Efficient differentiation of human induced pluripotent stem cells generates cardiac cells that provide protection following myocardial infarction in the rat

Induced pluripotent stem (iPS) cells are being used increasingly to complement their embryonic counterparts to understand and develop the therapeutic potential of pluripotent cells. Our objectives were to identify an efficient cardiac differentiation protocol for human iPS cells as monolayers, and demonstrate that the resulting cardiac progenitors could provide a therapeutic benefit in a rodent model of myocardial infarction. Herein, we describe a 14-day protocol for efficient cardiac differentiation of human iPS cells as a monolayer, which routinely yielded a mixed population in which over 50% were cardiomyocytes, endothelium, or smooth muscle cells. When differentiating, cardiac progenitors from day 6 of this protocol were injected into the peri-infarct region of the rat heart; after coronary artery ligation and reperfusion, we were able to show that human iPS cell-derived cardiac progenitor cells engrafted, differentiated into cardiomyocytes and smooth muscle, and persisted for at least 10 weeks postinfarct. Hearts injected with iPS-derived cells showed a nonsignificant trend toward protection from decline in function after myocardial infarction, as assessed by magnetic resonance imaging at 10 weeks, such that the ejection fraction at 10 weeks in iPS treated hearts was 62%±4%, compared to that of control infarcted hearts at 45%±9% (P<0.2). In conclusion, we demonstrated efficient cardiac differentiation of human iPS cells that gave rise to progenitors that were retained within the infarcted rat heart, and reduced remodeling of the heart after ischemic damage.     

骨髓干细胞动员与移植治疗心肌梗死的比较

目的：比较骨髓干细胞动员与骨髓单个核细胞移植对兔心肌梗死的治疗作用，探讨更有效、更适用的干细胞治疗心肌梗死的方法。 方法： 将30只新西兰兔采用结扎前降支的方法复制心肌梗死模型，随机分为动员组、移植组和对照组，动员组（n=10）心梗后3 h开始皮下注射粒细胞集落刺激因子（G-CSF）30 μg·kg-1·d-1，连续使用5 d，第5 d抽取静脉血约10 mL，分离单个核细胞(BMCs)用5-溴脱氧尿嘧啶核苷（BrdU）标记后，经静脉注入动物体内。移植组（n=10）心梗后7-10 d，抽取骨髓3-5 mL,分离MNCs用BrdU标记，然后开胸将细胞移植至梗死区，对照组（n=10）不采取任何治疗措施。心梗后1周及5周采用超声心动图（UCG）检查心脏功能变化，5周时作血液动力学测定，取心脏作免疫组织化学鉴定。 结果： 心梗后5周，动员组左室射血分数（EF）明显高于1周时，移植组无变化，对照组显著下降。5周时动员组及移植组左室舒张末压（LVEDP）、+dp/dtmax和-dp/dtmax与对照组相比均有显著差异。动员组及移植组在心肌梗死区均发现有BrdU标记的阳性细胞，两组梗塞区血管密度明显高于对照组，但均未发现有新生的平滑肌细胞及心肌细胞。 结论： 骨髓干细胞动员及BMCs移植治疗心肌梗死，均能通过促进梗死区血管新生，明显改善心脏功能，骨髓干细胞动员可能为心肌梗死的治疗提供一种新的无创性手段。     

骨形态发生蛋白-2在骨髓源性心肌干细胞向心肌分化中的作用

目的研究骨形态发生蛋白-2（BMP-2）对骨髓源性心肌干细胞（MCSC）向心肌分化的作用,探讨MCSC向心肌分化中的BMP-2信号转导机制.方法从SD大鼠骨髓中筛选MCSC,用BMP-2诱导向心肌定向分化.RT-PCR检测诱导前后BMP-2受体BMPRIA和BMPRII、心肌早期转录因子Nkx2.5和GATA-4以及cTnT mRNA的表达.免疫细胞化学标记诱导后细胞cTnT和Cx-43的表达.结果用BMP-2诱导后,MCSC的形态和排列发生变化.RT-PCR检测结果显示,诱导前BMPRIA和BMPRII以及Nkx2.5和GATA-4呈低表达,诱导后1周表达增加,3～4周表达明显.cTnT mRNA在诱导前不表达,诱导后1周开始表达,3～4周表达明显.免疫细胞化学染色显示,cTnT和Cx-43从诱导后2周开始表达.3～4周cTnT表达增强,呈现密集的横纹样结构.Cx-43在2周位于细胞膜下,3周分布于相邻细胞连接处,4周呈颗粒状密集分布于肌管的相邻细胞连接处. 结论BMP-2通过BMPRIA和BMPRII的介导作用诱导MCSC分化为心肌细胞.     

An oxygen release system to augment cardiac progenitor cell survival and differentiation under hypoxic condition

Stem cell therapy has the potential to regenerate heart tissue damaged by myocardial infarction (MI), but it experiences extremely low efficacy. One of the major causes is the inferior cell survival under hypoxic condition of the infarcted hearts. We examined whether an oxygen-releasing system capable of sustainedly supplying oxygen to stem cells would augment cell survival and cardiac differentiation under hypoxic condition mimicking that of the infarcted hearts. The oxygen-releasing system consisted of hydrogen peroxide (H(2)O(2))-releasing microspheres, catalase and an injectable, thermosensitive hydrogel. The microspheres were based on poly(lactide-co-glycolide) (PLGA) and a complex of H(2)O(2) and poly(2-vinlypyrridione) (PVP). The oxygen was generated after the released H(2)O(2) was decomposed by catalase. The hydrogel was designed to improve the retention of microspheres and stem cells in the beating heart tissue during myocardial injection. The oxygen-releasing system was capable of sustainedly releasing oxygen for at least two weeks. The release kinetics was dependent on the ratio of H(2)O(2)/VP. The hydrogel was based on N-isopropylacrylamide (NIPAAm), acrylic acid (AAc), and a macromer hydroxyethyl methacrylate-oligo(hydroxybutyrate) (HEMA-oHB). The hydrogel had a stiffness matching that of the heart tissue and was able to stimulate the cardiosphere-derived cells (CDCs) to differentiate into cardiomyocytes. Under hypoxic condition mimicking that of the infarcted hearts (1% O(2)), CDCs encapsulated in the hydrogel experienced massive cell death. Introduction of oxygen release in the hydrogel significantly augmented cell survival; no cell death was found after seven days of culture, and cells even grew after seven days. Under hypoxic condition, cardiac differentiation of CDCs was completely silenced in the hydrogel, as confirmed at both mRNA and protein levels. However, introduction of oxygen release restored the differentiation. These results demonstrate that the developed oxygen-releasing system has great potential to improve the efficacy of cardiac stem cell therapy.     

5-氮杂胞苷诱导骨髓源性心肌干细胞向心肌分化过程中心肌肌钙蛋白T的表达变化

目的研究5-氮杂胞苷诱导骨髓源性心肌干细胞(MCSC)向心肌分化过程中,心肌肌钙蛋白T(cTnT)的表达变化和超微结构。方法从SD大鼠骨髓间充质干细胞(MMSC)中筛选MCSC,用5-氮杂胞苷诱导向心肌定向分化。取分化后不同时间的细胞作cTnT免疫细胞化学染色,并对结果进行图像分析。透射电镜下观察分化细胞的超微结构。取不同发育期和成熟期的SD大鼠心肌作对比研究。结果用5-氮杂胞苷诱导后2周,细胞内开始表达cTnT;诱导后3周,cTnT表达增强,可见横纹样结构;诱导后4周,cTnT表达明显增强,横纹增多,但排列不规则。诱导后4周的细胞内出现心房粒,可见丰富的粗面内质网和糖原。胚胎11d大鼠的心肌内,横纹样结构较少且排列不规则。新生大鼠心肌内横纹增多,排列较规则。1月龄和3月龄心肌的横纹样结构发达,排列规则。诱导分化后4周的细胞cTnT表达特征与胚胎11d的心肌相似。结论MCSC经5-氮杂胞苷诱导后可分化为心肌细胞,表现为未成熟心肌的结构和功能特征。     

Use of long-term cultured embryoid bodies may enhance cardiomyocyte differentiation by BMP2

Purpose

Human embryonic stem cells (hESCs) can proliferate for a prolonged period and differentiate into cardiomyocytes in vitro. Recent studies used bone morphogenetic protein 2 (BMP2) to generate cardiomyocytes from hESCs, however, all those studies used early embryoid bodies (EBs) and did not retrieve cardiomyocytes with a high yield. In this study, we treated long-term cultured EBs with BMP2 in order to promote differentiation into cardiomyocytes from hESCs.

Materials and Methods

hESC lines, including SNUhES3 and SNUhES4, were used in this study. Undifferentiated hESC colonies were detached to form EBs and cultured for up to 30 days. These long-term cultured EBs were differentiated into cardiomyocytes in serum-containing media. In our protocol, BMP2 was applied for 5 days after attachment of EBs. Cardiac specific markers, beating of differentiated cells and electron microscopic (EM) ultrastructures were evaluated and analyzed.

Results

Compared to 10-day or 20-day EBs, 30-day EBs showed a higher expression level of cardiac specific markers, Nkx2.5 and α-myosin heavy chain (αMHC). Treatment of BMP2 increased expression of cardiac troponin (cTn) I and α-actinin when evaluated at 20 days after attachment of 30-day EBs. Beating of differentiated cells was observed from 7 to 20 days after attachment. Moreover, EM findings demonstrated fine structures such as Z bands in these differentiated cardiomyocytes. These long-term cultured EBs yielded cardiomyocytes with an efficiency of as high as 73.6% when assessed by FACS.

Conclusion

We demonstrated that the use of long-term cultured EBs may enhance differentiation into cardiomyocytes from hESCs when treated with BMP2.     

人脐血间充质干细胞的生物学特性及其成骨成脂肪分化*

背景：目前有关脐血间充质干细胞的生物学特性及分化能力的研究较少。 目的：观察人脐血间充质干细胞的生物学特性,及其向成骨、成脂肪细胞分化的能力。 方法：从不同胎龄脐血中分离间充质干细胞,对其进行原代和传代培养,并诱导其向成骨及成脂肪细胞分化。 结果与结论：倒置相差显微镜下见分离培养的脐血间充质干细胞贴壁生长,呈成纤维细胞样外观,细胞呈螺旋状排列;透射电镜下可见脐血间充质干细胞胞核比例大,细胞器少,为低分化细胞;原代及传代培养的脐血间充质干细胞生长曲线均呈S型,第3,5代细胞增殖能力最强,低胎龄的脐血间充质干细胞集落形成能力最强。流式细胞仪检测结果显示,脐血间充质干细胞稳定表达间充质干细胞相关抗原CD29,CD44 和CD90,不表达造血细胞标志CD34和CD45。成骨诱导后3 周,碱性磷酸酶染色为强阳性,茜素红染色可见大量钙化基质的形成;成脂诱导3周,油红O染色可检测到胞质中脂滴的形成。提示脐血间充质干细胞具有间充质干细胞的形态特征、生长增殖特点及细胞表面标志物等生物学特性,可向成骨细胞及脂肪细胞分化。     

重组增强型绿色荧光蛋白慢病毒载体示踪转染的脐血间充质干细胞移植治疗兔股骨头缺血性坏死

背景：目前国内外已有关于人脐血间充质干细胞移植修复鼠脊髓损伤、脑肿瘤、心肌梗死等的报道,将其在特定的条件下向成骨细胞诱导分化的研究也已有报道,但尚未有将脐血间充质干细胞移植治疗动物骨坏死的研究报道。 目的：观察重组增强型绿色荧光蛋白慢病毒载体示踪转染的脐血间充质干细胞移植修复兔股骨头缺血性坏死的效果。 方法：含骨形态发生蛋白2基因质粒与携带重组增强型绿色荧光蛋白的慢病毒载体与脐血间充质干细胞共培养;制作兔股骨头缺损模型,随机分为3组,正常组未作任何处理,对照组骨缺损未进行填充;实验组骨缺损填充重组增强型绿色荧光蛋白慢病毒载体示踪转染的脐血间充质干细胞;分别于治疗4周和8周时股骨头行影像学和组织学观察。 结果与结论：影像学和组织学检查显示实验组治疗4周时即有明显的成骨反应和新骨形成,8周时基本修复股骨头的骨缺损区;对照组治疗4周时骨缺损为纤维结缔组织填充,8周时股骨头缺损周边骨质硬化,骨缺损处充填纤维结缔组织,股骨头骨小梁紊乱。结果显示重组增强型绿色荧光蛋白慢病毒载体示踪转染的脐血间充质干细胞有较强的诱导成骨作用,可以成功的修复股骨头缺损性坏死。     

过氧化物酶体增殖物激活受体γ促进外源性骨髓间充质干细胞表达Cx43的作用及机制

BACKGROUND:Piglitazone, a peroxisome proliferator-activated receptor γ (PPAR-γ) agonist, has been demonstrated to promote survival and cardiac differentiation of exogenous bone marrow mesenchymal stem cells to improve cardiac function. In this study, we attempted to investigate whether pioglitazone could induce cardiac differentiation of endogenous bone marrow mesenchymal stem cells and improve cardiac function, and meanwhile, probed into the relevant mechanisms. OBJECTIVE:To compare the therapeutic efficacy of pioglitazone combined with bone marrow mesenchymal stem cell transplantation, pioglitazone alone and phosphate buffer solution (PBS) and to investigate the relevant mechanisms. METHODS:Thirty Sprague-Dawley rats with myocardial infarction induced by ligation of the left anterior descending coronary artery were randomized into combined group (combination of bone marrow mesenchymal stem cells and pioglitazone), pioglitazone group and PBS group. Two weeks later, PKH26-labeled bone marrow mesenchymal stem cells in PBS or PBS alone were injected into the local infarct zone in the combined group and the other two groups, respectively. Pioglitazone (3 mg/kg/d) was given by the oral gavage in the combined and pioglitazone groups for continuous 2 weeks after cells transplantation. At 2 weeks after treatment, cardiac functions were evaluated. In addition, expressions of PPAR-γ, connexin 43 and relative factors in transforming growth factor-β1/SMAD signaling pathway were examined in different areas of the left ventricle from each harvested heart. RESULTS AND CONCLUSION:There were no differences in the baseline parameters of cardiac function between the two groups. Two weeks after treatment, left ventricular end-diastolic diameter, left ventricular end-systolic diameter and left ventricular ejection fraction were significantly improved in the combined group compared with the other two groups; the expression of PPAR-γ was significantly increased in different zones of the left ventricle in the combined and pioglitazone groups. In the combined group, there was a significantly higher expression of connexin 43, and the levels of transforming growth factor-β1, SMAD2 and SMAD3 were obviously attenuated in the infarct and marginal zones. However, no differences were found in the above determinants between the pioglitazone and PBS groups. To conclude, pioglitazone cannot induce the differentiation and proliferation of endogenous bone marrow mesenchymal stem cells, but pioglitazone combined with exogenous bone marrow mesenchymal stem cells can improve cardiac function post myocardial infarction. In this process, PPAR-γ might promote the connexin 43 expression in exogenous bone marrow mesenchymal stem cells via the blockade of transforming growth factor-β1/SMAD signaling pathway.     

人工脑膜复合大鼠骨髓间充质干细胞修复心肌梗死

背景：干细胞移植治疗心肌梗死拥有广泛的应用前景,寻求理想的细胞类型和有效的移植方式是提高干细胞治疗效果的关键因素。 目的：探讨人工脑膜复合骨髓间充质干细胞修复心肌梗死的安全性及作用。 方法：采用全骨髓贴壁筛选法分离培养骨髓间充质干细胞,取培养良好的第3代骨髓间充质干细胞经DAPI标记后接种于人工脑膜制备细胞人工脑膜复合物。构建SD大鼠心肌梗死模型,60只大鼠随机数字表法均分为假手术组、心肌梗死组、人工脑膜组、细胞脑膜复合物组。移植4 周后检测心功能参数,Western blot检测心肌组织缝隙连接蛋白43的表达,计算心肌梗死后生存率。 结果与结论：构建心肌梗死模型并移植后4周,细胞脑膜复合物组心脏组织冰冻切片于荧光显微镜下可观察到心肌内少量核蓝染的细胞,表明骨髓间充质干细胞得以存活;细胞脑膜复合物组与心肌梗死组和人工脑膜组相比,左心室功能明显改善,Cx43蛋白的表达上调,生存率增加(P < 0.05)。说明人工脑膜复合骨髓间充质干细胞移植可提高心肌梗死大鼠心脏功能及生存率。     

丹酚酸B及丹参酮ⅡA诱导骨髓间充质干细胞分化为心肌样细胞

背景：目前大多数研究者采用5-氮胞苷诱导骨髓间充质干细胞分化为心肌细胞,存在着一定的不良反应,难以应用于临床。中药丹参本身在临床上广泛用于治疗心血管系统疾病,其主要化学成分为丹酚酸 B和丹参酮ⅡA。 目的：观察丹酚酸B及丹参酮ⅡA联合诱导骨髓间充质干细胞定向分化为心肌样细胞的效果。 方法：取SD大鼠四肢骨骨髓,分离培养骨髓间充质干细胞,应用丹酚酸B、丹参酮ⅡA及二者联合分别对第2代骨髓间充质干细胞定向诱导,不加诱导剂为空白对照组。3 d后各实验组去除诱导培养基,用正常培养基继续培养4周。 结果与结论：空白对照组细胞结蛋白、α-横纹肌肌动蛋白、肌钙蛋白T及缝隙连接蛋白43均为弱阳性或阴性表达。与空白对照组相比,丹酚酸B组,丹参酮ⅡA组,丹酚酸B+丹参酮ⅡA组骨髓间充质干细胞各标记物阳性表达均明显升高,且差异有显著性意义(P < 0.01)。其中,二者联合诱导组各标记物的阳性率均最高。荧光免疫细胞化学鉴定可见诱导组细胞质内结蛋白的表达呈红色,肌钙蛋白T的表达呈绿色,当两者同时被观察时可见其重叠的部位变成黄色。结果显示丹酚酸B及丹参酮ⅡA均可分别诱导骨髓间充质干细胞获得心肌分化表型,且二者联合诱导效果最好。     

诱导多能干细胞移植后对急性心肌梗死小鼠心律的影响

背景：诱导多能干细胞被认为是治疗缺血性心肌病最具前景的一种方法,但其移植的安全性、有效性仍需进一步研究。 目的：探讨诱导多能干细胞移植后对急性心肌梗死小鼠心脏节律产生的影响。 方法：建立ICR小鼠心肌梗死模型并将其随机分为急性心肌梗死组,急性心肌梗死+生理盐水组,急性心肌梗死+诱导多能干细胞组,急性心肌梗死+成纤维细胞组,同时设立正常对照组。各组分别于移植诱导多能干细胞5 min、1周、2周、3周后,应用BL-420生物机能系统检测各组小鼠体表心电图肢体Ⅱ导联心律的变化。免疫组化染色法检测各组小鼠心肌缝隙连接蛋白43的表达,并应用Image Proplus软件进行半定量分析。 结果与结论：与急性心肌梗死组和急性心肌梗死+成纤维细胞组比较,移植2,3周时急性心肌梗死+诱导多能干细胞组小鼠体表心电图Ⅱ导联室性早搏发生率明显减少,梗死心肌缝隙连接蛋白43表达明显增加(P < 0.05),前两组相比差异无显著性意义。结果说明诱导多能干细胞移植2周后可明显减少梗死后小鼠室性早搏发生率,进而改善心肌组织的电活动并增强其电位稳定性,可使小鼠梗死心肌缝隙连接蛋白43的表达增加,而成纤维细胞移植的小鼠中则未出现此现象。     

Enhancement of MSC adhesion and therapeutic efficiency in ischemic heart using lentivirus delivery with periostin

Many approaches have shown beneficial effects of modified mesenchymal stem cells (MSCs) for treatment of infarcted myocardium, but have primarily focused on enhancing the survival of transplanted MSCs. Here, we show the dual benefits of periostin-overexpressing MSCs (p-MSCs) for infarcted myocardium. P-MSCs led to the marked histological and functional recovery of infarcted myocardium by enhancing survival of MSCs and directly preventing apoptosis of cardiomyocytes. Survival of p-MSCs themselves and cardiomyocytes co-cultured with p-MSCs or treated with the conditioned media from p-MSCs was significantly increased under hypoxic conditions. Decreases in adhesion-related integrins were reversed in cardiomyocytes co-cultured with p-MSCs, followed by increases in p-PI3K and Akt, indicating that periostin activates the PI3K pathway through adhesion-related integrins. When p-MSCs were injected into myocardial infarcted rats, histological pathology and cardiac function were significantly improved compared to MSC-injected controls. Thus, periostin might be a new target of therapeutic treatments using MSCs as carriers for infarcted myocardium.     

不同年龄大鼠骨髓源性心肌干细胞生物学特性的比较

目的 研究不同年龄大鼠骨髓源性心肌干细胞(MCSCs)形态和衰老相关指标的差异,探讨年龄因素对MCSCs增殖、存活和向心肌细胞分化的影响. 方法 利用单细胞克隆培养技术从幼年、成年和老年雄性SD大鼠骨髓中筛选MCSCs,透射电镜下观察细胞超微结构改变.SA-β-半乳糖苷酶染色和活性氧(ROS)染色检测细胞衰老变化,流式细胞术分析细胞周期分布.Annexin V/PI双标流式细胞术和Hochest33342染色检测细胞存活和凋亡.用骨形态发生蛋白-2(BMP-2)诱导不同年龄组MCSCs向心肌细胞分化,通过RT-PCR检测诱导后心肌早期转录因子和心肌特异基因的表达,并通过免疫细胞化学染色检测各年龄组细胞经(BMP-2)诱导后细胞内心肌特异性肌钙蛋T(cTnT)表达的变化. 结果 老年组MCSCs核质比减小,胞质内可见髓样小体.随着年龄增长,处于增殖期的MCSCs比例下降,β-半乳糖苷酶和ROS阳性细胞数目增多.老年组存活细胞比例较幼年组降低.用BMP-2诱导后4周,幼年组细胞的Nkx2.5、GATA-4和cTnT、Cx-43 mRNA表达明显,成年组和老年组细胞表达低于幼年组,差异有显著性意义.免疫细胞化学染色显示,BMP-2诱导后幼年组细胞cTnT表达明显,老年组细胞表达较弱. 结论 随着年龄增长MCSCs发生衰老变化,其增殖、存活和向心肌细胞分化能力逐渐下降.     

Recovery of cardiac function mediated by MSC and interleukin-10 plasmid functionalised scaffold

Stem cell transplantation has been suggested as a treatment for myocardial infarction, but clinical studies have yet to demonstrate conclusive, positive effects. This may be related to poor survival of the transplanted stem cells due to the inflammatory response following myocardial infarction. To address this, a scaffold-based stem cell delivery system was functionalised with anti-inflammatory plasmids (interleukin-10) to improve stem cell retention and recovery of cardiac function. Myocardial infarction was induced and these functionalised scaffolds were applied over the infarcted myocardium. Four weeks later, stem cell retention, cardiac function, remodelling and inflammation were quantified. Interleukin-10 gene transfer improved stem cell retention by more than five-fold and the hearts treated with scaffold, stem cells and interleukin-10 had significant functional recovery compared to the scaffold control (scaffold: −10 ± 7%, scaffold, interleukin-10 and stem cells: +7 ± 6%). This improved function was associated with increased infarcted wall thickness and increased ratios of collagen type III/type I, decreased cell death, and a change in macrophage markers from mainly cytotoxic in the scaffold group to mainly regulatory in scaffold, stem cells and interleukin-10 group. Thus, treatment of myocardial infarction with stem cells and interleukin-10 gene transfer significantly improved stem cell retention and ultimately improved overall cardiac function.     

人脐带间充质干细胞分化为心肌细胞的实验研究

目的 探讨人脐带间充质干细胞(MSCs)在体外向心肌细胞分化的能力及移植后对急性心肌梗死大鼠心功能恢复的影响.方法 胶原酶胰酶消化法分离脐带MSCs.取第4-6代脐带干细胞,采用5-氮胞苷诱导,免疫组织化学和免疫荧光法对诱导后细胞进行鉴定.建立大鼠心肌梗死模型,并按完全随机法将其分为2组(n=10):细胞移植组和空白对照组.将培养脐带MSCs移植到大鼠梗死心肌周围,4周后,免疫荧光法鉴定移植细胞,并超声检测心功能改变.结果 体外诱导后,细胞的形态不断发生变化,诱导后的细胞表达心肌特异性α-肌动蛋白、肌球蛋白和肌钙蛋白T,阳性率在50%以上.细胞移植4周后,脐带MSCs在缺血心肌内存活并分化为心肌样细胞,心功能检测显示脐带MSCs移植组大鼠在移植后4周的左心室射血分数[(68.4±15.2)%]比对照组大鼠明显增加[(53.2±13.4)%,P＜0.05].结论 人脐带MSCs能够在体内外分化为心肌样细胞,并能促进心脏功能的恢复.     

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.