干/祖细胞在肺动脉高压中的研究进展

肺动脉高压是一类病死率极高、严重威胁人类健康的临床综合征，其病理特征以肺动脉内皮细胞损伤为始动因素，平滑肌细胞、成纤维细胞等参与肺血管重塑，最终导致不同程度右心功能衰竭。干/祖细胞具有多向分化潜能，即通过分化成为特定细胞参与肺血管重塑，也可以修复或替换受损肺血管结构，参与肺血管修复。本文对不同类型干/祖细胞在PAH肺血管重塑过程中的作用及以干/祖细胞为基础的PAH细胞移植治疗进行综述。     

外膜滋养血管新生的病理机制

<正>外膜是集成血管壁功能的主要监管机构,可以充当生物"中央处理器",外膜分布有多种细胞能够发挥强效免疫调节作用,包括成纤维细胞、巨噬细胞、树突状细胞、祖细胞、滋养血管以及肾上腺素能神经。成纤维细胞的激活能够促进巨噬细胞、树突状细胞、祖细胞作用的发挥,创建一个持久的炎症反应的微环境,引起滋养血管的新生〔1〕。由于研究血管滋养管的适合方法有限,观察动脉壁上微血管新生的病理生理环境也知之甚少。本文就今年来关于外膜滋养血管(VV)新生的生理、病理     

血管外膜在冠状动脉粥样硬化发病机制中的新进展

冠状动脉粥样硬化是一种慢性动脉炎症性疾病,影响着冠状动脉的结构和功能,进而导致一系列心血管事件。近年来,随着对动脉粥样硬化发病机制的深入研究,血管外膜在其中的作用逐渐受到关注。血管外膜由成纤维细胞、祖细胞、免疫细胞、微血管和肾上腺素能神经等构成,其外包绕着血管周围脂肪组织。血管外膜各类组织和细胞具有高度代谢活性,能够"从外向内"调控整个血管壁的结构和功能,参与着动脉粥样硬化的形成。文章综述了血管外膜在冠状动脉粥样硬化发病机制中的新进展。     

胃干细胞

干细胞研究于1999年度和2000年度连续两次被美国科学杂志评为世界十大科技成果之一,成为当今世界生命科学研究最前沿、最活跃的领域之一.由于(1)干细胞有自我更新和向多种细胞分化的能力,将为组织器官再生提供新的细胞来源途径;(2)目前研究认为,成年组织含有三个不同层次的细胞,即干细胞、祖细胞和成熟细胞,探讨疾病情况下干细胞、祖细胞的分化将很可能从细胞发育学的角度阐明一些疾病的发病机制;(3)研究如何促进干/祖细胞想所在组织的成熟细胞分化将可能成为疾病防治研究的新思路.因此,干/祖细胞研究具有重要的理论意义和潜在的临床应用价值.消化系统由多个器官组成,近年来国外对消化系统干/祖细胞的研究较多,为了了解国外消化系统干/祖细胞的研究状况、促进我国在该领域的研究,我们对消化系统主要器官胃、肠、肝脏及胰腺的干/祖细胞的研究文献进行了综述.     

内皮祖细胞生物学特性及其在心血管系统中的作用

血管内皮祖细胞(endothelial progenitor cells,EPCs)是指具有特异性归巢于血管新生组织并能分化增殖为成熟内皮细胞的一群干/祖细胞,是中胚层卵黄囊血岛原血干细胞(hemangioblast)向内皮细胞分化过程中的一个过渡阶段.该细胞在出生后的新生血管发生/生成中起重要作用.实验证实成人外周血存在能分化为血管内皮细胞的EPCs[1],并且由此生成的内皮细胞还在缺血性疾病和创伤愈合中发挥重要作用[2].     

血管祖细胞在烟雾病发病机制中的研究进展

烟雾病是一种病因不明、进展性、闭塞性并伴有异常侧支血管网形成的脑血管疾病,其发病机制至今未明,但目前认为与多种血管祖细胞有关.平滑肌祖细胞的增殖和迁移是血管闭塞的主要原因,内皮祖细胞相关的血管新生也是目前发病机制的研究热点,同样参与构成血管的周细胞和间充质干细胞对维持血管结构完整有着重要意义.该文拟综述以上几种血管祖细...     

外膜炎症诱发载脂蛋白E基因敲除鼠冠状动脉粥样硬化病灶

研究载脂蛋白E基因敲除(载脂蛋白E°)小鼠冠状动脉内粥样硬化病灶的分布、组成与动脉外膜炎症的关系.取载脂蛋白E°小鼠心脏作连续切片,Movat法染色,追踪冠状动脉主干及其心肌内的小分支;寻找病灶,观察病灶内组成,分析其分布规律.复制小鼠股动脉外膜无菌性炎症模型,用免疫组织化学方法检查内膜粘附分子的表达.结果发现,冠状动脉主干内有延伸病灶,在主干以下分支(包括心肌内小分支)内有在原位生成的病灶,在两类病灶相邻的外膜有炎性细胞浸润,外膜炎症面积大于动脉粥样硬化病灶累及的内膜面积,亦发现一些部位血管外有炎性细胞浸润,而尚无病灶形成.原位病灶均发生于心室壁,大的原位病灶多发生在左室壁心肌内、血管分支处和乳头肌附近的冠状动脉分支内.股动脉外膜炎症可诱发内膜表达细胞间粘附分子1和血管细胞粘附分子1,同时伴白细胞的附壁.以上提示血管外膜炎症是小鼠冠状动脉内病灶的一个始动环节.     

脐带血于细胞移植的进展

近年来,美国和法国的专家们合作,从实验和临床两方面研究脐带血于细胞移植治疗某些血液病的可能性,并已取得引人注目的结果,现就其进展介绍如下。前言在成人的循环血液中可以发现造血干/祖细胞,但其数量只为骨髓的10～100分之一。在个体发育中,干/祖细胞最早发生于卵黄囊,稍后在肝脏,然后发生于胎儿骨髓内。人的脐带血一般被抛弃不用,但在试管内作克隆试验证明其内含有造血干/祖细胞,     

基质细胞衍生因子1/CXC化学趋化因子受体4信号通路:干细胞治疗缺血性疾病的新靶点

越来越多的证据表明骨髓来源的干/祖细胞(干细胞),如内皮祖细胞(endothelial progenitor cell,EPC)和间充质干细胞(mesenchymal stem cell,MSC),在出生后血管发生的生理以及病理生理过程中起重要作用[1-2]。这些细胞能转化为脉管的结构成分、介导细胞     

内皮祖细胞对血管紧张素Ⅱ诱导的血管平滑肌细胞表型转化的影响

目的 观察内皮祖细胞对血管紧张素Ⅱ诱导的血管平滑肌细胞表型转化的影响.方法 采用6%羟乙基淀粉沉降法和密度梯度离心法分离人脐血单个核细胞,EGM-2细胞培养基进行培养,诱导单个核细胞贴壁向内皮祖细胞分化.采用荧光显微镜双染色、流式细胞术鉴定内皮祖细胞,间接免疫荧光检测血管平滑肌细胞标志物平滑肌α-肌动蛋白、钙调节蛋白的表达,采用逆转录聚合酶链反应和免疫印迹检测早期内皮祖细胞条件培养液、晚期内皮祖细胞条件培养液以及人脐静脉内皮细胞条件培养液对血管紧张素Ⅱ诱导的血管平滑肌细胞收缩表型标志基因平滑肌α-肌动蛋白以及合成表型标志基因骨桥蛋白表达变化的影响.结果 与对照组比较,血管紧张素Ⅱ(10-6mmol/L)诱导血管平滑肌细胞增殖48 h后,平滑肌α-肌动蛋白mRNA和蛋白表达明显减少,而骨桥蛋白mRNA和蛋白表达明显增加,提示血管平滑肌细胞从收缩表型向合成表型转化;与血管紧张素Ⅱ组比较,早期内皮祖细胞条件培养液、晚期内皮祖细胞条件培养液以及人脐静脉内皮细胞条件培养液处理后均不同程度抑制血管紧张素Ⅱ诱导的平滑肌α-肌动蛋白表达减少和骨桥蛋白表达增加,其中以早期内皮祖细胞条件培养液的抑制效果最明显.结论 内皮祖细胞能够抑制血管紧张素Ⅱ诱导的血管平滑肌细胞从收缩表型向合成表型转化.     

The role of stem cells in atherosclerosis

Accumulating evidence indicates the involvement of stem cells and/or progenitors in the development of arteriosclerosis, including transplant arteriosclerosis, angioplasty-induced restenosis, vein graft atherosclerosis and spontaneous atherosclerosis. Recently, it was demonstrated that stem/progenitor cells existing in the circulation and adventitia contribute to endothelial repair and smooth muscle cell (SMC) accumulation. Atherosclerosis can be initiated by endothelial death in specific areas, e.g. bifurcation regions, and subsequent replacement by stem/progenitor cells. Meanwhile, progenitor cells from blood and the adventitia migrate into the intima where they proliferate and differentiate into neo-SMC. Stem/progenitor cells are responsible for the formation of atherosclerotic lesions, which appear as an inflammatory disease. Thus, these cells may be a source of endothelial cells and SMC, and might have implications for cellular, genetic, and tissue engineering approaches to vascular disease.     

The adventitia: a dynamic interface containing resident progenitor cells

Conventional views of the tunica adventitia as a poorly organized layer of vessel wall composed of fibroblasts, connective tissue, and perivascular nerves are undergoing revision. Recent studies suggest that the adventitia has properties of a stem/progenitor cell niche in the artery wall that may be poised to respond to arterial injury. It is also a major site of immune surveillance and inflammatory cell trafficking and harbors a dynamic microvasculature, the vasa vasorum, that maintains the medial layer and provides an important gateway for macrophage and leukocyte migration into the intima. In addition, the adventitia is in contact with tissue that surrounds the vessel and may actively participate in exchange of signals and cells between the vessel wall and the tissue in which it resides. This brief review highlights recent advances in our understanding of the adventitia and its resident progenitor cells and discusses progress toward an integrated view of adventitial function in vascular development, repair, and disease.     

Adventitial biology: differentiation and function

Recent evidence indicates that stem/progenitor cells are present in the adventitia and participate in vascular repair and the formation of neointimal lesions in severely damaged vessels. Data have also demonstrated that these resident stem/progenitor cells could differentiate into endothelial or smooth muscle cells in response to different stimuli. Under pathological conditions, adventitial inflammation results in releasing a panel of cytokines, such as stromal cell-derived factor-1 and tumor necrosis factor-α, that may lead to local stem/progenitor mobilization and differentiation. Overall, these data support the impact of the adventitial progenitors in pathophysiological processes of lesion development in the arterial wall. In the present review, we aim to summarize the data concerning the presence of the resident stem cells and discuss the pathological impact of the adventitia in vascular diseases. We will also discuss the possible signal pathways orchestrating stem cell differentiation toward vascular lineage and highlight controversial issues related to the role of adventitial progenitors.     

Adventitial progenitor cells contribute to arteriosclerosis

Accumulating evidence indicates the involvement of vascular progenitor cells in the development of arteriosclerosis, including transplant arteriosclerosis, angioplasty-induced restenosis, vein graft atherosclerosis, and spontaneous atherosclerosis. Recently, it was found that the adventitia of the arterial wall contains a large number of progenitor cells, which can differentiate into smooth muscle cells in vitro and in vivo. These progenitor cells were able to migrate from the adventitia into the intima, where they accumulate to contribute to atherosclerotic lesions of vein grafts in apoE-deficient mice. Thus, these cells may be a source of smooth muscle cells and might have implications for cellular, genetic, and tissue engineering approaches to vascular disease.     

Characterisation of progenitor cells in human atherosclerotic vessels

Recent data from animal models has demonstrated that both endothelial and smooth muscle progenitor cells contribute to the development of atherosclerosis. However, no data exists concerning the presence of progenitor cells in human atherosclerotic vessels. In the present study, a range of normal and atherosclerotic human arteries were collected from patients undergoing coronary artery bypass surgery. Segments of internal mammary artery (normal controls), and segments of proximal ascending aorta with visible fatty streak were analysed. Immunofluorescence was used to detect a panel of progenitor cell markers. A small number of progenitor cells were identified within neointimal lesions and the adventitia with variable expression of CD34, stem cell antigen (Sca-1), c-kit and VEGF receptor 2 (VEGFR2) markers, but no CD133 expression. On average there was a two- to three-fold increase in progenitor cell number in the adventitia of atherosclerotic vessels compared with normal controls, with a significant difference (p<0.05) in the frequency of cells expressing VEGFR2. Thus, we have provided the first evidence that vascular progenitor cells exist within atherosclerotic lesions, and identified an increased number of progenitor cells in the adventitia of human atherosclerotic vessels. These cells might be a source for smooth muscle cells (SMCs), macrophages and endothelial cells (ECs) that form atherosclerotic lesions.     

Flt3 Ligand prolongs survival of CD34+++ human umbilical cord blood myeloid progenitors in serum-depleted culture medium

 Flt3 Ligand (L), a newly identified stimulating/co-stimulating cytokine for hematopoietic stem and progenitor cells, was assessed for its capacity, in comparison to that of steel factor, to prolong the survival in culture of hematopoietic stem and progenitor cells from CD34⁺⁺⁺ human cord blood. The addition of Flt3-L to serum-depleted cultures significantly prolonged the survival of high-proliferative-potential colony-forming cells (HIPP-CFC) as well as that of multipotential (CFU-GEMM) and granulocyte-macrophage (CFU-GM) progenitor cells. The concentrations of Flt3-L necessary for these effects were similar to those of SLF, and low concentrations of Flt3-L and SLF which were inactive when used alone were active in these effects when used together. These results may be of practical value for short-term storage, treatment and/or transport of purified population of cord blood stem and progenitor cells. Received: 22 May 1995 / Accepted: 15 November 1995     

Resident Vascular Progenitor Cells��Diverse Origins, Phenotype, and Function

The fundamental contributions that blood vessels make toward organogenesis and tissue homeostasis are reflected by the considerable ramifications that loss of vascular wall integrity has on pre- and postnatal health. During both neovascularization and vessel wall remodeling after insult, the dynamic nature of vascular cell growth and replacement vitiates traditional impressions that blood vessels contain predominantly mature, terminally differentiated cell populations. Recent discoveries have verified the presence of diverse stem/progenitor cells for both vascular and non-vascular progeny within the mural layers of the vasculature. During embryogenesis, this encompasses the emergence of definitive hematopoietic stem cells and multipotent mesoangioblasts from the developing dorsal aorta. Ancestral cells have also been identified and isolated from mature, adult blood vessels, showing variable capacity for endothelial, smooth muscle, and mesenchymal differentiation. At present, the characterization of these different vascular wall progenitors remains somewhat rudimentary, but there is evidence for their constitutive residence within organized compartments in the vessel wall, most compellingly in the tunica adventitia. This review overviews the spectrum of resident stem/progenitor cells that have been documented in macro- and micro-vessels during developmental and adult life and considers the implications for a local, vascular wall stem cell niche(s) in the pathogenesis and treatment of cardiovascular and other diseases.     

Cell Cycle Entry of Hematopoietic Stem and Progenitor Cells Controlled by Distinct Cyclin-Dependent Kinase Inhibitors

The therapeutic promise of hematopoietic stem cells in medicine has been expanded as broader differentiation potential of the cells has gained experimental support. However, hurdles for stem cell manipulation in vitro and tissue regeneration in vivo remain because of lack of the molecular biology of the stem cells. In particular, elucidating the molecular control of cell cycle entry is necessary for rational stem cell expansion strategies. Understanding how the stem and progenitor cell populations are controlled by negative regulators of cell cycle entry may provide one basis for manipulating these cells. In this mini-review, we focus on the rationale of targeting the cyclin-dependent kinase inhibitors (CKIs) in stem cell biology. Two CKI members, p21(Cip1/Waf1) (p21) and p27kip1 (p27), have been shown to govern the pool sizes of hematopoietic stem and progenitor cells, respectively. Of note, their inhibitory roles in primitive hematopoietic cells are distinct from the action of the inhibitory cytokine, transforming growth factor-beta1 (TGF-beta1). Therefore, the distinct roles of p21, p27, and TGF-beta1 in hematopoietic cells offer attractive targets for specific manipulation of the stem or progenitor cell populations in therapeutic strategies.     

Isolation and expansion of functionally-competent cardiac progenitor cells directly from heart biopsies

The adult heart contains reservoirs of progenitor cells that express embryonic and stem cell-related antigens. While these antigenically-purified cells are promising candidates for autologous cell therapy, clinical application is hampered by their limited abundance and tedious isolation methods. Methods that involve an intermediate cardiosphere-forming step have proven successful and are being tested clinically, but it is unclear whether the cardiosphere step is necessary. Accordingly, we investigated the molecular profile and functional benefit of cells that spontaneously emigrate from cardiac tissue in primary culture. Adult Wistar-Kyoto rat hearts were minced, digested and cultured as separate anatomical regions. Loosely-adherent cells that surround the plated tissue were harvested weekly for a total of five harvests. Genetic lineage tracing demonstrated that a small proportion of the direct outgrowth from cardiac samples originates from myocardial cells. This outgrowth contains sub-populations of cells expressing embryonic (SSEA-1) and stem cell-related antigens (c-Kit, abcg2) that varied with time in culture but not with the cardiac chamber of origin. This direct outgrowth, and its expanded progeny, underwent marked in vitro angiogenic/cardiogenic differentiation and cytokine secretion (IGF-1, VGEF). In vivo effects included long-term functional benefits as gauged by MRI following cell injection in a rat model of myocardial infarction. Outgrowth cells afforded equivalent functional benefits to cardiosphere-derived cells, which require more processing steps to manufacture. These results provide the basis for a simplified and efficient process to generate autologous cardiac progenitor cells (and mesenchymal supporting cells) to augment clinically-relevant approaches for myocardial repair.     

Cotransplantation with specific populations of spina bifida bone marrow stem/progenitor cells enhances urinary bladder regeneration

Spina bifida (SB) patients afflicted with myelomeningocele typically possess a neurogenic urinary bladder and exhibit varying degrees of bladder dysfunction. Although surgical intervention in the form of enterocystoplasty is the current standard of care in which to remedy the neurogenic bladder, it is still a stop-gap measure and is associated with many complications due to the use of bowel as a source of replacement tissue. Contemporary bladder tissue engineering strategies lack the ability to reform bladder smooth muscle, vasculature, and promote peripheral nerve tissue growth when using autologous populations of cells. Within the context of this study, we demonstrate the role of two specific populations of bone marrow (BM) stem/progenitor cells used in combination with a synthetic elastomeric scaffold that provides a unique and alternative means to current bladder regeneration approaches. In vitro differentiation, gene expression, and proliferation are similar among donor mesenchymal stem cells (MSCs), whereas poly(1,8-octanediol-cocitrate) scaffolds seeded with SB BM MSCs perform analogously to control counterparts with regard to bladder smooth muscle wall formation in vivo. SB CD34⁺ hematopoietic stem/progenitor cells cotransplanted with donor-matched MSCs cause a dramatic increase in tissue vascularization as well as an induction of peripheral nerve growth in grafted areas compared with samples not seeded with hematopoietic stem/progenitor cells. Finally, MSC/CD34⁺ grafts provided the impetus for rapid urothelium regeneration. Data suggest that autologous BM stem/progenitor cells may be used as alternate, nonpathogenic cell sources for SB patient-specific bladder tissue regeneration in lieu of current enterocystoplasty procedures and have implications for other bladder regenerative therapies.