肌源干细胞可塑性研究进展

目前已证实肌肉中至少存在两种干细胞:肌卫星细胞和肌源干细胞。肌源干细胞被认为是卫星细胞的前体细胞,具有较高的增殖能力、更好的细胞生存能力和更宽的分化能力。肌源干细胞不仅能够分化成血、肌肉、脂肪、骨、软骨、内皮等中胚层细胞,而且也能打破胚层限制分化成外胚层和内胚层细胞。文章对肌源干细胞的分离纯化、鉴定、可塑性及临床应用做一综述。     

从人胚胎干细胞畸胎瘤中有效获取间充质干细胞和神经前体细胞

通过人胚胎干细胞(human embryonic stem cells,hESC)体外分化方法和畸胎瘤形成可以分化获得多种成体细胞．但目前尚不清楚是否可以从hESCs畸胎瘤中分离某些特异性细胞．通过体外筛选方法,有效地从hESCs畸胎瘤中分离出神经前体细胞(neural progenitor cells,NPCs)和间充质干细胞(mesenchymal stem cells,MSCs)．这种hESCs畸胎瘤来源的NPCs和MSCs与体内神经前体细胞和间充质干细胞有着相似的分子标记和特性,并具有进一步的分化潜能——分别可以诱导成为神经元、神经胶质细胞、脂肪细胞和骨骼细胞等．根据人胚胎干细胞畸胎瘤中含有不同分化阶段的外胚层、中胚层和内胚层的组织或细胞,认为人胚胎干细胞畸胎瘤可以作为另一个细胞来源以获取多种(包括人胚胎干细胞体外分化难以得到的)各种前体/干细胞和终末分化细胞．     

成体干细胞在泌尿系统疾病修复与重建中的应用

干细胞是目前生命科学研究的热点方向。干细胞具有自我更新及定向分化的潜在能力。近年来,干细胞移植治疗在治疗压力性尿失禁和膀胱损伤方面已成为研究重点,不同来源的干细胞在治疗膀胱损伤已取得瞩目的研究成果。干细胞对阴茎勃起神经和海绵体血管内皮细胞起着修复保护作用。干细胞具有向多种谱系细胞转化的能力来治疗压力性尿失禁。干细胞移植为泌尿系统的神经肌肉疾病的修复重建提供了一条新途径,使认为不可修复的的神经肌肉疾病的结构修复和组织重建成为可能。干细胞包括脂肪干细胞(adipose-derived stem cells,ADSCs)、骨髓间充质干细胞(bone narrow mesenchymal stem,BMSCs)和肌源性干细胞(muscle-derived stem cell,MDSCs)等。组织工程学是一类交叉学科,主要包括综合细胞培养、材料构建和细胞种植等。组织工程技术为泌尿外科临床医师提供了一条修复乃至重建受损脏器的新思路。本文就利用干细胞作为种子细胞,对膀胱缺损、压力性尿失禁、勃起功能障碍泌尿系疾病的组织工程修复进行综述。     

miR-221在肝癌干细胞亚群中的差异表达

目的：分离肝癌细胞系MHCC97中肝癌干细胞并分析肝癌细胞高表达miR-221在肝癌干细胞和非干细胞亚群中的表达差异情况,探讨miR-221表达水平与肝癌干细胞分化之间的关系。方法：利用流式细胞荧光激活分选法从肝癌细胞系MHCC97中分选出肝癌干细胞（hepatocareinoma stem cells,HSCs）和非干细胞（non-hepatocareinoma stem cells,non-HSCs）两个亚群。采用实时荧光定量RT-PCR（Real-time RT-PCR）检测miR-221在两个不同肝癌细胞亚群中的表达。结果：HSC亚群肝癌细胞仅占细胞总体的2.59%;HSC亚群细胞中miR-221的表达明显高于non-HSC亚群（P〈0.01）。结论：miR-221在HSC亚群肝癌细胞中的明显高表达,提示miR-221可能在维持HSC亚群肝癌细胞的干细胞特性方面具有重要意义。通过调控肝癌干细胞中miR-221的表达,可以促进其分化成熟,从而为肝癌治疗提供新的思路。     

胃癌干细胞研究进展

胃癌是仅次于肺癌的第二大致死率癌症,尽管近年来对胃癌研究有了很大进展,但由于缺乏良好的动物模型,对胃癌的发病机理仍然不是很清楚.近年的研究表明,肿瘤组织不是由均一细胞构成的,其中存在一些少量细胞可以自我更新并可以分化为肿瘤组织的其他细胞,这类细胞具有类似成体组织干细胞（tissue stem cells）的特性称之为肿瘤干细胞（cancer stem cells）.肿瘤干细胞被认为在肿瘤的生长、转移、复发中发挥着重要作用.有证据表明在胃癌组织中存在胃癌干细胞（gastric cancer stem cells）,但是对胃癌干细胞的来源仍然不是十分明确.对肿瘤干细胞的研究有助于癌症的治疗,改变目前药物针对所有癌细胞的治疗策略.     

胎儿肺组织来源间充质干细胞的分离、培养、鉴定及重编程初探

该文主要研究将进行胎儿肺部组织来源的间充质干细胞（mesenchymal stem cells derived from fetal lung,FL-MSCs）转变成为诱导多能干细胞（induced pluripotent stem cells,iPS细胞）。首先使用酶消化法对胎儿肺部组织进行分离,然后采用常规方法进行培养并成功获得成纤维细胞样细胞。使用共聚焦技术检测获得的细胞,发现角蛋白表达呈阴性;共聚焦技术检测c-Myc、Oct4、Nanog以及Nestin四个干性相关因子,发现它们呈阳性;检测成纤维细胞样细胞的免疫表型,符合间充质干细胞的表型判断标准;然后进行诱导分化实验,发现这些细胞可以向成脂、成骨细胞分化,经过以上实验鉴定获得的成纤维细胞为FL-MSCs。使用Yamanaka四因子体系对FL-MSCs进行诱导,可以形成类似人胚胎干细胞（human embryonic stem cells,hES细胞）的克隆,采用核型分析、STR检测分析以及畸胎瘤形成实验初步验证获得的克隆为iPS。     

胚胎干细胞及诱导多能干细胞向心肌细胞分化和调控的研究进展

胚胎干细胞（embryonic stem cells,ESCs）具有自我更新、无限增殖和多向分化的特性,包括分化成心脏组织的多种类型细胞。经体细胞重编程产生的诱导多能干细胞（induced pluripotent stem cells,iPS）也被证明有类似胚胎干细胞的特性。但这些多能干细胞向心肌细胞自发分化的效率非常低,因此,如何有效地诱导这些多能干细胞向心肌细胞的定向分化对深入认识心肌发生发育的关键调控机制和实现其在药物发现和再生医学,如心肌梗塞、心力衰竭的细胞治疗以及心肌组织工程中的应用均具有非常重要的意义。该文重点综述了近年来胚胎干细胞及诱导多能干细胞向心肌细胞分化和调控的研究进展,并探讨了这一研究领域亟待解决的关键问题和这些多能干细胞的应用前景。     

猪多能干细胞的研究进展

多能干细胞,如胚胎干细胞（embryonic stem cells,ESCs）、诱导多能干细胞（induced pluripotent stem cells,iPSCs）和成体干细胞（adultstemcells,ASCs）,是一类具有巨大潜能的独特细胞。猪作为试验材料,在遗传、代谢、生理生化及基因序列等方面较小鼠更接近于人类,正逐渐成为人类异种移植和再生医学研究的理想生物学模型。然而,目前对猪多能干细胞种类、来源、特征及机制的有限认识直接阻碍了其相关应用。该文将分别对猪ASCs的研究现状、猪类ESCs的分离培养、猪iPSCs的研究进展、多能干细胞间的联系和展望进行论述,以期为从事该领域研究的科研人员提供参考。     

大鼠应激耐受多系分化细胞的分离、扩增改良技术

目的 探讨体外从大鼠骨髓间充质干细胞（BMSCs）中分离应激耐受多系分化细胞（Muse cells）及其扩增培养的技术方法.方法 分离、扩增、鉴定BMSCs,应用长时间应激方法酶消化分离Muse细胞,悬浮扩增培养4d后Western blot鉴定特异性抗原.结果 第3代生长良好的BMSCs中表达CD29、CD90而不表达CD45的占细胞总数的97.89%.长时间酶消化结合悬浮培养后,以酶消化8h组细胞表达CD105显著高于其余各组（P〈0.05）,符合Muse细胞特征.结论 Muse细胞可由BMSCs经消化分离扩增获得,可望为其进一步研究应用奠定基础.     

胎牛雄性生殖干细胞源类ES细胞的分离培养与多能性研究

雄性生殖干细胞（male germ stem cells, mGSCs）来源于原始生殖细胞(primordial germ cells, PGCs),且终生存在于性分化后的睾丸中。从20周胎牛分离睾丸细胞,2步连续贴壁速率差法能有效纯化胎牛mGSCs,经流式细胞仪检测,CD9阳性细胞的比例达到 95.8%。原代与支持细胞共培养,出现隆突状和鸟巢状两种细胞集落。获得1株传至4代仍呈现集落生长的细胞株,且集落AKP染色阳性。对第3代鸟巢状细胞集落免疫组化和诱导分化分析,结果显示：SSEA1和Oct-4免疫组化染色阳性;短期内可自发形成c-kit染色阳性的分化态精原细胞;定向诱导分化形成了表达神经丝蛋白(Neuro filament,NF)的神经样细胞和表达α-actin的心肌样细胞团。试验结果表明：20周胎牛雄性生殖干细胞在体外可形成具有多分化潜能性的类胚胎干（embryonic stem, ES）细胞。     

Aging induced loss of stemness with concomitant gain of myogenic properties of a pure population of CD34+/CD45− muscle derived stem cells

Aging is accompanied by the functional decline of cells, tissues, and organs, as well as, a striking increase in susceptibility to a wide range of diseases. Within a tissue, both differentiated cells and adult stem cells are susceptible to intrinsic and extrinsic changes while aging. Muscle derived stem cells (MDSCs) are tissue specific stem cells which have been studied well for their multipotential nature. Although there are reports relating to diminished function and regenerative capacity of aged MDSCs as compared to their young counterparts, not much has been reported relating to the concomitant gain in unipotent nature of aged MDSCs. In this study, we report an inverse correlation between aging and expression of adult/mesenchymal stem cell markers and a direct correlation between aging and myogenecity in MDSCs. Aged MDSCs were able to generate a greater number of dystrophin positive myofibres, as compared to, the young MDSCs when transplanted in muscle of dystrophic mice. Our data, therefore, suggests that aging stress adds to the decline in stem cell characteristics with a concomitant increase in unipotency, in terms of, myogenecity of MDSCs. This study, hence, also opens the possibilities of using unipotent aged MDSCs as potential candidates for transplantation in patients with muscular dystrophies.     

Histological changes induced by Polyglycolic-Acid (PGA) scaffolds seeded with autologous adipose or muscle-derived stem cells when implanted on rabbit bladder

Purpose: To evaluate the morphological and histological changes induced by PGA scaffold seeded with autologous adipose or muscle derived stem cells implanted on rabbit bladder wall. Material and Methods: Adipose derived stem cells (ADSCs) were obtained from the inguinal fat of eight rabbits and muscle derived stem cells (MDSCs) from the anterior tibial muscle of other eight rabbits. After culture and isolation, the cells were stained with Vybrant Red CM DiI and then implanted at third passage. Two PGA scaffolds were implanted on the bladder submucosa of each animal. On the right bladder side was implanted unseeded PGA scaffold while on the left side was implanted ADSCs or skeletal MDSCs seeded PGA scaffold. ADSCs were implanted in eight animals and MDSC in other eight animals. The animals were sacrificed at four and eight weeks. Histological evaluation was performed with Hematoxylin and Eosin, Masson's Trichrome and smooth muscle α-actin. Results: We observed a mild inflammatory response in all the three groups. Seeded scaffolds induced higher lymphocytes and lower polimorphonuclear migration than controls. Fibrosis was more pronounced in the control groups. Smooth muscle α-actin was positive only in ADSC and MDSC seeded scaffolds. At four and eight weeks ADCSs and skeletal MDSCs labeled cells were found at the implant sites. Conclusions: The implantation of PGA scaffolds seeded with ADSC and MDSC induced less fibrosis than control and smooth muscle regeneration.     

Histological changes induced by Polyglycolic-Acid (PGA) scaffolds seeded with autologous adipose or muscle-derived stem cells when implanted on rabbit bladder

Purpose: To evaluate the morphological and histological changes induced by PGA scaffold seeded with autologous adipose or muscle derived stem cells implanted on rabbit bladder wall. Material and Methods: Adipose derived stem cells (ADSCs) were obtained from the inguinal fat of eight rabbits and muscle derived stem cells (MDSCs) from the anterior tibial muscle of other eight rabbits. After culture and isolation, the cells were stained with Vybrant Red CM DiI and then implanted at third passage. Two PGA scaffolds were implanted on the bladder submucosa of each animal. On the right bladder side was implanted unseeded PGA scaffold while on the left side was implanted ADSCs or skeletal MDSCs seeded PGA scaffold. ADSCs were implanted in eight animals and MDSC in other eight animals. The animals were sacrificed at four and eight weeks. Histological evaluation was performed with Hematoxylin and Eosin, Masson's Trichrome and smooth muscle α-actin. Results: We observed a mild inflammatory response in all the three groups. Seeded scaffolds induced higher lymphocytes and lower polimorphonuclear migration than controls. Fibrosis was more pronounced in the control groups. Smooth muscle α-actin was positive only in ADSC and MDSC seeded scaffolds. At four and eight weeks ADCSs and skeletal MDSCs labeled cells were found at the implant sites. Conclusions: The implantation of PGA scaffolds seeded with ADSC and MDSC induced less fibrosis than control and smooth muscle regeneration.     

Liver transplantation of hepatic stem cells: potential use for treating liver diseases

Hepatic stem cells are an alternative means for repopulating the liver after various injuries instead of liver transplantation. The first step before use is to select stem cells that will be good candidates. This review discusses the different candidates including fetal progenitor bipotential hepatic stem cells; adult hepatocytes, which can be considered as unipotential committed stem cells; and oval cells, a type of nonparenchymal pluripotential hepatic stem cell. The advantages and disadvantages of each type of cell are discussed and several other possible alternatives, such as the use of hematopoietic stem cells are analyzed. This revised version was published online in July 2006 with corrections to the Cover Date.     

Isolation and passage of muscle-derived stem cells from the rat penile corpora cavernosa and induction of differentiation into smooth muscle cells

This study treated the isolation and passage of muscle-derived stem cells (MDSCs) from rat penile corpora cavernosa, detection of stem cell marker expression, observation of their self-renewal and continuous proliferation, and demonstration of their potential to differentiate into smooth muscle cells in co-culture. Muscle-derived stem cells from the rat penile corpora cavernosa were isolated and purified. The expression of stem cell markers Sca-1 and desmin was detected in PP6 cells, thus confirming that the main components of PP6 cells are MDSCs. The expression of Sca-1 and desmin occurred both in PP6 cells and cells at passages 3, 6, and 8, and there was no significant decrease in the expression level with increasing passage number. The growth curves indicated that the cell doubling time was approximately 48 h. The cells entered the stationary phase after approximately 7 days of culture. The proliferative activity of the cells at passage 8 remained unchanged. After 2 days of co-culture with smooth muscle cells, the DAPI-labeled MDSCs tended to exhibit smooth muscle cell morphology and expression of α-SMA was detected. MDSCs exist in the rat penile corpora cavernosa and possess the potential to differentiate into smooth muscle cells. This discovery serves as the basis in view of the potential use of endogenous stem cells for the treatment of erectile dysfunction (ED).     

Tissue engineering with muscle-derived stem cells

Tissue engineering and cell therapy approaches aim to take advantage of the repopulating ability and plasticity of multipotent stem cells to regenerate lost or diseased tissue. Researchers continue to investigate stem cells in mature tissues and demonstrate the potential ability of organ-specific cells to differentiate into multiple lineages. One stem cell that displays such promise is the muscle-derived stem cell (MDSC). Data supporting the existence of MDSCs have emerged as part of investigations to improve myoblast cell transplantation for the treatment of muscular dystrophies. As these efforts continue, the potential for MDSC-based therapy for other musculoskeletal injuries, as well as for cardiac and smooth muscle injuries, is currently being explored.     

Vascular wall resident progenitor cells: A review

The vessel wall has usually been thought to be relatively quiescent. But the discovery of progenitor cells in many tissues and in the vasculature itself has led to a reconsideration of the vascular biology. The presence of circulating endothelial and smooth muscle progenitors able to home to the injured vascular wall is a firm acquisition; less known is the notion, coming from embryonic and adult tissue studies, that stem cells able to differentiate into endothelial cells and smooth muscle cells also reside in the arterial wall. Moreover, the existence of a vasculogenic zone has recently been identified in adult human arteries; this niche-like zone is believed to act as a source of progenitors for postnatal vasculogenesis. From the literature it is already apparent that a complex interplay between circulating and resident vascular wall progenitors takes place during embryonal and postnatal life; a structural/functional disarray of these intimate stem cell compartments could hamper appropriate vascular repair, the development of vascular wall disease being the direct clinical consequence in adult life. This review gives an overview of adult large vessel progenitors established in the vascular wall during embryogenesis and their role in the maintenance of wall homeostasis.     

Identification of a putative pathway for the muscle homing of stem cells in a muscular dystrophy model

Attempts to repair muscle damage in Duchenne muscular dystrophy (DMD) by transplanting skeletal myoblasts directly into muscles are faced with the problem of the limited migration of these cells in the muscles. The delivery of myogenic stem cells to the sites of muscle lesions via the systemic circulation is a potential alternative approach to treat this disease. Muscle-derived stem cells (MDSCs) were obtained by a MACS(R) multisort method. Clones of MDSCs, which were Sca-1+/CD34-/L-selectin+, were found to adhere firmly to the endothelium of mdx dystrophic muscles after i.v. or i.m. injections. The subpopulation of Sca-1+/CD34- MDSCs expressing L-selectin was called homing MDSCs (HMDSCs). Treatment of HMDSCs with antibodies against L-selectin prevented adhesion to the muscle endothelium. Importantly, we found that vascular endothelium from striate muscle of young mdx mice expresses mucosal addressin cell adhesion molecule-1 (MAdCAM-1), a ligand for L-selectin. Our results showed for the first time that the expression of the adhesion molecule L-selectin is important for muscle homing of MDSCs. This discovery will aid in the improvement of a potential therapy for muscular dystrophy based on the systemic delivery of MDSCs.     

成体干细胞的生物学特点及应用前景

成体干细胞存在于人和哺乳动物组织中,具有自我更新和一定的分化潜能,现已从骨髓,软骨,血液,神经,肌肉,脂肪,皮肤,角膜缘,肝脏,胰腺等许多组织中获得成体干细胞,发现部分组织成体干细胞具有多向分化潜能,成体干细胞的研究在再生医学中有十分广阔的应用前景。