardiomyocyte-specific markers were able to make a coupling with cardiomyocytes but not to selfbeat. The pathophysiologic significance of in vitro results was confirmed using the rat AMI model. The protein amount of TGF-beta(1) and BMP-2 in myocardium of AMI was significantly higher than that in normal myocardium. When MSCs were transplanted to the heart and analyzed 8 weeks later, they expressed cardiomyocyte-specific markers, leading to improved cardiac function. These in vitro and in vivo results suggest that infarct-related biological and physical factors in AMI induce commitment of MSCs to cardiomyocyte-like cells through TGF-beta/BMP-2 pathways.     

同种异体脂肪组织源性间质干细胞移植治疗大鼠急性心肌梗死

目的：建立体外分离扩增脂肪组织源性间质干细胞方法，并探讨同种异体脂肪干细胞移植治疗大鼠心肌梗死的效果及可行性。方法: 18只雄性SD大鼠随机分为假手术组、急性心肌梗死对照组（AMI组）及AMI+细胞移植组。分离大鼠腹部脂肪组织干细胞，体外扩增，BrdU标记后于结扎左冠状动脉前降支后1h移植入梗死心肌，移植后4周进行血流动力学检测心功能并取出心脏进行病理切片观察和免疫组织化学染色检测移植细胞在梗死心脏中的定居、存活情况。结果: 大鼠腹部脂肪组织可分离培养出大量间质干细胞。细胞移植治疗组左心室收缩压高于AMI对照组（P＜0.01），舒张末压显著降低（P＜0.01），左心室内压最大上升、下降速率明显加快（P＜0.05）；病理组织切片显示梗死边缘区心肌面毛细血管计数明显增加，梗死区心肌组织内及毛细血管壁中均可见移植标记细胞。结论: 脂肪组织可作为干细胞又一新的来源，同种异体脂肪干细胞移植治疗AMI有效、可行。     

干细胞生长因子和粒细胞集落刺激因子与心肌梗死大鼠体内骨髓间充质干细胞的迁移

背景：外周静脉移植间充质干细胞只有1%~5%的移植细胞能归巢到心肌梗死区域。 目的：观察干细胞生长因子、粒细胞集落刺激因子对骨髓间充质干细胞归巢的影响。 方法：采用贴壁培养法分离培养SD大鼠骨髓间充质干细胞,取传至3~5代细胞。建立SD大鼠急性心肌梗死模型,干细胞生长因子组、粒细胞集落刺激因子组、干细胞生长因子+粒细胞集落刺激因子组在骨髓间充质干细胞移植前3 d和移植后3 d单独或混合皮下注射干细胞生长因子、粒细胞集落刺激因子,骨髓间充质干细胞组不注射细胞因子。 结果与结论：荧光显微镜下观察,骨髓间充质干细胞迁移至心肌梗死组织,骨髓间充质干细胞组、干细胞生长因子组、粒细胞集落刺激因子组迁移至心肌梗死区的骨髓间充质干细胞数量没有明显的区别(P > 0.05),干细胞生长因子+粒细胞集落刺激因子组的骨髓间充质干细胞数量明显高于其他3组(P < 0.05)。免疫荧光组织化学显示,植入的部分骨髓间充质干细胞表达心肌特异蛋白cTnI。结果说明干细胞生长因子和粒细胞集落刺激因子两种细胞因子联合应用可以促进骨髓间充质干细胞归巢至心肌梗死区域,在体内微环境的诱导下,骨髓间充质干细胞能够转化为心肌样细胞。     

Repair of infarcted myocardium using mesenchymal stem cell seeded small intestinal submucosa in rabbits

Myocardial infarction (MI) remains a common and deadly disease. Using tissue-engineered cardiac grafts to repair infarcted myocrdium is considered to be a therapeutic approach. This study tested the feasibility of using MSCs-seeded SIS to repair chronic myocardial infarction in a rabbit model. MI in rabbits was created by ligation of the left anterior descending artery. BrdU-labeled mesenchymal stem cells (MSCs) were seeded on the small intestinal submucosa and cultured for 5–7 days prior to implantation. Four weeks after myocardial infarction, cardiac grafts were implanted onto the epicardial surface of infarcted myocardium. Four weeks after implantation of the membranes, a serial of tests including echocardiography, hemodynamics, histology and immunohistochemistry were undertaken to evaluate the effect of the implanted grafts on recovery of the infarcted myocardium. It was shown that left ventricular contractile function and dimension, the capillary density of the infarcted region, and myocardial pathological changes were significantly improved in rabbits implanted either SIS or MSCs-seeded SIS. But the MSCs-seeded SIS was more effective. Immunofluorescence staining demonstrated the migration of Brdu-labeled MSCs from the membrane into the infarcted area and their differentiation to cardiomyocytes and smooth muscle cells. Taken together, these results suggest that MSCs-seeded SIS can be used to repair chronic myocardial infarction, which enhances myocardial regeneration.     

骨髓间质干细胞在扩张型心肌病微环境中的分化研究

目的：探讨骨髓间质干细胞（MSCs）自体移植后在扩张型心肌病（DCM）微环境中分化为心肌细胞和血管内皮细胞的可行性。 方法： 用健康日本大耳白兔分离培养MSCs，盐酸阿霉素耳缘静脉注射复制兔DCM模型，将5溴脱氧尿嘧啶(BrdU)标记的MSCs移植到扩张型心肌病心肌内,4周后观察移植细胞的增殖分化情况。 结果： 细胞移植4周后，可以在实验组心肌内找到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（troponin 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，对照组中没有发现。 结论： MSCs自体移植到扩张型心肌病后可以分化为心肌细胞和血管内皮细胞。     

Cell transplantation into ischemic myocardium using mesenchymal stem cells transfected by vascular endothelial growth factor

Aims: To investigate the effects of mesenchymal stem cells (MSCs) transplantation combining with vascular endothelial growth factor (VEGF) gene therapy on myocardium rebuilding, angiogenesis, and heart function improvement in rats with myocardial infarction. Methods: SD rat MSCs were isolated, cultured in vitro, labeled with BrdU and transfected by Ad.VEGF gene. Four weeks after left anterior descending artery was ligated to create rat myocardial infarction, cardiac function was examined with echocardiography. Rats were randomly divided into four groups (n = 10 in each group): Group I: MSCs/Ad.VEGF implantation; Group II: MSCs implantation; Group III: Ad.VEGF injection; Group IV: Control. MSCs differentiation was observed 4 weeks after transplantation. Immunohistochemistry and angiogenesis were observed. Echocardiography was performed to detect the effects on heart function. Results: MSCs labeled with BrdU could be identified in host hearts in group I and II, most of them positively stained with cTnT antibody. Echocardiography indicated that the improvement of the LVEF value in group I was more significant than that in the other three groups (P < 0.01, respectively). Some cells were incorporated into the coronary capillaries in the infarcted region. The capillary density in group I was higher than that in the other three groups (P < 0.01, respectively). Conclusion: MSCs implantation combining with VEGF gene therapy can obviously repair damaged myocardium and enhance the angiogenesis in ischemic heart tissue.     

心肌梗死大鼠血清促进大鼠骨髓间质干细胞分化为心肌细胞的作用

 目的: 探讨急性心肌梗死（AMI）大鼠血清在体外对大鼠骨髓间质干细胞（BMSC）分化为心肌细胞的作用。方法: 将大鼠BMSC分为6组进行细胞培养：Ⅰ组为未诱导组(对照组),Ⅱ组为5-aza诱导组,Ⅲ组为5-aza＋AMI血清诱导组,Ⅳ组为5-aza＋正常大鼠血清诱导组,Ⅴ组为AMI血清诱导组,Ⅵ组为正常大鼠血清诱导组。培养30 d后进行分化细胞鉴定，检测细胞的形态变化和心肌肌钙蛋白（cTnT）、心肌细胞转录因子GATA-4和结蛋白（desmin）的表达。结果: 大鼠BMSC经5-aza或5-aza联合血清诱导后，向心肌样细胞分化，其cTnT、GATA-4、desmin表达阳性。对照组和单纯血清诱导组的BMSC未见形态改变，其cTnT亦为阴性，但GATA-4、desmin却呈弱阳性。另外，5-aza联合血清诱导组在诱导2周后可观察到部分细胞呈缓慢而有节律的跳动，而单纯5-aza诱导组未见细胞跳动。结论: 单纯用AMI大鼠血清不能诱导BMSC向心肌细胞分化，但AMI血清能促进5－aza诱导的BMSC向心肌细胞分化，并促进分化的心肌细胞成熟。     

Monocyte chemotactic protein 1 increases homing of mesenchymal stem cell to injured myocardium and neovascularization following myocardial infarction

Objective:To investigate the effect of MCP-1 on mesenchymal stem cells(MSCs) homing to injured myocardium in a rat myocardial infarction(MI) model. Methods:Rat myocardial infarction model was established by permanent left anterior descending branch ligation. Mesenchymal stem cells from donor rats were cultured in IMDM and labeled with BrdU. The Rats were divided into two groups. Monocyte chemotactic protein 1(MCP-1) expression were measured by in situ hybridization and immunohistochemistry in the sham operated or infarcted hearts at 1,2, 4,7,14 and 28 days post operation in MCP-1 detection group. The rats were injected with MCP-1, anti-MCP-1 antibody or saline 4 days after myocardial infarction in intervention group. Then, a total of 5 × 106 cells in 2.5 ml of PBS were injected through the tail vein. The number of the labeled MSCs in the infarcted hearts was counted 3 days post injection. Cardiac function and blood vessel density were assessed 28 days post injection. Results:Self-generating MCP-1 expression was increased at the first day, peaked at the 7th day and decreased thereafter post MI and remained unchanged in sham operated hearts. The MSCs enrichment in the host hearts were more abundant in the MI groups than that in the non-Mi group(P = 0.000), the MSCs enrichment in the host hearts were more abundant in the MCP-1 injected group than that in the anti-MCP-1 antibody and saline injected groups (P = 0.000). Cardiac function was improved more in MCP-1 injected group than anti-MCP-1 antibody and saline injected groups(P= 0.000). Neovascularization in MCP-1 injected group significantly increased compared with that of other groups(P = 0.000). Conclusion: Myocardial MCP-1 expression was increased only in the early phase post MI. MCP-1 may enhance MSCs homing to the injured heart and improve cardiac function by promoting neovascularization.