Adipose-derived stem cells for the regeneration of damaged tissues

As the promise of stem cell-based therapies begins to be realised, and efforts to bring advances to the clinic mount, the source of these cells is increasingly important. The morbidity associated with harvesting stem cells from solid organs and the invasive nature of bone marrow biopsies may limit their practicality for wider clinical applications. An emerging body of literature suggests that adipose tissue may provide an abundant, readily accessible source of cells with similar potential to that described of other adult stem cells. This review will address advances in the use of adipose stem cells in fields as divergent as soft tissue reconstruction and cerebral infarction recovery. Numerous challenges will also be discussed; however, rapidly accumulating advances suggest that adipose stem cells may be as effective as they are abundant.     

Adult stem cells and heart regeneration

Cardiovascular disease remains the single greatest cause of death in the Western world, claiming more lives in the USA than the next four leading causes combined. Among these diseases, the incidence of heart failure continues to rise at a staggering rate. Recent advances in medical and device therapies have dramatically improved both the survival and quality of life of many of these patients; however, limited strategies are available to address the central pathophysiology underlying the development of heart failure, namely, the loss of functional cardiomyocytes. Therefore, one recent strategy has been the development of cell-based therapies, aiming towards the replacment of injured or lost cardiomyocytes and thereby improved cardiac function. In this review, we will examine the cell types undergoing investigation as potential cell-based therapies and provide an overview of current clinical trials utilizing cell-based therapeutic approaches in patients with heart disease.     

Progenitor and stem cells for bone and cartilage regeneration

Research in regenerative medicine is developing at a significantly quick pace. Cell‐based bone and cartilage replacement is an evolving therapy aiming at the treatment of patients who suffer from limb amputation, damaged tissues and various bone and cartilage‐related disorders. Stem cells are undifferentiated cells with the capability to regenerate into one or more committed cell lineages. Stem cells isolated from multiple sources have been finding widespread use to advance the field of tissue repair. The present review gives a comprehensive overview of the developments in stem cells originating from different tissues and suggests future prospects for functional bone and cartilage tissue regeneration. Copyright © 2009 John Wiley & Sons, Ltd.     

Epigenetic approaches to regeneration of bone and cartilage from stem cells

Introduction: Embryonic stem cells (ESCs) or adult stem cells, especially mesenchymal stem cells (MSCs), have been intensively studied for skeletal tissue regeneration including bone and cartilage. Epigenetic mechanisms play essential roles in stem cell maintenance and differentiation. However, little is known about the epigenetic regulation of osteogenesis and chondrogenesis of stem cells.

Areas covered: In this review, features of ESCs and adult stem cells, epigenetics and chromatin structure, as well as epigenetic mechanisms, such as chromatin remodeling, DNA methylation and histone modifications, polycomb group (PcG) proteins and microRNAs are described. Epigenetic researches of stem cell are introduced.

Expert opinion: Epigenetic alterations of stem cell during the in vitro differentiation can be controlled for clinical applications. MSCs are effective resources for skeletal tissue regeneration in both undifferentiated and differentiated states. Understanding epigenetic signatures of MSC is crucial to maintain the stemness. In addition, investigation of epigenetic changes in the differentiation of MSCs is very important to develop methods or chemicals to promote efficient differentiation of MSCs. Inhibition of PcG protein enhancer of zeste (Ezh2) a chromatin modifier, could be a promising candidate to improve MSC differentiation by decreasing Ezh2-mediated H3K27me3.     

大鼠骨髓间充质干细胞重建表皮细胞及皮肤附件简

背景：研究报道用烧伤大鼠血清作为诱导剂可以诱导间充质干细胞分化为表皮细胞。目的：体外诱导骨髓间充质干细胞分化为表皮细胞,单独或与必要的诱导剂组合移植修复皮肤创面缺损与重建表皮。方法：无菌环境取大鼠骨髓,选取贴壁细胞用L-DMEM培养液培养至第4代,通过流式细胞术鉴定骨髓间充质干细胞。用含20%烧伤大鼠血清 DMEM-F12培养液诱导骨髓间充质干细胞分化成表皮细胞,通过免疫组织化学鉴定。将Wistar大鼠制造全层皮肤缺损创面,分为3组,将BrdU标记的自体骨髓间充质干细胞及含有经诱导的骨髓间充质干细胞分别单次涂布到烧伤大鼠模型创面上,以未移植骨髓间充质干细胞做对照,观察再生皮肤创面收缩率及表皮层细胞与皮肤附件再生情况。结果与结论：分离、培养的骨髓间充质干细胞24 h后少部分细胞贴壁生长,形态长梭形,类似成纤维细胞,16 d时细胞贴满瓶底,呈鱼群样或网状排列,经流式细胞仪鉴定后加入20%烧伤大鼠血清的DMEM F-12培养基继续培养,细胞形态渐变为圆形或椭圆形细胞,经免疫组织细胞化学法和流式细胞术分析细胞角蛋白表达阳性,证实已分化为表皮细胞。动物实验结果表明无论是骨髓间充质干细胞单独移植还是与必要的诱导剂组合移植其皮肤的修复与再生情况均超过大鼠皮肤自然愈合,且不仅皮肤再生快,而且皮肤附件如毛囊等的再生也比对照组明显改善。初步推断间充质干细胞参与了表皮和皮肤附件毛囊的重建,从而改善皮肤愈合方式。     

Adipose-derived stem cell therapies for bone regeneration

Introduction: Cell-based therapies exploit the heterogeneous and self-sufficient biological environment of stem cells to restore, maintain and improve tissue functions. Adipose-derived stem cells (ASCs) are, to this aim, promising cell types thanks to advantageous isolation procedures, growth kinetics, plasticity and trophic properties. Specifically, bone regeneration represents a suitable, though often challenging, target setting to test and apply ASC-based therapeutic strategies.

Areas covered: ASCs are extremely plastic and secrete bioactive peptides that mediate paracrine functions, mediating their trophic actions in vivo. Numerous preclinical studies demonstrated that ASCs improve bone healing. Clinical trials are ongoing to validate the clinical feasibility of these approaches. This review is intended to define the state-of-the-art on ASCs, encompassing the biological features that make them suitable for bone regenerative strategies, and to provide an update on existing preclinical and clinical applications.

Expert opinion: ASCs offer numerous advantages over other stem cells in terms of feasibility of clinical translation. Data obtained from in vivo experimentation are encouraging, and clinical trials are ongoing. More robust validations are thus expected to be achieved during the next few years, and will likely pave the way to optimized patient-tailored treatments for bone regeneration.     

Stem cells for tendon tissue engineering and regeneration

Importance of the field: Tendon injuries are common especially in sports activities, but tendon is a unique connective tissue with poor self-repair capability. With advances in stem cell biology, tissue engineering is becoming increasingly powerful for tissue regeneration. Stem cells with capacity of multipotency and self-renewal are an ideal cell source for tissue engineering.

Areas covered in this review: This review focus on discussing the potential strategies including inductive growth factors, bio-scaffolds, mechanical stimulation, genetic modification and co-culture techniques to direct tendon-lineage differentiation of stem cells for complete tendon regeneration. Attempting to use embryonic stem cells as seed cells for tendon tissue engineering have achieved encouraging results. The combination of chemical and physical signals in stem cell microenvironment could be regulated to induce differentiation of the embryonic stem cells into tendon.

What the reader will gain: We summarize fundamental questions, as well as future directions in tendon biology and tissue engineering.

Take home message: Multifaceted technologies are increasingly required to control stem cell differentiation, to develop novel stem cell-based therapy, and, ultimately, to achieve more effective repair or regeneration of injured tendons.     

关于簇蛋白（clusterin）和前列腺干细胞功能的关系研究

目的 明确簇蛋白（elusterin）和前列腺干细胞功能的关系。方法 取10只实验犬，分别于去势前及去势后近期（〈15d）、占势后远期（〉15d）取前列腺组织制成石蜡切片。通过双标免疫组化检测前列腺组织中clusterin的表达及其表达部位。结果 去势前后clusterin在前列腺基底细胞中的表达没有显著性的差异。结论 Clustenri在前列腺基底细胞中不存在表达。     

Dental stem cells in tooth regeneration and repair in the future

Introduction: Human dental stem cells can be obtained from postnatal teeth, extracted wisdom teeth or exfoliated deciduous teeth. Due to their differentiation potential, these mesenchymal stem cells are promising for tooth repair. Therefore, the development of dental tissue regeneration represents a suitable but challenging, target for dental stem cell therapies.

Areas covered: In this review, the authors provide an overview of human dental stem cells and their properties for regeneration medicine. Numerous preclinical studies have shown that dental stem cells improve bone augmentation and healing of periodontal diseases. Clinical trials are ongoing to validate the clinical feasibility of these approaches. Dental stem cells are also important for basic research.

Expert opinion: Dental stem cells offer numerous advantages for tooth repair and regeneration. Data obtained from different studies are encouraging. In the next few years, investigations on dental stem cells in basic research, pre-clinical research and clinical studies will pave the way to optimizing patient-tailored treatments for repair and regeneration of dental tissues.     

骨髓间充质干细胞促进胰岛再生的作用与研究现状

背景：研究发现,骨髓间充质干细胞移植入糖尿病大鼠后能够降低其血糖。目的：综述骨髓间充质干细胞在促进胰岛再生方面的作用与研究现状。方法：应用计算机检索2003年7月至2011年12月PubMed数据库相关文章,检索词为＂bone marrow derive mesenchymal stem cell,islet cells＂,并限定文章语言种类为English。同时计算机检索2003年7月至2011年12月万方数据库相关文章,检索词为＂骨髓间充质干细胞,胰岛细胞＂,并限定文章语言种类为中文。最终纳入符合标准的文献25篇。结果与结论：目前,移植胰岛治疗糖尿病已取得良好疗效,但由于胰岛来源匮乏和异种或异体来源的胰岛引起免疫排斥反应而难以使众多糖尿患者受益。骨髓间充质干细胞取材方便,容易进行体外分离、培养和纯化,且具有多向分化潜能。若将骨髓间充质干细胞诱导分化为胰岛细胞,可望解决胰岛细胞来源和免疫排斥问题。文章对骨髓间充质干细胞分化为胰岛细胞治疗糖尿病的研究进展进行综述,并指出了存在问题和今后的研究方向。     

Advances in stem cell therapy for cartilage regeneration in osteoarthritis

Introduction: Osteoarthritis (OA) is a progressive joint disease that compromises the structural integrity of cartilage tissue. Conventional treatments based on medication or surgery are nowadays inefficient and cell-based therapy has emerged as one of the most promising methods for cartilage regeneration. The first therapy developed for cartilage defects was autologous chondrocyte implantation, but in the last few decades stem cells (SCs) from different sources have been proposed as a possible alternative for OA.

Areas covered: SC sources and available delivery procedures (scaffolds/hydrogels) are presented, along with the main issues arisen in this regard. Thereafter, preclinical and clinical trials performed in recent years are reviewed in order to take a glance toward the potential benefits that such therapies could deliver to the patients.

Expert opinion: SCs have proven their potential and safety for OA treatment. Nevertheless, there are still many questions to be resolved before their widespread used in clinical practice, such as the treatment mechanism, the best cell source, the most appropriate processing method, the most effective dose and delivery procedure, and their efficacy. In this sense, long-term follow-up and larger randomized controlled trials utilizing standardized and established outcome scores are mandatory to make objective conclusions.     

骨髓间充质干细胞对急性百草枯中毒肺损伤的保护作用

目的:通过骨髓间充质干细胞(BMSCs)的植入,观察其对急性百草枯(paraqua)中毒肺损伤的保护效果.方法:54只雌性受体大鼠随机分4组:百草枯组、BMSCs治疗组、BMSCs对照组和正常对照组,将体外分离和培养的BMSCs通过尾静脉注入受体体内,观察14 d内各组大鼠的存活率、肺干湿比、血浆中IL-1β、TNF-α、MDA、SOD、GSH- PX的水平变化.结果:与百草枯组相比,BMSCs治疗组明显延长大鼠的生存期,降低肺干湿比(P ＜ 0.05)和炎症介质IL-1β、TNF-α的含量(P ＜ 0.01),降低血浆中MDA的水平(P ＜ 0.05)和升高SOD、GSH- PX的水平(P ＜ 0.01).结论: BMSCs对急性百草枯中毒肺损伤具有保护作用.     

Microencapsulated rabbit adipose stem cells initiate tissue regeneration in a rabbit ear defect model

Cell‐based tissue engineering can promote cartilage tissue regeneration, but cell retention in the implant site post‐delivery is problematic. Alginate microbeads containing adipose stem cells (ASCs) pretreated with chondrogenic media have been used successfully to regenerate hyaline cartilage in critical size defects in rat xiphoid suggesting that they may be used to treat defects in elastic cartilages such as the ear. To test this, we used microbeads made with low viscosity, high mannuronate medical grade alginate using a high electrostatic potential, and a calcium cross linking solution containing glucose. Microbeads containing rabbit ASCs (rbASCs) were implanted bilaterally in 3 mm critical size midcartilage ear defects of six skeletally mature male New Zealand White rabbits (empty defect; microbeads without cells; microbeads with cells; degradable microbeads with cells; and autograft). Twelve weeks post‐implantation, regeneration was assessed by microCT and histology. Microencapsulated rbASCs cultured in chondrogenic media expressed mRNAs for aggrecan, Type II collagen, and Type X collagen. Histologically, empty defects contained fibrous tissue; microbeads without cells were still present in defects and were surrounded by fibrous tissue; nondegradable beads with rbASCs initiated cartilage regeneration; degradable microbeads with cells produced immature bone‐like tissue, also demonstrated by microCT; and autografts appeared as normal auricular cartilage but were not fully integrated with the tissue surrounding the defect. Elastin, the hallmark of auricular cartilage, was not evident in the neocartilage. This delivery system offers the potential for regeneration of auricular cartilage, but vascularity of the treatment site and use of factors that induce elastin must be considered.     

肺癌干细胞与肺癌的发生

背景：肺癌具有高度异质性,能够抵抗化疗药物治疗,5年生存率小于15%,目前难以确定肺癌的异质性和耐药性的发病基础。肿瘤干细胞模型近年来吸引了相当多的关注,通过这种模型可以解释各种肿瘤的异质性、耐药性、休眠、复发和转移的机制。目的：通过综述各类肺癌的组织学类型和肿瘤生长部位的特征,概括肺癌干细胞与各种肺癌发生的关系,从而为消灭肺癌干细胞攻克肺癌提供理论依据。方法：以英文检索词为“lung cancer,cancer stem cel ,lung cancer stem cel ,lung cancer occur,tumor heterogeneity, drug resistance,gene mutation,signal pathways”由第一作者检索1990至2014年Sciencedirect/PubMed 数据库,查阅近年肺癌干细胞对肺癌发生的影响的相关文献,最终保留48篇文献。结果与结论：肿瘤干细胞模型近年来吸引了相当多的关注,通过这种模型可以解释各种肿瘤的异质性、耐药性、休眠、复发和转移。肺癌干细胞被认为是一类异质的细胞群,多种信号通路可以有针对性的有效的消除他们,从而有助于增强治疗效果。目前多学科通力合作,正在进行肺癌干细胞表征和靶定,这将给肺癌治疗领域带来显著的治疗受益。     

角化细胞生长因子对骨髓间充质干细胞体外诱导分化为肺泡上皮细胞的实验研究

目的观察角化细胞生长因子(KGF)对体外小鼠骨髓间充质干细胞(MSCs)向肺泡上皮细胞诱导分化的影响。方法建立体外非接触共培养诱导小鼠MSCs向肺泡上皮细胞分化的实验模型,并在培养液中加入KGF(10μl/ml),小鼠分4组(6只/组),实验组A:MSCs(1×105)单独培养组+KGF;实验组B:MSCs+正常肺组织悬液(1×105)+KGF;实验组C:MSCs+损伤肺组织悬液+KGF;实验组D:MSCs+损伤肺组织悬液(1×105)。共同培养8 d,应用激光共聚焦显微镜和RT-PCR检测共培养体系下室MSCs中的SP-C和AQP5的表达情况。结果实验组C于共培养的d 8,较其它实验组的AQP5 mRNA的表达量明显增多(5550.00±244.39vs1650.17±184.02,1600.83±193.00,2890.00±179.09,P均<0.05);于共培养的d 5,与实验组A相比差异也有统计学意义(1743.17±228.41vs1482.00±156.11,P<0.05)。只有实验组C和D表达SP-C,且实验组C各培养时间点的SP-C的mRNA的表达量均较实验组D明显增多(2632.50±231.11vs1599.00±158.95;3976.67±221.81vs2066.83±101.31;5388.33±347.96vs3893.17±178.61,P均<0.01)。结论KGF可以进一步促进体外小鼠MSCs诱导分化为肺泡上皮细胞。     

Mesenchymal stem cells: Cell therapy and regeneration potential

Rapid advances in the isolation of multipotent progenitor cells, routinely called mesenchymal stromal/stem cells (MSCs), from various human tissues and organs have provided impetus to the field of cell therapy and regenerative medicine. The most widely studied sources of MSCs include bone marrow, adipose, muscle, peripheral blood, umbilical cord, placenta, fetal tissue, and amniotic fluid. According to the standard definition of MSCs, these clonal cells adhere to plastic, express cluster of differentiation (CD) markers such as CD73, CD90, and CD105 markers, and can differentiate into adipogenic, chondrogenic, and osteogenic lineages in vitro. However, isolated MSCs have been reported to vary in their potency and self‐renewal potential. As a result, the MSCs used for clinical applications often lead to variable or even conflicting results. The lack of uniform characterization methods both in vitro and in vivo also contributes to this confusion. Therefore, the name “MSCs” itself has been increasingly questioned lately. As the use of MSCs is expanding rapidly, there is an increasing need to understand the potential sources and specific potencies of MSCs. This review discusses and compares the characteristics of MSCs and suggests that the variations in their distinctive features are dependent on the source and method of isolation as well as epigenetic changes during maintenance and growth. We also discuss the potential opportunities and challenges of MSC research with the hope to stimulate their use for therapeutic and regenerative medicine.     

Stem cell therapy for cartilage regeneration in osteoarthritis

Enhancing the regeneration potential of hyaline cartilage tissue remains a great challenge. During embryonic development, some of the cells of the inner cell mass will turn into the mesoderm. This will be the founder of the mesenchymal cells in connective tissues of adult life, such as bone, tendon, muscle, and cartilage. Some of these embryonic mesenchymal cells are believed not to differentiate, but reside in each of the tissues. These are now collectively described as adult mesenchymal stem cells, which are thought to be capable of repairing injured tissue. We will briefly summarize the current knowledge about stem cell-related cells in cartilage tissue and carefully discuss the potential of the cell population we described recently as a starting-point for a regenerative therapy for osteoarthritis. We found that repair tissue from human articular cartilage during the late stages of osteoarthritis harbors a unique progenitor cell population, termed chondrogenic progenitor cells (CPC). These exhibit stem cell characteristics combined with a high chondrogenic potential. They offer new insights into the biology of progenitor cells and may be relevant in the development of novel therapeutic approaches for a cell-based therapy for late stages of osteoarthritis.     

Regenerating the kidney using human pluripotent stem cells and renal progenitors

Introduction: Chronic kidney disease is a major health-care problem worldwide and its cost is becoming no longer affordable. Indeed, restoring damaged renal structures or building a new kidney represents an ambitious and ideal alternative to renal replacement therapy. Streams of research have explored the possible application of pluripotent stem cells (SCs) (embryonic SCs and induced pluripotent SCs) in different strategies aimed at regenerate functioning nephrons and at understanding the mechanisms of kidney regeneration.

Areas covered: In this review, we will focus on the main potential applications of human pluripotent SCs to kidney regeneration, including those leading to rebuilding new kidneys or part of them (organoids, scaffolds, biological microdevices) as well as those aimed at understanding the pathophysiological mechanisms of renal disease and regenerative processes (modeling of kidney disease, genome editing). Moreover, we will discuss the role of endogenous renal progenitors cells in order to understand and promote kidney regeneration, as an attractive alternative to pluripotent SCs.

Expert opinion: Opportunities and pitfalls of all these strategies will be underlined, finally leading to the conclusion that a deeper knowledge of the biology of pluripotent SCs is mandatory, in order to allow us to hypothesize their clinical application.     

干细胞若干定义的相关探讨

背景：近10年来干细胞研究所取得的巨大进展,不仅影响和促进了生物学及其相关基础科学,而且还在医学、药物开发、农业等许多领域得到广泛的应用,目前已成为研究的热点问题。目的：在干细胞的定义上还存在一些需要探讨的问题,明确定义将有利于干细胞研究的快速发展。方法：回顾干细胞的发展和概念提出,特别是通过中英文权威定义的比较,提出作者的看法。结果与结论：干细胞的定义上还存在一些问题值得探讨,特别是一些中英文表述不同影响了理解。例如,“多能干细胞”对应译成两个单词：PluripotentStemCell和MultipotentStemCell,然而Pluripotent和Multipotent两个单词的英文意义不同。为了学术交流和沟通,作者提出将PluripotentStemCell称为“万能干细胞”,而保留MultipotentStemCell为“多能干细胞”的定义。以上结论供广大同仁探讨,以利于抛砖引玉。