胚胎干细胞的心脏应用

心肌梗死期间死亡的心肌细胞将由没有收缩功能的疤痕组织替代,因而极可能引起心力衰竭。对治疗心衰来说,修复死亡或损伤的心肌以及改善心功能仍面临着极大挑战。干细胞移植已在近年来的实验中用于修复损失的心肌。本文总结了近期在心肌损伤动物中实施胚胎干细胞移植的实验结果,并着重介绍对这类特定细胞的研究进展。胚胎干细胞取源于早期哺乳类胚胎的胚芽细胞,属于多功能干细胞。这类细胞具有长期增殖而不分化的能力,或台色够在培养过程中分化成包括心肌细胞在内的所有特殊体细胞。由于胚胎干细胞具有极大的增殖和分化为成熟组织的能力,它们可能成为一种潜在的很有实用价值的细胞来源,可用于对病态心脏的功能心肌再生的细胞治疗。新近的研究表明,在心肌梗死动物模型中,心肌内移植胚胎干细胞或由其分化成的心肌样细胞,能导致已损伤心肌的再生,并改善心脏功能。另外,在病毒性心肌炎小鼠中,静脉输入胚胎干细胞可明显提高生存率和减轻心肌损伤。有关人类胚胎干细胞在体外分化成心肌细胞以及这些细胞的特性,近来已有报道。然而,要在临床能应用人类胚胎干细胞或由其分化成的心肌细胞来治疗晚期心脏疾病,还必须越过大量的伦理、法律和科学上的障碍。     

间充质干细胞的生物学特性及心血管修复潜能的研究进展

间充质干细胞存在于成体组织中,来源于骨髓、脂肪组织等,在体外易分离和培养,是具有塑料粘附性的一群非均质细胞。它们具有分化的潜能,在适当的条件下可分化为心肌和血管。临床前期研究显示,在心脏损伤模型中移植间充质干细胞有利于心肌修复和心血管形成。其作用机制与间充质干细胞再生和旁分泌能力密切相关。在临床应用中,间充质干细胞具有免疫抑制作用,也可用于异体移植。总之,虽然间充质干细胞的研究尚有许多问题亟待解决,但是它在心脏疾病的细胞治疗和组织工程中已显示出广阔的前景。     

培养于生物降解支架膜内的胚胎干细胞可修复小鼠的梗塞心肌

我们以往的研究表明,直接在心肌梗塞（myocardial infarction,MI）动物的心脏缺血区注射胚胎干细胞（embryonic stemceils,ESCs）可以提高其心肌功能,干细胞组织工程学可以使组织再生、修复。本研究旨在观察将ESCs接种到生物降解膜内并移植到梗塞部位的效果。通过结扎小鼠左冠状动脉制作MI模型,将培养3d的带有小鼠ESCs的聚羟基乙酸膜（polyglycolicacid,PGA）移植到心肌缺血及边缘区表面。实验小鼠分成4组：假手术组、MI组、MI＋PGA组、MI＋ESC组,移植操作8周后检测血流动力学和心肌功能。MI组的血压和左心室功能显著降低。与MI组和MI＋PGA组相比,MI＋ESC组的血压和心室功能显著改善,存活率也显著增高,在梗塞区检测到GFP阳性组织,表明ESCs存活,并可能有心肌再生。以上结果表明,移植生物降解膜内的ESCs可修复小鼠梗塞区心肌细胞并提高心脏功能。将ESCs和生物降解材料联合运用可能为修复受损心脏提供一个新的治疗方法。     

IL-6促进小鼠胚胎干细胞多能性并以发育依赖的方式调控心肌分化（英文）

白细胞介素6 (interleukin 6, IL-6)是心脏微环境的重要组成部分。在不同模型中，IL-6通过促进心肌细胞再生帮助心脏修复。胚胎干细胞是心脏修复中心肌再生的良好来源。本研究旨在探讨IL-6对小鼠胚胎干细胞(mouse embryonic stem cells,mESCs)及其心肌分化的影响。IL-6处理mESCs两天，用CCK-8法检测mESCs增殖情况，用实时荧光定量PCR(quantitative real-time PCR, qPCR)检测干性和胚层分化基因mRNA表达水平，用Western blot检测干细胞相关信号通路的磷酸化水平，用siRNA干扰STAT3磷酸化功能。通过检测搏动拟胚体(embryoid bodies, EBs)比例和qPCR检测心脏前体细胞标记物和心肌细胞离子通道mRNA表达水平来评估mESCs的分化能力。从胚胎干细胞分化第1天(EB0)开始使用IL-6中和抗体阻断内源性IL-6的作用，分别在EB7、EB10和EB15检测心肌细胞分化；在EB15用免疫组织化学染色法示踪心肌细胞，并用Western blot检测干细胞相关信号通路的磷酸化情况...     

诱导胚胎干细胞心肌定向分化的方法及其机制

胚胎干细胞是具有分化为各种类型组织细胞潜能的全能干细胞,可在体外大量扩增,细胞因子、激素、诱导剂和细胞内转录因子等可诱导和调控胚胎干细胞进行心肌细胞定向分化．这将使干细胞移植治疗心肌损伤性疾病成为可能。该文介绍胚胎干细胞定向心肌分化的诱导因素及其机制的研究进展。     

诱导骨髓间充质干细胞向心肌细胞分化研究进展

骨髓间充质干细胞(one marrow mesenchymal stem cells, BMSCs)是骨髓内的一类非造血干细胞,具有自我更新和多向分化的潜能。心肌细胞本身不能再生,受损伤的心肌细胞无法通过自身的增殖和分化完成修复。BMSCs在体内外不同的诱导条件下可分化为心肌细胞,应用于缺血性心脏病的治疗,是目前心肌再生治疗的理想种子细胞。本文主要从外界干预诱导、缺氧条件影响、基因转染、临床自体移植方面将近年诱导BMSCs向心肌细胞分化的研究进行综述,以期为今后临床应用BMSCs治疗心肌梗死等心脏疾病提供理论依据。     

干细胞与心肌细胞替代治疗

胚胎干细胞及来源于骨髓、骨骼肌、血管、肝脏、皮肤、脂肪等组织器官的成体干细胞均有多向分化潜能。胚胎干细胞可分化为3个胚层的所有组织细胞。成体干细胞具有可塑性和转分化的潜能。在一定条件下,这些干细胞可被诱导分化为心肌细胞。成年心脏可能存在心肌干细胞,具有增殖和分化为包括跳动性心肌细胞的多种细胞的潜能。因此,干细胞可用于心肌细胞替代治疗,以替代死亡的心肌细胞,改善心脏功能,防治心肌梗塞后心衰、减少心肌重构等症状。本文对干细胞治疗心肌梗塞有关进展及问题作一综述。     

抑制心肌纤维化促进心肌再生治疗慢性心血管疾病

以心肌肥厚、心肌细胞丢失和心肌组织纤维化为特征的心脏组织异常重构是各种慢性心血管疾病的核心病理改变。以组织异常重构,特别是以组织纤维化为靶点,利用小分子化合物如松弛素、KNK437,生物制剂如BCG、抗TLR2抗体或中药复方CFX等改变炎症性质,抑制甚至逆转纤维化不仅可以有效地改善心脏功能,还可为干细胞的动员和生长提供适宜环境,促进心肌再生,是治疗慢性心血管疾病的重要途径。     

心肌球源性细胞在心力衰竭中的应用

冠状动脉或其分支阻塞而引起心肌缺血可导致急性心肌梗死,梗死区域周围形成瘢痕组织后心脏收缩功能下降,心室发生病理性重塑,最终出现充血性心力衰竭。心肌球源性细胞（CDC）是来自心肌的干细胞,在体外可以分化为心肌细胞和血管内皮细胞。在体内可以触发自身心肌细胞增殖和通过旁分泌募集祖细胞。旁分泌介质不但拥有干细胞的作用,且没有细胞移植相关的并发症。临床实验证明了CDC可以促进心肌梗死后的心脏功能的恢复。长期疗效还有待大规模临床试验的验证。     

骨髓间质干细胞向心肌细胞分化的可塑性及应用研究进展

减少心肌缺血后损伤,促进心肌细胞和血管再生是治疗心肌缺血损伤、心力衰竭的重要思路,而干细胞移植为该思路带来了新的曙光。骨髓间质干细胞（-mesenchymal stem cells,MSCs）,也称为骨髓基质细胞,能分化为骨、软骨和脂肪细胞表型。研究表明,MSCs还能分化为内皮细胞、神经细胞、平滑肌细胞、骨骼肌细胞和心肌细胞表型。MSCs具有多向分化的潜能,且自体移植可以避免免疫排斥反应,同时也易于在体外大量扩增。研究显示,MSCs移植能抑制损伤心肌的重塑和改善心肌功能。因此,骨髓间质干细胞移植给人们展示了一个诱入的前景。本文综述了近年来有关MSCs特性的新认识,尤其是MSCs向心肌细胞方向分化的可塑性、影响因素和信号转导机制,以及MSCs治疗心肌梗死的动物实验和临床研究进展。     

Plasticity of mesenchymal stem cells--regenerative medicine for diseased hearts

The phenomenon of regeneration is of growing interest to medical researchers. Until recently this was an area in which research in flatworms and newts predominated, but there is now a proliferation of research concerning regeneration in virtually all of the organs, not only the heart. One of the object is restoration of function to a failing heart through cell transplantation, and there have been many reports seeking donor sources of somatic stem cells, i.e.: stem cells in marrow or skeletal muscle and ES cells, beginning with those in embryonic myocardial cell transplant experiments. In particular, reports of mesenchymal stem cell differentiation into nerve cell, myocardial cell, skeletal muscle cell, and vascular endothelial cell series have drawn attention to cell plasticity, and clinical applications are awaited.     

Cell therapy for ischaemic heart disease: focus on the role of resident cardiac stem cells

Myocardial infarction results in loss of cardiomyocytes, scar formation, ventricular remodelling, and eventually heart failure. In recent years, cell therapy has emerged as a potential new strategy for patients with ischaemic heart disease. This includes embryonic and bone marrow derived stem cells. Recent clinical studies showed ostensibly conflicting results of intracoronary infusion of autologous bone marrow derived stem cells in patients with acute or chronic myocardial infarction. Anyway, these results have stimulated additional clinical and pre-clinical studies to further enhance the beneficial effects of stem cell therapy. Recently, the existence of cardiac stem cells that reside in the heart itself was demonstrated. Their discovery has sparked intense hope for myocardial regeneration with cells that are obtained from the heart itself and are thereby inherently programmed to reconstitute cardiac tissue. These cells can be detected by several surface markers (e.g. c-kit, Sca-1, MDR1, Isl-1). Both in vitro and in vivo differentiation into cardiomyocytes, endothelial cells and vascular smooth muscle cells has been demonstrated, and animal studies showed promising results on improvement of left ventricular function. This review will discuss current views regarding the feasibility of cardiac repair, and focus on the potential role of the resident cardiac stem and progenitor cells. (Neth Heart J 2009;17:199–207.)     

Myocardial regeneration with bone-marrow-derived stem cells

Despite significant therapeutic advances, heart failure remains the predominant cause of mortality in the Western world. Ischaemic cardiomyopathy and myocardial infarction are typified by the irreversible loss of cardiac muscle (cardiomyocytes) and vasculature composed of endothelial cells and smooth muscle cells, which are essential for maintaining cardiac integrity and function. The recent identification of adult and embryonic stem cells has triggered attempts to directly repopulate these tissues by stem cell transplantation as a novel therapeutic option. Reports describing provocative and hopeful examples of myocardial regeneration with adult bone-marrow-derived stem and progenitor cells have increased the enthusiasm for the use of these cells, yet many questions remain regarding their therapeutic potential and the mechanisms responsible for the observed therapeutic effects. In this review article we discuss the current preclinical and clinical advances in bone-marrow-derived stem or progenitor cell therapies for regeneration or repair of the ischaemic myocardium and their multiple related mechanisms involved in myocardial repair and regeneration.     

The role of stem cells in cardiac regeneration

After myocardial infarction, injured cardiomyocytes are replaced by fibrotic tissue promoting the development of heart failure. Cell transplantation has emerged as a potential therapy and stem cells may be an important and powerful cellular source. Embryonic stem cells can differentiate into true cardiomyocytes, making them in principle an unlimited source of transplantable cells for cardiac repair, although immunological and ethical constraints exist. Somatic stem cells are an attractive option to explore for transplantation as they are autologous, but their differentiation potential is more restricted than embryonic stem cells. Currently, the major sources of somatic cells used for basic research and in clinical trials originate from the bone marrow. The differentiation capacity of different populations of bone marrow-derived stem cells into cardiomyocytes has been studied intensively. The results are rather confusing and difficult to compare, since different isolation and identification methods have been used to determine the cell population studied. To date, only mesenchymal stem cells seem to form cardiomyocytes, and only a small percentage of this population will do so in vitro or in vivo. A newly identified cell population isolated from cardiac tissue, called cardiac progenitor cells, holds great potential for cardiac regeneration. Here we discuss the potential of the different cell populations and their usefulness in stem cell based therapy to repair the damaged heart.     

Repair of Ischemic Heart Disease with Novel Bone Marrow-Derived Multipotent Stem Cells

Congestive heart failure is a growing, worldwide epidemic. The major causes of heart failure are related to irreversible damage resulting from myocardial infarction (heart attack). The long-standing axiom has been that the myocardium has a limited capacity for self-repair or regeneration; and the irreversible loss of cardiac muscle and accompanying contraction and fibrosis of myocardial scar tissue, sets into play a series of events, namely, progressive ventricular remodeling of nonischemic myocardium that ultimately leads to progressive heart failure. The loss of cardiomyocyte survival cues is associated with diverse pathways for heart failure, underscoring the importance of maintaining the number of viable cardiomyocytes during heart failure progression. Currently, no medication or procedure used clinically has shown efficacy in replacing the myocardial scar with functioning contractile tissue. Therefore, given the major morbidity and mortality associated with myocardial infarction and heart failure, new approaches have been sought to address the principal pathophysiologic deficits responsible for these conditions, resulting from the loss of cardiomyocytes and viable blood vessels. Recently, the identification of stem cells from bone marrow capable of contributing to tissue regeneration has ignited significant interest in the possibility that cell therapy could be employed therapeutically for the repair of damaged myocardium. In this review, we will discuss the currently available bone marrow-derived stem progenitor cells for myocardial repair and focus on the advantages of using recently identified novel bone marrow-derived multipotent stem cells (BMSC)     

Mesenchymal stem cells are superior to angiogenic growth factor genes for improving myocardial performance in the mouse model of acute myocardial infarction

Summary Both cell therapy and angiogenic growth factor gene therapy have been applied to animal studies and clinical trials. Little is known about the direct comparison between cell therapy and angiogenic growth factor gene therapy. The goal of this study was to compare the effects of human bone marrow-derived mesenchymal stem cells (hMSCs) transplantation and injection of angiogenic growth factor genes in a model of acute myocardial infarction in mice. The hMSCs were obtained from adult human bone marrow and expanded in vitro. The purity and characteristics of hMSCs were identified by flow cytometry and immunophenotyping. Immediately after ligation of the left anterior descending coronary artery in male severe combined immunodeficient (SCID) mice, culture-expanded hMSCs or angiogenic growth factor genes were injected intramuscularly at the left anterior free wall. The engrafted hMSCs were positive for cardiac marker, desmin. Infarct size was significantly smaller in the hMSCs-treated group than in the angiopoietin-1 (Ang-1) or vascular endothelial growth factor (VEGF)-treated group at day 28 after infarction. hMSCs transplantation was better in decreasing left ventricular end-diastolic dimension and increasing fractional shortening than Ang1 or VEGF gene therapy. Capillary density was markedly increased after hMSCs transplantation than Ang1 and VEGF gene therapy. In conclusion, intramyocardial transplantation of hMSCs improves cardiac function after acute myocardial infarction through enhancement of angiogenesis and myogenesis in the ischemic myocardium. hMSCs are superior to angiogenic growth factor genes for improving myocardial performance in the mouse model of acute myocardial infarction. Transplantation of MSCs may become the future therapy for acute myocardial infarction for myocardial regeneration.     

Integrin β‐3 is required for the attachment,retention and therapeutic benefits of human cardiospheres in myocardial infarction

Cardiovascular diseases remain the leading causes of death worldwide. Stem cell therapy offers a promising option to regenerate injured myocardium. Among the various types of stem cells, cardiosphere cells represent a mixture of intrinsic heart stem cells and supporting cells. The safety and efficacy of cardiosphere cells have been demonstrated in recent clinical trials. Cell–matrix interaction plays an important role in mediating the engraftment of injected stem cells. Here, we studied the role of integrin β‐3 in cardiosphere‐mediated cell therapy in a mouse model of myocardial infarction. Our results indicated that inhibiting integrin β‐3 reduced attachment, retention and therapeutic benefits of human cardiospheres in mice with acute myocardial infarction. This suggests integrin β‐3 plays an important role in cardiosphere‐mediated heart regeneration.     

细胞药物的研发现状——细胞药物连载之三

近年来,细胞药物的研究受到了国内外重视。特别是干细胞药物,已成为世界各国竞相研究的热点领域,但各国的干细胞药物绝大多数仍处于研究阶段,全球真正上市的干细胞药物很少。目前正在研发的干细胞药物主要集中在治疗慢性疾病（关节炎、糖尿病和癌症等）和心脏相关疾病（心肌梗死、心脏衰竭等）。一些传统体细胞药物（软骨细胞、心肌细胞、胰岛细胞等）和免疫细胞药物已在临床应用。     

Timing of transplantation of autologous bone marrow derived mesenchymal stem cells for treating myocardial infarction

It is still unclear whether the timing of intracoronary stem cell therapy affects the therapeutic response in patients with myocardial infarction.The natural course of healing the infarction and the presence of putative homing signals within the damaged myocardium appear to favor cell engraftment during the transendothelial passage in the early days after reperfusion.However,the adverse inflammatory environment,with its high oxidative stress,might be deleterious if cells are administered too early after reperfusion.Here we highlight several aspects of the timing of intracoronary stem cell therapy.Our results showed that transplantation of bone marrow mesenchymal stem cells at 2 4 weeks after myocardial infarction is more favorable for reduction of the scar area,inhibition of left ventricular remodeling,and recovery of heart function.Coronary injection of autologous bone marrow mesenchymal stem cells at 2 4 weeks after acute myocardial infarction is safe and does not increase the incidence of complications.     

Myocardial regeneration potential of adipose tissue-derived stem cells

Various tissue resident stem cells are receiving attention from basic scientists and clinicians as they hold promise for myocardial regeneration. For practical reasons, adipose tissue-derived stem cells (ASCs) are attractive cells for clinical application in repairing damaged myocardium based on the following advantages: abundant adipose tissue in most patients and easy accessibility with minimally invasive lipoaspiration procedure. Several recent studies have demonstrated that both cultured and freshly isolated ASCs could improve cardiac function in animal model of myocardial infarction. The mechanisms underlying the beneficial effect of ASCs on myocardial regeneration are not fully understood. Growing evidence indicates that transplantation of ASCs improve cardiac function via the differentiation into cardiomyocytes and vascular cells, and through paracrine pathways. Paracrine factors secreted by injected ASCs enhance angiogenesis, reduce cell apoptosis rates, and promote neuron sprouts in damaged myocardium. In addition, Injection of ASCs increases electrical stability of the injured heart. Furthermore, there are no reported cases of arrhythmia or tumorigenesis in any studies regarding myocardial regeneration with ASCs. This review summarizes the characteristics of both cultured and freshly isolated stem cells obtained from adipose tissue, their myocardial regeneration potential, and the underlying mechanisms for beneficial effect on cardiac function, and safety issues.