Mesenchymal stem cell transplantation for treatment of myocardial infarction:Transplantation strategy and efficacy evaluation

doi:10.3969/j.issn.2095-4344.2013.14.027

Abstract

Abstract:

BACKGROUND: Numerous studies have demonstrated that mesenchymal stem cells exhibit great potential in treatment of myocardial infarction.
OBJECTIVE: To review the strategies of mesenchymal stem cell transplantation for treatment of myocardial infarction and evaluate the therapeutic effects after cell transplantation.
METHODS: A computer-based online retrieval of PubMed, CNKI, CQVIP and FMJS databases was performed to search papers regarding therapeutic effects of mesenchymal stem cell transplantation with key words “mesenchymal stem cell; function, angiogenesis or survival” in Chinese and English. Papers describing different transplantation methods to enhance heart function recovery, angiogenesis and survivalrate after mesenchymal stem cell transplantation were searched. In the same research field, papers published recently or in high-impact journals were selected. A total of 220 papers were acquired in the initial retrieval. According to inclusion criteria, 20 papers were suitable for final analysis.
RESULTS AND CONCLUSION: Stem cell in vitro expansion and differentiation followed by transplantation have emerged as a promising alternative therapeutic approach for cardiovascular disease, but existing strategies are restricted by low cell engraftment, differentiation and survival. In addition, it is also important that reasonable methods should be adopted to accurately assess transplantation efficacy for determining later transplantation strategies. Heart function reconstruction, myocardial fibrosis inhibition and angiogenesis are mainly used as evaluation criteria. From the global to the local function and from the right single imaging to “multimodality noninvasive imaging” are two new developments. How to choose appropriate transplantation strategies and efficacy evaluation method to enhance the efficacy of mesenchymal stem cell therapy needs further studies.

Key words: stem cells, stem cell academic discussion, mesenchymal stem cells, myocardial infarction, transplantation, functional reconstruction, efficacy, myocardial homing, myocardial fibrosis, other grants- supported paper

CLC Number:

R318

Chen Ling-ling, Yin Li-xue. Mesenchymal stem cell transplantation for treatment of myocardial infarction:Transplantation strategy and efficacy evaluation[J]. Chinese Journal of Tissue Engineering Research, 2013, 17(14): 2656-2660.

Figures/Tables 1

2.1 纳入文献基本情况文献[1]研究了间充质干细胞移植治疗心肌梗死现状，文献[2-15]研究了间充质干细胞移植分别联合低氧预处理、基因治疗、细胞因子及生物材料几方面治疗心肌梗死的情况，文献[12,16-20]介绍了评价间充质干细胞移植疗效的现状及进展。 2.2 结果描述 2.2.1 增强间充质干细胞的移植策略大量研究者尝试在移植不同阶段采用恰当的、不同的移植策略如移植前联合低氧预处理、基因转染、细胞因子预处理、移植过程中联合细胞因子、生物医学材料等方式以期增强移植疗效。低氧预处理：在治疗心肌梗死时，间充质干细胞必须适应从体积分数21%O2的培养环境到低于体积分数1% O2的缺血组织中生长，而多数研究显示此时间充质干细胞的存活停留能力极差。Wang等[2]研究认为体外缺氧预处理间充质干细胞能保护其移植后免受缺血环境的致死性缺氧损害和增加修复缺血心肌的能力。此外，体外预处理间充质干细胞也能增强其增殖能力和旁分泌/自分泌信号。然而，现有缺氧预处理间充质干细胞治疗心肌梗死的研究结果并不全然相同，可能原因是氧体积分数、暴露时间和传代条件不同。基因治疗：间充质干细胞为转基因的良好载体，通过体外修饰可以安全灵活地调节目的基因过表达或抑制而提高其在恶劣心肌缺血微环境下的生存和心肌分化率或释放基因表达产物而增强移植疗效。常用修饰间充质干细胞的治疗性基因有以下4方面：第一，丝氨酸/苏氨酸蛋白激酶、糖原合酶激酶3、肿瘤坏死因子受体等基因修饰间充质干细胞通过启动相关调节因子来促进增殖或减少凋亡而增加其存活率[3]；第二，血管内皮生长因子[4]、血管紧张素等基因修饰间充质干细胞促进缺血心肌局部血管新生；第三，趋化因子受体、基质细胞衍生因子1等基因修饰间充质干细胞以补充内源性归巢因子促进其归巢到缺血心肌；第四，Wnt 11基因等修饰间充质干细胞通过上调GATA-4等表达促其向心肌分化[5]。有研究显示趋化因子受体、糖原合酶激酶3过表达，不但增加间充质干细胞的移植存活率，还可诱导其向心肌分化和促进缺血心肌局部血管新生[6]。为最大化干细胞的抗凋亡、诱导心肌分化和促血管新生效应，Jiang等[7]使间充质干细胞共表达转染丝氨酸/苏氨酸蛋白激酶和血管紧张素两种基因，发现不仅提高移植后细胞在鼠急性心肌梗死模型的长期存活率，也促其向心肌和内皮细胞分化。但目前如何实现永久、可逆的、特定的基因修饰间充质干细胞并促其归巢到心肌仍是待解决的问题。细胞因子：近年研究发现一些细胞因子能用于促进间充质干细胞归巢到缺血心肌或体外诱导其向心肌细胞分化。心肌梗死后触发释放参与自身修复的多种细胞因子和趋化因子到外周血并发出干细胞动员信号，其中内源性干细胞归巢因子基质细胞衍生因子1在促使干细胞归巢到缺血/缺氧心肌中起关键作用，但其体内表达时间短、水平低，且与心肌梗死后超急性期炎症反应时间窗重叠；粒细胞集落刺激因子是临床常用增加循环中性粒细胞数的外源性动员因子。为增加间充质干细胞的心肌归巢量，陈鑫等和Zhang等[8]分别尝试移植时补充基质细胞衍生因子1和增加粒细胞集落刺激因子，发现不仅能显著增加心肌梗死区间充质干细胞归巢量和新生毛细血管密度，还能促进心功恢复。Yu等[9]研究显示联合粒细胞集落刺激因子和促红细胞生成素注射能增加间充质干细胞表达基质金属蛋白酶而促进细胞迁移，提示要最大化心肌梗死后粒细胞集落刺激因子的归巢能力可考虑联合其他因子。Pasha等[10]体外用基质细胞衍生因子1诱导间充质干细胞心肌化，发现预处理细胞植入体内能高表达心肌标志物和明显改善心功，提示心肌化间充质干细胞较未处理间充质干细胞移植到心脏可能带来更大程度的心肌再生。诱导间充质干细胞心肌分化的细胞因子种类众多，但如何实现间充质干细胞最大程度导分化而又不影响活力还需进一步研究。生物医学材料：已有研究显示生物医学材料中的生物材料和微泡在干细胞治疗心肌梗死中具有一定的应用潜力。Jawad等[11]认识到良好的生物材料在干细胞移植中的重要性，认为其不仅可以支持干细胞，也能影响其存活、成熟及与宿主细胞的整合。Jin等[12]对比间充质干细胞联合弹性可降解聚乳酸己内酯支架和单纯干细胞移植治疗心肌梗死的疗效，发现联合支架移植组的心肌标志物表达更多、心肌梗死面积减少更明显。Schantz等[13]通过一种生物支架来可控性脉冲释放血管内皮生长因子、骨形态发生蛋白6等多种细胞因子以控制间充质干细胞的归巢量，证实通过生物支架直接募集内源性间充质干细胞修复损伤组织的可能性。基于第二代超声对比剂和心肌声学造影发展起来的超声辐照微泡破坏技术，其产生的空化效应是近几年的研究热点。Zhong等[14]发现利用该效应改变心肌微环境而增加干细胞归巢率、新生血管密度和提高心功恢复，Otani等[15]则发现该技术可以提高siRNA对间充质干细胞的转染效率，证实其用于干细胞基因修饰的可行性。目前生物医学材料用于干细胞移植治疗心肌梗死仅处于实验研究阶段，其生物相容性、安全性、有效性及时效性等还有待确认。 2.2.2 间充质干细胞移植后的疗效评估大量的临床前实验通过间充质干细胞治疗心肌梗死希望实现以下3个目标：心脏结构功能重建(心肌再生、心肌再同步及功能性恢复)、血管新生和减少心肌重塑，后者也成为目前间充质干细胞移植疗效和移植策略优劣的评估指标。心脏结构功能重建：非侵入性显像如放射性核素显像、计算机断层扫描(CT)、磁共振成像(MRI)和超声心动图在评价这方面疗效起重要作用，其中以后两者应用最多。常规超声心动图主要用于研究间充质干细胞移植后的心功改变，多以左室容积和射血分数[12]为最常用整体心功指标，如Wolf等[16]用常规超声证实静脉移植间充质干细胞到心肌梗死猪后可见左室短轴缩短率和心脏同步性增加。然而，近年来多数学者认为评价细胞移植后局部心功的改变可能更有意义，因而实时三维超声和应变率显像技术等定量评价局部心功的超声新技术开始尝试用于干细胞的心脏再生研究中。Herbots等[17]将应变率显像首次用于测量经冠脉移植前体细胞治疗心肌梗死的局部心功改变，发现移植组在心肌梗死室壁的二尖瓣瓣环纵向位移显著高于对照组。Das等[18]则采用常规超声、组织速度成像技术及应变率显像技术多种超声显像方法来综合评价干细胞治疗鼠心肌梗死后的心功变化。Cine MRI是评价心脏解剖结构和整体心功改变的常用心脏成像方式，已有研究用其来评估细胞移植后心功和重塑的改变情况，如Grauss等[19]显示鼠心肌梗死模型移植人间充质干细胞后左室功能改善和重塑减轻。此外，磁共振波谱成像能提供心肌能量研究，Feygin等利用该技术发现心肌梗死边缘区直接注射间充质干细胞能显著提高心肌能量，并证实这些生物能量提高是依赖心脏局部和整体收缩功能增强。随着干细胞治疗心肌梗死的深入研究，不仅促使研究者从心脏整体功能到局部功能的疗效评估过渡，也促使多种医学显像技术集合，即“非侵入性融合显像”的诞生。“非侵入性融合显像”用于干细胞治疗的基础研究中具有显著的优势，不但可以通过了解体内细胞治疗所带来的解剖和功能效果而减少动物使用数量，且能连续、定量的评价疾病治疗后进展情况，而达到单独某种显像技术无法实现的测量水平，如Amado等[20]使用心脏CT联合MRI追踪技术研究梗死猪移植间充质干细胞后心肌再生，前者显示心内膜下组织边缘增厚和心肌梗死面积减少，后者测量证实该区域心肌收缩功能恢复。血管新生及心肌纤维化减轻：研究表明间充质干细胞移植后可抑制心肌梗死后左室重塑并促进心区及周围毛细血管新生。目前多用病理基础技术来定量评价毛细血管新生和心肌纤维化减轻程度，如前者用苏木精-伊红染色后进行光电镜观察、通过CD146、CD31、CD34或血管内皮生长因子染色后进行免疫组化或用RT-PCR法检测血管内皮生长因子mRNA的表达等，后者用苏木精-伊红染色、Van Gieson染色、Masson染色等结合图像分析仪定量心肌组织胶原含量以评定心肌纤维化情况。目前影像学方法尚无法实现两者的定量评价。"

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